Darzalex Faspro (Daratumumab and Hyaluronidase-fihj) Before Standard Desensitization and Allogeneic Peripheral Blood Stem Cell Transplantation in Adult Patients at High-risk for Primary Graft Failure Secondary to Donor Specific Antibodies

This research is being done to investigate the safety and effectiveness of Darzalex Faspro (daratumumab and hyaluronidase-fihj) (a monoclonal antibody that targets plasma cells that make antibodies) and whether it can lower donor specific antibodies (DSA) levels to low enough levels to permit patients to proceed with allogeneic peripheral blood transplant (alloBMT). Those being asked to participate have high DSA levels that puts those being asked to participate at high risk of rejecting the available donor's blood stem cells and making those being asked to participate ineligible to receive a stem cell transplant.

Allogeneic blood or bone marrow transplant (alloBMT) remains the definitive curative treatment for many with relapsed or refractory hematologic malignancies. In recent years, increased use of alternative (non-fully human leukocyte antigen (HLA)-matched) donors has led to increased rates of donor specific antibodies (DSA). DSA are pre-formed HLA-antibodies in the recipient directed against the donor's class I and/or class II HLA antigens. DSA can be formed by exposure to foreign HLA antigens most commonly by pregnancy, blood transfusions, and previous organ or blood transplantation. High levels of circulating anti-HLA antibodies directed towards mismatched donor HLA antigens at the time of alloBMT can dramatically increase the risk of primary graft failure (PGF). The strength of these donor specific antibodies (DSA) can be assessed with several methodologies including cross-matched cellular based assays (cytotoxic or flow cytometric assessment) or the more sensitive solid phase immunoassay (SPI) that estimates antibody level. Methods to "desensitize" patients with elevated DSAs using therapeutic plasma exchange (TPE), intravenous immunoglobulin (IVIG), and immunosuppression (i.e., mycophenolate mofetil and tacrolimus) are successful in patients with moderate levels of DSAs. However, in many patients, the DSA levels are considered too high for desensitization, or, desensitization has failed to lower levels of the DSA, and suitable alternative donors cannot be readily identified. In this single-institution study at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center (SKCCC), we will identify patients in whom alloBMT is indicated, but where DSA levels are above a pre-defined threshold using a proprietary algorithm that combines information from flow cytometric crossmatch (FCXM) and SPI (the Johns Hopkins (JH)-DSA Semi-Quant Screen Score). Patients who meet eligibility criteria will undergo 4 weekly doses of treatment with Darzalex Faspro, an anti- 38 (cluster of differentiation 38) antibody that kills plasma cells and lowers immunoglobulin levels, followed by standard desensitization with TPE, IVIG, and immunosuppression. Eight subjects will be treated in this pilot study. The primary endpoint will be based on safety of Darzalex Faspro and the number of patients who have DSA levels lowered enough to proceed to conditioning based on a pre-defined algorithm called JH-DSA Semi-Quant Response Score.