ATLANTA – More than one-third of patients with refractory large B-cell lymphomas treated with the chimeric antigen receptor (CAR) T-cell product axicabtagene ciloleucel (Yescarta), often called axi-cel, had durable responses, with some patients having complete responses lasting more than 1 year after a single infusion, according to investigators in the ZUMA-1 trial.

Updated combined phase 1 and phase 2 results in 108 patients with diffuse large B-cell lymphoma (DLBCL), primary mediastinal B-cell lymphoma (PMBCL), or transformed follicular lymphoma (TFL) showed an objective response rate (ORR) of 82%, including 58% complete responses, after a median follow-up of 15.4 months, reported Sattva S. Neelapu, MD, from the University of Texas MD Anderson Cancer Center in Houston.

“Axi-cel is highly effective in patients with large B-cell lymphoma who otherwise have no curative treatment options,” he said in a briefing at the annual meeting of the American Society of Hematology, prior to his presentation of the data in an oral session.

The trial results were also published simultaneously in the New England Journal of Medicine.As previously reported, in the multicenter phase 2 ZUMA-1 trial, 111 patients with treatment refractory DLBCL, PMBCL, or TFL were enrolled and treated with axi-cel at a target dose of 2 x 10⁶ cells/kg, following a conditioning regimen with low-dose cyclophosphamide and fludarabine.

The median patient age was 58 years. Patients had stage III or IV disease, 48% had International Prognostic Index scores of 3-4, 76% had disease that was refractory to third-line therapies or beyond, and 21% had disease that relapsed within 12 months of an autologous bone marrow transplant

Axi-cel was successfully manufactured with sufficient cells for transfusion in all but one of the 111 patients, and 101 patients eventually received infusions in phase 2 (modified intention-to-treat population). The average turnaround time from apheresis to the clinical site was 17 days.

Dr. Neelapu also presented data on seven patients enrolled in phase 1; the data were combined with the phase 2 results for an updated analysis of those patients who had at least 1 year of follow-up.

The phase 2 trial met its primary endpoint at the time of the primary analysis, with an 82% ORR, consisting of 54% complete responses and 28% partial responses at a median follow-up of 8.7 months.

In the updated analysis, the ORR and respective remission rates were 82%, 58%, and 34%, at a median of 15.4 months follow-up.

The median duration of response in the updated analysis was 11.1 months. The median duration of complete responses had not been reached at the time of data cutoff in August 2017. The median duration of partial responses was 1.9 months.

At the 15.4-month mark, 42% of patients remained free of disease progression, and 56% were alive, with the median overall survival not yet reached.

The treatment had generally acceptable toxicities, with only 13% of patients in phase 2 experiencing grade 3 or greater cytokine release syndrome (CRS), although one patient with CRS died from hemophagocytic lymphohistiocytosis, and one with CRS died from cardiac arrest. Grade 3 or greater neurologic events occurred in 28% of patients, and included encephalopathy, confusional state, aphasia, and somnolence.

The events were generally reversible, and the rates of each declined over time. The use of tocilizumab or steroids to control adverse events did not have a negative effect on responses.

Since the primary analysis with at least 6 months of follow-up, there have been no new axi-cel–related cases of CRS, neurologic events, or deaths.

Dr. Neelapu also presented safety data on serious adverse events occurring more than 6 months after therapy in 10 patients who developed symptoms after the data cutoff.

Grade 3 events in these patients included lung infection, recurrent upper respiratory viral infection, and rotavirus infection, pneumonias, atrial fibrillation with rapid ventricular response, lung infection, febrile neutropenia, and influenza B infection. One patient had grade 4 sepsis.

In an editorial accompanying the study in the New England Journal of Medicine, Eric Tran, PhD, and Walter J. Urba, MD, PhD, from the Earle A. Chiles Research Institute and the Providence Portland (Ore.) Medical Center, and Dan L. Longo, MD, deputy editor of the journal, praised ZUMA-1 as “a landmark study because it involved 22 institutions and showed that a personalized gene-engineered T-cell product could be rapidly generated at a centralized cell-manufacturing facility and safely administered to patients at transplantation-capable medical centers.”

They noted, however, that about half of all patients with relapsed or refractory large B-cell lymphomas will not have durable responses to CAR T-cell therapy directed against CD19, and that new strategies will be needed to improve responses (N Engl J Med. 2017 Dec 10; doi: 10.1056/NEJMe1714680).

In the question and answer session at the end of the briefing, Dr. Neelapu said the preliminary observations of mechanisms of relapse or disease progression in some patients may be related to the loss of the CD19 antigen, which occurs in about one-third of patients who experience relapse, and to high expression of the programmed death ligand-1, which can potentially inhibit CAR-T cell function. A clinical trial is currently underway to evaluate potential strategies for improving response rates to CAR-T therapies, he said.

ZUMA-1 is supported by Kite Pharma and the Leukemia and Lymphoma Society Therapy Acceleration Program. Dr. Neelapu reported receiving advisory board fees from the company. Myriad coauthors also reported financial relationship with multiple companies.

SOURCE: Neelapu S et al. ASH 2017 Abstract 578.

Updated ZUMA-1 data show durable CAR-T responses in B-cell lymphomas