Cidara Therapeutics is exploring echinocandin derivatives. The company’s clinical candidate rezafungin is a derivative of anidulafungin, a compound originally discovered at Eli Lilly and Company and currently marketed by Pfizer. Chemists placed a choline group at a critical point on the molecule, a feature that stabilizes the echinocandin ring and prevents metabolic breakdown of the molecule, explains Cidara’s president and CEO, Jeff Stein.