Hyperprogressive disease (HPD) during nivolumab (Nivo) or irinotecan (IRI) as salvage line in patients with metastatic gastric cancer (MGC).

126Background: Nivo was approved in heavily treated MGC patients in September 2017 in Japan. HPD have been reported in patients with various tumor types treated with anti-PD-1/PD-L1 antibody therapy, but no data was existed in gastric cancer. Methods: We retrospectively compared tumor growth kinetics (TGK) on Nivo or IRI as salvage line and TGK on last treatment in patients with MGC in our hospital. The TGK ratio (TGKR, ratio of the slope of tumor growth before treatment and the slope of tumor growth on treatment) was calculated. HPD was defined as a TGKR ≥ 2. Results: 51 patients have been treated Nivo (n = 31) or IRI (n = 20) as salvage line before Aug 2018 in our hospital. The median age was 67 years (range 37-81) in Nivo and 68 years (range 46-80) in IRI.; 20 males and 11 females in Nivo and 16 males and 4 females in IRI; PS 0-1/2 score 19/12 in Nivo and 19/1 in IRI. Thirty-five patients (Nivo : IRI = 16:19) had target lesions according to RECIST 1.1 and performed CT pre, baseline and during treatment...