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Low intensity bridging may be best path to CAR T in adult ALL



– A low intensity chemotherapy regimen may be the best approach to bridge patients waiting for chimeric antigen receptor (CAR) T-cell therapy, according to a retrospective analysis of adults with acute lymphoblastic leukemia (ALL).

Investigators found that high intensity bridging regimens provided no clear outcome benefit, but did produce a greater number of infections.

But the decision on the type of regimen is very much dependent on the individual patient, Karlo Perica, MD, PhD, of Memorial Sloan Kettering Cancer Center in New York, said at the annual meeting of the American Society of Clinical Oncology.

Mary Ellen Schneider/MDedge News

Dr. Karlo Perica

Dr. Perica and his colleagues at Memorial Sloan Kettering examined the effectiveness and toxicity of bridging therapies provided to relapsed or refractory ALL patients waiting to receive CD19 CAR T-cell therapy as part of a phase 1 trial (N Engl J Med. 2018 Feb 1;378[5]:449-59).

Bridging therapy was defined as any therapy given from leukapheresis to cell infusion.

The low-intensity regimens included POMP (6-mercaptopurine, vincristine, methotrexate, and prednisone, or combinations), liposomal vincristine, mini-hyper CVD (reduced cyclophosphamide, dexamethasone, methotrexate, Ara-C), blinatumomab, inotuzumab, oral tyrosine kinase inhibitor-based regimens, or hydroxyurea.

The high-intensity regimens included hyper-CVAD (cyclophosphamide, vincristine, doxorubicin, dexamethasone), high-dose cytarabine, attenuated FLAG/FLAG-IDA (reduced fludarabine, cytarabine, G-CSF plus or minus idarubicin), and pediatric-type induction.

Of the 53 patients who were ultimately infused with CAR T cells, 19 received some type of high intensity regimen, 29 received low intensity regimens, and 5 received no bridging treatment. The group overall was heavily pretreated. Nearly a third of the low intensity and no bridging patients and 42% of the high intensity patients had previously undergone transplant. More than 40% of the low intensity and no bridging patients and about a quarter of the high intensity bridging group had four or more prior lines of therapy.

The use of high intensity bridging therapy was not associated with improved overall response or relapse-free survival to CAR T-cell therapy, the investigators reported. In a subgroup with 23 high disease burden patients with greater than 20% blasts, there was no difference in MRD-negative complete response by intensity (75% versus 60%, Fisher’s P = .65).

High intensity bridging was also not associated with successful CAR T-cell infusion, versus low intensity regimens (63% versus 79%, P greater than .05) or a combined endpoint of CAR T-cell infusion plus transplant or alternative treatment (80% versus 86%, P greater than .05).

In terms of toxicity, the high intensity bridging regimens were associated with a higher rate of grade 3 or 4 infections – 15 versus 11 infections (Fisher’s P = .002). But there was no association with post-infusion grade 3 or 4 cytokine release syndrome or neurotoxicity.

Dr. Perica said the results reflect that the real goal of bridging is not to reduce disease burden but instead to successfully bring patients to the next phase of their treatment. “The goal of the bridging therapy is to get the patient to the CAR infusion,” he said.

Due to the retrospective nature of the study, Dr. Perica said he can’t recommend any single bridging regimen and he emphasized that the decisions are patient-specific.

The original study was funded by several foundations and Juno Therapeutics. Dr. Perica reported royalties from technology licensed to Neximmune.

SOURCE: Perica K et al. ASCO 2019, Abstract 2520.

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