Mechanisms of Idelalisib-Associated Diarrhea in Patients With Relapsed Chronic Lymphocytic Leukemia, Indolent Non-hodgkin Lymphoma, or Small Lymphocytic Lymphoma

Inclusion Criteria:

Food and Drug Administration (FDA)-approved indications for idelalisib of relapsed, histologically confirmed B-cell indolent non-hodgkin lymphoma (iNHL) or chronic lymphocytic leukemia (CLL)
For iNHL: measureable nodal disease, defined as the presence of >= 1 nodal lesion that measures >= 2 cm in a single dimension as assessed by computed tomography (CT) or magnetic resonance imaging (MRI)
Discontinuation of all other therapies (including radiotherapy or chemotherapy) for the treatment of iNHL >= 3 weeks before initiation of study treatment
Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2
Absolute neutrophil count > 750
Platelets > 50,000
Total bilirubin < 2 X institutional upper limit of normal (ULN)
Aspartate transaminase (AST) serum glutamic-oxaloacetic transaminase (SGOT)/ alanine transferase (ALT) serum glutamate pyruvate transaminase (SPGT) < 3 X institutional ULN
Creatinine < 2 X institutional ULN
Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and for 90 days following completion of therapy; should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately
Ability to understand and the willingness to sign a written informed consent; all patients must have signed, witnessed informed consent prior to registration

Exclusion Criteria:

Prior exposure to idelalisib
Known histological transformation from iNHL to diffuse large B-cell lymphoma or Richter's Transformation for CLL
Ongoing treatment with any other investigational agents
Known central nervous system (CNS) involvement of lymphoma (CNS staging not required)
History of allergic reactions attributed to compounds of similar chemical or biologic composition to idelalisib
Uncontrolled inter-current illnesses including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
Known human immunodeficiency virus (HIV) infection (HIV testing not required)
Known John Cunningham (JC) virus infection and/or progressive multifocal leukoencephalopathy (PML)
Clinically active hepatitis A, B, or C infections
NOTE: Patients with chronic hepatitis C virus (HCV) or hepatitis B virus (HBV) infection may enroll if other laboratory criteria are met; those with HBV surface antigen positivity may enroll only if maintained on appropriate suppressive antiviral therapy for the duration of enrollment in the trial
Pregnancy or active nursing of an infant