The Efficacy and Safety of PRTX007-003 Combined With Pembrolizumab in Resectable Stage III Melanoma

NCT07565285 | Not Yet Recruiting Phase 2

• 1 other identifier: PRTX007-003
• Study Type: interventional
• Target: 48
• Locations: 0 countries
• Sites: N/A

Brief Summary

This Phase 2, multi-center, single-arm study evaluates the safety, tolerability, and activity of neoadjuvant PRTX007 in combination with pembrolizumab in participants with resectable Stage III melanoma. Neoadjuvant immunotherapy has demonstrated improved clinical outcomes compared with adjuvant-only approaches, but there remains a need to enhance pathologic response rates without significant added toxicity. Participants will receive oral PRTX007, a Toll-like receptor 7 (TLR7) agonist prodrug, administered in combination with intravenous pembrolizumab prior to surgical resection. The primary objective is to determine the major pathologic response (MPR) rate following neoadjuvant therapy. Secondary objectives include evaluation of safety, pathologic complete response, event-free survival, overall survival, pharmacokinetics, and immune-related biomarkers. This study aims to determine whether the addition of PRTX007 to pembrolizumab improves antitumor immune responses and clinical outcomes in patients with Stage III melanoma.

Conditions

Melanoma Stage III

Outcome Measures

Primary Outcomes (1)

• Major Pathologic Response (MPR) Rate

  Major pathologic response (MPR) is defined as ≤10% residual viable tumor cells in the resected tumor specimen following completion of neoadjuvant therapy, as assessed by central pathology review.

  At time of surgical resection (approximately 9 weeks after initiation of treatment)

Secondary Outcomes (9)

• Incidence of Adverse Events (AEs), Serious Adverse Events (SAEs), Immune-Related AEs (irAEs), and Dose-Limiting Toxicities (DLTs)

  From first dose of study treatment through end of study (approximately up to 52 weeks)

• Number of participants with abnormal physical examination findings, abnormal vital signs, abnormal Eastern Cooperative Oncology Group (ECOG) performance status, and abnormal clinical laboratory parameters

  Baseline through end of study (approximately up to 52 weeks)

• Pathologic Complete Response (pCR) Rate

  At time of surgical resection (approximately 9 weeks after initiation of treatment)

• Event-Free Survival (EFS)

  From first dose up to 1 year

• Overall Survival (OS)

  From first dose through end of study (approximately up to 52 weeks or longer if followed)

Study Arms (1)

Neoadjuvant PRTX007 + Pembrolizumab (Response-Adapted Adjuvant Therapy)

EXPERIMENTAL

Participants with resectable Stage III melanoma will receive neoadjuvant treatment with PRTX007 in combination with pembrolizumab prior to definitive surgical resection. Following surgery, participants will receive response-adapted adjuvant therapy based on pathologic response. Participants achieving a major pathologic response (MPR) may receive observation or pembrolizumab alone, while participants without MPR will receive adjuvant PRTX007 in combination with pembrolizumab.

Drug: PRTX007; Drug: Pembrolizumab

Interventions

PRTX007 DRUG

PRTX007 is an orally administered prodrug of PRX034, a Toll-like receptor 7 (TLR7) agonist designed to activate innate and adaptive immune responses. NEOADJUVANT REGIMEN * 600 mg orally once daily (safety run-in participants) or * 750 mg orally once daily (subsequent participants) * Administered 3 days on, 4 days off (7-day cycle) * Total of 9 cycles (9 weeks) ADJUVANT REGIMEN (IF NO MPR) * 750 mg orally once daily * Administered 3 days on, 4 days off * Total of 12 cycles (12 weeks)

Neoadjuvant PRTX007 + Pembrolizumab (Response-Adapted Adjuvant Therapy)

Pembrolizumab DRUG

Pembrolizumab is a programmed cell death protein-1 (PD-1) blocking antibody administered by intravenous infusion NEOADJUVANT REGIMEN * 200 mg IV every 3 weeks (Q3W) * Total of 3 cycles (9 weeks) ADJUVANT REGIMEN * 400 mg IV every 6 weeks (Q6W) for 7 cycles OR * 200 mg IV every 3 weeks (Q3W) for 14 cycles * Total duration: approximately 42 weeks

Neoadjuvant PRTX007 + Pembrolizumab (Response-Adapted Adjuvant Therapy)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adults aged 18 years or older
• Histologically confirmed, resectable Stage III cutaneous melanoma.
• Candidate for curative-intent surgical resection
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-2
• Adequate organ function
• Able to provide written informed consent

You may not qualify if:

• Prior systemic therapy for melanoma, including immunotherapy
• Uveal melanoma or mucosal melanoma.
• Active autoimmune disease requiring systemic treatment
• Primary immunodeficiency or use of systemic immunosuppressive therapy
• Women who are pregnant or breastfeeding
• Recent treatment with another investigational therapy
• Any condition that, in the opinion of the investigator, would interfere with study participation or safety

Sponsors & Collaborators

• Primmune Therapeutics, Inc.: lead

MeSH Terms

Conditions

Melanoma

Interventions

pembrolizumab

Condition Hierarchy (Ancestors)

Neuroendocrine Tumors; Neuroectodermal Tumors; Neoplasms, Germ Cell and Embryonal; Neoplasms by Histologic Type; Neoplasms; Neoplasms, Nerve Tissue; Nevi and Melanomas; Skin Neoplasms; Neoplasms by Site; Skin Diseases; Skin and Connective Tissue Diseases

Central Study Contacts

Shinam Garg

CONTACT

+61-2-9171-3260; Shinam.garg@novotech-cro.com

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 20, 2026
• First Posted: May 4, 2026
• Study Start: May 1, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): June 1, 2029
• Last Updated: May 4, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share