An Open-Label Study to Assess the Safety & Efficacy of Leniolisib in Japanese Patients With APDS

This is a 2-part, open-label, non-randomized study to assess the safety and efficacy of leniolisib in Japanese patients with APDS. At least3 patients, aged 12 to 75 years (inclusive), will be enrolled. Patient eligibility will be assessed during a 7-week Screening Period (Day -50 to Day -1). This will be followed by a 12-week Treatment Period (Part 1), in which patients will be administered leniolisib doses ranging from 40 to 70 mg twice daily (BID) based on body weight (see dose regimen table below). A Part 1 clinical study report will be generated once the last patient completes the Day 85 Visit for Part 1. Patients who complete the Day 85 Visit will enter the Extension Period of the study (Part 2), in which patients will be administered leniolisib doses ranging from 40 to 70 mg BID (based on body weight) for 1 year or until marketing approval in Japan, whichever is longer. A 4-week Follow-up Period will occur after the last dose of study treatment is received.

It is anticipated that a total of 3 patients will be enrolled into the study.

Objectives:

Part 1:

Primary:

* To assess the safety and tolerability of leniolisib * To assess the efficacy of leniolisib on lymphoproliferation (sum of product diameters \[SPD\] of index lymph node lesions) and immunophenotype normalization (percentage of naïve B cells out of total B cells)

Secondary:

* To assess the efficacy of leniolisib on lymphoproliferation (non-index lymph node lesions and spleen) * To assess the pharmacokinetics (PK) of leniolisib in the Japanese population * To assess the efficacy of leniolisib to modify health-related quality of life * To assess the efficacy of leniolisib by the Patient's and Physician's Global Assessments * To assess the frequency of infections, antibiotic use, and immunoglobulin (Ig) replacement therapy and assessment of impact on other disease-related outcomes (e.g., cytopenia, colitis, and lung function) * To assess biomarkers reflecting the efficacy of leniolisib to reduce systemic inflammatory components of the disease * To assess the treatment benefit to individual patients

Part 2:

Primary:

\- To assess the long-term safety and tolerability of leniolisib