Chicago, IL — Juncell Therapeutics presented the first results of MIZAR-003, a Phase II randomized controlled trial evaluating GC101 tumor-infiltrating lymphocyte (TIL) therapy in advanced melanoma, at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting. The data, selected for late-breaking abstract (LBA) oral presentation, showed that GC101 significantly improved progression-free survival compared with chemotherapy.
The trial enrolled 98 patients with advanced melanoma who had progressed after anti-PD-1 therapy, making it one of the largest randomized TIL therapy studies reported to date. Notably, 81.8% of patients had acral or mucosal melanoma — subtypes that are less responsive to immunotherapy and account for the majority of melanoma cases in Asian populations.
The study was presented by Dr. Lu Si and led by principal investigator Dr. Jun Guo (郭军) of Peking University Cancer Hospital.
Key Efficacy Results
| Endpoint | GC101 TIL (n=49) | Chemotherapy (n=49) | Difference |
|---|---|---|---|
| Objective Response Rate (ORR) | 42.0% | 6.1% | +35.9 pp |
| Median Progression-Free Survival (PFS) | 4.3 months | 1.6 months | HR 0.43 [95% CI 0.28–0.65] |
| p-value | p = 0.0002 | ||
| 6-month PFS rate | 36.0% | 8.0% | +28 pp |
| Disease Control Rate (DCR) | 72.0% | 24.5% | +47.5 pp |
| Best Overall Response — Complete Response (CR) | 8.2% | 0% | — |
| Best Overall Response — Partial Response (PR) | 33.8% | 6.1% | — |
| pp = percentage points. As reported at ASCO 2026, LBA 9509. This was a single-trial analysis and further confirmatory studies are needed. | |||
Safety Profile
GC101 demonstrated a manageable safety profile consistent with known TIL therapy toxicities. No treatment-related deaths were reported in either arm. The most common adverse events in the GC101 arm were related to the lymphodepletion preparative regimen (febrile neutropenia, thrombocytopenia) and IL-2 administration, all of which were predictable and manageable per institutional protocols.
Trial Design
MIZAR-003 (NCT05417750) is a randomized, open-label, Phase II study conducted at Peking University Cancer Hospital. Key eligibility criteria included:
- Histologically confirmed advanced melanoma with progression after ≥1 prior systemic therapy including anti-PD-1
- ECOG performance status 0–1
- At least one resectable tumor lesion ≥1.5 cm for TIL generation
- Measurable disease per RECIST 1.1
Patients were randomized 1:1 to receive either GC101 TIL therapy (tumor resection → TIL manufacturing → lymphodepletion → TIL infusion → IL-2 support) or investigator's choice of chemotherapy (dacarbazine or temozolomide).
Implications for Patients
These results represent a significant step forward for TIL therapy as a treatment option for advanced melanoma, particularly for acral and mucosal subtypes that have limited effective treatment options after anti-PD-1 failure. The 42% objective response rate and HR of 0.43 for progression-free survival suggest meaningful clinical benefit, while the safety profile reinforces the feasibility of TIL therapy delivery.
About GC101 TIL Therapy
GC101 is an investigational TIL cell therapy developed by Juncell Therapeutics, a Chinese biotechnology company specializing in cellular immunotherapy. The therapy involves surgically harvesting a patient's own tumor-infiltrating lymphocytes, expanding them ex vivo, and reinfusing them to mount a targeted immune response against the tumor. GC101 is currently being evaluated in multiple clinical trials across lung cancer, melanoma, and other solid tumors.
Industry analysis on Substack
For a deeper analysis of the MIZAR-003 data, trial design details, and what these results mean for the TIL therapy landscape, read the full analysis on our Substack.