Discovery of a Novel Inhaled PI3Kδ Inhibitor for the Treatment of Respiratory Diseases.

Oral PI3Kδ inhibitors such as Idelalisib and Duvelisib have shown efficacy as anticancer agents and Idelalisib has been approved for the treatment of three B-cell cancers. However, Idelalisib has a black box warning on its product label regarding the risks of fatal and serious toxicities including hepatic toxicity, severe diarrhea, colitis, pneumonitis, infections, and intestinal perforation. Some of these side effects are mechanism-related and could hinder the development of Idelalisib for less severe conditions. For respiratory diseases, compounds administered by inhalation are delivered directly to the site of action and may improve the therapeutic index of a drug, minimizing undesired side effects. This work describes the discovery and optimization of inhaled PI3Kδ inhibitors intended for the treatment of severe asthma and COPD. Once the potency was in the desired range, efforts were focused on identifying the particular physicochemical properties that could translate into better lung retention. This medicinal chemistry exercise led to the identification of LAS195319 as a candidate for clinical development.

Structure-activity relationship of kahalalide F synthetic analogues.

Kahalalide F (KF) is a natural product currently under phase II clinical trials. Here, we report the solid phase synthesis of 132 novel analogues of kahalalide F and their in vitro activity on a panel of up to 14 cancer cell lines. The structure-activity relationship of these analogues revealed that KF is highly sensitive to backbone stereotopical modification but not to side chain size modification. These observations suggest that this compound has a defined conformational structure and also that it interacts with chiral compounds through its backbone and not through its side chains. The N-terminal aliphatic acid appears to be a hydrophobic buoy in a membrane-like environment. Moreover, significant improvement of the in vitro activity was achieved.