Combination Therapy With An Antibody Specific For Transferrin Receptor 1 (Ch128.1/Igg1) And Bortezomib Or Lenalidomide Results In Increased Survival In An In Vivo Model Of Human Multiple Myeloma

Multiple myeloma (MM) is a B-cell proliferative disorder of monoclonal malignant plasma cells. It is the second most common hematologic malignancy in the United States, after non-Hodgkin lymphoma (NHL). Clinical manifestations of MM include osteolytic bone lesions, hypercalcemia, renal failure, anemia, recurrent infections, and neuropathy. Standard treatments for MM include the proteasome inhibitor bortezomib, as well as lenalidomide, a thalidomide analog with immunomodulatory and antiangiogenic properties. Although the use of these two agents in combination with other therapies have significantly improved MM survival, the disease remains incurable. We previously developed a mouse/human chimeric antibody (ch128.1/IgG1) specific for human transferrin receptor 1 (TfR1). TfR1, also known as CD71, is a meaningful target for antibody-based cancer therapy, given its high expression on malignant cells and relevant role in cancer cell pathology. We have reported that treatment of SCID-Beige mice bearing disseminated human KMS-11, MM.1S, or MM.1R myeloma tumors with ch128.1/IgG1 results in significant antitumor activity in early and late disease stages. The mechanism of antitumor activity is Fc-mediated in which macrophages are considered to play a relevant role. Since combining multiple treatments with differing mechanisms of action is an effective antitumor strategy, and given the relevance of bortezomib and lenalidomide in MM therapy, we decided to explore, for the first time, the combination of these two agents with ch128.1/IgG1. We found that treatment with a single dose of ch128.1/IgG1, or multiple doses of bortezomib or lenalidomide used as single agents, results in significant antitumor activity in SCID-Beige mice bearing late stage disseminated human MM.1S tumors. However, this antitumor activity is superior when ch128.1/IgG1 was combined with bortezomib or lenalidomide, showing significantly longer survival compared to each therapy used alone. These results suggest that the addition of a ch128.1/IgG1 therapy arm in a combinatorial treatment regimen involving bortezomib and/or lenalidomide is a promising strategy against human B-cell malignancies such as MM. Citation Format: Pierre V. Candelaria, Miguel Nava, Otoniel Martinez-Maza, Tracy R. Daniels-Wells, Manuel L. Penichet. Combination therapy with an antibody specific for transferrin receptor 1 (ch128.1/IgG1) and bortezomib or lenalidomide results in increased survival in an in vivo model of human multiple myeloma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4436.