ORLANDO – Anti-CD5 chimeric antigen receptor (CAR) T cells can produce complete responses (CRs) in patients with relapsed or refractory T-cell malignancies, according to findings from a phase 1 trial.
Three of 11 patients achieved a CR after CAR T-cell therapy, and one patient achieved a mixed response that deepened to a CR after transplant. Three responders, all of whom had T-cell lymphoma, were still alive and in CR at last follow-up.
There were no cases of severe cytokine release syndrome (CRS) or severe neurotoxicity, no serious infectious complications, and no nonhematologic grade 4 adverse events in this trial.
, of Baylor College of Medicine, Houston, presented these results at the annual meeting of the American Society of Hematology.
“While CD19 CAR T cells have revolutionized the treatment of relapsed/refractory B-cell malignancies, development of CAR T-cell platforms targeting T-cell-driven malignancies have been hindered by three main factors: CAR T-cell fratricide due to shared expression of target antigens leading to impaired expansion, ablation of normal T cells continuing to cause profound immunodeficiency, and the potential of transduced tumor cells providing a means of tumor escape,” Dr. Hill said.
Researchers have theorized that anti-CD5 CAR T cells can overcome these obstacles. In preclinical studies, anti-CD5 CAR T cells eliminated malignant blasts in vitro and in vivo and resulted in “limited and transient” fratricide ().
With this in mind, Dr. Hill and her colleagues tested CD5.28z CAR T cells in a phase 1 trial (). Eleven patients have been treated thus far – five with T-cell acute lymphoblastic leukemia (T-ALL), three with peripheral T-cell lymphoma (PTCL), two with angioimmunoblastic T-cell lymphoma (AITL), and one with Sézary syndrome.
The patients’ median age at baseline was 62 years (range, 21-71 years), and 63% were men. They had received a median of 5 prior therapies (range, 3-18). Two patients had relapsed after allogeneic hematopoietic stem cell transplant (HSCT), three had relapsed after autologous HSCT, and five were primary refractory.
Patients underwent lymphodepletion with fludarabine and cyclophosphamide, then received CAR T cells at doses of 1 x 107 or 5 x 107.
Three lymphoma patients – two with AITL and one with PTCL – were still alive and in CR at last follow-up. The PTCL patient achieved a CR after CAR T-cell therapy and declined a subsequent HSCT. The patient has not received additional therapy and has retained the CR for 7 months.
One AITL patient achieved a CR and declined transplant as well. He relapsed after 7 months but received subsequent therapy and achieved another CR. The other AITL patient had a mixed response to CAR T-cell therapy but proceeded to allogeneic HSCT and achieved a CR that has lasted 9 months.
The remaining three lymphoma patients – two with PTCL and one with Sézary syndrome – progressed and died.
One T-ALL patient achieved a CR lasting 6 weeks, but the patient died while undergoing transplant workup. Two T-ALL patients did not respond to treatment and died. The remaining two patients progressed, and one of them died. The other patient who progressed is still alive and in CR after receiving subsequent therapy.