Sponsor's strategic business decision

This is a first in human (FIH) 2-part study using ACTM-838 in patients with advanced solid tumors resistant to standard of care treatment. Part 1a will evaluate dose escalation and Part 1b will evaluate dose expansion.

This study has 2 parts. Part 1a will evaluate the safety and tolerability and activity of escalating doses of ACTM-838 to estimate the maximum tolerated dose (MTD) and/or the optimum biological dose (OBD) for ACTM-838 as a monotherapy and determine the dose recommended for Part 1b.

Part 1b will further evaluate ACTM-838 in patients with advanced specific tumor types (defined pathologically, clinically and/or molecularly) based on data emerging from the Phase 1a and the pre-clinical program. The details on the Phase 1b dose expansion part will be incorporated in a future protocol amendment.

Inclusion Criteria:

1. Advanced solid tumor for which there is no remaining standard curative therapy and no therapy with a demonstrated survival benefit, or they must be ineligible to receive or refuse to receive such therapy
2. At least one measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST ) v1.1; amenable for biopsy, and radiographically apparent on computed tomography (CT) or magnetic resonance imaging (MRI )
3. Eastern Cooperative Oncology Group (ECOG) 0-1
4. Adequate hematologic, hepatic, pulmonary, and cardiac function
5. CD4 count >500/mL at screening
6. Additional protocol defined inclusion criteria may apply

Exclusion Criteria:

1. Active autoimmune disease requiring systemic treatment (i.e., with use of disease modifying agents, systemic corticosteroids or immunosuppressive drug) within the past 6 months prior to dosing of investigational product.
2. History of permanent artificial implants (e.g., prosthetic joints, artificial heart valves, pacemakers, orthopaedic screw[s], metal plate[s], bone graft[s], or other exogenous implant[s]
3. Known history of cholelithiasis or urolithiasis
4. History of valvular disease, arterial aneurisms or arterial or venous malformation
5. Known active brain metastases
6. Documented active Salmonella infection or vaccination with Salmonella typhi within 6 months prior to investigational product dosing
7. Additional protocol defined inclusion/exclusion criteria may apply

Open label