Non-Proliferation Assay

By Chase P. Monckton, Ph.D., Zheng Yang, Ph.D., Trevor Cabreros, Aniha Vijay Kumar, Savannah Ayyoub, Sofia Huertero, and Rob Tressler, Ph.D.

Tumor-infiltrating leukocytes (TILs) are immune cells naturally present within patient tumors and possess intrinsic anti-cancer activity. TIL-based therapies have emerged as a promising form of immunotherapy for treating various cancers, with the number of clinical trials involving TILs growing rapidly. These therapies involve isolating TILs from a patient’s tumor biopsy, followed by ex vivo expansion to generate a personalized cell therapy. The most effective method for expanding TILs outside the body requires co-culture with an unrelated secondary cell population — typically non-irradiated peripheral blood mononuclear cells (PBMCs) — which act as feeder cells to support TIL growth.

To meet the increasing demand in this field, we produce cGMP-compliant feeder cells specifically for TIL manufacturing. However, it is critical to ensure that these feeder cells do not proliferate within the final TIL product, as their presence could negatively impact safety and therapeutic efficacy due to immune incompatibility. To address this, we developed a replication competency assay that monitors feeder cell proliferation over extended culture, confirming their non-proliferative status before use in TIL expansion.