Method for estimation of apoptotic cell fraction of cytotherapy using in vivo fluorine-19 magnetic resonance: pilot study in a patient with head and neck carcinoma receiving tumor-infiltrating lymphocytes labeled with perfluorocarbon nanoemulsion

Background Adoptive transfer of T cells is a burgeoning cancer therapeutic approach. However, the fate of the cells, once transferred, is most often unknown. We describe the first clinical experience with a non-invasive biomarker to assay the apoptotic cell fraction (ACF) after cell therapy infusion, tested in the setting of head and neck squamous cell carcinoma (HNSCC). A patient with HNSCC received autologous tumor-infiltrating lymphocytes (TILs) labeled with a perfluorocarbon (PFC) nanoemulsion cell tracer. Nanoemulsion, released from apoptotic cells, clears through the reticuloendothelial system, particularly the Kupffer cells of the liver, and fluorine-19 (F-19) magnetic resonance spectroscopy (MRS) of the liver was used to non-invasively infer the ACF. MethodsA utologous TILs were isolated from a patient in their late 50s with relapsed, refractory human papillomavirus-mediated squamous cell carcinoma of the right tonsil, metastatic to the lung. A lung metastasis was resected for T cell harvest and expansion using a rapid expansion protocol. The expanded TILs were intracellularly labeled with PFC nanoemulsion tracer by coincubation in the final 24 hours of culture, followed by a wash step. At 22 days after intravenous infusion of TILs, quantitative single-voxel liver F-19 MRS was performed in vivo using a 3T MRI system. From these data, we model the apparent ACF of the initial cell inoculant. Results We show that it is feasible to PFC-label similar to 70x10(10) TILs (F-TILs) in a single batch in a clinical cell processing facility, while maintaining >90% cell viability and standard flow cytometry-based release criteria for phenotype and function. Based on quantitative in vivo F-19 MRS measurements in the liver, we estimate that similar to 30% cell equivalents of adoptively transferred F-TILs have become apoptotic by 22 days post-transfer. Conclusions Survival of the primary cell therapy product is likely to vary per patient. A non-invasive assay of ACF over time could potentially provide insight into the mechanisms of response and non-response, informing future clinical studies. This information may be useful to developers of cytotherapies and clinicians as it opens an avenue to quantify cellular product survival and engraftment.

Automated summary

This study describes the use of a non-invasive biomarker to assay the apoptotic cell fraction after cell therapy infusion in a patient with head and neck squamous cell carcinoma. The results showed that the survival of the cell therapy product varies per patient, and a non-invasive assay of apoptotic cell fraction could provide insight into response and non-response mechanisms.