Abstract
Abstract
Non-Hodgkin’s lymphoma (NHL) and Hodgkin’s disease (HD) account for about 9% of new cancer cases annually or 64,000 cases per year in the United States. Although the survival rate has significantly improved recently due to new combination therapy regimens, an unmet medical need remains for refractory or resistant patients. HCD122 is a fully human antagonistic anti-CD40 therapeutic monoclonal antibody (mAb) with a dual mechanism of action: blocking CD40 and CD40 ligand (CD40L) interactions and mediating antibody-dependent cellular cytotoxicity (ADCC). CD40 is expressed in all human B-cell malignancies, and the CD40/CD40L interaction is important for tumor cell proliferation and survival. Previously HCD122 was shown to potently inhibit CD40L-induced human B-cell and follicular NHL cell proliferation, mediate ADCC against CD40-positive human malignant B-cell lines and inhibit tumor growth in Burkitt’s lymphoma and multiple myeloma xenograft models. In this study the antitumor activity of HCD122 was assessed in preclinical models of HD and other subtypes of human NHL, such as Mantle cell and Follicular lymphoma. CD40 was expressed in 5 of 7 established human HD and 11 of 12 NHL tumor cell lines tested, including Hs445, HDLM-2, KM-H2, L428, L1236, Jeko-1 and WSU-NHL. Using purified human NK cells as effector cells, HCD122 mediated potent ADCC against these cell lines in vitro with a picomolar EC50. When human macrophages were used as effector cells, HCD122 also induced antibody-dependent cellular phagocytosis (ADCP) against the NHL Daudi cell line and the HD cell line Hs445. The antitumor activity of HCD122 was further evaluated in vivo in EBV-negative NHL and HD xenograft models. When tested in a staged human Mantle cell lymphoma Jeko-1 s.c. xenograft model in which treatment was initiated when the mean tumor volume reached 100 mm3, HCD122 was highly efficacious and induced complete tumor regression in 70% (7/10) of treated animals when administered intraperitoneally at 1 mg/kg weekly for 4 weeks. In a staged human HD L428 s.c. xenograft model, which expresses CD20 as well as CD40, the antitumor activity of HCD122 was compared to rituximab. HCD122 was highly efficacious and induced a mean 74 % tumor growth inhibition (TGI) when administered at 0.1 mg/kg weekly for 3 weeks (p<0.001). At the same dose and schedule, rituximab achieved only 40% TGI (HCD122 vs. rituximab: p<0.001). These data combined with our previous studies in multiple myeloma and EBV-positive Burkitt’s lymphoma models show that HCD122 is a potent anti-CD40 antibody with pronounced antitumor activity in both EBV-positive and EBV-negative malignant B cell preclinical models. HCD122 is currently in Phase I clinical trials in B-cell malignancies.