ALBERT

Description: CD40 is a type I transmembrane protein that upon binding to CD40 ligand regulates important biologic effects in the immune system. CD40 is also highly expressed on hematologic tumors, which has raised interest in the potential for its use as a tumor target for antibody-based cancer therapy. SGN-40 is a humanized monoclonal antibody that selectively binds to human CD40 and induces apoptosis and growth inhibition of a wide variety of B-cell derived cancer cell lines in vitro. Our preclinical work has confirmed the in vitro cytotoxicity of SGN-40 against human multiple myeloma (MM) cells via several mechanisms. These include induction of cytotoxic ligands of TNF superfamily; suppression of IL-6-induced proliferative and anti-apoptotic effects, as well as antibody-dependent cell-mediated cytotoxicity (Tai, et al, Cancer Research64, 2846–2852, April 15, 2004). Since ≥ 90% of MM cells express CD40, targeting CD40 using SGN-40 presents a potential novel treatment strategy. Based on these preclinical data, a phase I study is being conducted to define the toxicity profile, characterize the pharmacokinetics (PK), and evaluate antitumor effects of SGN-40 in patients with refractory or recurrent MM. Four weekly doses ranging from 0.5 to 16 mg/kg are planned to be administered to groups of at least three patients per cohort. Patients will be followed for up to 6 weeks post their last dose. Currently, a total of seven patients have been treated with SGN-40 at dose levels of 0.5 and 1.0 mg/kg. No grade 3 or 4 non-hematologic dose limiting toxicities have been observed. One patient experienced a transient Grade 3 decrease in hemoglobin. Decrease in CD19 positive B-cells were noted for patients treated at both dose levels. Changes in serum and urine M protein levels were measured to estimate potential anti-tumor effects of SGN-40. Of the seven patients evaluated, one patient at 0.5 mg/kg dose had stable disease, based on serum M protein, over the 10 week study period. Clinical evaluation with dose escalation of this agent continues and updated safety, PK and antitumor data will be presented.