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Treatment for adult patients with solid tumors that have a specific p53 mutation

GUARDIAN-101: A Phase 1 Dose Escalation and Expansion Study of CLSP-1025 in Adult Patients With Solid Tumors That Harbor the p53 R175H Mutation

Phase 1 Interventional Clasp Therapeutics, Inc. · NCT06778863

This study is testing a new treatment for adults with advanced solid tumors that have a specific p53 mutation to see if it is safe and effective.

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment90 (estimated)
Ages18 Years and up
SexAll
SponsorClasp Therapeutics, Inc. Industry-sponsored
Locations21 sites (Scottsdale, Arizona and 20 other locations)
Trial IDNCT06778863 on ClinicalTrials.gov

What this trial studies

This Phase 1, open-label, multicenter study evaluates the safety and effectiveness of CLSP-1025, a T cell engager targeting solid tumors with the p53 R175H mutation. The study consists of two parts: a dose escalation phase to determine the recommended doses for further testing and an expansion phase to assess the preliminary antitumor activity and safety of the treatment. Participants must be HLA-A*02:01 positive and have advanced solid tumors that have not responded to standard therapies.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older with advanced solid tumors harboring the p53 R175H mutation who have progressed after standard therapies.

Not a fit: Patients with Li-Fraumeni syndrome or those who have previously received p53 R175H-directed therapies may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new therapeutic option for patients with specific solid tumors that currently have limited treatment options.

How similar studies have performed: While this approach is novel in targeting the p53 R175H mutation specifically, similar T cell engager therapies have shown promise in other contexts.

Eligibility criteria

Show full inclusion / exclusion criteria 
Key Inclusion Criteria:

* Patients must be at least 18 years of age at the time of signing the informed consent.
* Patients must be willing and able to provide written informed consent
* Patients must have locally advanced or metastatic solid tumors that have progressed after standard of care therapy or for which no standard therapy exists
* Tumors must harbor a TP53 R175H variant mutation confirmed by an accredited laboratory-based test
* Patients must be HLA-A\*02:01 positive by central assay
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 at the time of enrollment
* Adequate hematological, renal and hepatic function
* Per Investigator judgement, patient is willing and able to complete study visits and/or procedures per the protocol and comply with study requirements for study participation

Key Exclusion Criteria:

* Patients with Li-Fraumeni syndrome or other known germline p53 R175H mutation
* Patients who have received other p53 R175H-directed therapies
* Patients who have not fully recovered from adverse events due to previous anticancer therapies
* Patients with active infection requiring systemic antimicrobial therapy
* Any other primary malignancy within the 2 years prior to enrollment (except for non- melanoma skin cancer, carcinoma in situ (eg, cervix, bladder, breast) or prostate cancer in remission.
* Known active central nervous system metastases and/or carcinomatous meningitis

Where this trial is running

Scottsdale, Arizona and 20 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 Advanced Solid TumorUnresectable Solid TumorMetastatic Solid TumorColorectal AdenocarcinomaPancreatic AdenocarcinomaLung CancerOvarian CancerBreast 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.