Silverback puts investors out of their misery

Give credit where credit is due. Having discovered that its TLR8 agonist conjugation theory was nonsense Silverback Therapeutics could easily have limped on like so many zombie biotechs, but instead it has thrown in the towel, on Friday agreeing to a lowball reverse merger with ARS Pharmaceuticals. What investors make of this is a separate question. Silverback’s December 2020 IPO had raised $278m, and at the end of last year the group had $319m in the bank, but with a market cap of just $137m the best it has been able to extract is a 37% share of a combined entity that will now focus purely on Neffy, ARS’s nasal epinephrine spray. Silverback's premise was that combining tumour targeting with TLR8 agonism (TLR8 was thought to activate myeloid cells in the tumour microenvironment) could improve efficacy. The theory foundered at last year’s Esmo conference, and the fact that Silverback’s lead, SBT6050, targeted Her2, a space hit by the Enhertu juggernaut, provided a double whammy. Silverback took 595 days to go from float to effective bust, which alongside Yumanity’s 531 days – that company reverse merged with Kineta last month – ranks among biotech’s fastest implosions.

A brief history of Silverback Therapeutics
Dec 2016 Company is founded, and later raises $221m in VC cash
Dec 2020 Nasdaq IPO raises $278m
Sep 2021 Lead asset SBT6050 (anti-Her2) disappoints at Esmo
Mar 2022 Company discontinues SBT6050, along with SBT6290 (anti-Nectin4, "expected to show a similar clinical profile"), to focus on SBT8230 (anti-ASGR1 for hep B)
Jul 2022 Reverse merger with ARS Pharmaceuticals; focus is epinephrine nasal spray; Silverback tech to be divested
Source: company filings.

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