The decision to discontinue the trial was made as part of a strategic review of the Sponsor's global development portfolio. It is not related to any safety concerns, efficacy findings, recruitment difficulties, or issues with trial conduct.

The purpose of this study is to test the safety and tolerability of HFB301001 in patients with advanced cancers. There are two parts in this study. During the escalation part, groups of participants will receive increasing doses until a safe and tolerable doses of HFB301001 is determined. During the expansion part, participants will take the dose of study drug that was determined from the escalation part of the study and will be assigned to a group based on the type of cancer they have.

This is a Phase I, first-in-human, open-label, dose escalation and expansion study in adult patients with advanced cancers. The study will comprise of:

1. A Screening Period of up to 28 days
2. A Treatment Period during which participants will receive the study drug on the first day of each cycle where each cycle is 28 days. Number of cycles depends on how the disease responds to the study drug
3. A Follow-Up Period which involves 1 visit

Inclusion Criteria:

• Previously received the following lines of systemic therapy for the advanced/metastatic disease:

  • Soft tissue sarcoma: at least 1 line of therapy

  • Renal cell carcinoma: at least 2 lines of therapy;

  • Uterine carcinosarcoma: at least 1 line of therapy;

  • Hepatocellular carcinoma: at least 1 line of therapy

  • Head and neck squamous cell carcinoma: at least 2 lines of therapy

  • Melanoma:

    • BRAF V600E mutant: must have received at least 2 lines of therapy
    • BRAF V600E wild type: must have received at least 1 line of therapy

• Suitable site to biopsy at pre-treatment and on-treatment

• Measurable disease as determined by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and immune-RECIST (iRECIST)

• Eastern Cooperative Oncology Group performance status of 0 or 1.

Exclusion Criteria:

• Systemic anti-cancer therapy within 2 weeks prior to start of study drug.

• For soft tissue sarcoma only: prior immune therapy or immune agonist antibodies

• For uterine carcinosarcoma patients only: prior immune therapy

• Therapeutic radiation therapy within the past 2 weeks

• Prior exposure to agents targeting the OX40 receptor;

• Active autoimmune disease requiring systemic treatment in the previous 2 years;

• Systemic steroid therapy (>10 mg/day of prednisone or equivalent) or any immune suppressive therapy.

• Persisting toxicity of >Grade 1 relating to prior anti cancer therapy with the following exceptions:

  • All grades of alopecia are acceptable;
  • Endocrine dysfunction on replacement therapy is acceptable.

• Severe or unstable medical condition, including uncontrolled diabetes, coagulopathy, or unstable psychiatric condition;

• Major surgery within 2 weeks of the first dose of study drug;

• History or presence of drug or non-drug induced interstitial lung disease or pneumonitis ≥Grade 2;

• History of allergic reactions attributed to compounds of similar chemical or biologic composition to monoclonal antibodies or any excipient of HFB301001;

• Known active malignancy, with the exception of the specific cancer under investigation in this trial, that required treatment within the previous 2 years.