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Tracon’s subcutaneous hopes evaporate

This week’s collapse in the shares of the micro-cap Tracon Pharmaceuticals reflects the group’s chances of becoming a player in the subcutaneous PD-(L)1 space. Tracon has US rights to envafolimab, a subcutaneous anti-PD-L1 MAb, under a 2020 deal with China’s Alphamab Oncology, and this relates specifically to soft tissue sarcoma, a niche indication in which no anti-PD-(L)1 drugs are approved. A US sarcoma filing hinged on the phase 2 Tracon-sponsored Envasarc trial, but according to a curious announcement on Wednesday this appears doomed. Tracon says Envasarc cleared an earlier futility boundary, and an independent data-review committee recommended that the trial continue. However, among an extra 27 patients versus December’s update there have been no further responses, and the resulting 5.5% ORR is short of Tracon’s hurdle of 11%; even 11% ORR was, according to Jones Research, “not sufficient for successful market adoption”, given that Keytruda, and Opdivo plus Yervoy, generated 23% and 29% respectively in trials not pursued to filing. It’s a separate question why envafolimab underperformed in this way; presumably the issue is baseline characteristics or hitting PD-L1 rather than PD-1, and not envafolimab’s SC delivery. In China envafolimab is approved for MSI-H/MMRd tumours.

 

Envasarc's progress

Dec 2020Envasarc starts: envafolimab +/- Yervoy in undifferentiated pleomorphic sarcoma or myxofibrosarcoma
Oct 2022IDMC recommendation to continue based on safety review from 12 patients
Dec 2022IDMC recommendation to continue based on efficacy review from 36 patients
Jun 2023Envafolimab + Yervoy cohort is discontinued (lack of efficacy vs envafolimab)
Sep 2023Envasarc clears IDMC’s futility threshold of 6.5% ORR
Dec 2023Interim ORR by BICR said to be 8.7% (4/46)
Apr 2024Final ORR by BICR said to be 5.5% (4/73), missing primary endpoint hurdle of 11%

Source: OncologyPipeline.