Background: Recent studies have shown that approximately 20% of patients have 4-5 year progression free survival (PFS) on BRAF/MEK inhibitors. The long-term safety and efficacy in these patients with more durable responses have not been studied.
Methods: This retrospective multicenter cohort study assessed response, progression, and adverse events in patients from eight institutions in four countries with >4-year PFS following BRAF/MEK inhibitors.
Results: Among 146 patients, 112 (76.7%) remained progression-free at median follow-up of 7.8 years from treatment start; 131 (89.7%) were alive. Among progressors (n = 34), 21 (62%) were on treatment at progression. Among those who discontinued treatment for reasons other than progression (toxicity, preference, etc.) (n = 68, with median 49 months treatment duration), 13 (19%) progressed (median 15.3 months from treatment cessation to progression). Surgery or radiation for single-organ progression resulted in durable benefit in 11 of 22 patients (50%). Subsequent systemic therapy included immune therapy (24% responded) and BRAF/MEK rechallenge (56% responded). Thirteen (8.9%) patients had ongoing toxicities at last follow-up, 10 (77%) of which remained on active treatment; all cardiac adverse events had resolved (n = 9). Twenty-four (16.4%) patients developed any new primary cancer, and 28 (19%) patients experienced other major health events.
Conclusions: Over 75% of patients with 4-year PFS from BRAF/MEK inhibitors had continued durable antitumor responses after nearly 8-year median follow-up, with similar results in patients who discontinued therapy for reasons other than progression. Long-term toxicities were uncommon and low-grade. These findings highlight the often-favourable outcomes in patients with extended benefit from BRAF/MEK inhibitors.
Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: MSC has served on advisory boards or as a consultant for Amgen, BMS, Eisai, Ideaya, MSD, Nektar, Novartis, Oncosec, Pierre-Fabre, Qbiotics, Regeneron, Roche, Merck and Sanofi, and received honoraria from BMS, MSD, and Novartis. AMM has served on advisory boards for BMS, MSD, Novartis, Roche, Pierre-Fabre and QBiotics. EL served as consultant and/or has received honoraria from Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis, Pierre-Fabre, Sanofi, Sunpharma, Takeda and travel support from Bristol-Myers Squibb, Pierre- Fabre, Sunpharma and Novartis, outside the submitted work. RJS has served on advisory boards or as a consultant for BMS, Marengo, Merck, Novartis, Pfizer, and Replimune. GVL is consultant advisor for Agenus, Amgen, Array Biopharma, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Evaxion, Hexal AG (Sandoz Company), Highlight Therapeutics S.L., Innovent Biologics USA, Merck Sharpe & Dohme, Novartis, OncoSec, PHMR Ltd, Pierre Fabre, Provectus, Qbiotics, Regeneron. DS has served on advisory boards for BMS, Immunocore, MSD, Neracare, Novartis, Pfizer, Philogen, Pierre Fabre, and Sanofi/Regeneron. LW has served on advisory boards for BMS, MSD and Novartis. DBJ has served on advisory boards or as a consultant for BMS, Catalyst Biopharma, Iovance, Jansen, Mallinckrodt, Merck, Mosaic ImmunoEngineering, Novartis, Oncosec, Pfizer, Targovax, and Teiko, has received research funding from BMS and Incyte, and has patents pending for use of MHC-II as a biomarker for immune checkpoint inhibitor response, and abatacept as treatment for immune-related adverse events. All remaining authors have declared no conflicts of interest.
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