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UPDATED: GSK aces pivotal studies for pair of melanoma drugs

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Look out Roche. Because here comes GlaxoSmithKline ($GSK) touting upbeat results of two Phase III studies of the targeted drugs dabrafenib and trametinib in patients with metastatic melanoma. And the London-based drugmaker is now out to see how the pair of drugs taken together compares with Roche's ($RHHBY) approved Zelboraf in combating the deadly skin cancer.

During the American Society for Clinical Oncology meeting in Chicago, GSK provided data from the two late-stage studies that compared each of its experimental treatments alone to standard chemotherapy in metastatic melanoma patients with BRAF mutations. In the BREAK3 study, patients on GSK's BRAF-blocking drug dabrafenib lived for 5.1 months without their cancer advancing compared with 2.7 months of PFS for patients on chemotherapy. And the METRIC study showed that patients on GSK's MEK inhibitor trametinib went 4.8 months without their cancer worsening, more than three times longer than patients who got chemo.

Some typical side effects for patients on trametinib included rashes, diarrhea and fatigue, while some patients taking dabrafenib had hyperkeratosis, headaches and pyrexia.  

GSK plans to submit applications for approval of each of the targeted drugs for treating the skin cancer. Yet investigators and company officials are most jazzed about the prospects of using a combo of the two drugs to treat melanoma, after a Phase I/II study showed that the tandem of treatments reduced the risk of a common side effect of therapy with BRAF inhibitors--the development of non-melanoma skin tumors. A new Phase III study compares the combo with Roche's BRAF inhibitor Zelboraf, which was approved last year, and another late-stage trial puts the combo of experimental drugs head-to-head with GSK's dabrafenib.

Citigroup analyst Andrew Baum provided some blockbuster sales estimates of the two GSK drugs, saying in note to investors that the pair could bring 1.5 billion pounds in 2020, according to Bloomberg, and he believes that the British drug giant could quickly draw business away from rival Roche for BRAF inhibitors.

For GSK, the rapid development of the two programs underscores the changing landscape of R&D in oncology.

"It has been the fastest experience of my entire career," Paolo Paoletti, the president of GSK Oncology, tells FierceBiotech.

Starting a little more than three years ago, GSK launched early-stage studies of the two drugs, adapting and expanding the studies to add patients and test doses. Luckily, he adds, GSK had the two drugs in-house. And the speed with which they've been developed will help investigators in other programs, where the emphasis will be on rapidly gaining proof-of-concept data on smaller groups of patients who share a specific mutation.

"We are rolling; the interest is so great the enrollment will be very quick," he told Bloomberg, of the late-stage trials of the combo treatment. And he added that his company could be on to a new gold standard for melanoma care if the trials pan out.

- here's GSK's release
- read Bloomberg's article
- and Reuters' report

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GSK lands one-two punch in melanoma trial
ASCO data to shine new light on Pfizer, Roche, J&J drugs

Editor's note: Updated with a quote and reporting from Editor-in-Chief John Carroll, who interviewed GSK today at the ASCO meeting.