Clinical significance of PD-1-binding soluble PD-L1 and MMPs in the microenvironment of gastric cancer and non-small cell lung cancer treated with PD-1/PD-L1 blockade

Purpose: The tumor microenvironment (TME) impacts the therapeutic efficacy of immune checkpoint inhibitors (ICIs). No liquid biomarkers are available to evaluate TME heterogeneity. Here, we investigated the clinical significance of PD-1-binding soluble PD-L1 (bsPD-L1) in gastric cancer (GC) patients and non-small cell lung cancer (NSCLC) patients treated with PD-1/PD-L1 blockade. Experimental Design: We examined bsPD-L1, matrix metalloproteinases (MMPs), and IFN-γ levels in plasma samples from GC patients (n =117) prior to surgery and NSCLC patients (n =72) prior to and two months after ICI treatment and extracellular matrix (ECM) integrity, PD-L1 expression, and T cell infiltration in tumor tissues from 25 GC patients. Results: bsPD-L1 was detected in 17/117 GC patients and 16/72 NSCLC patients. bsPD-L1 was strongly and moderately correlated with MMP13 and MMP3, respectively. In GC, bsPD-L1 expression was associated with IFN-γ levels and intra-tumoral T cell infiltration; MMP13 levels were associated with loss of ECM integrity, allowing tumor cells to access blood vessels. MMP3 and MMP13 levels were altered during ICI treatment. Combination of bsPD-L1 and MMP levels identified two patient groups; bsPD-L1+MMP13high in GC and bsPD-L1+(MMP3 and MMP13)increased in NSCLC were associated with poor prognosis, and bsPD-L1+MMP13low in GC and bsPD-L1+(MMP3 or MMP13)decreased in NSCLC were associated with favorable prognosis. Conclusions: Plasma bsPD-L1 and MMP13 levels indicate T cell response and loss of ECM integrity, respectively, in the TME. The combination of bsPD-L1 and MMPs may represent a non-invasive tool to predict recurrence in GC and the efficacy of ICIs in NSCLC. ### Competing Interest Statement Y. Iwai has past patent applications for immunopotentiating compositions (WO/2009/0297518, 2011/0081341, 2014/0314714, 2015/0093380, 2015/0197572, 2016/0158356, 2016/0158355, 2017/0051060, and 2020/0062846) and immune function evaluation method (WO/2019/049974). Y. Iwai reports a research grant from Sysmex Corporation. A. Gemma reports consulting fees from MSD, Nippon Kayaku, and Daiichi-Sankyo Company outside the submitted work. M. Seike reports receiving research grants from Taiho Pharmaceutical, Chugai Pharmaceutical, Eli Lilly, Nippon Kayaku, and Kyowa Hakko Kirin and honoraria from AstraZeneca, MSD, Chugai Pharmaceutical, Taiho Pharmaceutical, Eli Lilly, Ono Pharmaceutical, Bristol-Myers Squibb, Nippon Boehringer Ingelheim, Pfizer, Novartis, Takeda Pharmaceutical, Kyowa Hakko Kirin, Nippon Kayaku, Daiichi-Sankyo Company, Merck Biopharma, and Amgen outside the submitted work. The other authors declare no potential conflicts of interest. ### Funding Statement This work was supported by the Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JP19K07783 and 22K07262 to Y. I.) and a research grant from Sysmex Corporation (to Y. I.). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study protocols (B-2019-005, 28-09-646) were approved by the Ethics Committee of Nippon Medical School. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript.