Study to Evaluate 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.