Summary

This is a first-in-human (FIH), open label Phase 1/1b study in patients with advanced
metastatic solid tumors refractory to standard treatment. Phase 1 will identify potential
optimal biologically relevant doses (OBRD) and the maximum tolerated dose (MTD) of
MBRC-101 at one 1 or more dosing regimens. Phase 1b will evaluate the safety and
preliminary clinical activity of MBRC-101 at potential OBRDs. Phase 1 and Phase 1b will
both characterize single and multiple-dose PK profiles and evaluate incidence and
persistence of anti-MBRC-101 Ab.

Objectives

Phase 1, dose escalation, will enroll approximately 30 patients with advanced or
metastatic solid tumors refractory to standard therapy. EphA5 expression will not be
required for enrollment into Phase 1 but will be assessed retrospectively.

Phase1b, the dose expansion phase will evaluate the safety and preliminary clinical
activity of MBRC-101 at potential OBRDs and dosing regimens in patients with advanced or
metastatic solid tumors refractory to standard therapy. Phase 1b will enroll 3 expansion
cohorts of ˜ 20 patients per cohort (n ˜ 60 total).

Safety will be monitored by the Safety Review Committee (SRC) at each dose escalation in
Phase 1 and at regular intervals throughout Phase 1b.

Overall Response Rate (ORR), Progression Free Survival (PFS), Response Rate (RR), Overall
Survival (OS), and Complete and Partial response (CR and PR) will be used to evaluate
efficacy per RECIST v1.1 criteria based on the results of positron emission tomography
and computed tomography (PET-CT), computerized tomography (CT), and magnetic resonance
imaging (MRI) scans.

Eligibility

1. Provide written consent on an Informed Consent Form (ICF), approved by an Institutional Review Board (IRB)/Independent Ethics Committee (IEC), prior to any study-specific evaluation. Patients should have the ability to read and understand the ICF, ask for any clarifications from the study staff, and be able to comply with all planned study procedures.
2. 18 years of age or older at the time of informed consent.
3. Female patients must be at least 2 years postmenopausal (defined as 2 years without menses), surgically sterile (at least 6 months prior to dosing; must be documented) or practicing effective contraception (must agree to use 2 forms of contraception, 1 of which must be a barrier method) and willing to continue to use effective contraception for the duration of study participation and for 6 months after the final dose of study drug. Female patients must be nonlactating and have a negative serum pregnancy test result at screening and baseline.
4. Male patients must agree to use effective contraception (must agree to use 2 forms of contraception, 1 of which must be a barrier method) for the duration of study participation and for 6 months after the final dose of study drug.
5. Have a histologic or cytologic diagnosis of malignant solid tumor for which there are no standard of care treatment options known to confer a clinical benefit or for which the patient is ineligible or declines.
6. For Phase 1 dose escalation: histologic or cytologic diagnosis of malignant solid tumor of any type. The Sponsor may remove specific tumor indications based on emerging, real-time study data.
7. For Phase 1b dose expansion: i. Cohort A: Histologic or cytologic diagnosis of NSLC (adenocarcinoma and SCC). ii. Cohort B: Histologic or cytologic diagnosis of TNBC or HR positive, HER2 negative breast cancer. iii. Cohort C: Histologic or cytologic diagnosis of solid tumors irrespective of histologic tissue type (i.e., tumor agnostic), excluding NSCLC and breast cancer. The Sponsor may add or remove specific tumor indications based on emerging, real-time study data.
8. For Phase 1 and Phase 1b, availability of a tumor tissue sample (formalin-fixed paraffin-embedded [FFPE] or fresh biopsy tissue) must be confirmed for analysis of EphA5 expression based on IHC.
9. For Dose Escalation (Phase 1), tumor EphA5 expression will not be required for enrollment.
10. For Cohorts A and B of Dose Expansion (Phase 1b), tumor EphA5 expression will not be required for enrollment.
11. For Cohort C (basket cohort) of Dose Expansion (Phase 1b), patients must have tumor tissue positive (IHC H-score = 1) for EphA5 expression (as measured by a Sponsor-designated central laboratory using archival or fresh primary or metastatic invasive tumor tissue submitted for analysis). Tumor biopsies involving significant risk procedure should not be performed to assess eligibility. Confirmation of EphA5 expression in tumor tissue is required prior to patient enrollment in Cohort C (basket cohort) only.
12. For Dose Escalation (Phase 1), patients may have evaluable disease or measurable disease according to Response Evaluation Criteria In Solid Tumors [RECIST] v1.1). For Dose Expansion (Phase 1b), patients must have measurable disease according to RECIST v1.1.
13. Eastern Cooperative Oncology Group (ECOG) performance status = 2.
14. Life expectancy = 3 months as assessed by the investigator.
15. Hematologic function, as follows (no red blood cell (RBC) or platelet transfusions are allowed within 14 days of the first dose of MBRC-101):
16. Absolute neutrophil count (ANC) = 1.0 × 109/L
17. Platelet count = 100 × 109/L
18. Hemoglobin = 9 g/dL
19. Creatinine clearance of = 30 mL/min by the CKD-EPI or similar equation or as measured by 24-hour urine collection.
20. Total bilirubin = 1.5 × upper limit normal (ULN).
21. AST = 3.0 × ULN.
22. ALT = 3.0 × ULN.
23. International normalised ratio (INR) < 1.5 (or = 3.0 if on therapeutic anticoagulation).
24. Treatment with other agents for cancer, if received, must have been discontinued = 2 weeks prior to first dose of study drug. Prior ADC therapy is allowed. Prior agents conjugated to MMAE are allowed for Phase 1 but not Phase 1b.

Treatment Sites in Georgia