Pembrolizumab versus placebo after complete resection of high-risk stage III melanoma: New recurrence-free survival results from the EORTC 1325-MG/Keynote 054 double-blinded phase III trial at three-year median follow-up.
Alexander M.M. Eggermont, Christian U. Blank, Mario Mandalà, Georgina V. Long, Victoria Atkinson, Stéphane Dalle, Andrew Haydon, Andrey Meshcheryakov, Muhammad A. Khattak, Matteo S. Carlino, Shahneen Sandhu, Susana Puig, Paolo A. Ascierto, Alexander Christopher Jonathan Van Akkooi, Clemens Krepler, Nageatte Ibrahim, Sandrine Marréaud, Michal Kiciński, Stefan Suciu, Caroline Robert
Abstract
10000 Background: We conducted the phase 3 double-blind EORTC 1325/KEYNOTE-054 trial to evaluate pembrolizumab vs placebo in patients (pts) with resected high-risk stage III melanoma. Based on 351 recurrence-free survival (RFS) events and at a median follow-up of 1.25 years (yrs), pembrolizumab improved RFS (hazard ratio (HR) 0.57, P<0.0001) as compared to placebo (Eggermont, NEJM 2018). This led to the approval of pembrolizumab adjuvant treatment by EMA and FDA. Methods: Eligible pts included those ≥18 yrs of age with complete resection of cutaneous melanoma metastatic to lymph node(s), classified as AJCC-7 stage IIIA (at least one lymph node metastasis >1 mm), IIIB or IIIC (without in-transit metastasis). A total of 1019 pts were randomized (stratification by stage and region) to pembrolizumab at a flat dose of 200 mg (N=514) or placebo (N=505) every 3 weeks for a total of 18 doses (~1 year) or until disease recurrence or unacceptable toxicity. The 2 co-primary endpoints were RFS in the intention-to-treat overall population and in pts with PD-L1-positive tumors. Here, we report an updated RFS analysis based on a longer follow-up. Results: Overall, 15%/46%/39% of pts had stage IIIA/IIIB/IIIC. At 3.05-yr median follow-up, pembrolizumab (190 RFS events) compared with placebo (283 RFS events) prolonged RFS, in the overall population and in the PD-L1 positive tumor subgroup (see Table). RFS was consistently prolonged across subgroups, in particular according to AJCC-7 staging, BRAF-V600 E/K mutation status. Conclusions: Pembrolizumab, administered at 200 mg every 3 weeks for up to 1 year as adjuvant therapy, provided, at a 3-yr median follow-up, a sustained improvement in RFS, which was clinically meaningful, in resected high-risk stage III melanoma. This improvement was consistent across subgroups. In the overall population, the 3-yr cumulative incidence of distant metastasis being the first recurrence was 22.3% (pembrolizumab group) vs 37.3% (placebo group) (HR 0.55, 95% CI 0.44-0.69). Clinical trial information: NCT02362594. [Table: see text]