ALBERT

Description: ISF35 is a novel CD40-binding protein designed to maximize stable, high-level surface-expression of this potent immuno-stimulatory molecule on cells transduced to express this protein. In a recent clinical study, patients with chronic lymphocytic leukemia (CLL) received intravenous infusions of autologous leukemia cells transduced ex vivo to express ISF35 using a replication-defective adenovirus vector (Ad-ISF35). This treatment was well tolerated, did not have dose-limiting toxicity, and had apparent clinical activity. Moreover, injection of autologous, ISF35-expressing CLL cells induced upregulation of death receptors and pro-apoptotic proteins on bystander, non-infected CLL cells, resulting in acute cytoreductions in leukemia cell counts and reductions in the size of lymph nodes and spleen of the treated patients (Wierda et al. Blood. 2007; 110: a-2040). Because of this and preclinical studies demonstrating specific anti-lymphoma activity of Ad-ISF35 when directly injected into growing tumor nodules of experimental animals, we conducted a first-in-man phase I clinical study, evaluating the safety of direct intra-nodal injections of Ad-ISF35 in patients with CLL. Fifteen patients, ranging in age from 45 to 71 years (median age 55, 10 male and 5 female), with progressive CLL (Rai stage III and IV) and leukemia-cell doubling times of 0.9 to 22.5 months (median 3.3 months) participated in a dose-escalation study involving successive cohorts of 3 patients each. The patients in each cohort received a single injection of 1x1010, 3 x1010, 1x1011 or 3x1011 Ad-ISF35 viral particles into a pathologically enlarged axillary lymph node under ultrasound guidance. Intranodal injection with Ad-ISF35 was well tolerated. Adverse events included erythema, swelling and/or pain at the site of injection and “flu like symptoms”, which occurred primarily during the first 24 hours of treatment. At the two highest dosing cohorts, three of three patients in the 3x1011 cohort and two of six patients in the 1x1011 cohort developed Grade 3 and 4 asymptomatic and transient neutropenia and hypophosphatemia one to three weeks after the injection of Ad-ISF35. In all patients, the neutropenia and hypophosphatemia resolved following administration of filgastrim and oral phosphate. Although Ad-ISF35 was injected into only one axillary lymph node, we observed significant reductions in absolute numbers of CLL cells in the blood and reductions in the size of all lymph nodes and the spleen in 14 of 15 evaluable patients. The reduction was durable in 9 patients and the leukemia cell counts have remained below pre-treatment levels for up to four months after a single intra-nodal injection of Ad-ISF35, even in patients who had rapid CLL doubling times prior to therapy. Although we have no evidence for dissemination of Ad-ISF35 beyond the injected lymph node, we observed up-regulation of death receptors, immune co-stimulatory molecules, and pro-apoptotic proteins in the circulating, non-infected CLL cells of the treated patients, suggesting a bystander effect. In addition, we observed increased blood levels of interferon-gamma and interleukin-12 beginning 8 hours after injection. In summary, we found that direct intranodal injection of Ad-ISF35 into patients with CLL was well tolerated and had systemic biologic and clinical activity, suggesting that this approach might be effective in the treatment of patients with this disease and other B-cell lymphomas.