96291-114

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Abstract Disclosures

Background: Dabrafenib, a selective BRAF inhibitor, has shown activity with a manageable safety profile in phase I/II studies in patients (pts) with BRAF^V600E-mutated metastatic melanoma (MM). This phase III trial (NCT01227889) compared progression-free survival (PFS) in pts with advanced MM treated either with dabrafenib or dacarbazine (DTIC). Methods: Pts with previously untreated, unresectable stage III or IV BRAF^V600E-mutated melanoma were randomized (3:1) and stratified by stage to dabrafenib (150 mg po bid) or DTIC (1000 mg/m², IV, q3w). Primary endpoint was investigator-assessed PFS. Primary analysis for PFS was planned after 102 events. Pts on the DTIC arm were allowed to cross over once progression was confirmed by independent review (IR). Secondary endpoints included PFS by IR, overall survival (OS), response rate (RR), duration of response, safety and pharmacokinetics. Results: 250 pts were enrolled at 93 centers globally from February to September 2011. 187 were randomized to dabrafenib and 63 to DTIC. 141pts were on study treatment at the data cut-off at December 19, 2011 (dabrafenib n = 127; DTIC n = 14), including 21/28 DTIC pts crossed over to dabrafenib. Median age was 52 years, 31% of pts were ECOG >1, 66% M1c, 33% LDH > ULN. Demographics were well balanced between the two arms. At the time of the primary analysis, there were 118 events (77 dabrafenib and 41 DTIC). The hazard ratio for PFS was 0.30 (95% CI: 0.18–0.53; p < 0.0001). Median PFS was 5.1 months for dabrafenib and 2.7 for DTIC. OS data were immature, with 30 deaths reported. Confirmed RR was 53% for dabrafenib and 19% for DTIC. Benefits in PFS and RR were observed in all subgroups evaluated. Common adverse events (AEs) on the dabrafenib arm were hyperkeratosis (37%), headache (32%), pyrexia (28%), arthralgia (27%), skin papillomas (24%). Serious AEs (> 1%) on the dabrafenib arm included pyrexia (4%), squamous cell carcinomas (6%), and new primary melanomas (2%). Conclusions: Dabrafenib demonstrated a significant improvement in PFS and ORR over DTIC with an acceptable safety profile.