Anti-Macrophage monoclonal antibody, clone SRO393

Background: Advanced stage cancers with a suppressive tumor microenvironment (TME) are often refractory to immune checkpoint inhibitor (ICI) therapy. Recent studies have shown that focused ultrasound (FUS) TME-modulation can synergize ICI therapy, but enhancing survival outcomes in poorly immunogenic tumors remains challenging. Here, we investigated the role of focused ultrasound based boiling histotripsy (HT) and in-situ anti-CD40 agonist antibody (alpha CD40) combinatorial therapy in enhancing therapeutic efficacy against ICI refractory murine melanoma. Methods: Unilateral and bilateral large (similar to 330-400 mm(3)) poorly immunogenic B16F10 melanoma tumors were established in the flank regions of mice. Tumors were exposed to single local HT followed by an in-situ administration of aCD40 (HT+ alpha CD40: HT40). Inflammatory signatures post treatment were assessed using pan-cancer immune profiling and flow cytometry. The ability of HT40 +/- ICI to enhance local and systemic effects was determined by immunological characterization of the harvested tissues, and by tumor growth delay of local and distant untreated tumors 4-6 weeks post treatment. Results: Immune profiling revealed that HT40 upregulated a variety of inflammatory markers in the tumors. Immunologically, HT40 treated tumors showed an increased population of granzyme B+ expressing functional CD8+ T cells (similar to 4-fold) as well as an increased M1 to M2 macrophage ratio (similar to 2-3-fold) and CD8+ T: regulatory T cell ratio (similar to 5-fold) compared to the untreated control. Systemically, the proliferation rates of the melanoma-specific memory T cell population were significantly enhanced by HT40 treatment. Finally, the combination of HT40 and ICI therapy (anti-CTLA-4 and anti-PD-L1) caused superior inhibition of distant untreated tumors, and prolonged survival rates compared to the control. Conclusions: Data suggest that HT40 reprograms immunologically cold tumors and sensitizes them to ICI therapy. This approach may be clinically useful for treating advanced stage melanoma cancers.

Nabumetone is used to control pain and inflammation in rheumatoid arthritis. It works through inhibition of cyclooxygenases (COX), especially COX-2. In the current study, Nabumetone immunomodulatory effect was detected on cellular immunity in mice. The control group was administered normal saline orally as placebo. Nabumetone was administered orally in two treatment groups 14mg/kg and 28mg/kg, respectively by gavage needle. Macrophage engulfment, delayed type hypersensitivity (DTH), nitric oxide measurement and cyclophosphamide induced neutropenia assays were used to evaluate the immunomodulatory effects. In DTH, there was more thickness of the skin in control than Nabumetone treatment groups (p <= 0.05). In the macrophage engulfment assay, a significant decrease (p <= 0.05) in engulfment percentage were observed in treatment groups. In cyclophosphamide induced neutropenia, the levels of TLC and DLC were higher in the control group (p <= 0.05). In the nitric oxide measurement assay, there was significant reduction in nitric oxide production at higher doses of Nabumetone (p <= 0.05). Therefore, it is concluded that Nabumetone suppress cellular immune responses in mice.