Antitumor Activity of Ipilimumab or BRAF ± MEK Inhibition After Pembrolizumab in Patients With Advanced Melanoma: Analysis from KEYNOTE-006.

Long GV, Arance A, Mortier L, Lorigan P, Blank C, Mohr P, Schachter J, Grob JJ, Lotem M, Middleton MR, Neyns B, Steven N, Ribas A, Walpole E, Carlino MS, Lebbe C, Sznol M, Jensen E, Leiby MA, Ibrahim N, Robert C. Ann Oncol. (Epub 26 Oct 2021)

Abstract

Background: Antitumor activity of ipilimumab or BRAF ± MEK inhibitors (BRAFi ± MEKi) following pembrolizumab administration in melanoma is poorly characterized.

Patients and methods: In the phase III KEYNOTE-006 study, patients with unresectable stage III/IV melanoma received pembrolizumab (10 mg/kg) once every 2 or 3 weeks (Q3W) or ipilimumab (3 mg/kg) Q3W. The current post hoc analysis evaluates outcomes with ipilimumab or BRAFi ± MEKi as first subsequent systemic therapy after pembrolizumab administration and includes patients who completed or discontinued pembrolizumab after one or more dose. Pembrolizumab arms were pooled.

Results: At data cut-off (4 December 2017), median follow-up was 46.9 months. Of 555 pembrolizumab-treated patients, first subsequent therapy was ipilimumab for 103 (18.6%) and BRAFi ± MEKi for 59 (10.6%) [33 received BRAFi + MEKi, 26 BRAFi alone; 37 (62.7%) were BRAFi ± MEKi naïve]. In the subsequent ipilimumab group, ORR with previous pembrolizumab was 17.5% [1 complete response (CR); 17 partial response (PR)]; 79.6% had discontinued pembrolizumab due to progressive disease (PD); median overall survival (OS) was 21.5 months. ORR with subsequent ipilimumab was 15.5%; 11/16 responses (8 CRs; 3 PRs) were ongoing. ORR with subsequent ipilimumab was 9.7% for patients with PD as best response to pembrolizumab. Median OS from ipilimumab initiation was 9.8 months. In the subsequent BRAFi ± MEKi group, ORR with previous pembrolizumab was 13.5% (8 PR); 76.3% had discontinued pembrolizumab due to PD; median OS was 17.9 months. ORR with subsequent BRAFi ± MEKi was 30.5%, 7/18 responses (4 CR, 3 PR) were ongoing. Median OS from BRAFi ± MEKi initiation was 12.9 months. ORR for BRAFi ± MEKi-naïve patients who received subsequent BRAFi ± MEKi was 43.2%; 6/16 were ongoing (3 CR, 3 PR).

Conclusions: Ipilimumab and BRAFi ± MEKi have antitumor activity as first subsequent therapy after pembrolizumab in patients with advanced melanoma.

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