A phase I, dose escalation trial to assess the safety and biological activity of recombinant human interleukin-18 (SB-485232) in combination with pegylated liposomal doxorubicin in platinum-resistant recurrent ovarian cancer.

Abstract

5065 Background: SB-485232, a recombinant human form of interleukin-18 (IL-18), is being studied as a novel cytokine for tumor immunotherapy. IL-18 has been shown to increase the anti-tumor activity of doxorubicin in other cancer mouse models. Methods: This multi-center study enrolled 16 patients (pts), and evaluated four cycles (28 days each) of standard pegylated liposomal doxorubicin (PLD) (40 mg/m2 day 1) in combination with increasing doses of IL-18 (1, 3, 10, 30, and 100 mg/kg) on days 2 and 9 of each cycle with a 1 yr follow-up to further evaluate safety and efficacy. Results: Of the 16 pts, 10 (63%) completed study treatment and 6 (37%) did not because of disease progression (5 pts) and PLD hypersensitivity (1 pt). Thirteen (82%) were platinum resistant/refractory having received a median of > 3 prior lines of therapy. SB-485232 up to 100 mg/kg in combination with PLD had an acceptable safety profile. All 16 pts experienced at least 1 AE including chills (81%), nausea (75%), anemia (63%), fatigue (56%), hyperglycemia, and pyrexia (50% each). Eight of 16 pts had Grade 3 AEs including anemia (19%), and 6% each for abdominal pain, asthenia, dehydration, PLD hypersensitivity, edema, fatigue, hyperglycemia, hyperkalemia, jaundice, pain, nausea, vomiting, and pyelonephritis. There were no grade 4/5 AEs. Four subjects experienced 10 non-fatal SAEs with 3 related to study drug: anemia, PLD hypersensitivity, and cytokine release syndrome. Maximal SB-485232 biological activity, assessed by peripheral blood NK and T cell markers, was observed at 10mg/kg-100mg/kg. This drug combination resulted in a 6% partial response rate (RR) and a 38% stable disease rate using RECIST 1.0. Median (95% CI) time of progression-free survival (PFS) was 4.50 (3.52,--) months. Conclusions: The SB-485232/PLD combination was tolerable with minimal toxicity. These preliminary efficacy data are comparable to the historical RR and PFS observed with PLD monotherapy in platinum-resistant ovarian cancer. However, given the small sample size, this combination warrants further investigation.