GlaxoSmithKline plc's phase III study of the combination of Tafinlar (dabrafenib) and Mekinist (trametinib), compared to single agent therapy with Tafinlar in patients with BRAF V600 E or K mutation positive unresectable or metastatic melanoma, met its primary endpoint of Progression Free Survival (PFS) (p<0.05).This follows the recent accelerated approval of the combined therapy in the USA.

PFS, response rate and interim overall survival results for the combination arm were consistent with those seen in the phase I/II study. In this phase III study, PFS observed among patients in the single agent dabrafenib arm was greater than that seen in previous single agent dabrafenib studies, leading to a more modest difference in PFS between treatment arms than was observed in the phase I/II study. In the combination arm, the most commonly reported (>20%) adverse events were pyrexia, fatigue, nausea, headache, chills, diarrhoea, arthralgia, rash, hypertension, and vomiting. Full study results will be presented at an upcoming scientific meeting.

“We are pleased to report that the first of our phase III studies investigating the combination of Tafinlar and Mekinist met its primary endpoint. These results, along with data we expect to receive later in the year from our Phase III study comparing the combination to vemurafenib, will increase the body of evidence on the safety and efficacy of this combination in appropriate patients with melanoma,” said Dr Rafael Amado, senior vice president Oncology R&D, GSK.

The phase III programme for dabrafenib and trametinib in BRAF V600E/K metastatic melanoma comprises two studies: COMBI-d (also known as MEK MEK115306) and COMBI-v (also known as MEK116513).

Today’s results are from COMBI-d (NCT01584648) a phase III, randomised, double-blinded study comparing the combination of the BRAF inhibitor, dabrafenib and the MEK inhibitor, trametinib to dabrafenib and placebo as first-line therapy in patients with unresectable (Stage IIIC) or metastatic (Stage IV) BRAF V600E/K mutation-positive cutaneous melanoma. The primary endpoint of the study is progression-free survival and patients will be followed for overall survival.  The study randomised 423 patients from investigative sites in Australia, Europe, North and South America.

COMBI-v (NCT01597908) is a phase III, randomised, open-label study comparing the combination of the BRAF inhibitor, dabrafenib and the MEK inhibitor, trametinib to the BRAF inhibitor vemurafenib in patients with unresectable (Stage IIIC) or metastatic (Stage IV) BRAF V600E/K mutation-positive cutaneous melanoma. The primary endpoint of the study is overall survival and results are anticipated in 2014.

Combination use of Tafinlar and Mekinist in patients with BRAF V600E or K metastatic melanoma is approved for use only in the US and is not approved anywhere else in the world.

GSK is committed to improving the quality of human life by enabling people to do more, feel better and live longer.