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Lymphodepletion improves efficacy of CAR T cells in HL


 

© ASH/Rodney White 2018

Crowd exiting a session at the 2018 ASH Annual Meeting

SAN DIEGO—A phase 1 study suggests lymphodepletion can improve the efficacy of CD30-directed chimeric antigen receptor (CAR) T-cell therapy in patients with Hodgkin lymphoma (HL).

Researchers observed improved responses in HL patients treated with fludarabine and cyclophosphamide prior to CD30.CAR T-cell therapy.

This lymphodepleting regimen was also associated with increased toxicity, compared to no lymphodepletion. However, researchers consider the regimen safe.

Carlos A. Ramos, MD, of Baylor College of Medicine in Houston, Texas, presented these results at the 2018 ASH Annual Meeting (abstract 680*).

Without lymphodepletion

Dr. Ramos first discussed a previous phase 1 trial (NCT01316146), which was published in The Journal of Clinical Investigation in 2017.

In this trial, he and his colleagues had tested CD30.CAR T-cell therapy in patients with relapsed/refractory, CD30+ HL or T-cell non-Hodgkin lymphoma. None of these patients underwent lymphodepletion.

There were no dose-limiting toxicities in this trial—including no neurotoxicity or cytokine release syndrome—but responses were “limited,” according to Dr. Ramos.

Three patients achieved a complete response (CR), three had stable disease, and three progressed.

“Although we saw no significant toxicities and some good clinical responses . . ., the bottom line is that the responses were still quite limited, with several patients having, at most, stable disease or progressive disease,” Dr. Ramos said.

With lymphodepletion

Results from the previous trial prompted Dr. Ramos and his colleagues to conduct the RELY-30 trial (NCT02917083) and investigate whether lymphodepletion would improve responses to CD30.CAR T-cell therapy.

Thus far, 11 patients have been treated on this trial. All had relapsed, CD30+ HL at baseline. Six patients are male, and their median age at baseline was 30 (range, 17-69).

The patients had a median of 5 prior treatments (range, 2-9). This included PD-1 inhibitors (n=10), brentuximab vedotin (n=8), and transplant (n=6).

All patients received lymphodepletion with cyclophosphamide at 500 mg/m2 and fludarabine at 30 mg/m2 daily for 3 days. They then received CD30.CAR T-cell therapy at 2×107 cells/m2 or 1×108 cells/m2.

Dr. Ramos noted that CD30.CAR T-cell expansion was dose-dependent and increased by lymphodepleting chemotherapy.

“The peak expansion is much higher [with lymphodepletion], probably in the order of two to three logs higher than what we see without lymphodepleting chemotherapy,” he said. “So chemotherapy makes a difference.”

Increased CD30.CAR T-cell expansion was associated with improved response. Of the nine evaluable patients, six achieved a CR, and three progressed.

Four complete responders were still in CR at last follow-up, one of them for more than a year. However, two complete responders ultimately progressed.

In addition to improved responses, the researchers observed increased toxicity in this trial. Dr. Ramos said some of these toxicities are “probably attributable” to the lymphodepleting chemotherapy.

Toxicities included grade 1 cytokine release syndrome (no tocilizumab required), maculopapular rash, transient cytopenias, nausea, vomiting, and alopecia.

Dr. Ramos said these results suggest adoptive transfer of CD30.CAR T cells is “safe, even with chemotherapy.”

He noted that the duration of response with this treatment is unknown, but trial enrollment and follow-up are ongoing.

RELY-30 was sponsored by Baylor College of Medicine. Dr. Ramos reported relationships with Novartis, Celgene, Bluebird Bio, and Tessa Therapeutics.

*Data in the abstract differ from the presentation.

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