NEW YORK—For the first time, according to researchers, chimeric antigen receptor (CAR) T-cell therapy has been tested in a clinical trial in Sweden.
Early results have shown the treatment can produce complete responses (CRs) in leukemia and lymphoma, although most patients ultimately progressed.
Hannah Karlsson, PhD, of Uppsala University in Sweden, presented data from the phase 1/2a trial of the third-generation CD19 CAR T-cell therapy (abstract A041*) at the inaugural CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference.
The trial is a collaboration between Uppsala University and Baylor College of Medicine and was funded by AFA Insurances AB and the Swedish Cancer Society.
“Third-generation CAR T cells are being tested in clinical trials for leukemia patients in the United States with success,” said senior study author Angelica Loskog, PhD, also of Uppsala University.
“[T]he main purpose of our clinical trial was to evaluate whether we could reproduce the successful results in leukemia patients in Sweden and to also test if patients with lymphoma will also respond to this treatment.”
So the investigators enrolled 13 patients, 11 of whom were evaluable for efficacy at 3 months after CAR T-cell infusion. All patients had relapsed or refractory, CD19-positive, B-cell disease.
Two patients had acute lymphoblastic leukemia (ALL), 2 had chronic lymphocytic leukemia (CLL), and 7 had lymphoma—3 with diffuse large B-cell lymphoma (DLBCL), 2 with mantle cell lymphoma (MCL), 1 with follicular lymphoma (FL)/DLBCL, and 1 with Burkitt lymphoma.
All of the lymphoma patients received chemotherapy before CAR T-cell infusion to shrink their tumors. Seven patients—3 with leukemia and 4 with lymphoma—received pre-conditioning with cyclophosphamide plus fludarabine to reduce their immunosuppressive cell counts.
The investigators used CAR T cells containing signaling domains from both CD28 and 4-1BB and manufactured using a gamma retrovirus.
Patients received a single infusion of the CAR T cells, 2 patients at a dose of 2 x 107 cells/m2, 4 at a dose of 1 x 108 cells/m2, and 5 at 2 x 108 cells/m2.
Response and toxicity
Six patients had achieved a CR at the time of evaluation.
One patient with DLBCL experienced mild cytokine release syndrome (CRS) before achieving CR. However, the patient relapsed after a second CRS occurred (after 3 months).
Another DLBCL patient achieved a CR prior to T-cell infusion and remained in CR for 6 months before progressing.
One CLL patient and another DLBCL patient responded prior to T-cell infusion and remained in CR for more than 3 months. The CLL patient was still in CR at the time of the meeting.
One of the ALL patients achieved a CR after transient central nervous system toxicity but relapsed at 3 months with CD19-negative ALL. The other ALL patient was in CR for more than a month after experiencing CRS but ultimately progressed.
One CLL patient and 2 MCL patients had all progressed by 3 months.
The FL/DLBCL patient progressed after 1 month, with mild CRS. And the patient with Burkitt lymphoma had major CRS and progressive disease.
The investigators noted that 5 of the 6 patients who received pre-conditioning treatment had initial CRs.
The team is now analyzing whether there is any correlation between the level of immunosuppressive cells and patient response.
*Information presented at the meeting differs from the abstract.