Phase I Trial of ONX-0801 Once Weekly or Alternate Weekly

This is an open label, single-centre dose escalation phase 1 clinical trial of ONX-0801. The study will evaluate two schedules of ONX-0801 concurrently: once weekly and alternate week dosing, of repeated 28-day treatment cycles. The study will consist of two stages: the dose escalation phase, in which the recommended phase II dose will be determined; and the expansion phase, in which up to 30 patients will be treated at the recommended phase II dose and schedule to further support the design of subsequent trials of ONX-0801.

During the dose escalation phase, patients will be enrolled alternately to either: * a q1wk schedule in which ONX-0801 will be administered over a 1-hour IV infusion on Days 1, 8, 15 and 22 of repeated 28-day treatment cycles; the starting dose will be 1 mg/m2 for the first cohort; OR * a q2wk schedule in which ONX-0801 will be administered over a 1-hour IV infusion on Days 1 and 15 of repeated 28-day treatment cycles; the starting dose will be 2 mg/m2 for the first cohort; Cohorts of 3 patients will receive ONX-0801 at escalating doses on each schedule until a Dose Limiting Toxicities (DLTs) occur and an Maximum Tolerated Dose (MTD) is determined for each schedule. Once the recommended Phase II dose (RP2D) and schedule has been established, additional patients may be recruited in a dose expansion phase to a maximum total of 30 patients to further characterize safety, tolerability and pharmacodynamics. This subgroup of patients will be limited to those expected to have high rates of over expression of α-FR, such as patients with ovarian or endometrial, cancer. Approximately 66 patients with solid tumours will be entered into this study. Dose escalation: Approximately 18 patients in each schedule in the dose escalation phase. The final number for the dose escalation phase will depend on the number of dose escalations required to reach DLT. Dose expansion: Up to 30 patients will be enrolled in the dose expansion phase, and this cohort will be enriched with patients with tumour types expected to have high rates of over expression of α-folate receptor, including ovarian and endometrial cancer. A minimum of 20 patients with platinum resistant/refractory ovarian cancer will be enrolled.