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P41. Predictors of manufacturing success after tumor tissue procurement for tumor infiltrating lymphocyte cell therapy

Thursday, March 5, 2026
2:25 PM - 2:32 PM MST
Location: 301D
Introduction

Autologous tumor infiltrating lymphocyte (TIL) cell therapy is a treatment for patients with metastatic melanoma who have progressed on systemic therapy. TIL therapy requires surgical tumor tissue procurement (TTP) for product manufacturing, including TIL isolation, expansion, and infusion. Data is limited on how surgical factors impact TIL manufacturing success; the current standard is to select a site that will result in at least 1.5cm2 of viable tissue. FDA specifications for TIL products are largely undisclosed other than the final product contains 7.5 - 72x109 cells. The aim of the TIL TTP Working Group, a multi-institutional collaborative, is to optimize TTP. The aim of this study is to identify predictors of initial manufacturing success to guide future TTP site selection.

Methods

Patients who underwent TTP at a TIL TTP Working Group center with available manufacturing outcomes were included after local IRB approval. Clinical, oncologic, peri-operative, and outcome variables were collected. The primary outcome was initial manufacturing success, defined as production of an in-spec TIL product. Secondary outcomes were variables associated with manufacturing success.

Results

Between December 2023 and August 2025, 87 patients from six institutions underwent TTP for commercial TIL, 85% (74/87) of which resulted in manufacturing success. Aggregate size (cm2), history of immunosuppression or being on steroids at the time of TTP, donor tissue type, or preoperative Hounsfield units were not associated with manufacturing success. Four of the six patients who received radiation to the TTP donor site had successfully manufactured TIL (p=0.22). Although not statistically significant, higher SUV on pre-operative PET may be associated with a decreased likelihood of manufacturing success with a larger cohort (mean[SD] success: 16.09[14.60] vs 28.68[22.04], p=0.09). Necrosis on final pathology was not associated with a decreased likelihood of manufacturing success, though was not reported in 34.5% of patients. However, surgeon assessment of gross necrosis during TTP was associated with a decreased likelihood of manufacturing success (in-spec: 9%, out-of-spec: 33.3%, p=0.04).

Conclusions

The TIL TTP Working Group was established to optimize TIL TTP in the real-world setting. In this initial series, gross necrosis during TTP was associated with a decreased likelihood of manufacturing success, and elevated SUV of the donor site on PET warrants further investigation. Multi-institutional and academic-industry partnerships are essential to improve TIL TTP outcomes.

Learning Objectives:

  • Participants should recognize surgical factors of tumor tissue procurement associated with tumor infiltrating lymphocyte manufacturing success.
  • Participants should appreciate the need for multi-institutional and academic-industry relationships to improve tumor infiltrating lymphocyte therapy outcomes