Recent research, news and treatment trends.
Genentech’s RG7204 Shows Survival Benefit in Phase III Metastatic Melanoma Patients
A Phase III clinical study (BRIM3) of Genentech’s RG7204 (PLX4032) showed a significant survival benefit in people with previously untreated BRAF V600 mutation-positive metastatic melanoma. The study compared RG7204, an investigational, oral, small molecule that is designed to selectively inhibit a cancer-causing mutated form of the BRAF protein, to dacarbazine, which is the current chemotherapy standard of care.
Study Method
BRIM3 (Study NO25026) is a global, randomized, open-label, controlled, multicenter, Phase III study evaluating RG7204 compared to dacarbazine in patients with previously untreated, BRAF V600 mutation-positive metastatic melanoma. Mutation status of the 675 enrolled patients was determined by the cobas 4800 BRAF V600 Mutation Test (Roche Molecular Diagnostics), a companion diagnostic assay being co-developed with RG7204. Study participants were randomized to receive either RG7204 960 mg orally twice daily or dacarbazine 1000 mg/m2 intravenously every 3 weeks. Patients continued dosing until their disease progressed or there was unacceptable toxicity.
Study Results
The study met its co-primary endpoints of overall survival and progression-free survival; based on these interim analysis results, all patients in the control arm of the study (dacarbazine) will be allowed to cross over and receive RG7204. The most frequent Grade 3 adverse event was skin-related and included cutaneous squamous cell carcinoma. Additionally, generally mild and reversible increases in liver enzymes (GGT, ALT, AST, alkaline phosphatase and bilirubin) were observed in some patients. The most common adverse events were rash, photosensitivity, joint pain, hair loss and fatigue. “For the first time, a personalized investigational medicine, RG7204, has shown a significant survival benefit in metastatic melanoma. This is an important advance for people with the BRAF V600 mutation-positive form of the disease who have had extremely limited treatment options,” said Hal Barron, MD, Chief Medical Officer and Head, Global Product Development of the Roche Group, of which Genetech is a member.
Two New GSK Drugs Studied for Advanced or Metastatic Melanoma
GlaxoSmithKline has begun late-stage trials of two new drugs for advanced or metastatic melanoma patients. GSK2118436 and GSK1120212 are being studied to see if they stop or slow the progression of skin cancer in patients whose tumors contain a BRAF V600 mutation. The BRF113683 Phase III study will compare GSK’436, a BRAF inhibitor, to chemotherapy drug dacarbazine (DTIC) in previously untreated patients with BRAF V600 mutated advanced or metastatic melanoma. The second study, METRIC, will compare MEK inhibitor GSK’212 to chemotherapy (DTIC or paclitaxel) in advanced or metastatic melanoma patients with a BRAF V600 mutation. Paolo Paoletti, president of GSK oncology, said, “By focusing our research program on patients with the V600 mutation, we are striving to understand how our investigational MEK and BRAF inhibitors can best be used to treat patients with metastatic melanoma. In addition to our ongoing research in metastatic melanoma, we are also studying GSK’212 and GSK’436, both alone and in combination with other agents, in other difficult-to-treat forms of cancer, including pancreatic cancer, refractory or relapsed leukemias and other solid tumors.”
Biomarker Test Shows Promise For Melanoma Diagnosis
A ccording to a press release from University of North Carolina (UNC) at Chapel Hill School of Medicine, a new study shows that a test of biomarkers for DNA methylation is technically feasible and could aid in earlier, more precise diagnosis of melanoma. In a paper published in Pigment Cell & Melanoma Research, the UNC team of researchers tested whether DNA methylation profiling could be accomplished on melanoma and mole tissues that had been preserved in fixatives for typical pathology examination after biopsy. They found that results on tissues prepared in this way were reliable and DNA methylation distinguished malignant melanomas from non-malignant moles. “Melanomas and moles can appear similar on the skin and under the microscope making diagnosis of some melanomas difficult. That's why we wanted to determine whether a test for DNA methylation is feasible as a tool for diagnosis,” said Nancy Thomas, MD, PhD, professor of dermatology and a member of UNC Lineberger Comprehensive Cancer Center. Kathleen Conway Dorsey, PhD, who is assistant research professor of epidemiology at UNC’s Gillings School of Global Public Health and a member of UNC Lineberger Comprehensive Cancer Center, added this comment: “We are very excited because, with this study, we have shown that this type of testing is feasible and that it has the potential to reliably distinguish between melanoma and benign skin lesions. Devising a molecular test that could aid in the early specific diagnosis of melanoma could have significant benefit for patients.” The team’s research pinpointed sites on 22 genes that have significantly different methylation levels between melanomas and non-melanoma lesions, as well as 12 locations that are highly predictive of melanoma. According to Dr. Thomas, another goal of the team is to develop a DNA-methylation test for melanoma tumor DNA that is shed into the bloodstream and that can serve as a measure for disease activity. “If this test can be developed, it opens the door to diagnose recurrence early and initiate treatment while tumors are more likely to respond to treatment. It would also give us another way to monitor patients for response to treatment and help us better optimize treatments for each patient,” Dr. Thomas noted. The research was funded by the National Cancer Institute and a UNC Lineberger Pilot Grant.
Academy Issues Updated Position Statement on Vitamin D
A press release from the American Academy of Dermatology detailed its updated position statement on vitamin D, which was based on the results of a review of scientific literature on this vitamin and its importance for optimal health recently conducted by the National Academy of Sciences Institute of Medicine (IOM). The IOM reviewed the scientific literature examining the possible relationship between vitamin D and certain types of cancers, neurologic disease, infectious disease, autoimmune disease and cardiovascular disease. Based on review of more than 1,000 studies and expert and stakeholder testimony, the IOM concluded that while the evidence for associating vitamin D levels with bone health was strong, the evidence for other conditions was inconsistent, inconclusive and insufficient to inform nutritional requirements. “The IOM’s review of the scientific evidence about vitamin D supports the Academy’s long-standing recommendation on safe ways to get this important vitamin — through a healthy diet which incorporates foods naturally rich in vitamin D, vitamin D-fortified foods and beverages, and vitamin D supplements,” stated dermatologist William D. James, MD, FAAD, president of the American Academy of Dermatology. “Unprotected exposure to UV radiation from the sun or indoor tanning is not safe. Individuals who intentionally expose themselves to UV radiation for vitamin D are putting their health at risk for developing skin cancer.”
Combination Therapy For Drug-Resistant Melanoma
N oting the ultimate failure of what seemed to be successful therapy with the BRAF-specific inhibitor, PLX4032, scientists from the Wistar Institute tested their belief that some cancers must be treated with multiple targeted drugs at the outset of treatment. Their findings, detailed in a press release from the Wistar Institute and published in Cancer Cell, describe the study in which 7 months after therapy with PLX4032, the tumors of those patients whose melanoma lesions contain a mutation in the BRAF gene returned and resumed growing. The scientists believe the reason for this development is that the tumor learns to signal around the blocked gene by adjusting its molecular wiring. They also show how to overcome resistance by simultaneously targeting multiple signaling pathways. “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, DVM, DSc, 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.”
Why PLX4032 Therapy Failed
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, PhD, 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.”
Countering Drug Resistance
To find out which alternate pathways the drug-resistant cells use, Dr. 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, 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. A number of compounds in clinical development that could block signals along both these pathways exist. 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 Dr. 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,” Dr. 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.
Recent research, news and treatment trends.
Genentech’s RG7204 Shows Survival Benefit in Phase III Metastatic Melanoma Patients
A Phase III clinical study (BRIM3) of Genentech’s RG7204 (PLX4032) showed a significant survival benefit in people with previously untreated BRAF V600 mutation-positive metastatic melanoma. The study compared RG7204, an investigational, oral, small molecule that is designed to selectively inhibit a cancer-causing mutated form of the BRAF protein, to dacarbazine, which is the current chemotherapy standard of care.
Study Method
BRIM3 (Study NO25026) is a global, randomized, open-label, controlled, multicenter, Phase III study evaluating RG7204 compared to dacarbazine in patients with previously untreated, BRAF V600 mutation-positive metastatic melanoma. Mutation status of the 675 enrolled patients was determined by the cobas 4800 BRAF V600 Mutation Test (Roche Molecular Diagnostics), a companion diagnostic assay being co-developed with RG7204. Study participants were randomized to receive either RG7204 960 mg orally twice daily or dacarbazine 1000 mg/m2 intravenously every 3 weeks. Patients continued dosing until their disease progressed or there was unacceptable toxicity.
Study Results
The study met its co-primary endpoints of overall survival and progression-free survival; based on these interim analysis results, all patients in the control arm of the study (dacarbazine) will be allowed to cross over and receive RG7204. The most frequent Grade 3 adverse event was skin-related and included cutaneous squamous cell carcinoma. Additionally, generally mild and reversible increases in liver enzymes (GGT, ALT, AST, alkaline phosphatase and bilirubin) were observed in some patients. The most common adverse events were rash, photosensitivity, joint pain, hair loss and fatigue. “For the first time, a personalized investigational medicine, RG7204, has shown a significant survival benefit in metastatic melanoma. This is an important advance for people with the BRAF V600 mutation-positive form of the disease who have had extremely limited treatment options,” said Hal Barron, MD, Chief Medical Officer and Head, Global Product Development of the Roche Group, of which Genetech is a member.
Two New GSK Drugs Studied for Advanced or Metastatic Melanoma
GlaxoSmithKline has begun late-stage trials of two new drugs for advanced or metastatic melanoma patients. GSK2118436 and GSK1120212 are being studied to see if they stop or slow the progression of skin cancer in patients whose tumors contain a BRAF V600 mutation. The BRF113683 Phase III study will compare GSK’436, a BRAF inhibitor, to chemotherapy drug dacarbazine (DTIC) in previously untreated patients with BRAF V600 mutated advanced or metastatic melanoma. The second study, METRIC, will compare MEK inhibitor GSK’212 to chemotherapy (DTIC or paclitaxel) in advanced or metastatic melanoma patients with a BRAF V600 mutation. Paolo Paoletti, president of GSK oncology, said, “By focusing our research program on patients with the V600 mutation, we are striving to understand how our investigational MEK and BRAF inhibitors can best be used to treat patients with metastatic melanoma. In addition to our ongoing research in metastatic melanoma, we are also studying GSK’212 and GSK’436, both alone and in combination with other agents, in other difficult-to-treat forms of cancer, including pancreatic cancer, refractory or relapsed leukemias and other solid tumors.”
Biomarker Test Shows Promise For Melanoma Diagnosis
A ccording to a press release from University of North Carolina (UNC) at Chapel Hill School of Medicine, a new study shows that a test of biomarkers for DNA methylation is technically feasible and could aid in earlier, more precise diagnosis of melanoma. In a paper published in Pigment Cell & Melanoma Research, the UNC team of researchers tested whether DNA methylation profiling could be accomplished on melanoma and mole tissues that had been preserved in fixatives for typical pathology examination after biopsy. They found that results on tissues prepared in this way were reliable and DNA methylation distinguished malignant melanomas from non-malignant moles. “Melanomas and moles can appear similar on the skin and under the microscope making diagnosis of some melanomas difficult. That's why we wanted to determine whether a test for DNA methylation is feasible as a tool for diagnosis,” said Nancy Thomas, MD, PhD, professor of dermatology and a member of UNC Lineberger Comprehensive Cancer Center. Kathleen Conway Dorsey, PhD, who is assistant research professor of epidemiology at UNC’s Gillings School of Global Public Health and a member of UNC Lineberger Comprehensive Cancer Center, added this comment: “We are very excited because, with this study, we have shown that this type of testing is feasible and that it has the potential to reliably distinguish between melanoma and benign skin lesions. Devising a molecular test that could aid in the early specific diagnosis of melanoma could have significant benefit for patients.” The team’s research pinpointed sites on 22 genes that have significantly different methylation levels between melanomas and non-melanoma lesions, as well as 12 locations that are highly predictive of melanoma. According to Dr. Thomas, another goal of the team is to develop a DNA-methylation test for melanoma tumor DNA that is shed into the bloodstream and that can serve as a measure for disease activity. “If this test can be developed, it opens the door to diagnose recurrence early and initiate treatment while tumors are more likely to respond to treatment. It would also give us another way to monitor patients for response to treatment and help us better optimize treatments for each patient,” Dr. Thomas noted. The research was funded by the National Cancer Institute and a UNC Lineberger Pilot Grant.
Academy Issues Updated Position Statement on Vitamin D
A press release from the American Academy of Dermatology detailed its updated position statement on vitamin D, which was based on the results of a review of scientific literature on this vitamin and its importance for optimal health recently conducted by the National Academy of Sciences Institute of Medicine (IOM). The IOM reviewed the scientific literature examining the possible relationship between vitamin D and certain types of cancers, neurologic disease, infectious disease, autoimmune disease and cardiovascular disease. Based on review of more than 1,000 studies and expert and stakeholder testimony, the IOM concluded that while the evidence for associating vitamin D levels with bone health was strong, the evidence for other conditions was inconsistent, inconclusive and insufficient to inform nutritional requirements. “The IOM’s review of the scientific evidence about vitamin D supports the Academy’s long-standing recommendation on safe ways to get this important vitamin — through a healthy diet which incorporates foods naturally rich in vitamin D, vitamin D-fortified foods and beverages, and vitamin D supplements,” stated dermatologist William D. James, MD, FAAD, president of the American Academy of Dermatology. “Unprotected exposure to UV radiation from the sun or indoor tanning is not safe. Individuals who intentionally expose themselves to UV radiation for vitamin D are putting their health at risk for developing skin cancer.”
Combination Therapy For Drug-Resistant Melanoma
N oting the ultimate failure of what seemed to be successful therapy with the BRAF-specific inhibitor, PLX4032, scientists from the Wistar Institute tested their belief that some cancers must be treated with multiple targeted drugs at the outset of treatment. Their findings, detailed in a press release from the Wistar Institute and published in Cancer Cell, describe the study in which 7 months after therapy with PLX4032, the tumors of those patients whose melanoma lesions contain a mutation in the BRAF gene returned and resumed growing. The scientists believe the reason for this development is that the tumor learns to signal around the blocked gene by adjusting its molecular wiring. They also show how to overcome resistance by simultaneously targeting multiple signaling pathways. “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, DVM, DSc, 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.”
Why PLX4032 Therapy Failed
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, PhD, 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.”
Countering Drug Resistance
To find out which alternate pathways the drug-resistant cells use, Dr. 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, 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. A number of compounds in clinical development that could block signals along both these pathways exist. 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 Dr. 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,” Dr. 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.
Recent research, news and treatment trends.
Genentech’s RG7204 Shows Survival Benefit in Phase III Metastatic Melanoma Patients
A Phase III clinical study (BRIM3) of Genentech’s RG7204 (PLX4032) showed a significant survival benefit in people with previously untreated BRAF V600 mutation-positive metastatic melanoma. The study compared RG7204, an investigational, oral, small molecule that is designed to selectively inhibit a cancer-causing mutated form of the BRAF protein, to dacarbazine, which is the current chemotherapy standard of care.
Study Method
BRIM3 (Study NO25026) is a global, randomized, open-label, controlled, multicenter, Phase III study evaluating RG7204 compared to dacarbazine in patients with previously untreated, BRAF V600 mutation-positive metastatic melanoma. Mutation status of the 675 enrolled patients was determined by the cobas 4800 BRAF V600 Mutation Test (Roche Molecular Diagnostics), a companion diagnostic assay being co-developed with RG7204. Study participants were randomized to receive either RG7204 960 mg orally twice daily or dacarbazine 1000 mg/m2 intravenously every 3 weeks. Patients continued dosing until their disease progressed or there was unacceptable toxicity.
Study Results
The study met its co-primary endpoints of overall survival and progression-free survival; based on these interim analysis results, all patients in the control arm of the study (dacarbazine) will be allowed to cross over and receive RG7204. The most frequent Grade 3 adverse event was skin-related and included cutaneous squamous cell carcinoma. Additionally, generally mild and reversible increases in liver enzymes (GGT, ALT, AST, alkaline phosphatase and bilirubin) were observed in some patients. The most common adverse events were rash, photosensitivity, joint pain, hair loss and fatigue. “For the first time, a personalized investigational medicine, RG7204, has shown a significant survival benefit in metastatic melanoma. This is an important advance for people with the BRAF V600 mutation-positive form of the disease who have had extremely limited treatment options,” said Hal Barron, MD, Chief Medical Officer and Head, Global Product Development of the Roche Group, of which Genetech is a member.
Two New GSK Drugs Studied for Advanced or Metastatic Melanoma
GlaxoSmithKline has begun late-stage trials of two new drugs for advanced or metastatic melanoma patients. GSK2118436 and GSK1120212 are being studied to see if they stop or slow the progression of skin cancer in patients whose tumors contain a BRAF V600 mutation. The BRF113683 Phase III study will compare GSK’436, a BRAF inhibitor, to chemotherapy drug dacarbazine (DTIC) in previously untreated patients with BRAF V600 mutated advanced or metastatic melanoma. The second study, METRIC, will compare MEK inhibitor GSK’212 to chemotherapy (DTIC or paclitaxel) in advanced or metastatic melanoma patients with a BRAF V600 mutation. Paolo Paoletti, president of GSK oncology, said, “By focusing our research program on patients with the V600 mutation, we are striving to understand how our investigational MEK and BRAF inhibitors can best be used to treat patients with metastatic melanoma. In addition to our ongoing research in metastatic melanoma, we are also studying GSK’212 and GSK’436, both alone and in combination with other agents, in other difficult-to-treat forms of cancer, including pancreatic cancer, refractory or relapsed leukemias and other solid tumors.”
Biomarker Test Shows Promise For Melanoma Diagnosis
A ccording to a press release from University of North Carolina (UNC) at Chapel Hill School of Medicine, a new study shows that a test of biomarkers for DNA methylation is technically feasible and could aid in earlier, more precise diagnosis of melanoma. In a paper published in Pigment Cell & Melanoma Research, the UNC team of researchers tested whether DNA methylation profiling could be accomplished on melanoma and mole tissues that had been preserved in fixatives for typical pathology examination after biopsy. They found that results on tissues prepared in this way were reliable and DNA methylation distinguished malignant melanomas from non-malignant moles. “Melanomas and moles can appear similar on the skin and under the microscope making diagnosis of some melanomas difficult. That's why we wanted to determine whether a test for DNA methylation is feasible as a tool for diagnosis,” said Nancy Thomas, MD, PhD, professor of dermatology and a member of UNC Lineberger Comprehensive Cancer Center. Kathleen Conway Dorsey, PhD, who is assistant research professor of epidemiology at UNC’s Gillings School of Global Public Health and a member of UNC Lineberger Comprehensive Cancer Center, added this comment: “We are very excited because, with this study, we have shown that this type of testing is feasible and that it has the potential to reliably distinguish between melanoma and benign skin lesions. Devising a molecular test that could aid in the early specific diagnosis of melanoma could have significant benefit for patients.” The team’s research pinpointed sites on 22 genes that have significantly different methylation levels between melanomas and non-melanoma lesions, as well as 12 locations that are highly predictive of melanoma. According to Dr. Thomas, another goal of the team is to develop a DNA-methylation test for melanoma tumor DNA that is shed into the bloodstream and that can serve as a measure for disease activity. “If this test can be developed, it opens the door to diagnose recurrence early and initiate treatment while tumors are more likely to respond to treatment. It would also give us another way to monitor patients for response to treatment and help us better optimize treatments for each patient,” Dr. Thomas noted. The research was funded by the National Cancer Institute and a UNC Lineberger Pilot Grant.
Academy Issues Updated Position Statement on Vitamin D
A press release from the American Academy of Dermatology detailed its updated position statement on vitamin D, which was based on the results of a review of scientific literature on this vitamin and its importance for optimal health recently conducted by the National Academy of Sciences Institute of Medicine (IOM). The IOM reviewed the scientific literature examining the possible relationship between vitamin D and certain types of cancers, neurologic disease, infectious disease, autoimmune disease and cardiovascular disease. Based on review of more than 1,000 studies and expert and stakeholder testimony, the IOM concluded that while the evidence for associating vitamin D levels with bone health was strong, the evidence for other conditions was inconsistent, inconclusive and insufficient to inform nutritional requirements. “The IOM’s review of the scientific evidence about vitamin D supports the Academy’s long-standing recommendation on safe ways to get this important vitamin — through a healthy diet which incorporates foods naturally rich in vitamin D, vitamin D-fortified foods and beverages, and vitamin D supplements,” stated dermatologist William D. James, MD, FAAD, president of the American Academy of Dermatology. “Unprotected exposure to UV radiation from the sun or indoor tanning is not safe. Individuals who intentionally expose themselves to UV radiation for vitamin D are putting their health at risk for developing skin cancer.”
Combination Therapy For Drug-Resistant Melanoma
N oting the ultimate failure of what seemed to be successful therapy with the BRAF-specific inhibitor, PLX4032, scientists from the Wistar Institute tested their belief that some cancers must be treated with multiple targeted drugs at the outset of treatment. Their findings, detailed in a press release from the Wistar Institute and published in Cancer Cell, describe the study in which 7 months after therapy with PLX4032, the tumors of those patients whose melanoma lesions contain a mutation in the BRAF gene returned and resumed growing. The scientists believe the reason for this development is that the tumor learns to signal around the blocked gene by adjusting its molecular wiring. They also show how to overcome resistance by simultaneously targeting multiple signaling pathways. “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, DVM, DSc, 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.”
Why PLX4032 Therapy Failed
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, PhD, 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.”
Countering Drug Resistance
To find out which alternate pathways the drug-resistant cells use, Dr. 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, 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. A number of compounds in clinical development that could block signals along both these pathways exist. 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 Dr. 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,” Dr. 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.