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Testing HFB200603 alone and with Tislelizumab in adults with advanced cancers

A Phase 1a/1b, Open-Label, Multi-Center, Dose Escalation and Expansion Study of HFB200603 (Anti-BTLA Antibody) as a Single Agent and in Combination With Tislelizumab (Anti-PD-1 Antibody) in Adult Patients With Advanced Solid Tumors

Phase 1 Interventional HiFiBiO Therapeutics · NCT05789069

This study is testing a new cancer treatment called HFB200603, both alone and with another drug called Tislelizumab, to see how safe it is for adults with advanced solid tumors.

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment83 (estimated)
Ages18 Years and up
SexAll
SponsorHiFiBiO Therapeutics Industry-sponsored
Drugs / interventionstislelizumab, radiation, prednisone
Locations11 sites (Los Angeles, California and 10 other locations)
Trial IDNCT05789069 on ClinicalTrials.gov

What this trial studies

This clinical trial aims to evaluate the safety and tolerability of HFB200603, both as a standalone treatment and in combination with Tislelizumab, in adult patients suffering from advanced solid tumors. The study is divided into two parts: an escalation phase where participants receive increasing doses to determine a safe level, and an expansion phase where the established doses are administered based on the specific type of cancer. Participants will undergo a screening period, followed by a treatment period consisting of cycles of drug administration, and a follow-up period involving additional visits.

Who should consider this trial

Good fit: Ideal candidates include adults with advanced renal cell carcinoma, melanoma, non-small cell lung cancer, gastric cancer, or colorectal cancer who have previously undergone specific lines of systemic therapy.

Not a fit: Patients who have not received the required prior lines of therapy or those with certain exclusion criteria may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide a new treatment option for patients with advanced solid tumors who have limited therapeutic alternatives.

How similar studies have performed: While this approach is novel in its specific combination, similar studies involving immune-oncology therapies have shown promising results in treating advanced cancers.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Patient must have one of the following cancers and previously received the following lines of systemic therapy for the advanced/metastatic disease:

  * Renal cell carcinoma: at least 2 lines of therapy
  * Non-small cell lung cancer: at least 2 lines of therapy
  * Melanoma:

    * BRAF V600E positive: must have received at least 2 lines of therapy
    * BRAF V600E negative: must have received at least 1 line of therapy
  * Gastric cancer: at least 1 line of therapy
  * Colorectal cancer: at least 3 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
* 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 cytotoxic agents with major delayed toxicity (e.g., mitomycin C), 6 weeks of washout are mandated.
* Therapeutic radiation therapy within the past 2 weeks
* Active autoimmune diseases or history of autoimmune disease that may relapse
* Any malignancy ≤ 5 years before first dose of study drug except for the specific cancer under investigation in this study and any locally recurring cancer that has been treated curatively
* Systemic steroid therapy (\>10 mg/day of prednisone or equivalent) or any immune suppressive medication ≤ 14 days before first dose
* Patients with toxicities (as a result of prior anticancer therapy) which have not recovered to baseline or stabilized, except for adverse events not considered a likely safety risk (e.g., alopecia, neuropathy, and specific laboratory abnormalities)
* Severe or unstable medical condition, including uncontrolled diabetes, coagulopathy, or unstable psychiatric condition
* Major surgery within 28 days of the first dose of study drug
* History of interstitial lung disease, non-infectious pneumonitis, or uncontrolled lung diseases including pulmonary fibrosis or acute lung diseases. For combination only: non-small cell lung cancer patients, 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 HFB200603 or tislelizumab
* 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

Where this trial is running

Los Angeles, California and 10 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Renal Cell CarcinomaMelanomaNon Small Cell Lung CancerGastric CancerColorectal Cancer
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.