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Responses appear durable after completion of pembrolizumab therapy for melanoma
CHICAGO — Pembrolizumab demonstrated superior PFS and OS over ipilimumab after treatment ended among patients with advanced melanoma, according to long-term follow-up of the KEYNOTE-006 study presented at the ASCO Annual Meeting.
The anti–PD-1 antibody pembrolizumab (Keytruda, Merck) is approved in the United States and internationally for the treatment of advanced melanoma. Previous data from KEYNOTE-006 showed pembrolizumab conferred better long-term benefit over ipilimumab (Yervoy, Bristol-Myers Squibb) in ipilimumab-naive patients.
Caroline Robert, MD, PhD, head of the dermatology unit at Institute Gustave-Roussy in Paris, France, and colleagues conducted long-term follow-up of all patients who completed treatment with pembrolizumab.
The analysis included 834 patients assigned 10-mg/kg doses of pembrolizumab every 2 weeks or every 3 weeks, or 3-mg/kg ipilimumab every 3 weeks for four doses.
Treatment continued for pembrolizumab for 2 years or until disease progression, intolerable toxicity or patient/investigator decision to discontinue. Patients could interrupt pembrolizumab treatment for 12 or fewer weeks before discontinuing therapy.
Researchers performed tumor imaging at 12 weeks then every 6 weeks up to 48 weeks and every 12 weeks thereafter.
At the data cutoff of Nov. 3, 2016, median follow-up in the overall population was 33.9 months (range, 32.1-37.6).
Pooled data from patients treated with pembrolizumab showed 50% (n = 556) achieved 33-month OS compared with 39% (n = 278) of patients treated with ipilimumab. Researchers also reported higher rates of 33-month PFS (31% vs. 14%) and overall response rate (42% vs. 16%) in the pooled pembrolizumab arms.
The median duration of response was not reached for patients treated with pembrolizumab (range, 1.0+ month to 33.8+ months) or ipilimumab (range, 1.1+ month to 34.8+ months).
More than half of pembrolizumab-treated patients (68%) and ipilimumab-treated patients (58%) had a response lasting longer than 30 months.
The median exposure to pembrolizumab among patients who completed therapy (n = 104 of 556) was 24 months (range, 22.1-25.9). At a median follow-up of 9 months after completion of pembrolizumab, 102 (98%) of these patients remained alive.
At 9.7 months after completion of pembrolizumab, rates of PFS were 91% (95% CI, 80-96) in all 104 patients, 95% (95% CI, 69-99) in patients with complete response (n = 24), 91% (95% CI, 74-97) in patients with partial response (n = 68), and 83% (95% CI, 48-96) in patients with stable disease (n = 12).
Estimated risk for progression and mortality 10 months after completing pembrolizumab therapy was 9% and did not differ by best response to pembrolizumab.
“Data further support use of pembrolizumab as standard of care for patients with advanced melanoma,” Robert said during her presentation. – by Melinda Stevens
Reference:
Robert C, et al. Abstract 9504. Presented at: ASCO Annual Meeting; June 2-6, 2017; Chicago.
Disclosure: Robert reports consultant/advisory roles with Amgen, Bristol-Myers Squibb, GlaxoSmithKline, Merck, Merck Serono, Novartis and Roche. Please see the abstract for a list of all other researchers’ relevant financial disclosures.
Perspective
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This is an important update on the Keynote 006 study, which addresses whether it is safe to discontinue PD-1 blockade after the patients have completed a certain duration of treatment —generally up to 2 years in most trials of PD-1 blockade. This update provides us long-term follow-up on patients who had good response to pembrolizumab (Keytruda, Merck) and have stopped treatment. The progression free rate of approximately 90% at follow-up is excellent and suggests that immunotherapy responses are proving to be durable even after the discontinuation of immunotherapy.