The long-term outcome of cancer patients responding to an anti-PD-1/PD-L1 immunotherapy (IT) remains unknown. This study aimed to describe the long-term survival of patients responding to anti-PD-1/PD-L1 monotherapy across multiple cancer types.
306 patients treated with an anti-PD-1 or PD-L1 monotherapy in a phase 1 trial at Gustave Roussy were retrospectively analyzed over a period of 5 years. Major inclusion criteria were: at least 18 years-old, performance status 0-1, at least 1 infusion, evaluation by RECIST 1:1 and/or irRC. Multiple myeloma patients were excluded as they do not respond to anti-PD-1 monotherapy. All other cancer types (n = 19) were included.
The overall objective response rate within this cohort of 262 patients was 29% (n = 76; 77% being evaluated by irRC). The median PFS of responders was 22 months and the median OS was not reached. The OS of patients responding to IT at 3 years was 76% and at 5 years was 63%. Long responders (patients with enough follow up to have tumor responses lasting more than 2 years) represented 11.8% of the cohort (31 patients). No death occurred in the 21 complete responders over this long term follow up. The median duration of response was not reached. Out of the 33 patients who disontinued immunotherapy, 9 patients showed a disease relapse (median response duration after treatment discontinuation: 6 months). Clinical and biological factors associated with response, long term survival, and secondary refractory disease will be reported at the ESMO meeting.
This study shows that, across cancer types, patients with objective tumor responses under anti-PD-1/PD-L1 immunotherapy have a high level of overall survival. Best survivals are seen with complete responses (no deaths in our cohort). Complete response rate might be a good short term surrogate marker for overall survival benefits. Clinical trials aiming at putting patients with partial responses under immunotherapy into complete responses should be assessed in a near future.
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All authors have declared no conflicts of interest.