T-Cell Therapy With Lete-Cel Demonstrates Efficacy in Sarcoma Subtypes

A phase 2 trial assessing the T-cell therapy letetresgene autoleucel (lete-cel) met its primary endpoint, with responses observed in nearly 42% of patients with previously treated, advanced synovial sarcoma or myxoid/round cell liposarcoma.

Preliminary data from a phase 2 trial were announced in a press release from Adaptimmune Therapeutics, the developer of lete-cel, and also presented at a recent oncology conference.

Synovial sarcoma, according to the National Cancer Institute, is a cancer that typically formed in the tissue around joints in the arms or legs, and is commonly seen in children and young adults. Myxoid liposarcoma is a rare cancer that originates in fat cells, as noted on the National Cancer Institute’s website.

In particular, the primary analysis of the phase 2 IGNYTE-ESO trial included data from 64 patients with synovial sarcoma or myxoid/round cell liposarcoma treated with lete-cel. Of these patients, 42% responded to treatment with lete-cel, including six patients with complete responses and 21 patients with partial responses, according to the release. The response rate, when assessed by disease type, was 41% for the synovial sarcoma group and 43% for the myxoid/round cell liposarcoma group.

“Individuals with both synovial sarcoma and [myxoid/round cell liposarcoma] are commonly diagnosed under 40, facing a devastating disease with limited treatments in the prime of their lives,” Dr. Sandra D’Angelo, sarcoma medical oncologist and cell therapist at Memorial Sloan Kettering Cancer Center in New York, said in the release. “I’ve been seeing these patients throughout my career and have frequently faced the frustrating reality of having incredibly limited treatment options to offer them. I’m encouraged by these data, as they could lead to a potential therapeutic option and an improved prognosis for these patients.”

The median duration of response in patients included in the analysis was 12.2 months, according to the release. When grouped by disease type, the median duration of response was 18.3 months in patients with synovial sarcoma and 12.2 months in those with myxoid/round cell liposarcoma.

Patients with synovial sarcoma or myxoid/round cell liposarcoma treated with lete-cel had a median progression-free survival of 5.3 months, as noted in the release.

“We are thrilled to see that 42% of patients with synovial sarcoma or [myxoid/round cell liposarcoma] responded to treatment with lete-cel, following prior treatment with currently available therapies,” Dr. Elliot Norry, Chief Medical Officer of Adaptimmune Therapeutics, said in the release. “Responses were durable across both indications, with an overall median duration of response greater than 18 months for people with synovial sarcoma and greater than one year for [myxoid/round cell liposarcoma]. These data underscore lete-cel’s potential to transform the lives of people with these cancers who have a poor prognosis and few treatment options.”

The release also described the side effect profile of lete-cel as being consistent with that demonstrated in previous data. All patients in the trial experienced treatment-emergent side effects, with the most common being cytopenias, rash and cytokine release syndrome. “Overall, toxicities were manageable and consistent with an acceptable benefit-to-risk profile,” according to the release.

As a result of these findings, Adaptimmune Therapeutics plans to submit a rolling Biologics License Application to the Food and Drug Administration for lete-cel as a treatment for advanced or metastatic synovial sarcoma and myxoid/round cell liposarcoma by the end of 2025, as described in the release. 

Lete-cell, according to the release, is an engineered T-cell receptor therapy that targets the solid tumor antigen NY-ESO-1.

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