Absolute lymphocyte count recovery following initial acute myelogenous leukemia therapy: Implications for adoptive...

An adequate absolute lymphocyte count (ALC) is an essential first step in autologous chimeric antigen receptor (CAR) T-cell manufacturing. For patients with acute myelogenous leukemia (AML), the intensity of chemotherapy received may affect adequate ALC recovery required for CAR T-cell production. We sought to analyze ALC following each course of upfront therapy as one metric for CAR T-cell manufacturing feasibility in children and young adults with AML.

ALC data were collected from an observational study of patients with newly diagnosed AML between the ages of 1 month and 21 years who received treatment between the years of 2006 and 2018 at one of three hospitals in the Leukemia Electronic Abstraction of Records Network (LEARN) consortium.

Among 193 patients with sufficient ALC data for analysis, the median ALC following induction 1 was 1715 cells/microl (interquartile range: 1166-2388), with successive decreases in ALC with each subsequent course. Similarly, the proportion of patients achieving an ALC >400 cells/microl decreased following each course, ranging from 98.4% (190/193) after course 1 to 66.7% (22/33) for patients who received a fifth course of therapy.

There is a successive decline of ALC recovery with subsequent courses of chemotherapy. Despite this decline, ALC values are likely sufficient to consider apheresis prior to the initiation of each course of upfront therapy for the majority of newly diagnosed pediatric AML patients, thereby providing a window of opportunity for T-cell collection for those patients identified at high risk of relapse or with refractory disease.