Killing Drug-Resistant Melanoma Requires Combination Therapy

Killing Drug-Resistant Melanoma Requires Combination Therapy


The researchers see this as further evidence that some cancers must be treated with multiple targeted drugs at the outset of treatment. Their findings are published in the December 14 issue of the journal Cancer Cell.

"The evidence suggests that targeting mutant BRAF can kill cancer cells, but it is not enough by itself to finish off melanoma," said Meenhard Herlyn, D.V.M., D.Sc., director of The Wistar Institute Melanoma Research Center and leader of Wistar's Molecular and Cellular Oncogenesis program. "The good news is that drugs are being developed to work in combination with BRAF inhibitors, which our data clearly shows is our best option if we intend to beat advanced melanoma."

Melanoma is the deadliest, most aggressive form of skin cancer. While surgical treatment of early melanoma leads to 90 percent cure rates, advanced melanoma is notoriously resistant to chemotherapy and has a tendency to metastasize, or spread, throughout the body. According to the World Health Organization, cases of the disease continue to rise, which has helped spur research into therapies such as BRAF inhibitors.

To study how melanoma responds to BRAF inhibitors, the Herlyn lab took melanoma cells with the BRAF mutation and tested them against a variety of anti-mutant BRAF drugs. When exposed to the drugs, the cells died off dramatically only to grow back again. In fact, cells that became resistant to one type of BRAF drug became resistant to all of them, which suggests that the cells were biochemically "rewired" in such a way that they no longer needed BRAF to form tumors.

"Cells are complex machines that work, essentially, through chains of biochemical reactions that we refer to as signaling pathways," said Jessie Villanueva, Ph.D., senior author on the study and staff scientist in the Herlyn laboratory.

"Knocking out mutant BRAF shuts a major pathway down, but if some cells can use an alternate pathway, then they can survive."

To find out which alternate pathways the drug-resistant cells use, Villanueva and her colleagues looked for signs of increased activation among proteins along the pathways BRAF uses, as well as other pathways.

Their hunt turned up two paths that worked together to aid survival. First, they found that resistant cells used a protein similar to BRAF to carry the signal down the chain. Second, they found these cells received an additional boost from the IGF-1 receptor, a protein that sits on the surface of cells and sends signals that prevent cells from being killed. The resistant cells re-route the signal around BRAF by switching to an alternate protein (CRAF or ARAF), which promotes tumor cell growth, while IGF-1R signaling promotes survival of the resistant cells.

Fortunately, there are a number compounds in clinical development that could block signals along both these pathways. So-called MEK inhibitors target a protein along the same pathway as BRAF, and IGF-1 receptor inhibitors (and inhibitors of P13K, a protein that can be activated by the IGF-1 receptor pathway) block the cancer-enabling survival signal. To test these drug combinations in the BRAF-inhibitor resistant cells, the Herlyn laboratory used a tool they developed to simulate the real-world environment of human cells: 3-D melanoma tumor spheroids. Their 3-D tissue cultures allow melanoma cells to grow in all directions, much like a new melanoma tumor would grow after metastasis. As predicted, a combination of these two inhibitors killed BRAF-resistant melanoma cells in the Wistar 3-D model.

Moreover, the Herlyn laboratory confirmed in tissue samples from patients in the PLX4032 trial -- taken both before treatment and after they developed resistance -- that an increased expression of the IGF-1 receptor is associated with resistance to BRAF inhibitors. None of the laboratory-generated cell lines or the post-relapse patient's tumor samples analyzed had new mutations in the BRAF, NRAS, or c-Kit genes.

Additionally, the researchers noted an association between the loss of a tumor suppressor called PTEN, and resistance to BRAF inhibitors in melanoma cell lines. The scientists found that the relapsed tumor of one patient included in the study lost the PTEN gene, even though it was present before treatment. These findings suggest that loss of PTEN could be an additional way that melanoma cells gain resistance to BRAF inhibitors. The Wistar group continues to investigate these and other mechanisms of resistance, as they expect that several will likely arise given the heterogeneous nature of melanoma.

"Tumors are efficient engines of evolution -- they are going to find a way around most treatments, so we want to kill all the malignant cells from the very beginning," said Villanueva. "By targeting both pathways simultaneously you hit these cells with two punches from which they cannot recover."

"If you do this at the outset of treatment, we reason, it will prevent melanoma survival and hopefully improve patient outcomes," Villanueva added.

Support for this study was provided by grants from the National Cancer Institute and the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation.

Wistar co-authors in this study include Adina Vultur, Ph.D.; John T. Lee, Ph.D.; Rajasekharan Somasundaram, Ph.D.; Mizuho Fukunaga-Kalabis, M.D., Ph.D.; Angela K. Cipolla; James E. Hayden; and Ademi E. Santiago-Walker, Ph.D. University of Pennsylvania School of Medicine co-authors include Katherine L. Nathanson, M.D.; Xiaowei Xu, M.D., Ph.D.; Phyllis A. Gimotty, Ph.D.; Bradley Wubbenhorst; Richard Letrero; Kurt D'Andrea; and Anitha Pushparajan. Other authors included Grant A. McArthur, M.B., B.S., Ph.D.; and Damien Kee, MBBS, FRACP, of the Peter MacCallum Cancer Centre in Victoria, Australia; Jeffrey A. Sosman, M.D., and Kimberly Dahlman Brown of the Vanderbilt University Medical Center; and Sylvie Laquerre, Ph.D., of GlaxoSmithKline's division of Oncology Biology in Collegeville, Pa.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.


“It is not the strongest of the species that survives, nor the most intelligent, but the one most responsive to change.”

~Charles Darwin~
Take Care,
Jimmy B

Targeted therapy for metastatic melanoma: From bench to bedside..Jim Breitfeller

Targeted therapy for metastatic melanoma: From bench to bedside
Author: Wen-Jen Hwu, MD, PhD

Malignant melanoma is well known for its aggressive clinical behavior, propensity for lethal metastasis and therapeutic resistance. However, in the last decade, considerable excitement has been generated by the identification of genetic mutations in various components of signaling pathways involving melanoma initiation and progression, particularly those involved in the MAP and PI3 pathways. Most recently, clinical trials of pharmacological targeting of relevant molecular targets have demonstrated dramatic response even in patients with late-stage melanoma.

The emerging insights into the mechanisms of activation and negative regulation of innate and adaptive immunity to tumors have provided another breakthrough in melanoma therapy. A new family of immune-based agents of monoclonal antibodies that exert their functions by tampering with immune system cell molecules causing an enhancement of antitumor immune responses has entered clinical trials. In general, these new antitumor agents are designed to break down the barriers to tumor tolerance/immunity. This new group of agents holds promise for at least additive effects with conventional therapies, as well as signal transduction pathway targeted therapies.

Targeting signal transduction pathways

Several key genetic lesions governing melanoma initiation and progression have been identified, the earliest and most common being a point mutation (T1799A) in the BRAF proto-oncogene, which is detected in approximately 60% of metastatic melanoma. BRAFT1799A encodes BRAFV600E, a constitutively active protein serine kinase that elicits sustained activation of the BRAF® MEK1/2® ERK1/2 MAP kinase pathway.

In addition to BRAF, RAS oncogene (rat sarcoma viral oncogene homolog) is another constituent of the MAP kinase pathway. RAS mutations (in one of three isoforms) are found in approximately 20% of metastatic melanoma. RAS is capable of turning on several downstream pathways, including BRAF and other components of MAP kinase pathways, the PI3 kinase pathway, and the RAL-GDS pathway. In general, if a RAS mutation is present, there will be no BRAF mutation. However, the combination of mutated BRAF and silencing of PTEN expression is common in human melanoma (~20%). Dankort and colleagues have demonstrated in a preclinical model that “BRAFV600E cooperates with PTEN loss to induce metastatic melanoma.”

The prevalence of RAS/RAF alterations in human cancer has prompted significant efforts in the development of drugs targeting the MAP kinase pathway. Many of these are currently in clinical trials in patients with metastatic melanoma. Studies with the broad spectrum RAF inhibitor sorafenib (Nexavar, Bayer) as a single agent in patients with BRAF mutated melanoma have proved disappointing. What was unclear from these studies was whether the lack of efficacy was because BRAF was not a critical target or because of incomplete blocking of BRAF by sorafenib.

Since 2005, several BRAF inhibitors have entered clinical trials. These inhibitors are grouped in two categories: BRAF selective inhibitors, and broad spectrum multiple kinases inhibitors with high potency against BRAF.

BRAF inhibitors

PLX4032 (Plexxikon, also known as RO5185426) is a selective BRAF inhibitor and is the first of its kind tested in advanced melanoma. A response rate of 70% in 32 BRAF mutated melanoma patients was reported in the phase 2 study. In general, PLX4032 is well tolerated and most common toxicities include mild-to-moderate skin rash, sun sensitivity, fatigue, arthralgia and keratoacanthoma. Currently, there are two ongoing PLX4032 trials.


Wen-Jen Hwu

The first is a phase 2 study of PLX4032 as a single agent in BRAF mutated melanoma patients who have failed standard therapy for metastatic disease. This study will hopefully confirm the high response rates observed in previous phase 1/2 studies. The second is a phase 3 trial comparing PLX4032 with dacarbazine (standard chemotherapy) in chemotherapy-naive patients with BRAF mutated metastatic melanoma. Seven hundred patients will be enrolled; the primary endpoint is OS.

Another BRAF selective inhibitor is GSK2118436 (GlaxoSmithKline). This drug has already shown promising antitumor activity in the phase 1 portion of a study. The phase 2 portion is ongoing. The impressive high level of antitumor activity of BRAF selective inhibitors indicates that both PLX4032 and GSK2118436 have single-agent activity; BRAF is an important target in melanoma.

Currently, there are at least two nonselective BRAF inhibitors. XL281 (Bristol-Myers Squibb) and RAF265 (Novartis) are in phase 1 testing. Results are expected in the near future.

MEK is a kinase and is immediately downstream of BRAF. It is never mutated in cancer but is activated by BRAF and, in turn, activates the rest of the MAP kinase pathway. In the laboratory, MEK inhibitors have shown activity in a number of BRAF mutated cancers. Currently, there are many MEK inhibitors in clinical trials.

AZD6244 (AstraZeneca) is a MEK inhibitor that has been evaluated most extensively in melanoma. A phase 2 study comparing AZD6244 with temozolomide (oral chemotherapy) has found an objective response rate of 12% among 45 BRAF-mutated patients. However, patients in this study who received temozolomide had a similar response rate and PFS.

Melanomas from acral lentiginous, mucosal and chronic sun-damaged sites frequently harbor activating mutations and/or increased copy number in the KIT tyrosine kinase receptor gene, which are very rare in more common cutaneous melanomas. Multiple case reports and early observations from clinical trials suggested that targeting mutant KIT with small molecule KIT inhibitors such as imatinib (Gleevec, Novartis) and/or dasatinib (Sprycel, BristolMyersSquibb) is efficacious.

Although the dramatic clinical activity of BRAF selective inhibitors is a major breakthrough in the treatment of this disease, there are many hurdles to overcome to optimize this targeted therapy approach. Many of the patients who initially responded to PLX4032 have subsequently progressed with a median duration of response of approximately 8 months. The mechanisms that cause resistance are largely unknown.

Recently, a number of preclinical studies have demonstrated that BRAF inhibitors activate MEK and MAP kinases in melanoma cell lines with wild-type BRAF, including cell lines with mutant NRAS. These studies suggest at least one potential mechanism of resistance is through continued activation of the RAS-RAF-MEK-ERK signaling pathway. Thus, combination agents that target multiple components of this pathway have great potential to overcome drug resistance. Several ongoing clinical trials using the combination of BRAF and MEK targeted agents will be able to test this hypothesis.

Targeting tumor immunity barriers

Since the discovery of monoclonal antibodies in the late 1970s, it has become clear that these antibodies, which are of defined specificity and can be produced in large amounts, had potential for the management of various diseases, including malignancies.

The key property of antibodies to be used as therapeutic tools is their behavior as high-avidity ligands to protein or glycoprotein. Most recently, a new group of monoclonal antibodies that enhance the cellular immune response against cancer have entered clinical trials. These agents bind molecules on the surface of immune system cells. They either provide activating signals to lymphocytes and antigen presenting cells or block the action of receptors that normally down-regulate the immune response.

A humanized monoclonal antibodies (MDX-010, Medarex) against cytotoxic T-lymphocyte antigen 4 (CTLA-4) is the first to reach clinical trials. CTLA-4 is only expressed on the cell surface of activated T cells and regulatory CD4+ CD25+ T cells. In murine models, systemic treatment with transplantable immunogenic colon carcinoma cells with anti-CTLA-4 monoclonal antibodies induced complete tumor regression of established tumors through an immune response found to be critically dependent on the activity of cytotoxic T lymphocytes.

Various phase clinical studies have been conducted on the two anti-CTLA-4 monoclonal antibodies, ipilimumab (Bristol-Myers Squibb) and tremilimumab (Pfizer), as monotherpy, in combination with vaccines or other immunotherapies, and in combination with chemotherapies. Blockade by the T-cell inhibitory molecule CTLA-4 results in antitumor response with overall response rates from 10% to 20%. Most adverse events involve autoimmune toxicities, such as dermatitis, uveitis, colitis/enterocolitis, hepatitis and hypophysitis.

4-1BB (CD137) is a surface glycoprotein that belongs to the TNF receptor family. It is expressed by activated, but not resting, T and NK cells. A humanized anti-4-1BB monoclonal antibody (Bristol-Myers Squibb) has been tested in clinical trials. However, the phase 2 study in refractory melanoma was discontinued in May 2009 due to unusually high incidence of grade-4 hepatitis.

Programmed death 1 (PD-1) and its ligands, PD-L1 and PD-L2, deliver inhibitory signals that regulate the balance between T cell activation, tolerance and immunopathology. In vivo studies have shown B7-1 (CD80) is also a binding partner for PD-L1, and their interactions can lead to bidirectional inhibitory response in T cells.

PD-L1 is expressed on many tumors including melanoma and is a component of the immune suppression by the tumor microenvironment. Phase 1/2 experience of the anti-PD-1 monoclonal antibody, MDX-1106 (Medarex, Ono-4538), in refractory or relapsed malignancies was presented at the 2009 ASCO Annual Meeting. Clinical activity against melanoma was observed and, more importantly, no MDX-1106 related severe adverse events were noted.

In 2009, at M.D. Anderson Cancer Center, we participated in a phase 1 study of anti-PD-L1 monoclonal antibody (MDX-1105, Medarex) in refractory metastatic melanoma. MDX-1105 has been tolerated by all patients. Most adverse events were mild and were related to inflammatory responses in the tumors, not immune-related toxicity. Clinical responses were observed at all dose levels (1 mg/kg to 10 mg/kg every 2 weeks). Durable partial responses and stable disease were noted in patients whose disease had progressed after at least one, and as many as five, prior systemic therapies. Based on the low toxicity and impressive clinical activity, a phase 2 study of MDX-1105 in advanced melanoma is warranted.

In summary, the treatment of metastatic melanoma is changing rapidly due to the great success in translational research from bench to bedside. Although such studies, to date, have focused on the treatment of advanced metastatic disease, the approaches of targeting signal transduction pathway, as well as targeting tumor immunity barrier, hold great promise to the development of preventive strategies and personalized therapies in malignant melanoma.

Wen-Jen Hwu, MD, PhD, is a professor in the department of melanoma medical oncology at The University of Texas M.D. Anderson Cancer Center and is a member of the HemOnc Today Editorial Board.

Source:http://www.hemonctoday.com/article.aspx?rid=65856


“It is not the strongest of the species that survives, nor the most intelligent, but the one most responsive to change.”

~Charles Darwin~

Take Care,
Jimmy B

What If you combine Therapies? Response from Dr. Keith Flaherty..Melanoma ..Jim Breitfeller

What If you combine Therapies? Response from Dr. Keith Flaherty

Jim,


Thanks for the note.




"It is actually critical “patient advocates” which obviously includes patients, as well as those who are motivated to advocate on behalf of patients get involved in this process. One of the very reasons why I thought that a consortium was important to form, so that there could at least a body of researchers to point to as a group jointly focused on this direction. You see, companies find it very easy to say no to individual investigators when it comes to “difficult” requests. We need to make it harder for them when it involves losing time that our patients don’t have."



A very obvious combination that we are trying to move forward now is PLX4032 with ipilimumab. There is unanimity among the academic researchers that this must be investigated. Both companies see the logic, but are reluctant with neither of their drugs yet being FDA approved. As you know ipilimumab (and tremelimumab) have not overwhelmed the FDA yet as they were told to show a response rate greater than 10% and neither drug could do so. Most melanoma researchers believe that there are additional patients who get real and long-term benefit without having their tumors shrink significantly in size, but the randomized trials are needed to show that. The worrying sign is the outcome of the tremelimumab randomized trial. So, now we are down to waiting for the results of the dacarbazine vs. dacarbazine plus ipilimumab phase III trial. If this is negative, we are in trouble as ipilimumab will have no clear path forward with the FDA. If it’s positive, then the idea of moving ahead with combinations becomes much, much easier. But, even it that trial is negative, we know that CTLA-4 blockade can induce phenomenal responses in some. So, in that case, we have to figure out (1) who those patients are and, (2) how to make those responses happen in more patients. The other way of thinking of #2 is that PLX4032 doesn’t work for as long as we would like and that making those responses more durable would be desirable.

The companies need to hear it from patients and all patient-advocates that fairly obvious directions need to be pursued to find multiplicative effects. For the first time in melanoma, we have the building blocks in front of us and scientific rationale to guide us for the next steps.


Best regards, Keith

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Keith,


Base on my research, Ipi doesn’t work well is because it is lacking the tumor-specific antigens. DTIC+ Patrin-2, Irradiation, Oblimersen and others. We need the tumors to shed antigenic protein. To get the immune response into motion.


By using PLX-4032, my guess it will shed the protein needed. Then Anti-CTLA-4 Blockage comes in. It leaves the cd4+ T-cell activated and at the same time suppresses the Treg function allowing the CD8+ T-cells to get crossed primed and have them break though the tumor microenvironment. The HD IL-2 is added at the peak expansion of the CD8+ T-cells ( 50 days after Ipi is introduced into the host.). IL-2 is essential in the survival and function of the CTLs.


The above is my take on this combinatorial therapy. If you want, I can send you all the supporting papers of this theory.


Also, Can I get your permission to post your reply on my Blog?

Best Regards

Jim

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

What If you Combine three Therapies? PLX-4032 after remission, to let the tumor burden be low, Than add one dose of Anti-CTLA-4 Blockage. Wait 50 days so the CD8 T-cells would be at their maximum expansion. Then add two cycles of HD IL-2 to help grow and differentiate the CD8 T-cells into Cytotoxic T Lymphocytes (CTL's). You use the PLX-4032 to lower the tumor burden and shed the antigenic protein from the tumor.



For the patients that have the Braf mutation, use PLX-4032 to shed the antigenic protein and lower the tumor burden.

If you don't have the mutation, use radiation, chemo DTIC+ Patrin-2, Oblimersen and other small molecules to shed the antigenic protein.







Take Care,

Jimmy B

Melanoma Drugs (BRAF Inhibitors) Have Unintended Effects in Some Tumors..Jim Breitfeller

Some patients with advanced melanoma have had dramatic responses to a new class of targeted drugs in early stage clinical trials. While the long-term effects of these drugs, called BRAF inhibitors, are not yet known, two reports suggest that these drugs may have unintended consequences in patients whose tumors lack mutations in the BRAF gene.

In separate studies, scientists in Great Britain and the United States tested the drugs in the laboratory to better understand how BRAF inhibitors behave in cells. To their surprise, the drugs actually spurred the growth of some tumors. The preliminary findings raise the possibility that certain patients should not receive BRAF inhibitors because the drugs could make their cancers worse.

Source:NCI Cancer Bulletin February


Take care

Jimmy B

Melanoma_Missionary


"Today might be the worst day of your life...but tomorrow could be the best. You just have to get there."
~Unknown~

Lifesaver... PLX-4032 Therapy for BRAF Mutations..Melanoma ..Jim Breitfeller

"Now, an incredible breakthrough. A tiny capsule that can stop even advanced Melanoma in its tracks.

It's called PLX 4032 — and the results are so swift and dramatic that it's got even the usually conservative medical community excited. Even better, this drug could mark the beginning of a cure for other forms of cancer. Already, it's giving some patients back their lives and, for people like 24-year-old Brendan Robbins, offering hope — just in time."

Reporter: Liz Hayes
Producer: Phil Goyen

Lifesaver... PLX-4032 Therapy for BRAF Mutations



Source:http://sixtyminutes.ninemsn.com.au/stories/927744/lifesaver-cancer

You may want to be checked for the BRAF Mutation.

Take Care,

Jimmy B

Main roads to melanoma..Jim Breitfeller

Main roads to melanoma

This paper is very technical but gives great insight into Melanoma and the pathways that are associated with it. It is quite long and should be read in small bites. Please don't be intimidated by it.

Giuseppe Palmieri1, MariaElena Capone2, MariaLibera Ascierto2, Giusy Gentilcore2, David F. Stroncek3, Milena Casula1, MariaCristina Sini1, Marco Palla2, Nicola Mozzillo2, and Paolo A. Ascierto*2


ABSTRACT

The characterization of the molecular mechanisms involved in development and progression of melanoma could be helpful to identify the molecular profiles underying aggressiveness, clinical behavior, and response to therapy as well as to better classify the subsets of melanoma patients with different prognosis and/or clinical outcome. Actually, some aspects
regarding the main molecular changes responsible for the onset as well asthe progression of melanoma toward a more aggressive phenotype have been described. Genes and molecules which control either cell proliferation, apoptosis, or cell senescence have been implicated. Here we provided an overview of the main molecular changes underlying thepathogenesis of melanoma. All evidence clearly indicates the existence of a complex molecular machinery that provides checks and balances in normal melanocytes. Progression from normal melanocytes to malignant metastatic cells in melanoma patients is the result of a combination of downor up-regulation of various effectors acting on different molecular pathways.

Source:
http://www.translational-medicine.com/content/pdf/1479-5876-7-86.pdf

Main Roads to Melanoma



Take Care,

Jimmy B

A follow up with Dr. Paul Chapman and PLX4032 .. BRAF Mutation..Melanoma..Jim Breitfeller

Advancements in the treatment of metastatic malignant melanoma
23. September 2009 05:05

Researchers have made significant advances in the treatment of metastatic malignant melanoma - one of the most difficult cancers to treat successfully once it has started to spread - according to a study to be presented at Europe's largest cancer congress, ECCO 15 - ESMO 34, in Berlin on Thursday.

In the phase I extension study, researchers have seen rapid and dramatic shrinking of metastatic tumours in patients treated with a new compound that blocks the activity of the cancer-causing mutation of the BRAF gene, which is implicated in about 50% melanomas and 5% of colorectal cancers. In new results from 31 melanoma patients with the BRAF mutation who were treated with 960mg of PLX4032 twice a day, 64% (14) of the 22 patients who could be evaluated so far met the official criteria for partial response (this involves the diameter of tumours shrinking by at least 30% for at least a month). A further six of the 22 patients also showed a response, but, at the time of the congress presentation, it was too early to say whether the tumours would shrink far enough to meet these criteria.

Dr Paul Chapman, an attending physician on the Melanoma/Sarcoma service at Memorial Sloan-Kettering Cancer Center (New York, USA) and who was one of the leaders of the trial, told a news briefing: "We are very excited about these results. Of the 22 patients we have been able to evaluate so far, 20 have had some objective tumour shrinkage. This is impressive as they all had metastatic disease and most of them had failed several prior therapies. A lot of these patients were pretty sick but many of them had a significant and rapid improvement in the way they function. We've had patients come off oxygen and we've got several patients who have been able to come off narcotic pain medication soon after starting treatment."

The trial is investigating PLX4032 in patients with the BRAF mutation, and results from the first 55 patients were reported at a cancer meeting earlier this year (ASCO 2009). These data had been aimed at finding the best dose of PLX4032 to give to patients. However, the phase I extension data reported at ECCO 15 - ESMO 34 focuses on a subsequent group of an additional 31 patients who were all treated at the maximum tolerated dose of the drug (a 960 mg pill twice a day). All the patients had the BRAF mutation.

Dr Chapman said: "What makes this treatment different from standard chemotherapy is that standard chemotherapy attacks the machinery involved in cell division; so to stop the cancer cells dividing uncontrollably, most standard chemotherapy aims to block the mechanism of division by interfering directly with DNA replication or with microtubules in the dividing cells. PLX4302 is different because it attacks the genetic programme that is causing the cells to divide uncontrollably, and we think the BRAF mutation is driving that programme. The drug is blocking the genetics of the tumour, rather than trying to interfere with the proliferation of the cells and, as a result, there are fewer side effects, although there are some. We are seeing some pretty dramatic and rapid responses, and they are occurring in sites where we rarely see responses to chemotherapy, such as in the bone.

"There are some important caveats. All these patients had failed previous therapies, either chemotherapy or treatment with Interleukin 2, as well as surgery. However, we know that only 10-30% of patients will respond to standard chemotherapy, so it's not surprising that our patients had not responded, or have responded and then the cancer has recurred. In our study 64% of patients have had a partial response, but because we are only treating patients with the BRAF mutation, we are cutting out about 40% of melanoma patients who do not have this mutation and whom we know will not respond to this treatment. That is one reason why we are seeing a much higher response than with conventional treatments.

"Also, we don't know yet how long these responses will last, and we have had patients whose cancer has progressed after initially responding; so we are putting a lot of effort in to studying the patients who do relapse, trying to understand how their tumours have become resistant.

"In addition, one of the main side effects we've seen is that some patients develop early, non-melanoma skin cancers such as squamous cell skin cancer. We are very vigilant about this and although they are very easy to cut out, it's something we are keeping a close eye on."

Dr Chapman and his colleagues are planning a phase II trial of 90 patients starting at the end of this year. In addition, a large phase III randomised controlled trial involving several hundred patients is planned to start either at the end of this year or beginning of next year involving centres in North America, Europe and Australia.

Dr Chapman said it was too early to be talking about a cure for advanced melanoma, but that this drug had potential. "Most of us think that a drug like this would ultimately be part of the regimen, but that we might need additional drugs with it to complete the cure. Right now we are seeing dramatic responses but it's too early to say whether we've actually cured people because most patients still have evidence of some level of tumour on their skin. I think this is a huge step forward; whether or not it will be sufficient by itself really remains to be seen."

http://www.ecco-org.eu/Conferences-and-Events/ECCO-15/


You need to be genetically tested for the BRAF Mutation.



Take Care,

Jimmy B

Plexxikon Announces PLX4032 Phase 1 Data Showing Objective Responses in Metastatic Melanoma Patients.Melanoma .Jim Breitfeller

Personalized Medicine for Deadliest Form of Skin Cancer --


Business Wire
posted: 1 HOUR 58 MINUTES AGO

Plexxikon Inc. today announced preliminary data from a Phase 1 clinical study investigating PLX4032 (R7204). PLX4032 is a novel, oral and highly selective drug that targets the BRAF V600E cancer-causing mutation that occurs in most melanomas and about eight percent of all solid tumors. In patients whose cancer harbors this mutation and who were treated with therapeutic doses of PLX4032, tumor shrinkage and extended progression-free survival have been observed. Currently, two extension studies are being conducted in mutation-positive melanoma and colorectal cancer patients. Following the initial positive findings announced today, larger clinical trials to support a registration program for product approval are targeted to start later in 2009. Plexxikon and Roche are co-developing PLX4032 under their 2006 license and collaboration agreement.
“PLX4032 has shown both tumor shrinkage and delay in tumor progression in patients whose tumors harbor a BRAF mutation as well as reports of clinical symptom improvement in some patients,” stated Keith T. Flaherty, M.D., assistant professor at the Abramson Cancer Center of the University of Pennsylvania and principal investigator for the PLX4032 Phase 1 clinical trial. “Seven years after BRAF mutations were first identified, we have validation that this mutation is a cancer driver and therapeutic target. This is a new and important chapter in the story of targeted therapy development in cancer, and we are especially excited for our melanoma patients, for whom there are currently few treatment options.” Link to video clip of Dr. Flaherty
In the dose escalation phase of the study, 55 cancer patients have been treated, including 24 mutation-positive melanoma patients and 3 mutation-positive thyroid patients, as well as 28 melanoma, rectal and ovarian cancer patients who did not have the mutation or whose mutation status was not known.
In 16 BRAF mutation-positive melanoma patients treated with PLX4032 doses at or above 240 mg twice daily (BID), representing targeted drug exposure levels, data show:
PLX4032 is well tolerated at very high doses, with 960 mg BID under evaluation as the maximum tolerated dose
Partial responses in 9 patients showing greater than 30% tumor regression by RECIST (Response Evaluation Criteria in Solid Tumors) criteria, with 7 confirmed
Regression of metastatic lesions in every site to which melanoma commonly spreads, including liver, lung and bone
Minor responses in 4 patients showing tumor regression greater than 10% but less than 30%
Disease control lasting up to 14 months with continuous therapy, with many patients still receiving treatment
Interim median progression-free survival of at least six months, with many responding patients still receiving treatment
By contrast, no treatment response was observed in a small group of patients without the mutation, and progression-free survival was less than 2 months, consistent with historical data.
Dose-limiting toxicities, primarily rash, fatigue and joint pains, were seen at 1120 mg BID. Drug-related adverse events have been predominantly mild in severity and transient, including rash and photosensitivity. Serious adverse events were observed in some patients after chronic treatment, including possibly drug-related cutaneous squamous cell carcinoma. A risk management plan has been implemented for baseline evaluation of the skin and monitoring of all patients while on study. Cutaneous squamous cell carcinoma is typically excised by a patient’s dermatologist.

“This is a significant day for us at Plexxikon. The clinical data for PLX4032 so far support our hypothesis that a truly selective drug can target tumors harboring this cancer-causing mutation, while at the same time, deliver a treatment that is well tolerated by patients,” stated K. Peter Hirth, Ph.D., chief executive officer of Plexxikon. “In conjunction with bio-response markers and a companion diagnostic test, PLX4032 has all the hallmarks of an ideal personalized medicine. Plexxikon’s pipeline includes several highly selective kinase inhibitors, including novel therapies for other cancers as well as other chronic diseases such as rheumatoid arthritis where such precision is anticipated to provide a safety advantage.”

Companion Diagnostic in Parallel Development
Along with the development of PLX4032 therapy, a diagnostic test to identify patients with the BRAF mutation is being co-developed by Plexxikon and Roche, under a separate 2005 agreement. This test is already being used to identify mutation-positive patients for ongoing clinical trials. Most importantly, this companion diagnostic enables the identification of mutation-positive cancer patients considered most likely to respond to PLX4032 treatment.

Source:http://money.aol.com/article/plexxikon-announces-plx4032-phase-1-data/484608?icid=sphere_searchsphere_news


Take care

Jimmy B

Proof-of-concept for V600E BRAF mutation as a therapeutic target in human cancer..Melanoma..Jim Breitfeller

Proof-of-concept for V600E BRAF mutation as a therapeutic target in human cancer

Phase 1 study of PLX4032: Proof-of-concept for V600E BRAF mutation as a therapeutic target in human cancer”
Oral presentation to be made on June 1, 2009, 4:30 p.m. to 6:00 p.m. EDT by Keith T. Flaherty, assistant professor, University of Pennsylvania Abramson Cancer Center, in the “Molecular Phenotype of Melanoma Subtypes and Patient-Specific Therapy” session

Link to video clip of Dr. Flaherty


We just may be getting a handle on this deadly disease!!!!!!!!!


Take care

Jimmy B

Melanoma Update: Highlights of research presented at ASCO and an update on vaccines trials.Melanoma..Jim Breitfeller

Issue Number:
Volume 17 - Issue 3 - March 2009
author:
John Otrompke, Contributing Editor
Mixed Melanoma Trial Results Point to Need for Tailored Studies

"Effective melanoma therapies may be inching forward, with a number of the new class of potential therapeutics in the pipeline entering Phase III trials, and researchers presenting some of the first published data on other agents at this year’s annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago.

But with mixed results, some disappointing, some surprising, some researchers say clinicians and clinical trial designers must rethink development strategies, including patient selection, if some of the new class of biological therapeutics for melanoma are to make significant headway.

“The problem with melanoma is that, other than surgery, there really are no very good effective therapies. The chemotherapies that are out there are not curative but palliative treatments,” explains David Solit, MD, Elizabeth and Felix Rohatyn Chair and Assistant Attending Physician, Department of Medicine, Sloan-Kettering Cancer Center.

But medical science is progressing, says Dr. Solit, who spoke at the ASCO conference. “We actually know a lot of the genetic alterations that cause the cancer. In 2002 there was a mutation in a protein called BRAF that was identified, and the mutation is found in the tumor in 50% to 70% of patients with melanoma. Then there’s a protein called NRAS, which also gets mutated in 15% to 20% of melanoma patients. But when you have an NRAS mutation, you don’t have a BRAF mutation. In total, between 60% and 90% of patients have one of the two,” says Dr. Solit, who gave the presentation, “Genetic Predictors of RAF/MEK Dependence.”

But the news at ASCO was not all good for the new therapies.

Early Promise, Mixed Results

Some of the most important new strategies for treating advanced melanoma focus on the patient’s immune system.

“Two of the strategies use anti-CTLA 4 and anti-PD1 agents to take the brakes off the patient’s immune system. Both are receptors on a patient’s T-cells, which are part of the normal braking system, which is a good thing at most times, but not a good thing in regards to a cancer cell,” says Walter Urba, MD, PhD, Director of Cancer Research at the Earle A. Chiles Research Institute in Portland, Oregon.

“The other two strategies use antibodies 41BB or OX 40. At ASCO this year, we saw some late clinical trial results with the anti-CTLA 4 product, and the first published results with anti-41BB and anti-PD1,” says Dr. Urba, who also discussed very early results with his own institution’s investigational agent, OX 40.

A disappointing trial of a new potential therapeutic agent was a head-to-head trial of an agent called a MEK inhibitor, which was tested against temozolomide, a standard pre-existing chemotherapy for melanoma. There was no significant difference between the standard arm and the MEK inhibitor (AZD 6244 by Astra Zenaca), according to the trial results.

However, patient selection may be the problem. “Genetic differences are relevant, because the BRAF mutation found so often in melanoma patients, activates a protein called MEK. “If you have a RAF mutation, you may respond a lot better to a MEK inhibitor,” explains Dr. Solit, noting that in addition to the Astra Zenaca drug, another MEK inhibitor in research is a drug from Pfizer called PD 0325901. The Astra Zenaca drug, which encountered the disappointing result, is in Phase II trials, whereas the MEK inhibitor from Pfizer is only in Phase I.

“The problem with the Astra Zenaca trial is that they didn’t look for BRAF-mutated patients. It’s possible temozolomide is as good or better than AZD 6244 in unselected patients, but five of the six responders in the MEK inhibitor arm had BRAF mutations,” Dr. Solit says. “There is technology out there already to start looking for these mutations, and it has already become routine in lung cancer for other genes.”

There were some positive, surprising results presented as well, however. A Phase II trial of ipilimumab, an investigational immunomodulatory agent from Bristol Meyers Squibb, which is in late Phase III trials, was studied in a population of 115 patients in combination therapy with Budesonide, a currently existing therapy. “Our primary endpoint was to see whether in a randomized trial we could reduce the amount of diarrhea that occurs as a side effect of the Budesonide, and our primary endpoint was not successful, but ironically, the clinical results were outstanding. Our median survivals were over a year,” says Jeffrey Weber, MD, PhD, Director of the Donald A Adam Comprehensive Melanoma Research Center and Professor of Oncologic Sciences at the University of South Florida.

Updated survival data of three Phase 2 studies of ipilimumab in patients with metastatic melanoma (Stage III or IV) who had previously been treated were presented at the European Society for Medical Oncology in Stockholm. Study results show that approximately half of patients who received ipilimumab (10 mg/kg) remained alive beyond 1 year. The results are based on follow-up of the patient population from studies 008, 022 and 007 treated with 10 mg/kg of ipilimumab (induction and maintenance) and show a consistent 1-year survival rate between 47% and 51%.

Combination Therapies of the Future, Today

Another promising strategy offering hope to advanced melanoma patients is to stimulate the patient’s immune system, by mimicking signal’s sent naturally by the body.

“We have learned from studying patients with melanoma just how powerful the immune system can be, but we need to supplement the response, and free it from some of its limitations,” says Robert H. Vonderheide, MD, Assistant Professor of Medicine at Abramson Cancer Center at the University of Pennsylvania.

The immune response in melanoma patients can be so pronounced that in rare cases, tumors even shrink in the face of it, says Dr. Vonderheide.

Dr. Urba agreed. “The immune response in melanoma is different from other cancers,” he explains. “One of the thoughts is that melanoma tumors are more immunogenic. Sometimes the response occurs after disease progression. In a couple percent of every patient population, the patient comes in and looks for all the world like they’re having tumor progression, and they end up having the tumor go away in response. The rationale is, that maybe it takes time for an immune response to build up and eliminate tumor cells following these investigational therapies,” he says, noting that these delayed responses can occur 8 or 12 weeks following therapy.

To attempt to take advantage of melanoma’s unique immunogenicity, Pfizer has developed an investigational agent that acts on an immune receptor called CD40, according to Dr. Vonderheide. “This is an antibody that binds to CD40 and mimics the signal sent to activate the immune system.”

The CD40 agonist has been tested by itself and in conjunction with standard chemotherapy drugs carboplatin and paclitaxel. The first clinical trial with the agent started about 4 years ago, and was reported 2 years ago at ASCO. Though the drug is only in Phase I trials, “taking it to Phase II is definitely warranted,” notes Dr. Vonderheide. “In the second study, we saw clinical activity: one patient has regressed, and remained in remission for years.”

In another study, the CD40 agonist will be given, along with chemotherapy, every 3 weeks, and the trial is enrolling as many as 30 patients, according to Dr. Vonderheide.

With some of the therapies, lack of experience in testing them may lead to unpredictable future results; in others, the sheer longevity of their period in trials can lead to skepticism.

“Anti-CTLA 4, an anti-inhibitory drug, has probably been in clinical trials for about 7 years, whereas anti-PD1, which is also an anti-inhibitory drug, has probably not been in trials for much more than a year,” says Dr. Urba, noting that the 41BB has also been in trials for 2 years.

For some drugs, clinical trials have enrolled hundreds of patients over the years, while other novel agents have only been tested in a few dozen humans. “The delayed response phenomenon, for example, has not been seen with other agents besides ipilimumab and tremilimumab, but with the other agents, the number of patients who have been treated is so small I’m not sure if we would have seen it,” he adds.

Still, the novel agents, whether young or old, often offer the only hope for advanced melanoma patients to hold onto.

“Nonetheless, it’s probably going to be a long series of trials to figure out which are the patients who are going to benefit. It’s a targeted therapy, and it doesn’t work for everybody. But we have insight into who it would work in, and we need to incorporate that information into our clinical trial design,” Dr. Solit says."


source: http://www.skinandaging.com/content/melanoma-update-highlights-research-presented-asco-and-update-vaccines-trials

Melanoma Update: Highlights of research presented at ASCO and an update on vaccines trials


Take care
Jimmy B

New Method For Detection Of Phosphoproteins Reveals Regulator Of Melanoma Invasion Melanoma..Jim Breitfeller

Main Category: Melanoma / Skin Cancer
Also Included In: Cancer / Oncology; Genetics
Article Date: 13 Apr 2009 - 2:00 PDT

Scientists have developed a new approach for surveying phosphorylation, a process that is regulated by critical cell signaling pathways and regulates several key cellular signaling events. The research, published by Cell Press in the April 10th issue of the journal Molecular Cell, describes the regulation of a previously uncharacterized protein and demonstrates that it plays an important role in cancer cell invasion.

Many cancers, including melanoma, are associated with mutations in the gene encoding the protein kinase B-Raf. Kinases are proteins that regulate the function of other proteins by attaching a phosphate group to them. B-RAF mutations often lead to dysregulation of protein phosphorylation by the mitogen-activated protein (MAP) kinase signaling pathway. Identification and characterization of MAP kinase target proteins is critical for understanding the mechanisms involved in cancer progression.

"In contrast to targets regulated at the level of gene expression, little is known about how proteins are modified in response to oncogenic B-Raf signaling in melanoma cells. In particular, identifying cellular targets for phosphorylation is needed to gain a more comprehensive understanding of the responses to MAP kinase pathway dysregulation in melanoma," explains senior study author Dr. Natalie G. Ahn from the Department of Chemistry and Biochemistry at the University of Colorado and the Howard Hughes Medical Institute.


SOURCE:http://www.medicalnewstoday.com/articles/145821.php?nfid=76490
New Method For Detection Of Phosphoproteins Reveals Regulator Of Melanoma Invasion


As scientists peel back each layer of this Melanoma Onion,they discover new things along the way.With each new discovery we get closer to a cure/stabiization. And there are many ways to peel an onion.

Take care

Jimmy B

Experts find gene trigger for deadly skin cancer !!! Melanoma..Jim Breitfeller

Last Updated: 2009-04-06 13:27:13 -0400 (Reuters Health)

LONDON (Reuters) - Up to 70 percent of melanoma skin cancers may be triggered by a gene mutation that causes cells to become cancerous after excessive exposure to the sun, researchers said on Monday.

The discovery could lead to better treatments for the most deadly form of skin cancer after scientists at Britain's Institute of Cancer Research established the BRAF gene mutation is often the first event in the cascade of genetic changes leading to melanoma.

Scientists already knew the BRAF gene was frequently damaged in patients with melanoma, but it was unclear if this was a cause or effect of the cancer.

The British institute published its findings in the journal Cancer Cell.

"Our study shows that the genetic damage of BRAF is the first step in skin cancer development," said lead author Richard Marais. "Understanding this process will help us develop more effective treatments for the disease."

The hope is that knowing the genetics behind skin cancer will lead to the development of targeted drugs that can fix the faulty genetic machinery.

While melanoma accounts for only a small percentage of skin cancers, it is responsible for most skin cancer deaths. The disease is characterised by the uncontrolled proliferation of pigment-producing skin cells called melanocytes.

Over-exposure to sunlight is to blame for at least two-thirds of cases as DNA in sunburnt skin cells become damaged, leading to the genetic mutations.

Source:http://www.reutershealth.com/archive/2009/04/06/eline/links/20090406elin014.html

Jimmy B

A Conversation with Dr. Natalie Ahn ..Melanoma..Jim Breitfeller

Associate Professor at University of Colorado at Boulder

Ph.D.: University of California, Berkeley, 1985
Postdoctoral Fellow: University of Washington,

Awards:
Howard Hughes Medical Institute Investigator
Searle Scholar, 1993-1996
Merck Fellow, 1988-1991

Background:

“When Natalie Ahn was a postdoctoral student from 1988 to 1990 in the laboratory of Edwin Krebs at the University of Washington in Seattle, she was one of a group of scientists who discovered a signal transduction pathway (the mitogen activated protein or MAP kinase pathway) growth factors. Her approach was painstaking, requiring more than 10,000 assays. She also found an enzyme called MAP kinase kinase, which adds a phosphate to the enzyme MAP kinase to make it active.

Today, as a chemistry professor at the University of Colorado at Boulder, Ahn continues researching the subtleties of the MAP kinase and other signaling pathways, and their possible role in cancer. She also studies the fundamental chemical behavior of proteins.”

Source: Howard Hughs Medical Institute



Dr. Ahn, I as a Melanoma stage IV Patient/ Survivor applauded you and your colleagues on the research that you are doing for the Melanoma Cause.

Do you see some day that there will be genomic testing at the clinical level in the near future? Is the Molecular diagnostics keeping up with the research?


My type of Melanoma was the Nodular, which must be a mutation in the BRAF and or NRAS. Would doing the CTLA-4 therapy and then IL-2 correct those mutations? Or is it a temporarily response?

Any insight would be greatly appreciated.

To answer your last question first:

Mutations in B-Raf and N-Ras have been shown to cluster at specific nucleotides. This strongly suggests that there is a cellular mechanism which targets these sites in each gene. However, you are probably right, that anti-CTLA4 and IL2 are working by enhancing immune surveillance of your melanoma.

Therefore, I think it is unlikely that these therapies would reverse the mutations in cells which harbor them. On the other hand, it seems possible that immune therapy might somehow select for a subpopulation of melanoma cells within the heterogeneous tumors which lack mutations in B-Raf or N-Ras, so that after extended treatment, the cells with mutations die and cells without mutations expand. This could lead to an apparent switch in cell population within the tumors.



To answer your first two questions:

Yes, I believe that genomic testing will be feasible to predict disease susceptibility as well as treatment routes. This is already being used for some cancers. For example, markers such as estrogen receptor, progesterone receptor, or HER2 are already being used to predict responsiveness to different therapies for breast cancer. Such markers are less well developed for melanoma, but I think it is a matter of time and effort to discover and characterize them. One aim of my research is to develop new technologies for profiling proteins and chemical modifications of proteins, in hopes of identifying protein markers that can be used to diagnose melanomas and predict responsiveness to different therapies.

With respect to molecular diagnostics:

I think that there are many powerful technologies for molecular diagnostics -- such as gene chips which are used to survey transcripts. But other diagnostic technologies, e.g. for surveying proteins, are still immature. Also difficult is developing good laboratory medicine assays that can be performed with high accuracy and sensitivity. There are many blood markers that can be used to diagnose diseases, but a serious bottleneck is in the assays for quantifying these markers. So new technologies in laboratory medicine remains an important goal for the future.

I am also studying how B-Raf causes melanoma metastasis, and why targeted therapeutics which inhibit this pathway work in cells outside the body, but fail to work in patients. I believe that by studying mechanisms for resistance to these drugs, we might understand what else is needed in order to trigger melanomas to respond to these compounds. This would provide alternative therapies to melanoma patients, especially the many who fail to respond to current therapies.

Thank you for contacting me. I wish you the very best for your
treatment, and hope that your disease continues to remain stable for
many years to come.

Sincerely yours,

Natalie Ahn

Subject: BRAF V600E mutational analysis 7-11-2008 ..Melanoma..Jim Breitfeller

Memorandum


To: All Medical Staff

From: Harry S. Cooper, M.D., Director of Clinical Laboratories and Andrew K. Godwin, Ph.D., Director of Clinical Molecular Genetic Laboratory

Date: July 11, 2008

Subject: BRAF V600E mutational analysis

The Clinical Molecular Genetics Laboratory (CMGL) (W232, x4785, Betsy Bove, Ph.D., laboratory manager) Department of Pathology, is pleased to add to their menu of clinical molecular tests the analysis of mutation for BRAF (V600E). The test is performed on DNA extracted from formalin fixed paraffin embedded tissue blocks.

BRAF is a kinase encoding gene for the RAS/RAF/MARK pathway and has been identified to be mutated in a wide variety of human cancers, including melanomas, sporadic colorectal carcinomas (CRC) and thyroid carcinomas. In sporadic microsatellite unstable (MSI–H) CRC, a specific BRAF mutation (V600E) is found in 31-45% of the cases analyzed. To date, this BRAF (V600E) mutation has not been found in MSI-H hereditary non polyposis (HNPCC) colorectal cancers. These findings make BRAF (V600E) testing important in the algorithm in separating sporadic MSI-H CRC vs MSI-H CRC due to HNPCC. In those patients with MSI-H CRC lacking expression of MLH1, the presence of a BRAF (V600E) mutation indicates sporadic MSI-H (via methylation) ruling out HNPCC and circumventing the need for germline testing. Those patients with MSI-H CRC that lack MSH-2 and/or MSH6 expression or with Amsterdam criteria should proceed directly to germline mutational testing.

Orders for BRAF V600E mutational analysis can be submitted either through the online appointment slip or by filling out a CMGL requisition available in clinic areas.

We are pleased to add BRAF V600E mutational analysis testing to our present menu of clinical molecular tests:
• microsatellite instability testing (MSI)
• epidermal growth factor receptor testing (EGFR, exons 18-21)
• paraffin embedded block BRCA1/2 AJ founder alteration testing
• BRCA1/2 AJ founder and site specific testing
• UGT1A1*28
• C-KIT/PDGFRa (exons 9, 11, 13, 17/exons 12, 18)
• KRAS (codons 12 and 13)



cc Michael Seiden, M.D, Ph.D
Robert Ozols, M.D., Ph.D
J.Robert Beck, M.D.
Betsy Bove, Ph.D
Arthur S. Patchefsky, M.
Lucinda Kalnick-Loose
Dorothy Riehs
John J. Gricoski
Robert E. Spallone
Lisa Emgushov



http://www.fccc.edu/docs/research/facilities/clinical/clinicalMolecularGeneticsLab/BRAFannouncement.doc
BRAF V600E mutational analysis



Jimmy B