(P-BT-12) Factors Affecting Apheresis CD3+ Cell Counts For Autologous Chimeric Antigen Receptor (CAR) T Cell Therapy: Insights Of A Prospective Analysis From Tertiary Care Oncology Centre

CAR-T cell therapy has emerged as a promising treatment modality for patients with refractory or relapsed (r/r) malignancies like Lymphoma and Leukemia. However, its success relies on the efficient collection of lymphocytes (CD3+ T cells) through apheresis procedures. The study aimed to analyse factors influencing apheresis CD3+ cell counts for CAR-T cell therapy of oncology patients.

Study

Design/Methods:

This was prospective observational study conducted between January and December 2023 after approval by the Institutional Ethics Committee and registration with Clinical Trial Registry of India.

< !a) Patients:

Total 48 autologous lymphapheresis procedures were conducted in 44 patients with r/r Lymphoma (mostly Diffuse Large B cell lymphoma (DLBCL)), or Leukemia, (mostly B-ALL) after obtaining written informed consent. Pre-apheresis hematological parameters and flow cytometry analysis of the patients was done to estimate absolute lymphocyte counts (ALC) and peripheral blood CD3+ cell count respectively.

< !b) Lymphapheresis procedures:

All procedures were performed on Spectra Optia Apheresis System (Terumo BCT, Japan) with Continuous Mononuclear Cell Collection (cMNC) protocol using Acid Citrate Dextrose (ACD) solution with target yield of 6 × 10⁸ CD3+ cells/ unit.

< !c) Apheresis product:

Product volume, Total leukocyte counts (TLC), ALC, and CD3+ cell count in the apheresis product were recorded. CD3+ cells were estimated by flow cytometry.

< !d) Statistical analysis:

Predictive factors for CD3+ cells in the product were analyzed using the Pearson correlation coefficient and regression models, and p< 0.05 was considered statistically significant. Statistical analyses were performed using SPSS Software (Version 25.0. Armonk, NY: IBM Corp.)

Results/Findings:

The patient details, lymphapheresis procedure, and apheresis product details are described in the Table 1. Pre- apheresis patient TLC, ALC, and CD3+ cells showed significant positive correlation with absolute CD3+ cells in the apheresis product (p< 0.05). Multivariate analyses revealed that pre- apheresis lower hematocrit levels, and higher platelet counts reduced absolute CD3+ cells in the apheresis product. Target CD3+ cell count was achieved in 96% (46/48) of the procedures.

Conclusions:

Pre-apheresis patient TLC, ALC, CD3+ cells, haematocrit and platelet counts are the important factors which plays a crucial role in harvesting adequate CD3+ cells in the apheresis product. Thus, understanding different variables that affect the lymphocyte collection will aid in ensuring sufficient Cd3+ cells are collected for manufacturing.