A little over a year after AbbVie exited the cystic fibrosis (CF) space due to disappointing clinical results, Sionna Therapeutics is reviving the abandoned compounds, bagging exclusive worldwide rights to develop and commercialise multiple assets from the pharma.Financial specifics were not disclosed, but the deal includes an upfront payment to AbbVie along with potential late-stage development and commercial milestones and royalties. AbbVie has also made an equity investment in Sionna, which raised $182 million in an oversubscribed series C round earlier this year.The agreement encompasses ABBV-2222 (galicaftor) and ABBV-3067 (navocaftor), both of which have completed Phase II, and ABBV-2851, which is in Phase I development. ABBV-2222 and ABBV-2851 are both TMD1-directed correctors, while ABBV-3067 functions as a CFTR potentiator.AbbVie had discontinued its CF programme after a triple combination therapy that included the C2 corrector ABBV-576 added to a backbone of ABBV-2222 plus ABBV-3067 failed to meet efficacy criteria in a proof-of-concept study.Dual combinationsSionna, however, sees untapped potential in the compounds when combined with its proprietary NBD1 stabilisers, pointing to preclinical assays that have shown promising results. "Our strategy is to build a CF franchise anchored on our novel correctors that stabilise the NBD1 of the CFTR protein," said CEO Mike Cloonan.Sionna is looking to pair one of its NBD1 stabilisers with either an AbbVie compound or its own ICL4-directed corrector, SION-109, to create more effective dual combinations. The company reports that some pairings have shown promise in preclinical studies, with "potential for superior efficacy" over current treatments, while some combos have shown the ability "to fully correct ΔF508 CFTR and achieve wild type levels of CFTR function."Sionna has said it expects to complete a Phase I trial of SION-109 in the second half. Phase I studies of two NBD1 stabilisers, SION-451 and SION-719, are also due to start this year.Its most advanced NBD1 corrector is SION-638, which is poised to enter Phase II, while the company is also developing the TMD1-directed corrector SION-676.