“Prior treatment with immunotherapy did not limit response to BRAF inhibitors among patients with metastatic melanoma, according to results of a retrospective study.
“However, patients who underwent initial treatment with BRAF inhibitors and subsequently received immunotherapy with ipilimumab (Yervoy, Bristol-Myers Squibb) demonstrated poorer outcomes, results showed.
“Patients with BRAF-positive metastatic melanoma have several treatment options, including BRAF inhibitors vemurafenib (Zelboraf, Hoffmann-La Roche) and dabrafenib (Taflinar, GlaxoSmithKline), the MEK inhibitor trametinib (Mekinist, GlaxoSmithKline), and the immunotherapy agents ipilimumab and interleukin-2. Yet, there are limited data with regard to optimal sequencing, according to researchers.”
“As reported in The Lancet Oncology by Larkin et al, interim results of a safety study designed to reflect the spectrum of patients encountered in routine practice suggest that vemurafenib (Zelboraf) has a safety profile in patients with BRAF V600–mutated metastatic melanoma similar to that observed in the more select patient population included in registration trials. The study included patients with limited treatment options and sizable proportions with brain metastases, elevated lactate dehydrogenase (LDH), poor performance status, and age ≥ 75 years.”
Editor’s Note: The important takeaway from this story is that the drug vemurafenib can be used safely and effectively in some melanoma patients with poor prognoses, who may not fit the profile of patients typically enrolled in clinical trials to test the drug. To learn more about clinical trials and “targeted therapies” like vemurafenib, visit our Melanoma Basics.
“Half of melanoma patients with the BRAF mutation have a positive response to treatment with BRAF inhibitors, but nearly all of those patients develop resistance to the drugs and experience disease progression.
“Now, a new preclinical study published online ahead of print in the Journal of Clinical Investigation from Penn Medicine researchers found that in many cases the root of the resistance may lie in a never-before-seen autophagy mechanism induced by the BRAF inhibitors vermurafenib and dabrafenib. Autophagy is a process by which cancer cells recycle essential building blocks to fuel further growth. Block this pathway with the antimalarial drug hydroxycholoroquine [sic] (HCQ), the authors found, and the BRAF inhibitors will be able to do their job better…
“Based on these promising preclinical results, Dr. Amaravadi and his team have already launched a clinical trial for patients with advanced BRAF mutant melanoma to see how well-tolerated HCQ is with the BRAF inhibitor vemurafenib. ‘So far,’ he said, ‘we are seeing a benefit to patients and low toxicity.’ “
“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
The US Food and Drug Administration just granted accelerated approval for a treatment that combines two drugs that target melanomas with BRAF mutations — but this was contingent on the results of an ongoing phase III clinical trial. The drugs are the BRAF inhibitor dabrafenib (Tafinlar) and the MEK inhibitor trametinib (Mekinist). Now the latest results of the trial are in and they look good. This combination treatment is not approved elsewhere in the world, and the trial included 423 people from Australia, Europe, and North and South America. Final results are expected later this year and will be presented at a scientific meeting. In addition, another trial is comparing this combination treatment to the BRAF inhibitor vemurafenib (Zelboraf), which is also FDA-approved.
More than one-third of melanomas are ‘pan-negative,’ meaning they lack known mutations that can be targeted for treatment. But now researchers have identified two new genetic abnormalities in pan-negative melanomas. These abnormalities consist of the BRAF gene joined with another gene (PAPSS1 or TRIM24), and so are called BRAF fusions. The new study showed that about 8% of pan-negative melanomas have BRAF fusions. Next, the researchers grew melanoma cells with these BRAF fusions in the lab and tested known targeted treatments on them. While these cultured cells were not sensitive to the BRAF inhibitor vemurafenib, they were sensitive to the MEK inhibitor trametinib, suggesting that MEK inhibitors could be used to target melanomas with these BRAF fusions.
Because melanomas can quickly resist BRAF inhibitor drugs alone or in combination with MEK inhibitors, researchers are testing a new combination treatment: the BRAF inhibitor vemurafenib and PX-866, which inhibits a cancer pathway called PI3K. In a phase I/II clinical trial of 19 people with melanomas that have BRAF mutations, the vemurafenib/PX-866 combination shrank tumors in 10 of them. These findings were presented at the 10th International Congress of the Society for Melanoma Research in Philadelphia. However, while results so far are encouraging, it will take larger trials to see if this new combo treatment really overcomes drug resistance in melanomas. This ongoing trial is still accepting new participants.
We already knew that melanomas can resist BRAF inhibitor drugs by activating a particular cancer pathway (a group of proteins in a cell that work together to control cell multiplication, which can lead to tumor growth)—but new research shows that this resistance can also be caused by activating a second cancer pathway. The first pathway is called MAPK and the second is called PI3K-PTEN-AKT. The researchers studied 100 melanomas that resisted the BRAF inhibitors vemurafenib or dabrafenib, and found that 70% had mutations in the first pathway, while 22% had mutations in the second pathway. Moreover, mutations in both pathways could occur in the same tumor, suggesting that thwarting resistance to BRAF inhibitors may require targeting both pathways with a combination treatment.