Abstract
7534 Background: CD40 is a member of the TNF receptor family and is widely expressed on hematologic malignancies of B-cell origin. SGN-40 is a humanized antibody against CD40 with effector cell function and mild agonistic activity. Preclinical toxicity studies and efficacy data supported initiation of a multi-institutional phase I study to test the safety, pharmacokinetics, immunogenicity, and efficacy of SGN-40 in patients with relapsed NHL. Methods: Cohorts of 3–6 pts were treated weekly with a maximum dose of 2, 3, or 4 mg/kg/wk SGN-40. A dose escalation schedule is used such that patients receive 1 mg/kg on D1 and D4, 2 mg/kg on D8, and higher doses on weeks 3–5. Responding patients may receive a second cycle. Further dose escalation up to 8 mg/kg is planned. Results: 16 pts have been treated with multiple histologic subtypes: follicular (1), marginal zone (MZL; 1), mantle cell (4), and diffuse large B-cell (DLBCL; 10). One patient (2 mg/kg) developed a reversible Grade 3 unilateral conjunctivitis and ipsilateral loss of visual acuity. No other dose limiting toxicity has been observed up to 4 mg/kg. Preliminary pharmacokinetic data suggest that the antibody has a relatively short half-life, perhaps reflecting a route of elimination or binding that is not saturated at current doses. Two partial responses have been observed at 3 mg/kg (1 MZL, 1 DLBCL) and one partial response has been observed at 4 mg/kg dose (DLBCL relapsed after autologous stem cell transplant with small volume tumor). Conclusions: Using an intra-patient dose escalation schedule, SGN-40 has been well-tolerated at doses up to 4 mg/kg/wk. Further dose-escalation is ongoing to determine the maximum tolerated dose. Three objective responses have been seen, including two in patients with extensively treated aggressive disease. Correlative studies are underway measuring soluble CD40, cytokine release, effect of FcR polymorphisms, and SGN-40-induced immunogenicity. Given the favorable tolerability and activity, phase II studies in NHL are planned. [Table: see text]