Functional tumor cell-intrinsic STING, not host STING, drives local and systemic antitumor immunity and therapy efficacy following cryoablation

Abstract

BackgroundDespite its potential utility in delivering direct tumor killing and in situ whole-cell tumor vaccination, tumor cryoablation produces highly variable and unpredictable clinical response, limiting its clinical utility. The mechanism(s) driving cryoablation-induced local antitumor immunity and the associated abscopal effect is not well understood.MethodsThe aim of this study was to identify and explore a mechanism of action by which cryoablation enhances the therapeutic efficacy in metastatic tumor models. We used the subcutaneous mouse model of the rhabdomyosarcoma (RMS) cell lines RMS 76-9STINGwtor RMS 76-9STING-/-, along with other murine tumor models, in C57BL/6 or STING-/-(TMEM173-/-) mice to evaluate local tumor changes, lung metastasis, abscopal effect on distant tumors, and immune cell dynamics in the tumor microenvironment (TME).ResultsThe results show that cryoablation efficacy is dependent on both adaptive immunity and the STING signaling pathway. Contrary to current literature dictating an essential role of host-derived STING activation as a driver of antitumor immunity in vivo, we show that local tumor control, lung metastasis, and the abscopal effect on distant tumor are all critically dependent on a functioning tumor cell-intrinsic STING signaling pathway, which induces inflammatory chemokine and cytokine responses in the cryoablated TME. This reliance extends beyond cryoablation to include intratumoral STING agonist therapy. Additionally, surveys of gene expression databases and tissue microarrays of clinical tumor samples revealed a wide spectrum of expressions among STING-related signaling components.ConclusionsTumor cell-intrinsic STING pathway is a critical component underlying the effectiveness of cryoablation and suggests that expression of STING-related signaling components may serve as a potential therapy response biomarker. Our data also highlight an urgent need to further characterize tumor cell-intrinsic STING pathways and the associated downstream inflammatory response evoked by cryoablation and other STING-dependent therapy approaches.

Piezo1 facilitates optimal T cell activation during tumor challenge

“…Cryoablation in P1KO mice yielded tumors that initially regressed but then rebounded 12 days after the procedure ( Figure 2a ), with only 20% tumor-free survival compared to 80% of WT mice receiving cryoablation ( Figure 2b ), an observation very similar to RMS response to cryoablation in WT mice depleted of CD4 + T cells. 16 Interestingly, the overall CD45 + leukocyte and CD3 + T cell infiltration were similar in the TME ( Figure 2c,d ) and the tDLN ( Figure 2e ). Next, we assessed the quality of the effector T cells that may account for the ineffective response in P1KO mice.…”

“…RMS 76–9 induces a potent immunosuppressive TME that overwhelms the endogenous immune response over extended time periods ( Figure 2a ) 25 To mitigate this, we employed cryoablation, which induces immunogenic death and tumor clearance in a CD4 + and CD8 + T cell-dependent matter. 16 CD8 depletion yields cryoablated tumors no different in size than unablated tumors, while CD4 depletion results in partial therapeutic efficacy to cryoablation. Cryoablation in P1KO mice yielded tumors that initially regressed but then rebounded 12 days after the procedure ( Figure 2a ), with only 20% tumor-free survival compared to 80% of WT mice receiving cryoablation ( Figure 2b ), an observation very similar to RMS response to cryoablation in WT mice depleted of CD4 + T cells.…”

“…P1KO mice experienced enhanced tumor growth in vivo with two distinct tumor types, RMS and MM1 ( Figure 1d and S4b). Cryoablation, known to induce a potent T cell-dependent tumor rejection, 16 failed to induce an effective anti-tumor response in P1KO mice ( Figure 2a,b ). Underlying this ineffective response is a depressed CD4 + :CD8 + T cell ratio in the tDLN and TME ( Figure 1e,h and S2h,i), the significance of which is not immediately apparent.…”

“…Tumor-bearing P1KO mice fail to respond to cryotherapy, which stimulates a potent inflammatory TME that results in tumor rejection in WT mice. 16 The P1KO antitumor response is characterized by a depressed CD4 + :CD8 + T cell ratio in the tumor draining lymph node (tDLN) and TME that inversely correlates with tumor size. At the heart of this immunodeficiency is a deficit in antigen-specific T cell priming resulting in decreased helper CD4 + T cell functional activity and subsequent blunting of cytotoxic CD8 + T cell activation.…”