After spending more than two years in stealth mode, Sionna Therapeutics is unveiling with $111 million in series B funds to catapult its cystic fibrosis pipeline and take on market leader Vertex Pharmaceuticals.
Having raised roughly $150 million in total, the company is looking to launch two assets into phase 1 studies for patients with CF within a year, according to an announcement Tuesday.
The inherited disease causes mucus-making cells to secrete thick fluids that can plug up airways and passages in organs like the lungs or pancreas. As a result, patients’ life spans are significantly impacted, with the life expectancy of recently born CF patients projected to be just 46 years.
Sionna’s top brass includes former executives from biotechs and large pharmas alike and is led by Mike Cloonan, who left his role as chief operating officer at Sage Therapeutics in search of a CEO position in biopharma. He has been joined by Chief Medical Officer Charlotte McKee, M.D., who as VP of clinical development in cystic fibrosis at Vertex Pharmaceuticals oversaw the development of four FDA-approved CF treatments. McKee will be overseeing trials rivaling her previous team, and Cloonan said her move to Sionna validates the promise of the biotech's platform.
“We’re really fortunate with people like Charlotte," the CEO said in an interview with Fierce Biotech. "She brings that level of expertise, she brings the leadership, the passion for what we’re doing and that’s what we wanted across all of our team.”
Right now, Vertex has a tight grip on the CF market, developing half of the FDA-approved drugs for the disease. The hope for Cloonan's team is that Sionna’s batch of small molecules will be the first to fully restore function to the cystic fibrosis transmembrane conductance regulator (CFTR) protein, which is defective in CF patients and only partially restored by currently available treatments.
“If you can normalize CFTR function, what we do know, and what we believe, is that you’re going to give patients the optimal clinical benefit … and that’s not what exists today,” Cloonan said. “The vast majority can’t get there because the existing therapies can only partially correct CFTR.”
To do this, the company is using small molecules and “other complimentary modulators” to target and regulate a mutation on CFTR’s first binding domain, NBD1—or as Cloonan refers to it, “the holy grail target.” By correcting this mutation, the company hopes to improve fluid flow and, ultimately, clinical efficacy.
The assets also target other components of CFTR, intracellular loop 4 (ICL4) and transmembrane domain 1 (TMD1), which when grouped with the larger NBD1 compounds could potentially bolster efficacy even further. As Sionna fleshes out a firmer timeline for the year ahead, the company is prioritizing its lead NBD1 compound, SION-638, followed by its ICL4 program, SION-109.
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The latest fundraising round was led by OrbiMed with contributors including previous investor the Cystic Fibrosis Foundation. Sionna's relationship with the non-profit has been invaluable as the company prepares to chart regulatory waters in the year ahead, Cloonan said.
“As a partner and an investor, we’re able to leverage the expertise of the CF Foundation and really pick their brain on certain things we should be thinking about,” the CEO said. “We feel like we’re uniquely positioned with this relationship and the differentiation of our compounds to be in a great position to engage the FDA.”