Immunomodulatory effects of bevacizumab in metastatic malignant melanoma

82 Background: Metastatic malignant melanoma is a nearly uniformly fatal disease. Systemic therapy has notable but limited success. Novel therapeutic strategies are urgently needed. To that end, we’ve pursued combinatorial therapeutics using conventional chemotherapy added to an inhibitor of angiogenesis (bevacizumab) with some evidence of clinical benefit. Preliminary analysis of one of our trials suggested a previously unrecognized immunomodulatory effect of bevacizumab when added to chemotherapy in patients with metastatic melanoma, and this may have a potential impact on clinical outcome. Herein we evaluate the immunomodulatory effect of bevacizumab when added to chemotherapy in patients with metastatic melanoma. Methods: We measured levels of peripheral blood mononuclear cell phenotypes in addition to 42 cytokines, chemokines and growth factors in plasma of 55 patients who received albumin-bound paclitaxel and carboplatin (AC) and of 73 patients who received AC with bevacizumab (ACB) on clinical trials N057e and N0775 respectively. The relative percent change in PBMC cell counts and cytokine levels were determined from baseline at their restaging evaluation after two cycles of therapy. The Mann Whitney U test was used to compare responses between the groups. Results: There was a significant increase in CD197+type 1 macrophages in the group that received ACB (35.3%, -11.8-142.7%) compared to AC (-11.6%, -45.9-38.3%; p=0.004). There was a significant decrease in IL-6 in the group that received ACB (-42.4%, -87.7-0.0%) compared to AC (28.4%, -37.4-480%; p=0.0018). Conclusions: The addition of bevacizumab to chemotherapy for the treatment of metastatic melanoma modulates cellular immunity and a pro-inflammatory cytokine. Patients who received bevacizumab had a significant increase in CD197+ type 1 macrophages and a significant decrease in IL-6. Clinical significance of these findings is the subject of ongoing work.