CLIO-8221 treatment for advanced solid tumors

A Phase 1/2 Study of CLIO-8221 in Patients With Advanced Solid Tumors

Phase1; Phase2 Interventional Callio Therapeutics · NCT07300943

This trial tests CLIO-8221 in adults with metastatic or unresectable advanced solid tumors to find a safe dose and see if it can shrink tumors or slow disease.

Quick facts

PhasePhase1; Phase2
Study typeInterventional
Enrollment306 (estimated)
Ages18 Years and up
SexAll
SponsorCallio Therapeutics Industry-sponsored
Drugs / interventionsprednisone
Locations11 sites (Boston, Massachusetts and 10 other locations)
Trial IDNCT07300943 on ClinicalTrials.gov

What this trial studies

This multicenter Phase 1/2 trial begins with dose-escalation and expansion cohorts to determine the maximum tolerated dose and/or recommended dose for expansion, with dosing decisions guided by a Safety Monitoring Committee. Backfill enrollment and PK/PD sampling will be used to further characterize safety, tolerability, and pharmacology. Phase 2 consists of tumor-specific expansion cohorts to optimize dosing and gather preliminary evidence of antitumor activity. Data on safety, PK/PD, and tumor response will support selection of a recommended Phase 2 dose for later development.

Who should consider this trial

Good fit: Adults with metastatic or unresectable solid tumors who have measurable disease per RECIST 1.1, ECOG performance status 0–1, LVEF ≥50%, and prior appropriate therapies (unless ineligible or without access) are the intended participants.

Not a fit: Patients previously treated with an ATR inhibitor, those with competing active malignancies that interfere with assessment, or those with poor cardiac function or ECOG >1 are unlikely to benefit or are excluded.

Why it matters

Potential benefit: If successful, CLIO-8221 could provide a new treatment option that shrinks tumors or slows disease progression for some patients with advanced solid tumors.

How similar studies have performed: Early-phase studies of other ATR inhibitors have shown preliminary activity in selected tumors, particularly those with DNA-repair defects, but large confirmatory successes remain limited.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Patients with advanced solid tumors
* Patients must have metastatic or unresectable disease not suitable for further local treatment and should have received prior beneficial therapies unless ineligible, unwilling, or lacking access.
* LVEF ≥50% by echocardiogram (ECHO) or multigated acquisition (MUGA) scan.
* An Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1
* Measurable disease per RECIST version 1.1 at baseline

Exclusion Criteria:

* Prior anti-tumor treatment with an ATRi.
* Prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the safety or efficacy assessment of the investigational regimen. Exceptions are malignancies with a negligible risk of metastasis or death (e.g., 5-year OS ≥90%), including, but not limited to, adequately treated carcinoma in situ of the cervix, non-melanoma skin carcinoma, localized prostate cancer, ductal carcinoma in situ, and Stage I uterine cancer.
* History of uncontrolled seizure disorders or clinically significant neurodegenerative disorders, including progressive peripheral neuropathy. Stable Grade ≤ 2 peripheral neuropathy is allowed.
* Clinically significant autoimmune disease, either currently present or present within the previous 2 years, including a current requirement for systemic immunosuppressive therapy equivalent to \>10 mg/prednisone daily (local immunosuppressive therapy such as inhaled or topical corticosteroids is allowed).
* Any uncontrolled Grade ≥ 3 (per NCI CTCAE version 6.0) viral, bacterial, or fungal infection within 2 weeks prior to Cycle 1 Day 1. Routine antimicrobial prophylaxis is permitted.
* History of hepatic cirrhosis, autoimmune hepatitis, or drug-associated hepatitis within the past 12 months.
* Uncontrolled diabetes mellitus, defined as Hgb A1c ≥8% or Hgb A1c between 7% and \<8% with associated diabetes symptoms (polyuria or polydipsia) that are not otherwise explained.
* Any other medical, social, or psychosocial factors that, in the opinion of the investigator, could impact safety or compliance with study procedures.

Additional protocol defined inclusion/exclusion criteria may apply

Where this trial is running

Boston, Massachusetts 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.
Conditions Advanced Solid Tumor
Last reviewed 2026-06-15 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.