Phase I dose escalation study of the anti-IGF-1R monoclonal antibody CP-751,871 in patients with refractory solid tumors

3586 Background: The insulin-like growth factor 1 receptor (IGF-IR), a tyrosine kinase, and its ligands (IGF-I & -2) are upregulated in many human tumors (e.g., breast, prostate, colon and non-small cell lung cancer) and enhance proliferative and prosurvival signaling. Inhibition of IGF-IR activation in tumor models suppresses tumor growth and increases tumor sensitivity to chemotherapy, supporting the development of agents targeting IGF-IR. CP-751,871 is a potent, highly specific, fully humanized, monoclonal antibody that inhibits IGF-IR autophosphorylation and induces receptor internalization. Methods: A Phase I dose escalation study was initiated to define the safety and tolerability, and to characterize the pharmacokinetic properties of CP-751,871 in patients with advanced solid tumors refractory to standard therapies. Results: Following informed consent and screening, a total of 24 patients with refractory solid tumors (e.g. colorectal, NSCLC, sarcoma and prostate cancer; 1–6 previous regimens) were enrolled. Patients received 3 to 20 mg/kg of CP-751,871 by IV infusion on Day 1 of 3-week cycles in four dose-escalation cohorts of 3 patients. No dose limiting toxicities were identified and the maximum feasible dose (MFD) cohort of 20 mg/kg was extended with 12 additional patients. No higher than grade 3 CTCAE v3.0 toxicities, attributed to study drug, have been so far reported. Grade 3 toxicities, all reported in patients dosed with 20 mg/kg of CP-751,871, are increased GGT (4%) and fatigue (4%). Grade 2 toxicities include: anorexia (7%), diarrhea (7%), increased GGT (4%), hyperglycemia (4%), fatigue (4%), increased urinary frequency (4%), nausea (4%), increased ALT (4%) and increased AST (4%). Pharmacokinetic analysis is currently ongoing. No objective responses were observed. At the MFD, patients received a median of 4 cycles (1–16). Three patients were stable for > 6 months and one patient, currently at cycle 16, remains on study. An additional cohort of 12 adrenocortical cancer patients is under evaluation. Conclusions: These data indicate that CP-751,871 is safe and well tolerated. Due to its good safety profile, CP-751,871 may constitute a suitable targeted agent to use in combination with approved therapies in multiple tumor types. No significant financial relationships to disclose.