The routes by which antibody-based therapeutics reach malignant cells are poorly defined. Tofacitinib, an FDA-approved JAK inhibitor, reduced tumor-associated inflammatory cells and allowed increased delivery of antibody-based agents to malignant cells. Alone, tofacitinib exhibited no antitumor activity, but combinations with immunotoxins or an antibody-drug conjugate resulted in increased antitumor responses. Quantification using flow cytometry revealed that antibody-based agents accumulated in malignant cells at higher percentages following tofacitinib treatment. Profiling of tofacitinib-treated tumor-bearing mice indicated that cytokine transcripts and various proteins involved in chemotaxis were reduced compared with vehicle-treated mice. Histological analysis revealed significant changes to the composition of the tumor microenvironment, with reductions in monocytes, macrophages, and neutrophils. Tumor-associated inflammatory cells contributed to non-target uptake of antibody-based therapeutics, with mice treated with tofacitinib showing decreased accumulation of therapeutics in intratumoral inflammatory cells and increased delivery to malignant cells. The present findings serve as a rationale for conducting trials where short-term treatments with tofacitinib could be administered in combination with antibody-based therapies.
Keywords: Breast cancer; Cancer; Cancer immunotherapy; Oncology; Therapeutics.