NCT06721689: PEEL-224

A Phase 1/2 Clinical Trial of the Novel Topoisomerase I Inhibitor PEEL-224 as a Single Agent and in Combination With Vincristine and Temozolomide in Children With Refractory, Progressive or Relapsed Solid Tumors

Recruiting now Phase 1/Phase 2 Last updated 13 April 2026

What this trial tests

Phase 1/Phase 2 trial testing PEEL-224 in Refractory Solid Tumors in 59 participants. Currently enrolling.

Timeline

23 March 2025

Primary endpoint
1 April 2030

1 April 2031

Quick facts

Lead sponsor	Theodore Laetsch
Phase	Phase 1/Phase 2
Status	Recruiting now
Study type	INTERVENTIONAL
Allocation	non randomized
Design	sequential
Masking	none
Primary purpose	treatment
Enrollment	59
Start date	23 March 2025
Primary completion	1 April 2030
Estimated completion	1 April 2031
Sites	7 locations across United States

Drugs / interventions tested

• PEEL-224 — full drug profile →
• Vincristine (vincristine) — full drug profile →
• Temozolomide (TMZ) — full drug profile →

Conditions studied

• Refractory Solid Tumors — all drugs for Refractory Solid Tumors →
• Relapsed Solid Tumors — all drugs for Relapsed Solid Tumors →
• Relapsed Neuroblastoma — all drugs for Relapsed Neuroblastoma →
• Refractory Neuroblastoma — all drugs for Refractory Neuroblastoma →

Sponsor

Theodore Laetsch

Who can join

Adults 1 to 30, any sex, with Refractory Solid Tumors or Relapsed Solid Tumors. Patients with the condition only — healthy volunteers not accepted.

What's being measured

Primary outcomes are the specific endpoints the trial is designed to prove or disprove.

• Phase 1A and Phase 1B: Number of participants who experience a dose limiting toxicity (DLT)
  Time frame: 1 month
  The observation of a dose-limiting toxicity (DLT) or lack of observation of DLT in the period between treatment initiation up to initiation of cycle 2 treatment. A dose limiting toxicity (DLT) describes side effects of a drug or other treatment that are serious enough to prevent an increase in dose or level of that treatment.
• Phase 2 Neuroblastoma Cohort (NBL): Number of paricptants who achieve a complete response (CR), partial response (PR), or minor response (MR)
  Time frame: 2 years
  Objective response as assessed by the Revised International Neuroblastoma Response Criteria (INRC). Response is defined as complete response (CR), partial response (PR) or minor response (MR), using best response measured at any point prior to local control.
• Phase 2 Rhabdomyosarcoma (RMS) Cohort: Number of participants who achieve a complete response (CR) or partial response (PR)
  Time frame: 2 years
  Objective response as assessed by Response Evaluation Criteria In Solid Tumors (RECIST) 1.1. Response is defined as complete response (CR) or partial response (PR), using best response measured at any point prior to local control.

Sponsor's own description

The phase 1 primary objective is to determine the pediatric recommended phase 2 dose (RP2D) of PEEL-224 as a single agent (phase 1A) and in combination with vincristine and temozolomide (phase 1B). The phase 2 primary objective is to estimate the objective response rate (ORR) in children with refractory, progressive and relapsed NBL and rhabdomyosarcoma (RMS) treated with the RP2D of PEEL-224 in combination with vincristine and temozolomide.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Sarcomas in Adolescents and Young Adults.
   Greenmyer JR, Allen-Rhoades W. · · 2026 · PMID 42159886 · DOI 10.1007/s11912-026-01781-8