Dive Brief:

• Firefly Bio, a startup working to develop a new kind of cancer medicine, announced Thursday it had raised $94 million in venture funding.
• The California-based company is putting a spin on antibody-drug conjugates, or ADCs, by merging them with technology that can degrade proteins. Essentially, Firefly aims to marry the targeting strengths of ADCs, which typically use antibodies to shepherd chemical toxins to cancer cells, with a more selective and efficient “payload” in protein degraders.
• Firefly was co-founded by 2022 Nobel Prize winner Carolyn Bertozzi, Merck and Genentech veteran John Flygare and former Merck executive Bernhard Geierstanger. Versant Ventures, MPM BioImpact, Decheng Capital and Eli Lilly participated in the company’s Series A round.

Dive Insight:

Firefly is among the many beneficiaries of an investor and pharmaceutical industry gold rush into new generations of targeted cancer drugs like ADCs. The success of medicines like Daiichi Sankyo and AstraZeneca’s Enhertu has proved the commercial potential, while technical advances have opened up new opportunities for startups to experiment with their own approaches.

Just this week, ProfoundBio announced $112 million in new funding for its pipeline of ADCs, while a few months ago Bristol Myers Squibb paid Orum Therapeutics $100 million for rights to a kind of degrader-antibody conjugate that shares similarities with Firefly’s.

As Firefly tells it, combining ADCs and protein degraders can offset each technology’s shortcomings. ADCs, for example, are well suited to targeting specific cells, but they’re not perfect at how they release their toxic payload, limiting how large of a dose can be safely used. Jerel Davis, a managing director at Versant Ventures and Firefly board member, calls this the “Achilles’ heel” of the technology.

Unlike the chemical toxins of ADCs, meanwhile, protein degraders are more selectively potent in their destruction.

Firefly’s medicines will swap out those chemical toxins for protein degrader compounds, ideally creating a drug that can better target cancer cells while keeping side effects to a minimum.

"DACs are akin to putting a new piece on the chess board," said Scott Hirsch, Firefly's CEO.

Firefly has also developed a new linker molecule to pair antibodies with protein degraders, one that is expected to be more stable than existing technologies.

“If this were easy to do, there would have been many companies doing this for years,” Hirsch said.

The company did not disclose which cancer types it aims to treat, but hinted at potential immunology uses for its degarder-antibody conjugates.

Firefly’s name, taken from the bug, “elicits curiosity and imagination,” Hirsch said. “The light on a firefly reminds us of a payload on an ADC.”

The company employs 15 people and plans to expand to as many as 40 by the end of the year, according to Hirsch.