A Study of MX006 in Patients With Advanced and/or Metastatic Tumors Known to Express B7-H3

A Phase 1a/b, Open-label, Dose-escalation and Dose-expansion, First-in-Human Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Antitumor Activity of MX006 in Patients With Selected Advanced Solid Tumor Types Known to Express B7-H3

This is a Phase 1a/1b, multicenter, open-label, first-in-human (FIH) study with MX006 treatment in patients with selected tumor types known to express B7-H3. The study will include 2 parts:

• Dose-escalation (Part A)
• Dose-expansion (Part B) A maximum of 120 patients may be enrolled in this study. The primary objective of the dose escalation (PART A) is to evaluate the safety and tolerability of MX006 and determine the maximum-tolerated dose (MTD) and the recommended doses for expansion (RDE) in patients with selected solid tumors; whereas the primary objective of the dose expansion (PART B) is to evaluate the safety and tolerability of MX006 at the dose level (s) recommended in Part A.

Inclusion Criteria:

• Male and female patients aged 18 years-or older at the time of signature of the informed consent form.
• Patients with advanced/metastatic cancer, with measurable disease as determined by RECIST v1.1 or the Prostate Cancer Clinical Trials Working Group 3 (for mCRPC only) as per Investigator discretion. Note: Patients with mCRPC can be enrolled without measurable disease but must have a minimum of 2 bone lesions and increased PSA.
• Histologically or cytologically confirmed unresectable locally advanced or metastatic solid tumors in patients with relapsed or refractory solid tumors known to express B7-H3 who have failed available standard therapy or who are not candidates for standard therapy.
• Has adequate bone marrow and organ function within 7 days before the start of study
• Has an adequate treatment washout period prior to start of study treatment, defined as:
• Major surgery: ≥4 weeks (or 2 weeks for low-invasive cases [e.g., colostomy]). Note: major surgery is defined for example as a surgical procedure that is complex, invasive (e.g., enters a body cavity), is associated with higher risk of complications, and may require general anesthesia and hospitalization.
• Radiation therapy: ≥4 weeks (if palliative single site stereotactic radiation therapy, ≥2 weeks.)

Exclusion Criteria:

• Prior treatment with an NMT inhibitor or any antibody-drug conjugate (ADC) that delivers an NMTi payload.
• Has other invasive malignancy within 2 years; prior or concurrent non-invasive malignancies (with the exception of the following: in situ carcinomas of the cervix, non-melanoma skin cancers) and/or patients with localized malignancies that were treated with curative intent (e.g., localized breast cancer) who remain disease-free and are considered low likelihood for recurrence who may be enrolled on a case-by-case basis after discussion with the Medical Monitor).
• Have clinically significant cardiac disease, known congestive heart failure (New York Heart Association classes II-IV) or a serious cardiac arrhythmia requiring treatment, and/ or a known decreased cardiac ejection fraction of < 45%. A baseline QT interval as corrected by Fridericia's formula (QTcF) > 470 msec, a complete left bundle branch block (defined as a QRS interval ≥ 120 msec in left bundle branch block form) or an incomplete left bundle branch block based on the average of triplicate 12-lead electrocardiogram (ECG) per local read.
• Received any of the following within the specified time frame prior to administration of study treatment: Any systemic agent from a previous treatment regimen or clinical study including anti-cancer chemotherapy or small molecule ≤14 days or 5 half-lives (whichever is shorter); any biologic or hormonal agent ≤28 days or 5 half-lives (whichever is shorter).
• Received any of the following within the specified time frame prior to administration of study treatment: Platelet transfusion, red blood cell transfusion and/or granulocyte colony-stimulating factor administration < 1 week prior to screening assessments.

Other protocol defined Inclusion/Exclusion criteria may apply.