Study of ONT-10 and Varlilumab to Treat Advanced Ovarian or Breast Cancer

This is a two-part Phase 1b, open-label study of ONT 10 administered in combination with varlilumab. Two different doses of varlilumab will be studied in combination with the single agent recommended dose of ONT 10. Intermediate and/or lower doses of varlilumab or ONT-10 may also be studied at the recommendation of the safety monitoring committee (SMC). Treatment will be administered in cycles of 12 weeks each. All patients will receive a single dose of cyclophosphamide on Day -3. During Cycle 1, patients will receive ONT-10 administered SC once per week for 8 weeks followed by ONT-10 once every 6 weeks starting with Cycle 2, in combination with varlilumab administered IV once every 3 weeks x 3 doses, and then once every 6 weeks for cycles 2 through 5. Each cohort will enroll an initial group of 6 evaluable patients with either breast or ovarian carcinoma. Initial enrollment into a cohort will be staggered, with the first patient treated in any new cohort to be followed for a minimum of two weeks for the occurrence of Unacceptable Toxicity prior to enrollment of the remaining 5 patients. Subsequent enrollment into a cohort may then continue without a staggered schedule until 6 patients treated are considered evaluable. Up to 24 additional evaluable patients may be enrolled and treated in Part 2 at the RD of varlilumab and ONT-10 identified in Part 1, including approximately equal numbers of patients with breast carcinoma (n\~12) and ovarian carcinoma (n\~12). Treatment in Part 2 will follow the same schedule as in Part 1.