Safety, Tolerability, and Pharmacokinetics of Idelalisib in Adults Receiving Ruxolitinib as Therapy for Primary, Post-Polycythemia Vera, or Post-Essential Thrombocythemia Myelofibrosis With Progressive or Relapsed Disease

Key Inclusion Criteria:

- Individuals must have been on a stable dose of ruxolitinib for at least 4 weeks prior
to study entry

- Individuals with PMF, post-PV MF, or post-ET MF classified as high risk or
intermediate risk as defined by the Dynamic International Prognostic Scoring System
(DIPSS) for PMF or DIPSS Plus, if cytogenetics are available

- Individuals with PMF, post-PV MF, or post-ET MF who are receiving ruxolitinib and meet
2013 Revised International Working Group for Myelofibrosis Research and Treatment
(IWG-MRT) and European Leukemia Net (ELN) response criteria with progressive and
relapsed disease, with modifications for progressive disease complete remission (CR),
partial remission (PR), or clinical improvement (CI)

- European Cooperative Oncology Group (ECOG) performance status of ≤ 2

- Required screening laboratory values as described in the protocol

- Willing and able to comply with scheduled visits, drug administration plan, imaging
studies, laboratory tests, other study procedures, and study restrictions including
mandatory prophylaxis for pneumocystis jiroveci pneumonia (PJP)

- Able to understand and willing to sign the informed consent form

Key Exclusion Criteria:

- Individuals on a stable ruxolitinib dose of 5 mg once daily

- History of prior allogeneic bone marrow progenitor cell or solid organ transplantation

- Ongoing drug-induced liver injury, alcoholic liver disease, non-alcoholic
steatohepatitis, primary biliary cirrhosis, extrahepatic obstruction caused by
cholelithiasis, cirrhosis of the liver

- Ongoing drug-induced pneumonitis

- Ongoing inflammatory bowel disease

- Ongoing alcohol or drug addiction

- Symptomatic congestive heart failure (New York Heart Association Classification >
Class II), unstable angina, or unstable cardiac arrhythmia requiring medication

- Known hypersensitivity to the study investigational medicinal product (IMP), the
metabolites, or formulation excipients

- Unwilling or unable to take oral medication

- Unresolved non-hematologic toxicities from prior therapies that are > Common
terminology Criteria for Adverse Events (CTCAE) Grade 1 (with the exception of
alopecia [Grade 1 or 2 permitted])

- Pregnant or lactating females

- Cytomegalovirus (CMV): Ongoing infection, treatment, or prophylaxis within the past 28
days

NOTE: Other protocol defined Inclusion/ Exclusion criteria may apply.