Apoptotic and antitumor activity of death receptor antibodies require inhibitory Fcγ receptor engagement

Abstract

By virtue of their ability to induce apoptosis and regulate growth, differentiation, and cytokine responses, the tumor necrosis factor receptor (TNFR) superfamily members have emerged as attractive targets for anticancer therapeutics. Agonistic antibodies to apoptosisinducing TNFRs, such as death receptor 5 (DR5), although displaying impressive activities against a variety of tumors in preclinical models, appear to be less active in clinical trials. We report that the in vivo apoptotic and antitumor activities of these antibodies have an absolute requirement for the coengagement of an inhibitory Fcγ receptor, FcγRIIB. Anti-DR5 antibodies of the type currently in clinical trials have weak FcγRIIB binding and thus are compromised in their proapoptotic and antitumor activities in both colon and breast carcinoma models. Enhancing FcγRIIB engagement increases apoptotic and antitumor potency. Our results demonstrate that Fc domain interactions are critical to the therapeutic activity of anti-DR5 antibodies and, together with previous reports on agonistic anti-CD40 antibodies, establish a common requirement for FcγRIIB coengagement for optimal biological effects of agonistic anti-TNFR antibodies.cancer immunotherapy | Fc engineering | human FCGR2B | antibody-dependent cell-mediated cytotoxicity

Antitumor activities of agonistic anti-TNFR antibodies require differential FcγRIIB coengagement in vivo

“…Many tumor necrosis factor receptor (TNFR) superfamily members such as CD40 and DR5 control key signaling pathways involved in immune and antitumor responses, and agonistic antibodies targeting these molecules have shown promising antitumor activities in preclinical studies (13). We and others have recently found that both agonistic αCD40 and αDR5 antibodies require Fc-FcγR interactions for their in vivo activities and, in contrast to cytotoxic effector antitumor antibodies, these agonistic antibodies require no activating FcγRs, but inhibitory FcγRIIB (14)(15)(16). These studies, together with previous and other recent studies (17,18), have established a general requirement of FcγRIIB for the in vivo activities of agonistic anti-TNFR antibodies (19).…”

“…These studies, together with previous and other recent studies (17,18), have established a general requirement of FcγRIIB for the in vivo activities of agonistic anti-TNFR antibodies (19). In addition, we have also demonstrated that Fcs that preferentially bind to inhibitory FcγRIIB are more potent for agonistic anti-TNFR antibodies, and that the potency of agonistic anti-TNFR antibodies can be enhanced through FcγRIIB-targeted Fc engineering (14,15). Although these studies have provided a logical approach to designing potent agonistic anti-TNFR antibodies, the in vivo mechanism underlying this general FcγRIIB requirement remains to be determined.…”

“…In contrast, activating FcγRs are clearly not sufficient, and even detrimental, in supporting the in vivo activities of these agonistic anti-TNFR antibodies (14)(15)(16)18). Among many possible reasons, the inconsistency between in vitro and in vivo studies could be due to oversimplification or fundamentally a lack of tissue structure in the in vitro systems, highlighting the importance of using in vivo models.…”

“…MC38 cells (10 6 per mouse) were implanted s.c. After 5-7 d, mice with palpable tumors were treated with 100 μg per mouse of MD5-1 or control hamster IgG i.v. three times at 4-d intervals, and monitored for tumor growth as described previously (15). In IIA1.6 and IIA1.6-derived B-cell lymphoma models, mice received 2.5 × 10 7 tumor cells on day 0 and 200 μg of 1C10 or control antibodies on day 7 and 10 through i.v.…”

“…All mouse studies had been approved by The Rockefeller University Institutional Animal Care and Use Committee. Agonistic antibodies against mouse CD40 [1C10, and 1C10-derived αCD40:mIgG1, αCD40: mIgG1(D265A), and αCD40:hIgG1(S267E)], DR5 (MD5-1), and Fas (Jo2) have been described previously (14,15,17).…”