Sato Pharmaceutical Co. Ltd. has divulged azaindole derivatives acting as hematopoietic prostaglandin D synthase (HPGDS) inhibitors reported to be useful for the treatment of amyotrophic lateral sclerosis, asthma, chronic obstructive pulmonary disease, cystic fibrosis, myocardial infarction, rheumatoid arthritis, sarcopenia and thromboangiitis obliterans (Buerger’s disease), among others.