Idelalisib

Idelalisib is an inhibitor of phosphatidylinositol 3-kinase, PI3Kδ, which is expressed in normal and malignant B-cells. Idelalisib induced apoptosis and inhibited proliferation in cell lines derived from malignant B-cells and in primary tumor cells.

• Zydelig is indicated, in combination with rituximab, for the treatment of patients with relapsed chronic lymphocytic leukemia (CLL) for whom rituximab alone would be considered appropriate therapy due to other co-morbidities. Zydelig is a kinase inhibitor indicated for the treatment of patients with: Relapsed chronic lymphocytic leukemia (CLL), in combination with rituximab, in patients for whom rituximab alone would be considered appropriate therapy due to other co-morbidities.ICD-10: C95.90

• Zydelig is contraindicated in patients with a history of serious hypersensitivity reactions to idelalisib, including anaphylaxis, or patients with a history of toxic epidermal necrolysis with any drug [see Warnings and Precautions (5.6 , 5.7) ] . History of serious hypersensitivity reactions to idelalisib, including anaphylaxis, or history of toxic epidermal necrolysis with any drug.contraindicated

Recommended dosage: 150 mg orally twice daily. ( 2.1 ) 2.1 Recommended Dosage The recommended dosage of Zydelig is 150 mg administered orally twice daily with or without food until disease progression or unacceptable toxicity. The optimal and safe dosing regimen for patients who receive treatment longer than several months is unknown. Swallow tablets whole. If a planned dose of Zydelig is missed by less than 6 hours, take the missed dose as soon as possible and take the next dose as usual. If a dose of Zydelig is missed by more than 6 hours, skip the missed dose and take the next dose at the usual time. 2.2 Dosage Modifications for Adverse Reactions Table 1 presents the dosage modification for specific adverse reactions. For other severe or life-threatening adverse reactions, withhold Zydelig until resolution. If resuming Zydelig after interruption for other severe or life-threatening toxicities, reduce the dosage to 100 mg orally twice daily. Permanently discontinue Zydelig for recurrence of other severe or life-threatening Zydelig-related toxicity upon rechallenge.

Severe Cutaneous Reactions : Monitor patients for the development of severe cutaneous reactions. Permanently discontinue Zydelig if confirmed. ( 2.2 , 5.6 ) Hypersensitivity Reactions : Permanently discontinue Zydelig and institute appropriate supportive measures. ( 2.2 , 5.7 ) Neutropenia : Monitor blood counts. Interrupt Zydelig until resolution and resume at reduced dose. ( 2.2 , 5.8 ) Embryo-fetal Toxicity : May cause fetal harm. Advise females of reproductive potential of potential risk to a fetus and to use effective contraception. ( 5.9 , 8.1 , 8.3 ) 5.1 Hepatotoxicity Fatal and/or serious hepatotoxicity occurred in 16% of patients treated with Zydelig in combination with rituximab or with unapproved combination therapies. Elevations in ALT or AST greater than 5 times the upper limit of normal have occurred [see Adverse Reactions (6.1) ]. These findings were generally observed within the first 12 weeks of treatment and were reversible with dose interruption. After resumption of treatment at a lower dose, 26% of patients had recurrence of ALT and AST elevations. Discontinue Zydelig for recurrent hepatotoxicity. Avoid concurrent use of Zydelig with other drugs that may cause liver toxicity. Monitor ALT and AST in all patients every 2 weeks for the first 3 months of treatment, every 4 weeks for the next 3 months, then every 1 to 3 months thereafter. Monitor weekly for liver toxicity if the ALT or AST rises above 3 times the upper limit of normal until resolved.

The following clinically significant adverse reactions are described elsewhere in the labeling. Hepatotoxicity [see Warnings and Precautions (5.1) ] Severe Diarrhea or Colitis [see Warnings and Precautions (5.2) ] Pneumonitis [see Warnings and Precautions (5.3) ] Infections [see Warnings and Precautions (5.4) ] Intestinal Perforation [see Warnings and Precautions (5.5) ] Severe Cutaneous Reactions [see Warnings and Precautions (5.6) ] Hypersensitivity Reactions [see Warnings and Precautions (5.7) ] Neutropenia [see Warnings and Precautions (5.8) ] The most common adverse reactions (incidence ≥30%) in patients treated with Zydelig in combination trials are diarrhea, pneumonia, pyrexia, fatigue, rash, cough, and nausea. ( 6.1 ) Common laboratory abnormalities are neutropenia, ALT elevations and AST elevations. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Gilead Sciences, Inc. at 1-800-GILEAD-5 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The pooled safety population described in the WARNINGS AND PRECAUTIONS reflect exposure to Zydelig at a dosage of 150 mg twice daily in 110 patients administered in combination with rituximab in Study 312-0116, and in combination with other drugs in 380 patients.

Lactation : Advise not to breastfeed. ( 8.2 ) 8.1 Pregnancy Risk Summary Based on findings in animal studies and the mechanism of action [see Clinical Pharmacology (12.1) ] , Zydelig may cause fetal harm when administered to a pregnant woman. There are no available data in pregnant women to inform the drug-associated risk. In animal reproduction studies, administration of idelalisib to pregnant rats during organogenesis resulted in decreased fetal weight and congenital malformations in rats at maternal exposures (AUC) 12 times those reported in patients at the recommended dosage of 150 mg twice daily (see Data ) . The estimated background risk of major birth defects and miscarriage for the indicated populations is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage of clinically recognized pregnancies 2–4% and 15–20%, respectively. Data Animal Data In an embryo-fetal development study in rats, pregnant animals receiving oral doses of idelalisib during the period of organogenesis (implantation to closure of the hard palate), embryo-fetal toxicities were observed at the mid- and high-doses that also resulted in maternal toxicity, based on reductions in maternal body weight gain.

Metabolism

Idelalisib exposure increased in a less than dose-proportional manner over a dose range of 50 mg to 350 mg twice daily (0.3 to 2.3 times the approved recommended dosage). Following 150 mg twice daily administration of idelalisib, average (% coefficient of variation) maximum concentrations (C max ) and area under the curve (AUC) at steady-state were 1861 (43%) ng/mL and 10598 (41%) ng∙h/mL for idelalisib.

• Jul 23, 2014NDANDA205858Gilead Sciences Inc

Reference statistics from the openFDA drug-shortage dataset. For a live view, consult the FDA database directly. Not clinical guidance.

• Zydelig, Tablet, 100 mg (NDC 61958-1701-1)To be discontinued
  Sponsor: Gilead Sciences, Inc.
  Updated Apr 7, 2026
• Zydelig, Tablet, 150 mg (NDC 61958-1702-1)To be discontinued
  Sponsor: Gilead Sciences, Inc.
  Updated Apr 7, 2026

1. 1Disease Progression1,22517%
2. 2Death80211%
3. 3Diarrhoea77111%
4. 4Off Label Use5728.1%
5. 5Pneumonia4376.2%
6. 6Pyrexia3755.3%
7. 7Drug Ineffective3174.5%
8. 8Fatigue3014.3%
9. 9Dehydration2443.5%
10. 10Neutropenia2243.2%
11. 11Dyspnoea2203.1%
12. 12Colitis2032.9%
13. 13Asthenia2022.9%
14. 14Pneumonitis2002.8%
15. 15Weight Decreased1762.5%

The 10 most recently updated of 75 ClinicalTrials.gov registrations naming Idelalisib as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• A Study of DZD8586 Versus Investigator's Choice in r/r CLL/SLL (TAI-SHAN6)
  Recruiting · Phase 3 · Interventional · 250 enrolled · Dizal Pharmaceuticals
  NCT07139873updated 2026-06-03
• A Study of BGB-16673 Compared to Investigator's Choice in Participants With Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma Previously Exposed to Both Bruton Tyrosine Kinase (BTK) and B-cell Leukemia/Lymphoma 2 Protein (BCL2) Inhibitors
  Recruiting · Phase 3 · Interventional · 250 enrolled · BeOne Medicines
  NCT06846671updated 2026-05-29
• A Study of Pirtobrutinib (LY3527727) in Participants With Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma
  Recruiting · Phase 4 · Interventional · 150 enrolled · Eli Lilly and Company
  NCT07218341updated 2026-05-22
• ACY-1215 in Combination With BCR Pathway Inhibitors in Relapsed CLL
  Active not recruiting · Phase 1 · Interventional · 3 enrolled · Dana-Farber Cancer Institute
  NCT02787369updated 2026-05-19
• A Study of Acalabrutinib vs Investigator's Choice of Idelalisib Plus Rituximab or Bendamustine Plus Rituximab in R/R CLL
  Active not recruiting · Phase 3 · Interventional · 310 enrolled · Acerta Pharma BV
  NCT02970318updated 2026-05-11
• A Phase 2 Study of CAL101 in Patients With Idiopathic Pulmonary Fibrosis
  Active not recruiting · Phase 2 · Interventional · 150 enrolled · Calluna Pharma AS
  NCT06736990updated 2026-04-27
• Study of LOXO-305 (Pirtobrutinib) Versus Investigator's Choice (Idelalisib Plus Rituximab or Bendamustine Plus Rituximab) in Patients With Previously Treated Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL)
  Active not recruiting · Phase 3 · Interventional · 238 enrolled · Loxo Oncology, Inc.
  NCT04666038updated 2026-04-24
• A Study of Idelalisib (GS1101, CAL101) + Ofatumumab in Previously Untreated CLL/SLL
  Completed · Phase 2 · Interventional · 27 enrolled · Dana-Farber Cancer Institute
  NCT02135133updated 2026-03-17
• A Study of Oral LOXO-305 in Patients With Previously Treated CLL/SLL or NHL
  Completed · Phase 1 · Phase 2 · Interventional · 803 enrolled · Loxo Oncology, Inc.
  NCT03740529updated 2026-01-27
• 1630GCC: Zydelig Maintenance in B-Cell Non-Hodgkin's Lymphoma After Autologous Stem Cell Transplantation
  Completed · Phase 2 · Interventional · 17 enrolled · University of Maryland, Baltimore
  NCT03133221updated 2025-06-27

Frequently asked questions

How does Idelalisib work?

Idelalisib is an inhibitor of phosphatidylinositol 3-kinase, PI3Kδ, which is expressed in normal and malignant B-cells. Idelalisib induced apoptosis and inhibited proliferation in cell lines derived from malignant B-cells and in primary tumor cells.

What is Idelalisib used for?

According to FDA labeling, Idelalisib carries indications including: Zydelig is indicated, in combination with rituximab, for the treatment of patients with relapsed chronic lymphocytic leukemia (CLL) for whom rituximab alone would be considered appropriate therapy due to other co-morbidities. Zydelig is a kinase inhibitor indicated for the treatment of patients with: Relapsed chronic lymphocytic leukemia (CLL), in combination with rituximab, in patients for whom rituximab alone would be considered appropriate therapy due to other co-morbidities.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Idelalisib?

Idelalisib is classified as Phosphatidylinositol-3-kinase (Pi3K) inhibitors, Kinase Inhibitor, Cytochrome P450 3A Inhibitors, Kinase Inhibitors, Cellular Proliferation Alteration, Increased Cellular Death.

What are the brand names for Idelalisib?

Idelalisib is marketed under brand names including Zydelig.

What are the contraindications for Idelalisib?

Idelalisib labeling lists contraindications including: Zydelig is contraindicated in patients with a history of serious hypersensitivity reactions to idelalisib, including anaphylaxis, or patients with a history of toxic epidermal necrolysis with any drug [see Warnings and Precautions (5.6 , 5.7) ] . History of serious hypersensitivity reactions to idelalisib, including anaphylaxis, or history of toxic epidermal necrolysis with any drug.. Always consult the full prescribing information and a clinician.