Phase 1 Study of the Safety, Pharmacokinetics, Pharmacodynamics and Preliminary Clinical Activity of RP-6306 in Patients With Advanced Solid Tumors (MYTHIC Study)

Phase 1, multi-center, open-label, dose-escalation study to:

• Evaluate the safety profile and MTD of RP-6306 when administered orally to establish the recommended Phase 2 dose and schedule
• Characterize the PK and pharmacodynamics of RP-6306 monotherapy
• Assess preliminary anti-tumor activity associated with RP-6306 monotherapy

Inclusion Criteria:

• Male or female and ≥12 years-of-age at the time of informed consent.
• Lansky performance status ≥50% for patients ≤16 years of age, or ECOG score of 0, 1, or 2 for patients >16 years of age.
• Locally advanced or metastatic resistant or refractory solid tumors.
• Patients <18 years of age must weigh at least 40 kg.
• Submission of available tumor tissue at screening or willingness to have a biopsy performed if safe and feasible
• Next generation sequencing (NGS) report obtained in a CLIA-certified or equivalent laboratory demonstrating eligible tumor biomarker.
• Measurable disease as per RECIST v1.1.
• Ability to swallow and retain oral medications.
• Acceptable hematologic and organ function at screening.
• Negative pregnancy test (serum) for women of childbearing potential (WOCBP) at Screening.
• Resolution of all toxicities of prior therapy or surgical procedures.
• Any prior radiation must have been completed at least 7 days prior to the start of study drugs, and patients must have recovered from any acute adverse effects prior to the start of study treatment.

Exclusion Criteria:

• Chemotherapy or small molecule antineoplastic agent given within 21 days or <5 half-lives, whichever is shorter, prior to first dose of study drug.
• History or current condition, therapy, or laboratory abnormality that might confound the study results or interfere with the patient's participation for the full duration of the study treatment.
• Patients who are pregnant or breastfeeding.
• Life-threatening illness, medical condition, active uncontrolled infection, or organ system dysfunction or other reasons which, in the investigator's opinion, could compromise the participating patient's safety.
• Major surgery within 4 weeks prior to first dose of RP-6306.
• Uncontrolled, symptomatic brain metastases.
• Uncontrolled hypertension.
• Psychological, familial, sociological, or geographical conditions that do not permit compliance with the protocol and/or follow-up procedures outlined in the protocol.