A Study of the Safety and Tolerability of INCB050465 in Pemphigus Vulgaris

Inclusion Criteria: * Clinically documented and confirmed diagnosis of pemphigus vulgaris: minimum of 6 months of pemphigus vulgaris diagnosis; positive for anti-desmoglein (DSG)1 or DSG3; Pemphigus Disease Area Index score of 8 to 45 points; active skin, scalp, or mucosal lesions. * Disease progression after treatment with standard therapies that are known to confer clinical benefit, or intolerant to treatment; there is no limit to the number of prior treatment regimens. * Willingness to avoid pregnancy or fathering children. * If required, willing to receive Pneumocystis jirovecii pneumonia prophylaxis during the study period. Exclusion Criteria: * Pregnant or breast-feeding female. * Participants with pemphigus vulgaris who are treatment-naive. * Use of protocol-specified medications within defined periods before baseline. * Evidence or history of clinically significant infection or protocol-defined medical conditions * Laboratory values outside the protocol-defined range at screening. * Known or suspected allergy to parsaclisib or any component of the study drug. * Known history of clinically significant drug or alcohol abuse in the last year before baseline. * Inability or unlikeliness of the participant to comply with the dose schedule and study evaluations, in the opinion of the investigator. * Any condition that would, in the investigator's judgment, interfere with full participation in the study, including administration of study drug and attending required study visits; pose a significant risk to the participant; or interfere with interpretation of study data.