PD1 Knockout CAR T-Cell Therapy Well-Tolerated, Yields Durable Response in DLBCL
A phase 2 trial evaluated the therapy in patients with diffuse large B-cell lymphoma, B-acute lymphocytic leukemia, and follicular lymphoma.
shRNA-mediated PD1 gene knock-down anti-CD19 chimeric antigen receptor (CAR) T-cell therapy had an acceptable safety profile with some signs of clinical activity in patients with
Data from the phase 2 trial evaluating the therapy in China were presented by Hong Cen, MD, Guangxi Medical University Affiliated Tumor Hospital and Oncology Medical Center, at the
“PD-1/PD-L1 binding can inhibit T cell activation. Many studies have proved that blockade of PD-1/ PD-L1 axis is effective to enhance the function of CAR-T cells. However, this strategy has mainly been studied in vitro and the antitumor properties of CAR-T cells that continuously knock down PD-1 in vivo have not been thoroughly investigated,” Cen said during his presentation.
The trial enrolled 16 patients with relapsed/refractory B-cell malignancies, including diffuse large B-cell lymphoma (DLBCL; n = 8), B-cell acute lymphocytic leukemia (B-ALL; n = 4), follicular lymphoma (FL; n = 2), chronic lymphocytic leukemia (CLL; n = 1), and high-grade B-cell lymphoma (HGBL; n = 1).
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The PD1 knock-out CAR T-cell therapy had a manageable safety profile, with no cases of neurotoxicity and 11 cases (68.8%) of cytokine release syndrome (CRS). Most cases of CRS were mild, with 7 cases of grade 1 and 4 cases of grade 2 CRS. There were no deaths due to treatment-related adverse events (AEs).
The investigators found that most participants had an increase in interleukin-6 (IL6) levels after CAR T-cell infusion. These levels varied greatly between participants and were not necessarily correlated with CRS severity. Furthermore, 2 patients that did not experience CRS had IL6 levels greater than 1000 pg/mL. Cen and colleagues also found that change in c-reactive protein and ferritin was not as significant after CAR T-cell infusion.
“Using cytokines may be difficult to predict occurrence and severity of CRS,” Cen said.
Cen and colleagues found that 6 patients achieved a complete response (CR), 3 with B-ALL, 2 with BLBCL, and 1 with FL. Four patients achieved a partial response (PR), 3 with DLBCL and 1 with FL. Three patients that achieved a CR, 2 with DLBCL and 1 with FL, have a continuing response for durations of 36, 34, and 29 months. The 3 other patients that achieved a CR with B-ALL relapsed on days 59, 78, and 110 after infusion.
“PD1 gene knock-down anti-CD19 CAR-T therapy showed acceptable safety and anti-tumor activity in patients with relapsed or refractory CD19+ B cell malignancies,” Cen concluded.
REFERENCE
Cen H, Ke Q, Li D, et al. shRNA-mediated PD1 gene knock-down anti-CD19 CAR-T cell therapy for relapsed/refractory b cell malignancies. Presented at: ESMO 2022 Congress, September 9-13, Paris, France. Abstract #619O.
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