In situ immunogenic clearance induced by a combination of photodynamic therapy and rho-kinase inhibition sensitizes immune checkpoint blockade response to elicit systemic antitumor immunity against intraocular melanoma and its metastasis

Abstract

BackgroundUveal melanoma (UM) is the most frequent intraocular malignancy and is resistant to immunotherapy. Nearly 50% of patients with UM develop metastatic disease, and the overall survival outcome remains very poor. Therefore, a treatment regimen that simultaneously targets primary UM and prevents metastasis is needed. Here, we suggest an immunotherapeutic strategy for UM involving a combination of local photodynamic therapy (PDT), rho-kinase (ROCK) inhibitor, and PD-1/PD-L1 immune checkpoint blockade.MethodsThe antitumor efficacy and immune response of monotreatment or combinational treatment were evaluated in B16F10-bearing syngeneic mouse models. Abscopal antitumor immune responses induced by triple-combinational treatment were validated in syngeneic bilateral B16F10 models. After each treatment, the immune profiles and functional examinations were assessed in tumors and tumor draining lymph nodes by flow cytometry, ELISA, and immunofluorescence assays. In orthotopic intraocular melanoma models, the location of the immune infiltrate in the tumor microenvironment (TME) was evaluated after each treatment by multiplex immunohistochemistry and metastatic nodules were monitored.ResultsPDT with Ce6-embedded nanophotosensitizer (FIC-PDT) elicited immunogenic cell death and stimulated antigen-presenting cells. In situ immunogenic clearance induced by a combination of FIC-PDT with ripasudil, a clinically approved ROCK inhibitor, stimulated antigen-presenting cells, which in turn primed tumor-specific cytotoxic T cells. Moreover, local immunogenic clearance sensitized PD-1/PD-L1 immune checkpoint blockade responses to reconstruct the TME immune phenotypes of cold tumors into hot tumors, resulting in recruitment of robust cytotoxic CD8+ T cells in the TME, propagation of systemic antitumor immunity to mediate abscopal effects, and prolonged survival. In an immune-privileged orthotopic intraocular melanoma model, even low-dose FIC-PDT and ripasudil combined with anti-PD-L1 antibody reduced the primary tumor burden and prevented metastasis.ConclusionsA combination of localized FIC-PDT and a ROCK inhibitor exerted a cancer vaccine-like function. Immunogenic clearance led to the trafficking of CD8+ T cells into the primary tumor site and sensitized the immune checkpoint blockade response to evoke systemic antitumor immunity to inhibit metastasis, one of the major challenges in UM therapy. Thus, immunogenic clearance induced by FIC-PDT and ROCK inhibitor combined with anti-PD-L1 antibody could be a potent immunotherapeutic strategy for UM.

Rho GTPase signaling in cancer progression and dissemination

“…In addition, combination of ROCK inhibitors and anti-PD1 reduced PD-L1 expression in both tumour cells and macrophages (155), likely via STAT3 (247). Finally, ROCK inhibitors in combination with photodynamic therapy induced immunogenic clearance involving increased CD8 T cell infiltration and the re-sensitisation to immune checkpoint blockage (483).…”

Rho-Kinase as a Target for Cancer Therapy and Its Immunotherapeutic Potential

“…Furthermore, in addition to this capacity of ROCK inhibitors of enhancing antigen presentation, a combination with immunogenic cell death (ICD) inducers such as doxorubicin or photodynamic therapy showed a synergistic effect in suppressing tumor growth. This combination of ‘Eat me’ signal increase by ICD inducers and the augmented phagocytosis by ROCK inhibitors collectively boosted antitumor immunity, effectively recruiting CD8 + T-cells, sensitizing the immune-excluded or immune desert tumors to improve their response toward immune checkpoint blockade therapies [ 132 , 133 ].…”

The role of interferons in melanoma resistance to immune checkpoint blockade: mechanisms of escape and therapeutic implications

“…These therapies are known inducers of immunogenic cell death and promote the release of type I IFNs that act in an autocrine/paracrine fashion on tumour cells and DCs 55,56 . Such mechanisms may indeed explain the therapeutic benefit achieved in murine melanoma models and patients with melanoma treated with these regimens in combination with checkpoint inhibitors 57,58 …”

“…55, 56 Such mechanisms may indeed explain the therapeutic benefit achieved in murine melanoma models and patients with melanoma treated with these regimens in combination with checkpoint inhibitors. 57,58 Other strategies to promote IFN signalling in tumours that maintain responsiveness to this pathway have also been explored. Delivery of exogenous type I IFNs into tumour tissue in the context of checkpoint blockade has shown therapeutic benefit in multiple murine tumour models.…”