Zydelig: Package Insert and Label Information (Page 3 of 4)

6.2 Postmarketing Experience

The following adverse reactions have been identified during postapproval use of Zydelig. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Skin and Subcutaneous Disorders — Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS)


7.1 Effects of Other Drugs on Zydelig

Table 6 lists the potential effects of the coadministration of strong CYP3A modulators on Zydelig.

Table 6 Drug Interactions with Zydelig that affect Idelalisib Concentrations
Strong CYP3A Inhibitors
Clinical Impact
  • Coadministration with strong CYP3A inhibitors may increase idelalisib concentrations [see Clinical Pharmacology (12.3)].
  • Increased idelalisib concentrations may increase the risk of exposure related adverse reactions.
Prevention or Management
  • Use other drugs that are not strong CYP3A inhibitors.
  • If unable to use alternative drugs, monitor patients more frequently for Zydelig adverse reactions [see Adverse Reactions (6.1)].
Strong CYP3A Inducers
Clinical Impact
  • Coadministration with strong CYP3A inducers may decrease idelalisib concentrations [see Clinical Pharmacology (12.3)].
  • Decreased idelalisib concentrations may reduce efficacy.
Prevention or Management Avoid coadministration of Zydelig with strong CYP3A4 inducers.

7.2 Effects of Zydelig on Other Drugs

The coadministration of Zydelig with a CYP3A substrate may increase the concentrations of this CYP3A substrate. Avoid coadministration of Zydelig with sensitive CYP3A substrates [see Clinical Pharmacology (12.3)].


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.


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. Adverse findings at idelalisib doses ≥ 75 mg/kg/day included decreased fetal weights, external malformations (short tail), and skeletal variations (delayed ossification and/or unossification of the skull, vertebrae, and sternebrae). Additional findings were observed at 150 mg/kg/day dose of idelalisib and included urogenital blood loss, complete resorption, increased post-implantation loss, and malformations (vertebral agenesis with anury, hydrocephaly, and microphthalmia/anophthalmia). The dose of 75 and 150 mg/kg/day of idelalisib in rats resulted in exposures (AUC) of approximately 12 and 30 times, respectively, the human exposure at the recommended dose of 150 mg twice daily.

8.2 Lactation

Risk Summary

There are no data on the presence of idelalisib or its metabolites in human milk or its effects on the breastfed child or on milk production. Because of the potential for serious adverse reactions in the breastfed child, advise women not to breastfeed during treatment with Zydelig and for 1 month after the last dose.

8.3 Females and Males of Reproductive Potential

Zydelig may cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)].


Pregnancy testing is recommended for females of reproductive potential prior to starting Zydelig.



Advise females of reproductive potential to use effective contraception during treatment with Zydelig and for 1 month after the last dose.


Advise males with female partners of reproductive potential to use effective contraception during treatment with Zydelig and for 3 months after the last dose [see Nonclinical Toxicology (13.1)].

8.4 Pediatric Use

Safety and effectiveness of Zydelig in pediatric patients have not been established.

8.5 Geriatric Use

Of the 490 patients with relapsed CLL who were treated with Zydelig in combination trials, 271 (55%) were 65 years of age and older. When comparing patients 65 years of age or older to younger patients with CLL, older patients had a higher incidence of discontinuation due to an adverse reaction (36% vs 28%), higher incidence of serious adverse reactions (73% vs 67%), and higher incidence of death (13% vs 9%).

8.6 Hepatic Impairment

No dose adjustment is recommended for patients with ALT or AST or bilirubin > upper limit of normal (ULN); however, limited safety and efficacy data are available for patients with baseline AST or ALT > 2.5 × ULN or bilirubin > 1.5 × ULN. Monitor patients with baseline hepatic impairment for adverse reactions [see Warnings and Precautions (5)]. Follow dosage modifications for adverse reactions [see Dosage and Administration (2.2)].


Idelalisib is a kinase inhibitor. The chemical name for idelalisib is 5-fluoro-3-phenyl-2-[(1S)-1-(9H -purin-6-ylamino)propyl]quinazolin-4(3H)-one. It has a molecular formula of C22H18FN7O and a molecular weight of 415.42 g/mol. Idelalisib has the following structural formula:

Chemical Structure

Idelalisib is a white to off-white solid with a pH-dependent aqueous solubility ranging from <0.1 mg/mL at pH 5–7 to over 1 mg/mL at pH 2 under ambient conditions.

Zydelig (idelalisib) tablets are for oral use. Each tablet contains either 100 mg or 150 mg of idelalisib with the following inactive ingredients: microcrystalline cellulose, hydroxypropyl cellulose, croscarmellose sodium, sodium starch glycolate, magnesium stearate and a tablet coating. The tablet coating consists of polyethylene glycol, talc, polyvinyl alcohol, and titanium dioxide and of FD&C Yellow #6/Sunset Yellow FCF Aluminum Lake (for the 100 mg tablet) and red iron oxide (for the 150 mg tablet).


12.1 Mechanism of Action

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. Idelalisib inhibits several cell signaling pathways, including B-cell receptor (BCR) signaling and the CXCR4 and CXCR5 signaling, which are involved in trafficking and homing of B-cells to the lymph nodes and bone marrow. Treatment of lymphoma cells with idelalisib resulted in inhibition of chemotaxis and adhesion, and reduced cell viability.

12.2 Pharmacodynamics

Cardiac Electrophysiology

At a dose 2.7 times the maximum recommended dose, Zydelig did not prolong the QT/QTc interval (i.e., ≤10 ms).

12.3 Pharmacokinetics

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 (Cmax ) and area under the curve (AUC) at steady-state were 1861 (43%) ng/mL and 10598 (41%) ng∙h/mL for idelalisib.


The median time to peak concentration (Tmax ) was observed at 1.5 hours.

Food Effect

The administration of a single dose of Zydelig with a high-fat meal (900 calories: 525 calories fat, 250 calories carbohydrates, and 125 calories protein) increased idelalisib AUC 1.4-fold relative to fasting conditions.


Protein binding of idelalisib is ≥ 84% with no concentration dependence.

The mean blood-to-plasma ratio was 0.7.

The apparent central volume of distribution at steady state is 23 L (%CV ~85%). Idelalisib is a substrate of P-glycoprotein (P-gp) and BCRP in vitro.


The population apparent systemic clearance at steady-state is 14.9 L/hr (%CV ~ 38%). The population terminal elimination half-life of idelalisib is 8.2 hours.


Idelalisib is metabolized via aldehyde oxidase and CYP3A with additional minor metabolism by UGT1A4.


Following a single 150 mg dose of radiolabeled idelalisib, 78% of the radioactivity was excreted in feces and 14% was excreted in the urine. Idelalisib is not a substrate of OATP1B1, OATP1B3, OAT1, OAT3, or OCT2.

Specific Populations

Age (18 to 91 years), sex, race (White, and non-Whites), renal impairment (creatinine clearance ≥ 15 mL/min) and weight (38 to 148 kg) had no effect on idelalisib exposure.

Patients with Hepatic Impairment

The mean AUC increased up to 1.7-fold in patients with hepatic impairment (defined as ALT or AST or bilirubin values ≥ ULN) compared to patients with normal hepatic function. There is limited information on idelalisib exposure in patients with baseline AST or ALT > 2.5 × ULN or bilirubin > 1.5 × ULN [see Specific Populations (8.6)].

Drug Interaction Studies

Effect of Other Drugs on Idelalisib

The coadministration of rifampin (strong CYP3A inducer and P-gp inducer) to healthy subjects decreased the mean idelalisib AUC by 75% and the mean Cmax by 58% [see Drug Interactions (7.1)].

The coadministration of ketoconazole (strong CYP3A inhibitor and P-gp inhibitor) to healthy subjects increased the mean idelalisib AUC by 1.8-fold. No changes in the mean Cmax were observed [see Drug Interactions (7.1)].

In vitro studies suggest that idelalisib inhibits CYP2C8, CYP2C19, and UGT1A1 and induces CYP2B6.

Effect of Idelalisib on Other Drugs

The mean Cmax of midazolam increased by 2.4-fold and the mean AUC of midazolam increased by 5.4-fold when midazolam (sensitive CYP3A substrate) was coadministered with Zydelig [see Drug Interactions (7.2)].

No changes in exposure to rosuvastatin (OATP1B1 and OATP1B3 substrate) or digoxin (P-glycoprotein substrate) were observed when coadministered with Zydelig.


13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Idelalisib was not carcinogenic in a 26-week study in transgenic mice when administered daily by oral gavage at doses up to 500 mg/kg/day in males and 1000 mg/kg/day in females. Idelalisib was not carcinogenic in a 2-year study in rats when administered daily by oral gavage at exposures 0.40/0.62-fold (male/female), compared to the exposure in patients with hematologic malignancies administered the recommended dose of 150 mg twice daily.

Idelalisib did not induce mutations in the bacterial mutagenesis (Ames) assay and was not clastogenic in the in vitro chromosome aberration assay using human peripheral blood lymphocytes. Idelalisib was genotoxic in males in the in vivo rat micronucleus study at a high dose of 2000 mg/kg.

Idelalisib may impair fertility in humans. In a fertility study, treated male rats (25, 50, or 100 mg/kg/day of idelalisib) were mated with untreated females. Decreased epididymidal and testicular weights were observed at all dose levels and reduced sperm concentration at the mid- and high doses; however, there were no adverse effects on fertility parameters. The low dose in males resulted in an exposure (AUC) that is approximately 50% of the exposure in patients at the recommended dose of 150 mg twice daily.

In a separate fertility study, treated female rats (25, 50, or 100 mg/kg/day of idelalisib) were mated with untreated males. There were no adverse effects on fertility parameters; however, there was a decrease in the number of live embryos at the high dose. The high dose in females resulted in an exposure (AUC) that is approximately 17-fold the exposure in patients at the recommended dose of 150 mg twice daily.

13.2 Animal Toxicology and/or Pharmacology

Toxicities observed in animals and not reported in patients include cardiac toxicity (cardiomyopathy, inflammation, and increased heart weight) and pancreatic findings (inflammation, hemorrhage, and low-incidence acinar degeneration and hyperplasia). These findings were observed in Sprague-Dawley rats in toxicology studies at exposures (AUCs) higher than those reported in patients at the recommended dose of 150 mg twice daily. Cardiac inflammation was mainly seen in a 28-day study in rats, the other findings were observed in the 13-week and/or 6-month studies.


Zydelig was evaluated in a randomized, double-blind, placebo-controlled study GS-US-312-0116 (referred to as 312-0116) (NCT01539512) in 220 patients with relapsed CLL who required treatment and were unable to tolerate standard chemoimmunotherapy due to coexisting medical conditions, reduced renal function as measured by creatinine clearance < 60 mL/min, or NCI CTCAE Grade ≥ 3 neutropenia or Grade ≥ 3 thrombocytopenia resulting from myelotoxic effects of prior therapy with cytotoxic agents. Patients were randomized 1:1 to receive 8 doses of rituximab (first dose at 375 mg/m2 , subsequent doses at 500 mg/m2 every 2 weeks for 4 infusions and every 4 weeks for an additional 4 infusions) in combination with either an placebo taken orally twice daily or with Zydelig 150 mg taken orally twice daily until disease progression or unacceptable toxicity.

The median age was 71 years (range 47, 92) with 78% over 65, 66% were male, and 90% were White. The median time since diagnosis was 8.5 years. The median number of prior therapies was 3. Nearly all (96%) patients had received prior anti-CD20 monoclonal antibodies. The most common (>15%) prior regimens were: bendamustine + rituximab (BR) (98 patients, 45%), fludarabine + cyclophosphamide + rituximab (75 patients, 34%), single-agent rituximab (67 patients, 31%), fludarabine + rituximab (37 patients, 17%), and chlorambucil (36 patients, 16%). The median CIRS (Cumulative Illness Rating Scale) score was 8 (range 0–17), and 85% of patients had a score of >6. Median Karnofsky score was 80. Median estimated Creatinine Clearance (eCLcr) was 63.6 mL/min, with 41% of patients having an eCLcr of <60 mL/min. At screening, 19.5% of patients had a platelet count of <50 × 109 /L, and 13.2% had an absolute neutrophil count (ANC) of <1 × 109 /L.

The efficacy of Zydelig was based on progression free survival (PFS), as assessed by an independent review committee (IRC). The trial was stopped for efficacy following the first pre-specified interim analysis. Results of a second interim analysis continued to show a statistically significant improvement for Zydelig + R compared to placebo + R for the major efficacy outcome measure of PFS (HR: 0.18, 95% CI [0.10, 0.32], p <0.0001).

At the final analysis, with a median follow-up of 8.3 months for the Zydelig + R group, and 5.6 months for the placebo + R group, the median PFS for the Zydelig + R group was 19.4 months (95% CI: 12.3, Not Reached) versus 6.5 months (95% CI: 4.0, 7.3) for the placebo + R group (HR: 0.15, 95% CI [0.09, 0.24], p < 0.0001).

Updated efficacy results are shown in Table 7 and the Kaplan-Meier curve for PFS is shown in Figure 1.

Table 7 Efficacy Results from Study 312-0116
Zydelig + RN = 110Placebo + RN = 110
PFS: progression-free survival; NR: not reached; ORR: overall response rate; PR: partial response; DOR: duration of response
The p value for PFS was based on stratified log-rank test.
ORR defined as the proportion of patients who achieved a complete response (CR) or PR. All PRs achieved; none of the patients achieved a CR.
PFS Median (months) (95% CI)19.4 (12.3, NR)6.5 (4.0, 7.3)
Hazard ratio (95% CI)0.15 (0.09, 0.24)
P-value< 0.0001 *
ORR (All PRs)92 (83.6%)17 (15.5%)
95% CI75.4, 90.09.3, 23.6
Odds Ratio (95% CI)27.8 (13.4, 57.5)
DOR Median (months) (95% CI)NR (12, NR)6.2 (2.8, 6.5)

Figure 1 Kaplan-Meier Plot of IRC-Assessed PFS for Study 312-0116

Figure 1
(click image for full-size original)

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