Study of 23ME-01473 in Patients With Advanced Solid Malignancies

Inclusion Criteria:

1. Phase 1: Adults ≥ 18 years of age
2. Phase 1: Histologically-diagnosed locally advanced (unresectable), or metastatic carcinoma or sarcoma that has progressed after standard therapy for the specific tumor type.
3. Adults 18+: Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
4. Life expectancy ≥ 12 weeks
5. Phase 1: Participants with evaluable disease are eligible regardless of tumor type, RECIST 1.1 can be used to assess disease progression.

Exclusion Criteria:

1. Females who are pregnant (positive serum pregnancy test within 7 days prior to study drug administration) or breastfeeding.
2. Immune-Related Medical History

   1. Active autoimmune disease that has required systemic disease-modifying or immunosuppressive treatment within the last 2 years
   2. Receipt of systemic immunosuppressive therapy (e.g. steroids) within 4 weeks prior to the start of study drug administration
   3. History of idiopathic pulmonary fibrosis, interstitial lung disease, organizing pneumonia, non-infectious pneumonia that required steroids, or evidence of active, non-infectious pneumonitis
   4. History of Grade ≥ 3 immune-mediated toxicity
3. Prior allogeneic or autologous bone marrow transplant, or other solid organ transplant
4. History of a positive test for:

   1. Hepatitis C virus (HCV) infection, except for those who have completed curative therapy for HCV and have undetectable HCV RNA
   2. Hepatitis B virus (HBV) infection, except for those who are receiving treatment with HBV-active nucleos(t)ide antiviral therapy at the time of study entry and have undetectable HBV DNA
   3. Human Immunodeficiency Virus (HIV) infection, except those who meet the following criteria: CD4+ T cells ≥ 350 cells/μL, no history of Acquired Immunodeficiency Syndrome (AIDS)-defining opportunistic infections, HIV RNA \< 50 copies/mL, and on a stable antiretroviral regimen for at least 3 months
5. Prior anticancer therapy, including chemotherapy, targeted therapy, biological therapy or immune-checkpoint inhibitors within 4 weeks or 5 drug half-lives (whichever is shorter)
6. History of another malignancy in the previous 2 years, unless cured by surgery alone and continuously disease free.
7. Uncontrolled or symptomatic CNS (central nervous system) metastases and/or carcinomatous meningitis
8. Recent history (within 6 months) of serious cardiovascular disease