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Small molecule inhibitor of BCL2 in combination with RCHOP is effective in CD20 negative lymphoma

ABSTRACT: Rituximab alone or in combination with chemotherapeutics is the first-line therapy for variety of lymphoproliferative disorders including low- and high grade non-Hodgkin’s lymphomas (NHL). Although the complete response rate is quite impressive, vast majority of patient presents recurrent disease. The association between CD20 expression and clinical outcome in patients strongly suggests that reduced CD20 expression leads to inferior response to RCHOP (rituximab, cyclophosphamide, vincristine, doxorubicin and prednisone). In order to understand how loss of CD20 leads to development of RCHOP resistance, we developed rituximab resistant DOHH2 model in vivo by chronic exposure to rituximab. Characterization of several resistant in vivo xenografts revealed one model that maintained resistance to an acute dose of rituximab and demonstrated loss of CD20. Further characterization of the model demonstrated a loss of CD20 is associated with over expression of BCL2 and BIM. In vivo efficacy studies showed resistant line is insensitive to acute dose of RCHOP and treatment with an inhibitor of BCL2 (ABT199) in combination with chemotherapy resulted in better efficacy than RCHOP alone. We have identified an in vivo model of DLBCL where loss of CD20 and over expression of anti-apoptotic protein BCL2 leads to RCHOP resistance. These data suggest the addition of BCL2 inhibitor to chemotherapy might be effective in treating CD20 negative lymphomas.

ORGANISM(S): Homo sapiens

PROVIDER: GSE54201 | GEO | 2014/09/01

SECONDARY ACCESSION(S): PRJNA235876

REPOSITORIES: GEO

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Project description:Purpose: Despite recent advances in the treatment of patients with aggressive lymphomas, still a significant fraction of patients will succumb to their disease. Thus, novel therapeutic strategies are urgently needed. As the anti-CD20 antibody rituximab and the CD19-targeting antibody tafasitamab share distinct modes of actions, we investigated if dual-targeting of aggressive lymphoma B-cells by combining rituximab and tafasitamab might increase cytotoxic effects. Experimental Design: Antibody single and combination efficacy was determined investigating different modes of action including direct cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) in vitro and in vivo models of aggressive B-cell lymphoma comprising diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL). Results: Overall, three different sensitivity profiles to antibody monotherapy or combination treatment were observed in in vitro models: while 2/11 cell lines were primarily sensitive to tafasitamab and 2/11 were predominantly sensitive to rituximab treatment, the combination of tafasitamab and rituximab resulted in enhanced cell death in 7/11 cell lines in at least one mode of action. Treatment with either antibody or the combination resulted in decreased expression of the oncogenic transcription factor MYC and inhibition of AKT signaling which mirrored the cell line-specific sensitivities to direct cytotoxicity. At last, the combinatorial approach of the two antibodies resulted in a synergistic survival benefit in a PBMC-humanized Ramos NOD/SCID mouse model. Conclusions: This study demonstrates that the combination of tafasitamab and rituximab improves efficacy compared to antibody mono treatment in models of aggressive B-cell lymphoma in vitro and in vivo. Translational Relevance: The immunochemotherapy of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) remains the standard of care for newly diagnosed DLBCL patients. However, 30-40% of patients are refractory or relapse after initial response to the immunochemotherapy, indicating a high-unmet medical need for these patients. Tafasitamab and rituximab target the B-cell surface proteins CD19 and CD20, respectively, and both antibodies feature overlapping modes of action , namely direct cytotoxicity, ADCC and ADCP. In this study, we show that the combination of tafasitamab and rituximab had additive and synergistic efficacy both in vitro and in vivo. Our findings shed new light on the underlying mechanism of the combination of both antibodies and lay the ground to translate the results into improved outcome for patients with aggressive lymphoma in future clinical trials.

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Small molecule inhibitor of BCL2 in combination with RCHOP is effective in CD20 negative lymphoma

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