An Open-label, Phase 1a/1b, Dose Escalation and Dose Expansion Study Investigating the Safety, Pharmacokinetics, Pharmacodynamics, and Antitumor Activity of PHST001 in Adult Patients With Advanced Relapsed and/or Refractory Solid Tumors

Key Inclusion Criteria:

• Histologically or cytologically confirmed advanced solid tumor which has relapsed from or been refractory to all locally available standard therapies.
• Adequate hepatic function:
• AST and ALT ≤ 2.5 × times ULN (≤ 5 × ULN if liver metastases)
• Total bilirubin ≤ 1.5 × ULN (<3 ×ULN for patients with elevations due to Gilbert syndrome)
• Lipase and amylase ≤ 2×ULN
• Adequate renal function: calculated creatinine clearance of ≥ 30 mL/min calculated per institutional standard
• Adequate bone marrow function without packed RBC transfusion within the prior 2 weeks. Patients can be on a stable dose of erythropoietin (approximately ≥ 3 months). Criteria must be met without platelet transfusion within 7 days of screening blood draw:
• Absolute neutrophil count (ANC) ≥1,500/µL
• Platelet count ≥100,000/µL
• Hemoglobin ≥9.0 g/dL or ≥5.6 mmol/La

Key Exclusion Criteria:

• History of a previous additional malignancy, unless potentially curative treatment has been completed, with no evidence of malignancy for 5 years. Patients with basal cell carcinoma of the skin, Stage I melanoma, melanoma in situ, squamous cell carcinoma of the skin, early-stage prostate cancer, or carcinoma in situ, excluding carcinoma in situ of the bladder, who have undergone potentially curative therapy are not excluded and can be enrolled regardless of disease-free period following completion of potentially curative therapy. Patients with early-stage breast cancer who have undergone curative intent treatment and with no disease recurrence for 2 years after treatment are not excluded.
• Active known CNS metastases and/or carcinomatous meningitis. Patients with previously treated CNS metastases may participate provided they are radiologically stable (ie, without evidence of progression for at least 2 weeks by repeat imaging [note that the repeat imaging should be performed during study screening]), clinically stable, and without requirement of steroid treatment for at least 14 days prior to the first dose of study treatment.
• Received prior systemic anticancer therapy including investigational agents within 21 days or, if shorter, within 5 half-lives prior to the first dose of study treatment. Patients must have recovered from all AEs due to previous therapies to Grade ≤1 or baseline. Patients with Grade ≤2 neuropathy may be eligible. Patients with endocrine-related AEs Grade ≤2 requiring treatment or hormone replacement may be eligible.
• Prior autologous or allogeneic hematopoietic stem cell transplant or solid organ transplant.
• Received previous treatment with another agent targeting CD24.