SHP-2 and PDL1 Inhibition Combined with Radiotherapy Enhances Systemic Antitumor Effects in an Anti-PD1-resistant Model of Non-small-cell-lung Cancer

Abstract

Immune checkpoint inhibitors such as anti-PD1/PDL1 have emerged as promising therapies for advanced non-small-cell-lung cancer (NSCLC). However, approximately 80% of patients do not respond to immunotherapy given alone because of intrinsic or acquired resistance. Radiotherapy (XRT) can overcome PD1 resistance and improve treatment outcomes, but its efficacy remains suboptimal. The tyrosine phosphatase SHP-2, expressed in some cancers and in immune cells, has been shown to negatively affect antitumor immunity. Our hypothesis was that SHP-2 inhibition in combination with α-PDL1 would enhance immune-mediated responses to XRT and synergistically boost antitumor effects in an anti-PD1-resistant mouse model. We treated 129Sv/Ev mice with anti-PD1-resistant 344SQ NSCLC adenocarcinoma xenografts with oral SHP099 (an SHP-2 inhibitor) combined with XRT and intraperitoneal α-PDL1. Primary tumors were treated with XRT (3 fractions of 12 Gy each), whereas abscopal (out-of-field) tumors were observed but not treated. In vitro experiments include: qRT-PCR, western blot, flow-cytometry, single-cell-sequence and nano-string. Results: o The Results single-cell-sequence of biopsies from advanced NSCLC patients showed that SHP-2 was significantly higher expressed in to anti-PD-1 non-responders (n = 8) compared to responders (n = 8) (P = 0.041). Then, in vitro and in vivo experiments confirmed that SHP-2 was higher expressed in PD-1 resistant NSCLC model comparing to sensitive model in qRT-PCR, western blot and flow-cytometry. o XRT in combination with SHP099 and α-PDL1 promoted local and abscopal responses, reduced lung metastases, and improved mouse survival. o Expression analysis of 770 immune-related genes indicated that triple therapy significantly increased macrophage function (P = 0.008 vs XRT alone, P = 0.028 vs XRT+α-PDL1), T-cell function (P = 0.003 vs control, P = 0.009 vs XRT alone), and decreased cancer progression (P = 0.048 vs control) in abscopal tumor sites. o Flow-cytometry immune profiling indicated that addition of anti-SHP-2 was associated with higher M1/M2 ratio, greater numbers of CD8+ T cells, and fewer regulatory T cells, compared to iRT group (XRT+anti-PD-L1). o The depletion experiment showed that the anti-tumor effects of triple therapy took place mainly through M1 TAMs and CD8+ T cells. This novel triple-combination therapy had strong antitumor effects in this mouse model of anti-PD1-resistant NSCLC, and may be a novel therapeutic approach for anti-PD1- resistant NSCLC in patients.