BackgroundNivolumab showed a survival benefit for advanced gastric cancer (AGC). However, an acceleration of tumour growth during immunotherapy, (hyperprogressive disease, HPD) has been reported in various cancers. This study reviewed the HPD in patients with AGC treated with nivolumab or irinotecan.MethodsThe subjects of this retrospective study were patients with AGC with measurable lesions, and their tumour growth rates (TGR) during nivolumab or irinotecan were compared with those during prior therapy. HPD was defined as an increase in TGR more than twofold.Results34 and 66 patients received nivolumab and irinotecan in third or later line between June 2009 and September 2018 at our hospital; 22 patients receiving nivolumab had prior treatment with irinotecan, and one patient received irinotecan after nivolumab. Nivolumab and irinotecan showed no differences in disease control rates (38.2% and 34.8%) and in progression-free survival (PFS) (HR 1.1, 95% CI 0.7 to 1.6, p=0.802). The incidence of HPD was slightly higher after nivolumab (29.4%) than after irinotecan (13.5%) (p=0.0656), showing no differences in background between the patients with and without HPD. Compared between HPD and PD other than HPD after nivolumab, the HRs for PFS and overall survival (OS) were 1.1 (95% CI 0.5 to 2.7; p=0.756), and 2.1 (95% CI 0.7 to 5.8; p=0.168), but such clear difference in OS was not observed after irinotecan.ConclusionsHPD was observed more frequently after nivolumab compared with irinotecan, which was associated with a poor prognosis after nivolumab but not so clearly after irinotecan.

BackgroundRecent studies have shown that immune-related adverse events (irAEs) caused by immune checkpoint inhibitors were associated with clinical benefit in patients with melanoma or lung cancer. In advanced gastric cancer (AGC) patients, there have been few reports about the correlation between irAEs and efficacy of immune checkpoint inhibitors. In this study, we retrospectively investigated the correlation between irAEs and efficacy in AGC patients treated with nivolumab.MethodsThe subjects of this study were AGC patients received nivolumab monotherapy between January 2015 and August 2018. IrAEs were defined as those AEs having a potential immunological basis that required close follow-up, or immunosuppressive therapy and/or endocrine therapy. We divided the patients who received nivolumab into two groups based on occurrence of irAEs; those with irAEs (irAE group) or those without (non-irAE group). We assessed the efficacy in both groups.ResultsOf the 65 AGC patients that received nivolumab monotherapy, 14 developed irAEs. The median time to onset of irAEs was 30.5 days (range 3–407 days). Median follow-up period for survivors was 32 months (95% CI, 10.8 to 34.5). The median progression-free survival was 7.5 months (95% CI, 3.6 to 11.5) in the irAE group and 1.4 months (95% CI, 1.2 to 1.6) in the non-irAE group (HR = 0.11, p < 0.001). The median overall survival was 16.8 months (95% CI, 4.4 to not reached) in the irAE group and 3.2 months (95% CI, 2.2 to 4.1) in the non-irAE group (HR = 0.17, p < 0.001). Multivariate analysis demonstrated that number of metastatic sites ≥2 (HR = 2.15; 95% CI, 1.02 to 4.54), high ALP level (HR = 2.50; 95% CI, 1.27 to 4.54), and absence of irAEs (HR = 9.54, 95% CI, 3.34 to 27.30 for yes vs. no) were associated with a poor prognosis. The most frequent irAEs was diarrhea/colitis (n = 5). Grade 3 adverse events were observed in 6 patients; hyperglycemia (n = 2), diarrhea/colitis (n = 1), adrenal insufficiency (n = 1), aspartate aminotransferase increased (n = 1), peripheral motor neuropathy (n = 1). There were no grade 4 or 5 adverse events related to nivolumab.ConclusionsDevelopment of irAEs was associated with clinical benefit for AGC patients receiving nivolumab monotherapy.

4049 Background: Recent studies have shown that immune-related adverse events (irAEs) caused by immune checkpoint inhibitors were associated with clinical benefit in patients with melanoma or lung cancer. In advanced gastric cancer (AGC) patients, there have been few reports about the correlation between irAEs and efficacy of immune checkpoint inhibitors. Therefore, in this study, we retrospectively investigated the correlation between irAEs and efficacy in AGC patients treated with nivolumab. Methods: The subjects of this study were AGC patients that had received nivolumab monotherapy between January 2015 and August 2018. IrAEs were defined as those AEs having a potential immunological basis that required close follow-up, or immunosuppressive therapy and/or endocrine therapy. We divided the patients who received nivolumab into two groups based on occurrence of irAEs; those with irAEs (irAE group) or those without (non-irAE group). We assessed the efficacy in both groups. Results: Of the 65 AGC patients that received nivolumab monotherapy, 14 developed irAEs. The median time to onset of irAEs was 30.5 days (range 3–407 days). Median follow-up period for survivors was 32 months (95% CI, 10.8 to 34.5). The median progression-free survival was 7.5 months (95% CI, 3.6 to 11.5) in the irAE group and 1.4 months (95% CI, 1.2 to 1.6) in the non-irAE group (HR = 0.11, p < 0.001). The median overall survival was 16.8 months (95% CI, 4.4 to not reached) in the irAE group and 3.2 months (95% CI, 2.2 to 4.1) in the non-irAE group (HR = 0.17, p < 0.001). Multivariate analysis demonstrated that high ALP level (HR = 2.88; 95% CI, 1.51 to 5.51) and absence of irAEs (HR = 3.06, 95% CI, 3.06 to 23.46 for yes vs. no) were associated with a poor prognosis. The most frequent irAEs was diarrhea/colitis (n = 5). Grade 3 adverse events were observed in 6 patients; hyperglycemia (n = 2), diarrhea/colitis (n = 1), adrenal insufficiency (n = 1), increased aspartate aminotransferase increased (n = 1), peripheral motor neuropathy (n = 1). One of the 14 patients experienced the irAE after discontinuation of nivolumab due to progression of disease. There were no grade 4 or 5 adverse events related to nivolumab. Conclusions: Development of irAEs was associated with clinical benefit for AGC patients receiving nivolumab monotherapy.

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Recurrence and treatment resistance are major causes of cancer-associated death. There has been a growing interest in better understanding epithelial-mesenchymal transition, stemness of cancer cells, and exhaustion and dysfunction of the immune system for which numerous genomic, proteomic, microenvironmental, and immunologic mechanisms have been demonstrated. However, practical treatments for such patients have not yet been established. Here we identified IL33 as a key driver of polyploidy, followed by rapid proliferation after treatment. IL33 induction transformed tumor cells into polyploid giant cells, showing abnormal cell cycle without cell division accompanied by Snail deregulation and p53 inactivation; small progeny cells were generated in response to treatment stress. Simultaneously, soluble IL33 was released from tumor cells, leading to expansion of receptor ST2-expressing cells including IL17RB þ GATA3 þ cells, which promoted tumor progression and metastasis directly and indirectly via induction of immune exhaustion and dysfunction. Blocking IL33 with a specific mAb in murine IL33 þ metastatic tumor models abrogated negative consequences and successfully elicited antitumor efficacy induced by other combined treatments. Ex vivo assays using tumor tissues and peripheral blood mononuclear cells of patients with cancer validated the clinical relevancy of these findings. Together, these data suggest that targeting the IL33-ST2 axis is a promising strategy for diagnosis and treatment of patients likely to be resistant to treatments in the clinical settings.Significance: These findings indicate that the functional role of IL33 in cancer polyploidy contributes to intrinsic and extrinsic mechanisms underlying treatment failure. Materials and Methods MiceFive-week-old female C57BL/6 mice were purchased from Charles River Laboratories, and were maintained under pathogen-free conditions. The mice were used according to the protocols approved by the Animal Care and Use Committee at the National Cancer Center Research Institute (Tokyo, Japan). Cell linesHuman breast cancer cell lines (MCF7 and MDA-MB-231) were purchased from ATCC, and were authenticated by short tandem repeat profiling. Murine melanoma B16-B10 cells were purchased from the Cell Resource Center for Biomedical Research at Tohoku University in Japan. We used B16-F10 cells transfected with plasmid vector pcDNA3.1(þ) encoding neomycin-resistant gene with or without murine snail (F10-snail þ or F10-mock) that we established before (7). All tumor cells were tested for Mycoplasma negativity using a Hoechst-staining Detection Kit (MP Biomedicals) and were expanded and frozen in liquid nitrogen to avoid changes occurred by a long-term culture until used in experiments. Establishment of B16-F10 subclonesF10-mock cells were harvested from subcutaneous tumors (F10primary) and femur bone marrow (F10-BM) of mice 25 days after implantation and were cultured in 10% FBS/DMEM with Geneticin