Summary

The purpose of this study is to evaluate the safety, tolerability, and clinical response of
ASP7517, and determine the Recommended Phase 2 Dose (RP2D) and/or the Maximum Tolerated Dose
(MTD) of ASP7517 when administered as a single agent and in combination with pembrolizumab.

This study will also evaluate other measures of anticancer activity of ASP7517 when
administered as a single agent and in combination with pembrolizumab based on central and
local assessment.

Objectives

This study consists of arms receiving ASP7517 monotherapy and arms receiving ASP7517 and
pembrolizumab combination therapy in Phase 1 (dose escalation cohort) and Phase 2 (dose
expansion cohort). Phase 2 monotherapy and combination dose expansion cohorts will be opened
after the phase 1 escalation cohort has been completed.

Eligibility

1. Participant has locally-advanced (unresectable) or metastatic solid tumor malignancy that is confirmed by available pathology records or current biopsy. Participant must also have received all standard therapies (unless the therapy is contraindicated or intolerable) appropriate to provide clinical benefit for his/her specific tumor type. However, participants with metastatic melanoma who have not received checkpoint inhibitors [CPIs] (i.e., CPIs naive) may enroll in the Phase 2 Combination Therapy Arm Dose Expansion Cohort to receive CPI: Pembrolizumab.
2. Participant must be diagnosed with solid tumor known to express WT1 antigen such as, but not limited to melanoma, ovarian cancer or Colorectal Cancer (CRC).
3. Participant consents to provide an archival tumor specimen in a tissue block or unstained serial slides, if available, prior to study treatment.
4. Participant has an Eastern Cooperative Oncology Group (ECOG) Performance Status of =
5. - Participant's last dose of prior antineoplastic therapy, including any immunotherapy, was 21 days or 5 half-lives, whichever is shorter, prior to initiation of IP administration. A participant with BRAF gene, epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) mutation positive non-small cell lung carcinoma is allowed to remain on epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) or anaplastic lymphoma kinase (ALK) or BRAF inhibitor therapy until 4 days prior to the start of Investigational Product (IP) administration.
6. Participant has completed any radiotherapy (including stereotactic radiosurgery) at least 2 weeks prior to IP administration.
7. Participant's Adverse Events (AEs) (excluding alopecia) from prior therapy have improved to grade 1 or baseline within 14 days prior to start of IP.
8. Participant has adequate organ function prior to start of IP. If a participant has received a recent blood transfusion, the laboratory tests must be obtained = 4 weeks after any blood transfusion.
9. A female participant is eligible to participate if she is not pregnant and at least 1 of the following conditions applies:
10. Not a woman of childbearing potential (WOCBP) OR
11. WOCBP who agrees to follow the contraceptive guidance from the time of informed consent through at least 6 months after the final IP administration.
12. Female participant must agree not to breastfeed starting at screening and throughout the IP and for 180 days after the final IP administration.
13. Female participant must not donate ova starting at screening and throughout the IP and for 180 days after the final IP administration.
14. A male participant with female partner(s) of childbearing potential (including breastfeeding partner) must agree to use contraception throughout the treatment period and for at least 180 days after the final IP administration.
15. Male participant must not donate sperm during the treatment period and for 180 days after the final IP administration.
16. Male participant with pregnant partner(s) must agree to remain abstinent or use a condom for the duration of the pregnancy throughout the study period and for 180 days after the final IP administration.
17. Participant agrees not to participate in another interventional study while receiving IP. Additional Inclusion Criteria for Participants in the Expansion Cohorts:
18. Participant meets one of the following:
19. Participant has the tumor type for which a confirmed response was observed in a monotherapy dose escalation cohort (monotherapy arm only) cohort; OR
20. For tumor specific expansion cohorts of ASP7517 or ASP7517 with pembrolizumab, participant has the applicable tumor type; CPI refractory metastatic melanoma (monotherapy and combination arms), CPI naïve melanoma (combination arm only), ovarian cancer, colorectal cancer (CRC).
21. Participant has at least 1 measurable lesion per response evaluation criteria in solid tumors (RECIST) v1.1. Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions.
22. Participant consents to provide a tumor specimen in a tissue block or unstained serial slides obtained within 56 days prior to first dose of IP. If a recent tissue sample cannot be provided due to medical or safety concerns, enrollment into the study must be discussed with the medical monitor.
23. Participant consents to undergoing a tumor biopsy (core tissue biopsy or excision) during the treatment period as indicated in the schedule of assessments if predose biopsy is available and if medically feasible.