Concurrent MEK2 Mutation and BRAF Amplification Confer Resistance to BRAF and MEK Inhibitors in Melanoma

“Although BRAF and MEK inhibitors have proven clinical benefits in melanoma, most patients develop resistance. We report a de novo MEK2-Q60P mutation and BRAF gain in a melanoma from a patient who progressed on the MEK inhibitor trametinib and did not respond to the BRAF inhibitor dabrafenib. We also identified the same MEK2-Q60P mutation along with BRAF amplification in a xenograft tumor derived from a second melanoma patient resistant to the combination of dabrafenib and trametinib. Melanoma cells chronically exposed to trametinib acquired concurrent MEK2-Q60P mutation and BRAF-V600E amplification, which conferred resistance to MEK and BRAF inhibitors. The resistant cells had sustained MAPK activation and persistent phosphorylation of S6K. A triple combination of dabrafenib, trametinib, and the PI3K/mTOR inhibitor GSK2126458 led to sustained tumor growth inhibition. Hence, concurrent genetic events that sustain MAPK signaling can underlie resistance to both BRAF and MEK inhibitors, requiring novel therapeutic strategies to overcome it.”

Speedy Review for Melanoma Combo Treatment

The U.S. Food and Drug Administration (FDA) has granted a priority review of whether two melanoma drugs work better together. The drugs are a BRAF inhibitor called Tafinlar (dabrafenib) and a MEK inhibitor called Mekinist (trametinib); both are already FDA-approved for use separately. Tumors, however, often become resistant to BRAF inhibitors, growing back after an initial period of shrinking. The hope is that adding a MEK inhibitor will prevent this resistance. The FDA’s ruling on this combination targeted treatment is expected in January 2014.

FDA Asked to Approve New Combination Treatment for Melanoma

Two new drugs that target melanomas were approved by the US Food and Drug Administration in May, and the drug developer has already filed for approval to use them in combination. The drugs are dabrafenib (Tafinlar), a BRAF inhibitor, and trametinib (Mekinist), a MEK inhibitor, and both are made by GlaxoSmithKline. The combination treatment request is based on promising results of a Phase I/II trial, which showed that the two drugs work better together than dabrafenib does alone. Results of a Phase III trial of the combination therapy are expected later this year.

FDA Greenlights Two New Targeted Treatments for Melanoma

Good news for people with melanomas that have spread—the U.S. Food and Drug Administration just approved two new drugs that target tumors with common mutations. The drugs are dabrafenib (Tafinlar), a BRAF inhibitor, and trametinib (Mekinist), an MEK inhibitor. Developed by the pharmaceutical firm GlaxoSmithKline, both drugs target BRAF V600E mutations, which occur in about half of melanoma tumors. In addition, trametinib also targets V600K mutations, which are the next most common BRAF abnormalities. While these drugs have been tested in combination, using them together is not yet approved. The FDA also okayed a new test for the BRAF V600E mutation that is made by diagnostics firm bioMerieux.

2 Skin Cancer Drugs Win FDA Approval

“Two new drugs for metastatic or inoperable melanoma, dabrafenib (Tafinlar) and trametinib (Mekinist), were approved by the FDA on Wednesday.The agency also approved a companion diagnostic test for both agents to detect certain mutations in the BRAF gene that render melanoma cells susceptible to the drugs.”

Europe Accelerates Trametinib Review

The European Medicines Agency has granted a speedy review of trametinib, an experimental MEK inhibitor made by pharmaceutical company GlaxoSmithKline. The firm’s application for a European license includes findings from two studies of melanomas that have BRAF V600 mutations: a phase III trial comparing trametinib to two standard chemotherapy drugs (dacarbazine and paclitaxel) and a phase I/II trial comparing trametinib alone and in combination with the experimental BRAF-inhibitor dabrafenib. If approved, trametinib could be available to people with melanoma within 6 months.

Plexxikon updates Zelboraf Phase 1 data on BRAF V600E mutation-positive melanoma

Plexxikon today announced that updated Phase 1 clinical data of Zelboraf (vemurafenib) were presented at the Society for Melanoma Research (SMR) 2012 Congress, held November 8-11 in Los Angeles, CA.

Combined BRAF and MEK Inhibition Improves Outcome in Metastatic Melanoma

The combination of dabrafenib and trametinib is safe and effective in BRAF-mutant melanoma.

Watchdog approves skin cancer drugs ipilimumab and vemurafenib

Patients with an advanced form of skin cancer were given new hope today after the health watchdog recommended that two life-extending treatments should be available on the NHS.