LAUSR

Background/Aim: Rapid tumor growth after administration of immune checkpoint inhibitors is designated hyper progressive disease (HPD). In this study, besides the conventional HPD category, we proposed the “super HPD” category where the disease is naturally rapidly growing. Patients and Methods: Patients treated for advanced gastric cancer with irinotecan or nivolumab as a third-line treatment were retrospectively compared. Results: Eighteen and 26 patients were treated with irinotecan or nivolumab, respectively. There were 3 HPD cases (16.7%) in the irinotecan group, 6 cases (23.1%) in the nivolumab group, and the frequency of HPD was not significantly different. Two cases satisfied the super HPD definition only in the nivolumab group. When one of them was analyzed immunologically, the number of regulatory T cells was found to be increased, resulting in a low neutrophil-to-lymphocyte ratio. Conclusion: Our proposed super HPD was likely to represent a true HPD, with a frequency of 7.7%.