TCRR - TCR2 Therapeutics stock rises 16% as cell therapy for solid tumors shows promise in trial

TCR2 Therapeutics ( NASDAQ: TCRR ) said its cell therapy gavo-cel showed clinical benefit in patients with mesothelin-expressing solid tumors in a phase 1 portion of a phase 1/2 trial.

As of Sept. 9, 32 patients (including 23 mesothelioma, eight ovarian cancer and one cholangiocarcinoma) had received a single gavo-cel infusion in the phase 1 portion. The patients were heavily pretreated with a median of five prior lines of therapy.

Gavo-cel showed a disease control rate (DCR - defined as response /sustained stable disease for at least three months) of 77%. Meanwhile, 28 of the 30 patients evaluable for efficacy saw tumor regression of their target lesions, ranging from 4% to 80%, the company said in a Sept. 28 press release.

TCR2 added that Eight patients saw target lesion regression >30%, six of whom (four with mesothelioma and two with ovarian cancer) achieved a partial response (PR)  according to RECIST 1.1 criteria, including one patient who also achieved a complete metabolic response. One patient with cholangiocarcinoma was also considered to have achieved a PR.

"These are remarkable data in the context of solid tumors where there have been significant challenges with current CAR-T therapies. I am particularly excited by this second RECIST response in ovarian cancer as it supports the meaningful clinical activity of gavo-cel in a large patient population," said TCR2 President and and CEO Garry Menzel.

TCR2 noted that the median overall survival (OS) for patients with malignant pleural/peritoneal mesothelioma (MPM) was 11.2 months, while median progression-free survival (PFS - length of time during/after therapy a patient lives with the disease without it getting worse) for patients with MPM was 5.6 months.

The overall response rate (ORR) among patients who received gavo-cel following lymphodepletion chemotherapy was 22% by blinded independent central review (BICR) and 26% by investigator assessment. By BICR, the ORR was 21% among patients with MPM and 29% among those with ovarian cancer, according to the company.

TCR2 noted that after dose-limiting toxicity (DLT) at dose level (DL) 5 was seen in September 2021 the study proceeded to a dose de-escalation portion.

The company said two DLTs were seen: one case of Grade 3 pneumonitis at DL1 that resolved with anti-cytokine therapy, and one case of Grade 5 bronchioalveolar hemorrhage at DL5.

All three patients treated at DL5 experienced severe cytokine release syndrome (CRS), which led to the safety review team recommending de-escalation, according to the company.

The most frequent Grade 3 or higher non-blood toxicity among patients treated at the RP2D was CRS, which was reported in 15% of patients, TCR2 noted.

Gavo-cel was generally well tolerated with a manageable adverse event profile up to DL 5, as per the company.

TCRR +15.98% to $1.96 premarket Sept. 28

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