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Conference Abstract - MAP Kinase Pathway Alterations in BRAF-Mutant Melanoma Patients With Acquired Resistance to Combined RAF/MEK Inhibition

Conference Abstract - MAP Kinase Pathway Alterations in BRAF-Mutant Melanoma Patients With Acquired Resistance to Combined RAF/MEK Inhibition | Melanoma Dispatch | Scoop.it

"Treatment of BRAF-mutant melanoma with combined dabrafenib and trametinib, which target RAF and the downstream MAP–ERK kinase (MEK)1 and MEK2 kinases, respectively, improves progression-free survival and response rates compared with dabrafenib monotherapy. Mechanisms of clinical resistance to combined RAF/MEK inhibition are unknown. This study represents an initial clinical genomic study of acquired resistance to combined RAF/MEK inhibition in BRAF-mutant melanoma, using WES and RNA-seq. The presence of diverse resistance mechanisms suggests that serial biopsies and genomic/molecular profiling at the time of resistance may ultimately improve the care of patients with resistant BRAF-mutant melanoma by specifying tailored targeted combinations to overcome specific resistance mechanisms."


Editor's note: We previously covered the benefits of a dabrafenib/trametinib combo for advanced-stage melanoma. However, some patients' tumors become resistant to this drug combination and new treatment routes need to be considered. This study is exploring how molecular testing of specific genetic mutations in patients' tumors might be used to help guide treatment decisions after they become resistant to the dabrafenib/trametinib combo.

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MDLinx  |  Apr 8, 2014

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New Drug Overcomes Resistance to BRAF Inhibitors in Mice and Cultured Human Cells

An experimental drug may strengthen treatments that target melanomas with mutations in the BRAF gene, reported researchers from the pharmaceutical company Merck at the American Association for Cancer Research's 2013 meeting. Treatments that target BRAF often stop working because tumors activate a related protein called ERK, which is the target of Merck's new drug. Called SCH772984, the drug inhibits ERK in cultured human tumor cells with BRAF, NRAS, or KRAS mutations; slows cell division in human tumor cells that resist treatments that target BRAF or MEK; and shrinks tumors in mice. The researchers have begun a phase I clinical trial of an ERK inhibitor in people with tumors.

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American Association for Cancer Research│Apr 7, 2013

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Resistance to BRAF Inhibitors Is More Complicated Than Thought

Resistance to BRAF Inhibitors Is More Complicated Than Thought | Melanoma Dispatch | Scoop.it

Two new studies show that several different genetic mutations can make melanoma tumors resist drugs known as BRAF inhibitors, complicating treatment. These mutations are in genes that are part of the 'MAPK pathway.' The first study was on BRAF-inhibitor resistant melanomas from 45 people. In about half of the tumors, one of a set of three genes (MEK1, MEK2, MITF) was abnormal, and in three of the tumors more than one was abnormal.

The second study compared melanomas before and after resistance to combination treatment with both BRAF and MEK inhibitors. Tumors from three of the five people in the study developed genetic abnormalities that were not seen before treatment. On a positive note, when cells from resistant melanomas with both BRAF and MEK mutations were grown in the laboratory, they responded to a drug that inhibits a related protein called ERK.

The mutations in this study were all found in genes that code for proteins in the MAPK pathway, a particular group of proteins in a cell that work together to control cell multiplication that can lead to tumor growth. Knowing exactly which mutations a melanoma has will help doctors target it with the right combination of treatments.

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Cancer Discovery│Nov 21, 2013

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First Report that Vemurafenib Can Trigger Leukemia

A melanoma patient treated with vemurafenib also developed leukemia temporarily, according to a case report in The New England Journal of Medicine. This drug was already known to cause squamous cell skin cancers in some people with melanomas that have BRAF mutations. Vemurafenib activates proteins called extracellular-signal-regulated kinases (ERK), which are involved in cell division and can lead to cancer in cells that have RAS mutations. The leukemia in the vemurafenib-treated patient had a RAS mutation and disappeared after treatment ended. The patient’s melanoma tumors, which did not have a RAS mutation, shrank during treatment.

 

Primary source: http://www.nejm.org/doi/full/10.1056/NEJMoa1208958

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MedPage Today | Nov 8, 2012

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