Conference Coverage

Universal CAR-T therapy produces CRs in relapsed/refractory T-ALL


 

FROM AACR 2020

A universal chimeric antigen receptor (CAR) T-cell therapy produced responses in adults with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL), according to initial findings from an ongoing study.

The first five patients enrolled in this first-in-human study received conditioning and an infusion of the premanufactured CD7-targeted CAR T-cell therapy, TruUCAR GC027.

All five patients achieved a complete remission (CR) or CR with incomplete count recovery (CRi), although one patient had a morphological relapse at 1 month.

Xinxin Wang, PhD, reported these results at the AACR Virtual Meeting I. Dr. Wang is employed by Gracell Biotechnologies in Shanghai, China, which is the company developing TruUCAR GC027.

The CAR T-cell therapy is manufactured using lentivirus and leukopaks from HLA-mismatched healthy donors, according to Dr. Wang. TruUCAR GC027 contains second-generation CAR T cells with genomic disruption of TCR-alpha and CD7 to help prevent graft-versus-host disease and fratricide.

TruUCAR GC027 was previously shown to expand and have antileukemic activity in a murine model, Dr. Wang noted.

Patients and treatment

The five patients in the phase 1 study had a median age of 24 years (range, 19 to 38 years). They had heavily pretreated T-ALL, with a median of 5 prior lines of therapy (range, 1-9). Baseline bone marrow tumor burden ranged from 4% to 80.2% (median, 38.2%).

None of the patients received prior allogeneic hematopoietic stem cell transplant.

All patients received a preconditioning chemotherapy regimen. One patient received TruUCAR GC027 at dose level 1 (6 x 106 cells/kg), three patients received dose level 2 (1 x 107 cells/kg), and one patient received dose level 3 (1.5 x 107 cells/kg) – each as a single infusion.

Expansion, response, and safety

“GC027 expansion, analyzed by flow [cytometry] was observed in most of the patients treated,” Dr. Wang said. “We started to see GC027 in the peripheral blood as early as day 5, with peaks around day 7-14.”

All five patients had a CR or CRi at the first postinfusion evaluation, which occurred at day 14 in four of the five patients. Four patients also achieved minimum residual disease (MRD) negativity by 1 month of follow-up and remained in MRD-negative CR at the February 6, 2020, data cutoff.

One patient achieved MRD-positive CR at day 14 but experienced morphological relapse at 1 month.

In the four patients with MRD-negative CR at 1 month, cellular expansion was observed as early as day 5 and continued for 2 weeks, but the patient who relapsed at day 29 showed no cellular expansion on flow cytometry, Dr. Wang said.

However, by a more sensitive quantitative polymerase chain reaction analysis, cellular expansion was observed in all five patients starting as early as day 1 after infusion, although the patient who relapsed had the shortest duration of expansion.

All patients developed cytokine release syndrome (CRS). Four patients experienced grade 3 CRS, and one experienced grade 4 CRS.

“The CRS was manageable and reversible,” Dr. Wang said, adding that none of the patients experienced neurotoxicity or graft-versus-host disease.

Prolonged cytopenia occurred in four patients, including one grade 1 case, two grade 3 cases, and one grade 4 case. Grade 3 pulmonary infections occurred in three patients, and grade 3 neutropenia occurred in all five patients.

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