Randomized phase II/III trial of active immunotherapy with OPT-822/OPT-821 in patients with metastatic breast cancer.
Abstract:
Background: Globo H is a glycolipid that is highly expressed in breast cancer (BC). Active immunotherapy with OPT-822, a Globo H–KLH conjugate, and the adjuvant OPT-821 in 2 phase (Ph) I trials, induced Globo H specific antibodies which could mediate in vitro binding and cytotoxicity to Globo H expressing BC cells.
Methods: In this international, randomized, double-blind, placebo-controlled Ph II/III trial (NCT01516307), patients (pts) with metastatic BC who had ≤ 2 events of progressive disease (PD) and who achieved at least stable disease (SD) after ≥ 1 anticancer regimen were randomized 2:1 to receive subcutaneous OPT-822 (30 μg Globo H)/OPT-821 (100 μg) or control (PBS) on weeks 1, 2, 3, 5, 9, 13, 17, 25, and 37 or until PD, in combination with low-dose cyclophosphamide (300 mg/m2). Hormone therapy was allowed. The primary and secondary efficacy end points were progression-free survival (PFS) and overall survival (OS), correlated with humoral antibody response.
Results: 349 pts were randomized, 348 received study drug (ITT), 168 (48%) received all 9 injections. 70% had hormone receptor positive BC, 13% were triple negative, and 62% received hormone therapy. No difference was observed in PFS (HR, 0.96 [95% CI, 0.74-1.25] P = .77) or in interim OS (HR, 0.79 [95% CI, 0.51-1.22] P = .29). However, PFS and OS were significantly improved in the 50% of pts who developed a Globo H specific IgG response to OPT-822/OPT-821 with a titer ≥ 1:160 at any time during treatment vs control (HR, 0.71 [95% CI, 0.52-0.97] P = .029 for PFS; HR, 0.57 [95% CI, 0.33-0.97] P = .04 for OS) and vs nonresponders (HR, 0.52 [95% CI, 0.37-0.71] P< .0001 for PFS; HR, 0.52 [95% CI, 0.29-0.92] P = .025 for OS), adjusted for baseline disease status/hormone use. In a time-dependent Cox model, PFS was improved in pts who received all 9 injections of OPT vs control (HR, 0.66 [95% CI, 0.42-1.01] P= .057). OPT-822/OPT-821 was well tolerated; the most common drug-related adverse event was grade 1/2 injection reaction.
Conclusion: Vaccination with OPT-822/OPT-821 did not improve PFS in the ITT; however, PFS and interim OS were significantly improved in pts who developed an immune response to the vaccine. These subgroup data will be used to design a definitive Ph III trial.
http://abstract.asco.org/176/AbstView_176_168513.html