A few weeks after receiving chimeric antigen receptor (CAR) T-cell (CAR-T) therapy, many patients experience prolonged reductions in blood cell counts, possibly making them more vulnerable to infections. 

Two recent studies characterized the extent and duration of post–CAR-T cytopenia among patients receiving CAR-T therapy for hematological malignancies — with 1 study offering insights on some of the possible factors that may influence hematological count recovery.

“What’s important to know is that by day 90, most patients recover,” noted Uroosa Ibrahim, MD, stem cell transplantation and cellular therapy fellow at the Tisch Cancer Institute of the Icahn School of Medicine at Mount Sinai, New York, who coauthored 1 of the studies. “We’re supporting them for [approximately] 3 months [with treatment], but then they’ll recover, which is good to know.”

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One study by Memorial Sloan Kettering Cancer Center (MSKCC) researchers followed 83 adult patients who received CAR-T therapy: 40 patients received 1 of 2 Food and Drug Administration (FDA)-approved therapies, axicabtagene ciloleucel (axi-cel; Yescarta®) or tisagenlecleucel (tisa-cel; Kymriah®), to treat relapsed/refractory B-cell lymphoma.

The remainder comprised 37 patients with relapsed/refractory B-cell acute lymphoblastic leukemia who were currently enrolled in a clinical trial in which they received an experimental CAR-T therapy where cells express the 19-28z CAR construct (ClinicalTrials.gov Identifier: NCT01044069), and 6 multiple myeloma patients who received a different experimental CAR-T construct that targets the B-cell maturation antigen (BCMA) (ClinicalTrials.gov Identifier: NCT03070327). The findings were presented at the annual Transplantation and Cellular Therapy Meetings of ASCT and CIBMTR in February 2020.1

By 1 month, the researchers observed that 24% of patients experienced a complete recovery of hemoglobin, platelets, absolute neutrophil count, and white blood cell counts — “recovery” being defined as reaching safe levels, and without requiring transfusions or treatment with growth factors.

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Recovery of hemoglobin was noted in 61% of patients, platelets in 51% of patients, absolute neutrophil count in 33% of patients, and white blood cell count in 28% of patients. Examining 41 patients at 3 months, those figures were 93%, 90%, 81%, and 59%, respectively, and overall, 56% saw a complete blood count recovery.

The results were broadly consistent with recent research by Dr Ibrahim and Keren Osman, MD, associate professor and director of medicine at the Icahn School of Medicine at Mount Sinai and director of cellular therapy service in the bone marrow and stem cell transplantation program at the school’s Tisch Cancer Institute. That study comprised 50 patients — 41 with multiple myeloma and 9 with diffuse large B-cell lymphoma — who received either axicabtagene ciloleucel, or 1 of 2 experimental anti-BCMA CAR-T therapies, bb2121 or bb21217.