Five years after Bristol Myers paid $13.1B for MyoKardia and its myosin inhibitor Camzyos, the founders return with a myosin activator and a three asset cardiovascular pipeline that now has to outperform a single $13B exit.
Kardigan's June 11 S-1/A lands like a deliberate sequel with a twist. The filing outlines a 23.3-million-share offer at $14 to $16, projecting $320.3 million in net proceeds at the midpoint, with a 3.5-million-share underwriter overallotment that would push the haul to roughly $369 million if exercised in full (Kardigan S-1/A SEC filing, June 11, 2026). The company's lead cardiovascular drug is the pharmacological inverse of the asset that made its founders' last fortune.
That is the story the filing tells, and it is not the story the wire copy will. Kardigan is led by CEO Tassos Gianakakos, who ran MyoKardia for seven years before Bristol Myers Squibb bought the company for $13.1 billion in 2020 (Fierce Biotech, June 11, 2026). Joining him are co-founders Jay Edelberg, M.D., Ph.D., the chief medical officer, and Bob McDowell, Ph.D., the chief scientific advisor, both also MyoKardia alumni. MyoKardia's mavacamten, sold as Camzyos, generated $1.07 billion in 2025 sales for Bristol Myers (Fierce Biotech, June 11, 2026). The mechanism that built that franchise: a myosin inhibitor that tamps down the hypercontractile sarcomere in obstructive hypertrophic cardiomyopathy. Kardigan's lead asset, danicamtiv, is a myosin activator that does the opposite.
The contrast is not a marketing detail. Danicamtiv, currently in phase 2b/3 for genetic dilated cardiomyopathy, aims to boost contractility in a chamber that cannot squeeze hard enough, the inverse problem from the one mavacamten solves. Asking investors to underwrite that inversion is the central scientific bet the filing discloses. The S-1/A earmarks $80 million to $90 million of net proceeds for danicamtiv, a parallel $80 million to $90 million for ataciguat, and $40 million to $50 million for tonlamarsen, with $50 million to $60 million reserved for general research and development and the remainder covering working capital and general corporate purposes (Kardigan S-1/A SEC filing, June 11, 2026). On paper, this is a three-legged pipeline, not a single-mechanism rerun.
Ataciguat is a soluble guanylate cyclase activator licensed from Sanofi and the Mayo Clinic, currently in phase 2b for calcific aortic valve stenosis with a planned push into phase 3 (Fierce Biotech, June 11, 2026). Calcific aortic valve stenosis is a slow, structural disease where medical options are thin, and ataciguat's path there is genuinely independent of the myosin program. Tonlamarsen is a liver-directed antisense oligonucleotide licensed from Ionis, in phase 2 for hypertension. Its readout to date is mixed: biomarker-positive, blood pressure endpoint missed. The filing's use of proceeds treats it as a co-equal third leg of the pipeline, but the data underneath it is the softest of the three. Public investors will need to price that, and the S-1/A's truncated indication language around the program preserves the optionality without resolving the question.
The market timing is real. Kardigan filed on a day when Parabilis priced an upsized $670 million offering, the largest biotech IPO on record, and Kailera had raised $625 million in April (Fierce Biotech, June 11, 2026). Kardigan itself raised a $300 million Series A in January 2025 and a $254 million Series B in August 2025, and reported $287.1 million in cash as of March per the S-1/A (Kardigan S-1/A SEC filing, June 11, 2026). The company is not going public to keep the lights on. It is going public to extend its runway through a clinical-stage portfolio that is genuinely three-armed, in a window where the public market is paying for clinical-stage cardiovascular stories.
The legitimate question the filing raises is also legitimate for the founders. Gianakakos, Edelberg, and McDowell did not need to come back to public markets. They chose to, with a pipeline that is wider than MyoKardia's but earlier than MyoKardia was at the equivalent point, and with a lead asset whose mechanism is the literal opposite of the one that made their last company worth $13.1 billion. Whether a clinical-stage three-asset cardiovascular portfolio can outperform a single $13 billion exit is now a question for the Nasdaq order book, not just for them, and the mixed tonlamarsen readout and the unproven myosin-activator thesis are the two numbers the market will look at first.