A Study of HFB200301 as a Single Agent and in Combination With Tislelizumab in Adult Patients With Advanced Solid Tumors

Inclusion Criteria:

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

  * Gastric cancer: at least 2 lines of therapy
  * Renal 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
  * Sarcoma: at least 1 line of therapy
  * Testicular germ cell tumor: at least 2 lines of therapy
  * Cervical cancer: at least 2 lines of therapy
  * Mesothelioma: at least 2 lines of therapy
  * Non-small cell lung cancer: at least 2 lines of therapy
  * Head and neck squamous cell carcinoma: at least 2 lines 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 or modified RECIST (mRECIST) for mesothelioma
* 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 or within 4 weeks for immune-oncologic therapy
* For soft tissue sarcoma and testicular germ cell tumor patients only: prior immune therapy
* Therapeutic radiation therapy within the past 2 weeks
* Prior exposure to agents targeting the Tumor Necrosis Factor Receptor type 2 (TNFR2) 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 ≤ 14 days before first dose
* Persisting toxicity of ≥Grade 2 (≥Grade 1 for diarrhea) 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 4 weeks of the first dose of study drug
* History or presence of drug or non-drug induced interstitial lung disease or pneumonitis ≥Grade 2. For combination only: non-small cell lung cancer patients, mesothelioma or patients with significantly impaired pulmonary function or who require supplemental oxygen at baseline must undergo an assessment of pulmonary function at screening
* History of allergic reactions, immune related reactions, or cytokine release syndrome (CRS) attributed to compounds of similar chemical or biologic composition to monoclonal antibodies or any excipient of HFB200301
* Using sensitive substrates of major cytochrome P450 (CYP450) enzymes
* Known active malignancy, with the exception of the specific cancer under investigation in this trial, that required treatment within the previous 2 years
* For combination only:

  * Prior randomization in a tislelizumab study regardless of the treatment arm, until the primary and key secondary endpoints of the study have read out
  * Hypersensitivity to tislelizumab or any of its excipients.