Adaptimmune says it's (nearly) ready to head to the FDA with TCR cancer therapy
Six months after an initial reveal at ASCO, Adaptimmune is back in the limelight with new data Thursday. And the company believes it now has enough to go to regulators for what would be the first-ever TCR therapy.
The biotech’s afami-cel program put out updated figures Thursday morning with researchers noting as of Sept. 1, 16 of 47 patients saw their tumors shrink while on the experimental treatment. It’s good enough for a 34% overall response rate and, while lower than the May update of 39%, makes Adaptimmune confident enough to say the study will reach its primary endpoint.
Though the final data cut is expected by the end of the year, “it is mathematically impossible not to meet the primary endpoint,” CEO Adrian Rawcliffe told Endpoints News. Following discussions with the FDA, the biotech had set an 18% response rate as an acceptable threshold to meet the primary.
“If you assume all future patients will not respond,” he added, “the ones that have yet to be assessed, the trial will still meet the primary endpoint.”
Despite Rawcliffe’s rosy picture, investors didn’t appear too convinced as Adaptimmune shares $ADAP closed down about 9% in Thursday trading.
As the trial approaches its end, Rawcliffe noted that the way in which responses are classified may have changed for some patients as independent investigators chimed in, leading to the lower numerical figure. Rawcliffe said it’s the main reason two patients who were previously said to have achieved complete responses are no longer labeled as such.
Nevertheless, the biotech is prepared to submit its BLA next year once the final data are ready. Rawcliffe described Adaptimmune is “very comfortable” with the whole data package as it stands and highlighted the study’s durability measures. Even though 75% of responders are still receiving treatment, the trial has not reached median duration of response.
Patients’ response times stretch from about four weeks to more than 65 weeks.
Adaptimmune had enrolled patients with two types of sarcomas: advanced synovial sarcoma or myxoid/round cell liposarcoma. By each cancer, the ORR was 36% in synovial sarcoma patients and 25% for those with MRCLS. Patients with these cancers generally don’t have many treatment options after chemo, Rawcliffe said, and the five-year mortality rate is around 70-80%.
Now looking toward its regulatory future, Adaptimmune may likely face similar questions as other companies that have brought forth cell therapies. TCR is similar to CAR-Ts, in that a patient’s cells are removed, re-engineered and replaced to target cancer cells, but TCR goes after a different protein.
TCRs have historically been met with a lot of skepticism, both from researchers and investors, but this is the second time this week a biotech is touting new data. Immatics revealed an early-stage study that saw eight of 16 patients register an objective response against a range of solid tumor types on Tuesday.
Rawcliffe himself admitted the company has already been asked about its CMC processes. It’s been at the top of the to-do list in the six months since ASCO, however, and the CEO is confident everything will be in order when the FDA comes knocking.
“There’s been five cell therapies approved to date, and they all came with challenges of their own,” Rawcliffe said. “Very few of those challenges were related to the clinical data, so anybody who tells you this is easy, or that there is zero risk associated with it, is living in cloud cuckoo land.”