Afami-cel Elicits Durable Responses With Tolerable Safety in Pre-Treated Synovial Sarcoma

With an overall response rate of 38.6% and a consistent safety profile of that seen in prior trials, afamitresgene autoleucel continues to show clinical responses in patients with late-stage synovial sarcoma.

After a single dose of afamitresgene autoleucel (afami-cel), pre-treated patients with late-stage synovial sarcoma continued to show clinical responses an acceptable safety profile in cohort 1 of the SPEARHEAD-1 trial (NCT04044768), according to Adaptimmune Therapeutics plc.

These findings continue to support the biologics license application submission for afami-cel in this patient population as 44 patients in the trial had an overall response rate of 38.6% by independent review which were consistent with previous data.

The median duration of response was 50 weeks (range, 11.7-122 weeks), showing durable response. Looking at safety, while there were toxicities including cytokine release syndrome and reversible hematologic toxicities, they were in line with previous findings indicating an acceptable safety profile

"With these results, we continue our excitement and optimism about the clear potential of afami-cel to address synovial sarcoma- a difficult-to-treat cancer with high unmet need," said Elliot Norry, chief medical officer of Adaptimmune Therapeutics plc, in the press release. "These data reaffirm our commitment to this therapy, and we are very pleased to be able to include these data in our upcoming BLA submission."

The open-label, phase 2, SPEARHEAD-1 trial is examining patients with advanced synovial sarcoma or myxoid/round cell liposarcoma. Investigators are evaluating the efficacy, safety, and tolerability of afami-cel in approximately 90 patients, including 45 in cohort 1 and 45 in cohort 2.

The primary end point of the study is ORR with secondary end points including safety, patients with treatment-emergent adverse events (AEs), serious AEs, efficacy, best overall response, time to response, duration of response, progression-free survival, overall survival, and more.

Across all the evaluated subpopulations in the trial, responses were observed. Higher response rates were seen in female patients as well as patients with higher MAGE-A4 expression, those with a lower disease burden at baseline, and patients who did not require bridging therapy.

These translational data show the potential of afami-cel as it drives tumor infiltration of activated and proliferative cytotoxic T-cells. This shifts the balance from immune-suppressive to a pro-immune in the tumor microenvironment which likely contributes to antitumor response.

Overall, findings from cohort 1 of the SPEARHEAD-1 trial met the primary end point for efficacy and these data will be used to support the agents BLA submission. Cohort 2 of SPEARHEAD-1 is ongoing with more than half of the treatment complete. So far, the ORR rate is nearly identical to what was observed in cohort 1.

"We are on the cusp of an exciting and important time for people impacted by synovial sarcoma, a cancer that for much too long has not seen innovative treatment options," said Brian A. Van Tine, MD, professor of medicine and pediatrics at Washington University School of Medicine in St. Louis, in the press release. "The SPEARHEAD-1 Trial results provide us a reason to be very optimistic about the game-changing potential to treat more people with this difficult cancer in the very near future."

REFERENCE:
Data from cohort 1 of SPEARHEAD-1 trial at CTOS continue to support BLA submission for afami-cell in synovial sarcoma - response rate and durability remain consistent. News release. Adaptimmune Therapeutics plc. November 18, 2022. Accessed November 21, 2022. https://bit.ly/3tRDJJb