The gist: A recent clinical trial with volunteer patients compared two treatments for metastatic melanoma. It showed that one of the treatments might give longer survival times for people whose tumors have mutations called BRAF V600E or BRAF V600K. This treatment combines the drugs dabrafenib and trametinib. In the trial, some patients were treated with the combination, and some were treated with only the drug vemurafenib (aka Zelboraf). People who took dabrafenib and trametinib lived several months longer than people who took vemurafenib. None of the patients had taken any previous treatments for their melanoma.
“The combination of dabrafenib and trametinib significantly extended OS compared with vemurafenib monotherapy in patients with treatment-naive metastatic melanoma who harbored BRAF V600E or V600K mutations, according to results of a randomized, open-label phase 3 study.
“The regimens demonstrated comparable toxicity profiles, researchers wrote.
“ ‘Together with the previously reported phase 2 and 3 trials of dabrafenib plus trametinib as compared with dabrafenib monotherapy, these data provide clear evidence for the benefit of this combination therapy over BRAF monotherapy in prolonging survival,’ Caroline Robert, MD, PhD, head of the dermatology unit at Institut Gustave-Roussy in Paris, and colleagues wrote.”
The gist: Researchers tested a new melanoma treatment in a clinical trial—a research study with volunteer patients. The treatment combines the targeted drugs dabrafenib and trametinib. All of the patients who participated in the trial had inoperable stage IIIC or stage IV melanoma. Also, each patient’s tumors had one of two particular mutations in the BRAF gene, known as V600E and V600K. In the trial, patients who were treated with the combination therapy had significantly lower chances of their cancer worsening and lower chances of death.
“A world-first study in today’s New England Journal of Medicine heralds the efficacy of a targeted combination drug therapy after reporting major declines in the risk of disease progression and death in people with metastatic melanoma.
“The multi-centre, double-blind, randomised, phase 3 trial compared oral dabrafenib (150 mg twice daily) and oral trametinib (2 mg once daily) combination therapy with oral dabrafenib (150 mg twice daily) and placebo.
“All trial patients had inoperable stage 3C or 4 metastatic melanoma that had a BRAF gene mutation V600E or V600K. Among cancer patients with metastatic melanoma, about 40 per cent have a BRAF gene mutation – an abnormality that assists some melanoma tumours to grow and spread.
“Led by Associate Professor Georgina Long of Melanoma Institute Australia at the University of Sydney, the finding affirms accumulating evidence of the efficacy of targeted combination therapies in extending life and halting disease progression in patients with cancers that carry genetic mutations that resist monotherapies.”
The gist: In the U.S. and Australia, oncologists are allowed to prescribe a treatment that combines the drugs Mekinist (trametinib) and Tafinlar (dabrafenib) for people with unresectable or metastatic melanoma whose tumors have a V600E or V600K mutation in the BRAF gene. European regulators would like to see more data on the benefits and risks of the treatment before approving it for European patients. The company that produces the treatment was conducting a clinical trial with volunteer patients to capture that data, but has now decided to halt the trial, which was comparing the combo treatment to the drug Zelboraf (vemurafenib). The trial found that the combo treatment has such a significant improvement on patient survival that the patients who had been taking vemurafenib for comparison should be allowed to switch to the combo treatment, and the trial ended early.
“GlaxoSmithKline has stopped a Phase III study of its combination therapy for advanced cutaneous melanoma ahead of schedule after it showed a significant survival benefit.
“The UK drug giant said an Independent Data Monitoring Committee (IDMC) has made the recommendation as it emerged patients with metastatic melanoma – carrying a BRAFV600 mutation – who took a combo of Mekinist (trametinib) and Tafinlar (dabrafenib) demonstrated an overall survival benefit compared to those taking vemarufenib.
“Safety signals were also good, remaining consistent with that for the MEK inhibitor and BRAF inhibitor observed to date, the firm said.”
“In the BRIM-3 trial, vemurafenib (Zelboraf) was associated with improved progression-free and overall survival vs dacarbazine in patients with advanced BRAF V600 mutation–positive melanoma. In an extended follow-up reported in The Lancet Oncology, McArthur et al found that superior survival outcomes were maintained and were present in both theBRAF V600E and BRAF V600K mutation subgroups.”
Editor’s note: Read more about vemurafenib here: http://www.nlm.nih.gov/medlineplus/druginfo/meds/a612009.html
Reuveni H, Flashner-Abramson E, Steiner L, Makedonski L, et al. Cancer Research. May 7, 2013.
“Insulin receptor substrates 1 and 2 (IRS1/2) mediate mitogenic and antiapoptotic signaling from insulin-like growth factor 1 receptor (IGF-IR), insulin receptor (IR), and other oncoproteins. IRS1 plays a central role in cancer cell proliferation, its expression is increased in many human malignancies, and its upregulation mediates resistance to anticancer drugs. IRS2 is associated with cancer cell motility and metastasis. Currently, there are no anticancer agents that target IRS1/2. We present new IGF-IR/IRS-targeted agents (NT compounds) that promote inhibitory Ser-phosphorylation and degradation of IRS1 and IRS2. Elimination of IRS1/2 results in long-term inhibition of IRS1/2-mediated signaling. The therapeutic significance of this inhibition in cancer cells was shown while unraveling a novel mechanism of resistance to B-RAFV600E/K inhibitors. We found that IRS1 is upregulated in PLX4032-resistant melanoma cells and in cell lines derived from patients whose tumors developed PLX4032 resistance. In both settings, NT compounds led to the elimination of IRS proteins and evoked cell death. Treatment with NT compounds in vivo significantly inhibited the growth of PLX4032-resistant tumors and displayed potent antitumor effects in ovarian and prostate cancers. Our findings offer preclinical proof-of-concept for IRS1/2 inhibitors as cancer therapeutics including PLX4032-resistant melanoma. By the elimination of IRS proteins, such agents should prevent acquisition of resistance to mutated-B-RAF inhibitors and possibly restore drug sensitivity in resistant tumors.”
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.
“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.”