Sirolimus

Sirolimus is an mTOR inhibitor immunosuppressant indicated for the prophylaxis of organ rejection in patients aged ≥13 years receiving renal transplants: – Patients at low- to moderate-immunologic risk: Use initially with cyclosporine (CsA) and corticosteroids. CsA withdrawal is recommended 2–4 months after transplantation ( 1.1 ). – Patients at high-immunologic risk: Use in combination with CsA and corticosteroids for the first 12 months following transplantation ( 1.1 ). Safety and efficacy of CsA withdrawal has not been established in high risk patients ( 1.1 , 1.2 , 14.3 ). Sirolimus is an mTOR inhibitor indicated for the treatment of patients with lymphangioleiomyomatosis ( 1.3 ).

1.1 Prophylaxis of Organ Rejection in Renal Transplantation Sirolimus is indicated for the prophylaxis of organ rejection in patients aged 13 years or older receiving renal transplants. In patients at low- to moderate-immunologic risk, it is recommended that sirolimus be used initially in a regimen with cyclosporine and corticosteroids; cyclosporine should be withdrawn 2 to 4 months after transplantation [ see Dosage and Administration (2.2) ]. In patients at high-immunologic risk (defined as Black recipients and/or repeat renal transplant recipients who lost a previous allograft for immunologic reason and/or patients with high panel-reactive antibodies [PRA; peak PRA level >80%]), it is recommended that sirolimus be used in combination with cyclosporine and corticosteroids for the first year following transplantation [ see Dosage and Administration (2.3) , Clinical Studies (14.3) ].

1.2 Limitations of Use in Renal Transplantation Cyclosporine withdrawal has not been studied in patients with Banff Grade 3 acute rejection or vascular rejection prior to cyclosporine withdrawal, those who are dialysis-dependent, those with serum creatinine >4.5 mg/dL, Black patients, patients of multi-organ transplants, secondary transplants, or those with high levels of panel-reactive antibodies [ see Clinical Studies (14.2) ]. In patients at high-immunologic risk, the safety and efficacy of sirolimus used in combination with cyclosporine and corticosteroids has not been studied beyond one year; therefore after the first 12 months following transplantation, any adjustments to the immunosuppressive regimen should be considered on the basis of the clinical status of the patient [ see Clinical Studies (14.3) ]. In pediatric patients, the safety and efficacy of sirolimus have not been established in patients <13 years old, or in pediatric (<18 years) renal transplant patients considered at high-immunologic risk [ see Adverse Reactions (6.5) , Clinical Studies (14.6) ]. The safety and efficacy of de novo use of sirolimus without cyclosporine have not been established in renal transplant patients [ see Warnings and Precautions (5.12) ]. The safety and efficacy of conversion from calcineurin inhibitors to sirolimus in maintenance renal transplant patients have not been established [ see Clinical Studies (14.4) ].

1.3 Treatment of Patients with Lymphangioleiomyomatosis Sirolimus is indicated for the treatment of patients with lymphangioleiomyomatosis (LAM).

• Tablets: 0.5 mg, 1 mg, 2 mg ( 3.1 ).

3.1 Sirolimus Tablets

• 0.5 mg, tan, triangular-shaped tablets marked "RAPAMUNE 0.5 mg" on one side.
• 1 mg, white, triangular-shaped tablets marked "RAPAMUNE 1 mg" on one side.
• 2 mg, yellow-to-beige triangular-shaped tablets marked "RAPAMUNE 2 mg" on one side.

Sirolimus is contraindicated in patients with a hypersensitivity to sirolimus [ see Warnings and Precautions (5.4) ]. Hypersensitivity to sirolimus ( 4 ).

• Hypersensitivity Reactions ( 5.4 )
• Angioedema ( 5.5 )
• Fluid Accumulation and Impairment of Wound Healing ( 5.6 )
• Hyperlipidemia ( 5.7 )
• Decline in Renal Function ( 5.8 )
• Proteinuria ( 5.9 )
• Latent Viral Infections ( 5.10 )
• Interstitial Lung Disease/Non-Infectious Pneumonitis ( 5.11 )
• De Novo Use Without Cyclosporine ( 5.12 )
• Increased Risk of Calcineurin Inhibitor-Induced Hemolytic Uremic Syndrome/ Thrombotic Thrombocytopenic Purpura/ Thrombotic Microangiopathy ( 5.13 )
• Embryo-Fetal Toxicity: Can cause fetal harm. Use of highly effective contraception is recommended for females of reproductive potential during treatment and for 12 weeks after final dose of sirolimus ( 5.15 , 8.1 )
• Male Infertility: Azoospermia or oligospermia may occur ( 5.16 , 13.1 )
• Immunizations: Avoid live vaccines ( 5.19 )

5.1 Increased Susceptibility to Infection and the Possible Development of Lymphoma Increased susceptibility to infection and the possible development of lymphoma and other malignancies, particularly of the skin, may result from immunosuppression. The rates of lymphoma/lymphoproliferative disease observed in Studies 1 and 2 were 0.7–3.2% (for sirolimus -treated patients) versus 0.6–0.8% (azathioprine and placebo control) [ see Adverse Reactions (6.1) and (6.2) ]. Oversuppression of the immune system can also increase susceptibility to infection, including opportunistic infections such as tuberculosis, fatal infections, and sepsis. Only physicians experienced in immunosuppressive therapy and management of organ transplant patients should use sirolimus for prophylaxis of organ rejection in patients receiving renal transplants. Patients receiving the drug should be managed in facilities equipped and staffed with adequate laboratory and supportive medical resources. The physician responsible for maintenance therapy should have complete information requisite for the follow-up of the patient.

5.2 Liver Transplantation – Excess Mortality, Graft Loss, and Hepatic Artery Thrombosis The safety and efficacy of sirolimus as immunosuppressive therapy have not been established in liver transplant patients; therefore, such use is not recommended. The use of sirolimus has been associated with adverse outcomes in patients following liver transplantation, including excess mortality, graft loss and hepatic artery thrombosis (HAT). In a study in de novo liver transplant patients, the use of sirolimus in combination with tacrolimus was associated with excess mortality and graft loss (22% in combination versus 9% on tacrolimus alone). Many of these patients had evidence of infection at or near the time of death. In this and another study in de novo liver transplant patients, the use of sirolimus in combination with cyclosporine or tacrolimus was associated with an increase in HAT (7% in combination versus 2% in the control arm); most cases of HAT occurred within 30 days post-transplantation, and most led to graft loss or death. In a clinical study in stable liver transplant patients 6–144 months post-liver transplantation and receiving a CNI-based regimen, an increased number of deaths was observed in the group converted to a sirolimus-based regimen compared to the group who was continued on a CNI-based regimen, although the difference was not statistically significant (3.8% versus 1.4%) [ see Clinical Studies (14.5) ].

5.3 Lung Transplantation – Bronchial Anastomotic Dehiscence Cases of bronchial anastomotic dehiscence, most fatal, have been reported in de novo lung transplant patients when sirolimus has been used as part of an immunosuppressive regimen. The safety and efficacy of sirolimus as immunosuppressive therapy have not been established in lung transplant patients; therefore, such use is not recommended.

5.4 Hypersensitivity Reactions Hypersensitivity reactions, including anaphylactic/anaphylactoid reactions, angioedema, exfoliative dermatitis and hypersensitivity vasculitis, have been associated with the administration of sirolimus [ see Adverse Reactions (6.7) ].

5.5 Angioedema Sirolimus has been associated with the development of angioedema. The concomitant use of sirolimus with other drugs known to cause angioedema, such as angiotensin converting enzyme (ACE) inhibitors, may increase the risk of developing angioedema. Elevated sirolimus levels (with/without concomitant ACE inhibitors) may also potentiate angioedema [ see Drug Interactions (7.2) ]. In some cases, the angioedema has resolved upon discontinuation or dose reduction of sirolimus.

5.6 Fluid Accumulation and Impairment of Wound Healing There have been reports of impaired or delayed wound healing in patients receiving sirolimus, including lymphocele and wound dehiscence [ see Adverse Reactions (6.1) ]. Mammalian target of rapamycin (mTOR) inhibitors such as sirolimus have been shown in vitro to inhibit production of certain growth factors that may affect angiogenesis, fibroblast proliferation, and vascular permeability. Lymphocele, a known surgical complication of renal transplantation, occurred significantly more often in a dose-related fashion in patients treated with sirolimus [ see Adverse Reactions (6.1) ]. Appropriate measures should be considered to minimize such complications. Patients with a body mass index (BMI) greater than 30 kg/m 2 may be at increased risk of abnormal wound healing based on data from the medical literature. There have also been reports of fluid accumulation, including peripheral edema, lymphedema, pleural effusion, ascites, and pericardial effusions (including hemodynamically significant effusions and tamponade requiring intervention in children and adults), in patients receiving sirolimus.

5.7 Hyperlipidemia Increased serum cholesterol and triglycerides requiring treatment occurred more frequently in patients treated with sirolimus compared with azathioprine or placebo controls in Studies 1 and 2 [ see Adverse Reactions (6.1) ]. There were increased incidences of hypercholesterolemia (43–46%) and/or hypertriglyceridemia (45–57%) in patients receiving sirolimus compared with placebo controls (each 23%). The risk/benefit should be carefully considered in patients with established hyperlipidemia before initiating an immunosuppressive regimen including sirolimus. Any patient who is administered sirolimus should be monitored for hyperlipidemia. If detected, interventions such as diet, exercise, and lipid-lowering agents should be initiated as outlined by the National Cholesterol Education Program guidelines. In clinical trials of patients receiving sirolimus plus cyclosporine or sirolimus after cyclosporine withdrawal, up to 90% of patients required treatment for hyperlipidemia and hypercholesterolemia with anti-lipid therapy (e.g., statins, fibrates). Despite anti-lipid management, up to 50% of patients had fasting serum cholesterol levels >240 mg/dL and triglycerides above recommended target levels. The concomitant administration of sirolimus and HMG-CoA reductase inhibitors resulted in adverse reactions such as CPK elevations (3%), myalgia (6.7%) and rhabdomyolysis (<1%). In these trials, the number of patients was too small and duration of follow-up too short to evaluate the long-term impact of sirolimus on cardiovascular mortality. During sirolimus therapy with or without cyclosporine, patients should be monitored for elevated lipids, and patients administered an HMG-CoA reductase inhibitor and/or fibrate should be monitored for the possible development of rhabdomyolysis and other adverse effects, as described in the respective labeling for these agents.

5.8 Decline in Renal Function Renal function should be closely monitored during the co-administration of sirolimus with cyclosporine, because long-term administration of the combination has been associated with deterioration of renal function. […]

The following adverse reactions are discussed in greater detail in other sections of the label.

• Increased susceptibility to infection, lymphoma, and malignancy [ see Boxed Warning , Warnings and Precautions (5.1) ]
• Excess mortality, graft loss, and hepatic artery thrombosis in liver transplant patients [ see Boxed Warning , Warnings and Precautions (5.2) ]
• Bronchial anastomotic dehiscence in lung transplant patients [ see Boxed Warning , Warnings and Precautions (5.3) ]
• Hypersensitivity reactions [ see Warnings and Precautions (5.4) ]
• Exfoliative dermatitis [ see Warnings and Precautions (5.4) ]
• Angioedema [ see Warnings and Precautions (5.5) ]
• Fluid accumulation and impairment of wound healing [ see Warnings and Precautions (5.6) ]
• Hypertriglyceridemia, hypercholesterolemia [ see Warnings and Precautions (5.7) ]
• Decline in renal function in long-term combination of cyclosporine with sirolimus [ see Warnings and Precautions (5.8) ]
• Proteinuria [ see Warnings and Precautions (5.9) ]
• Interstitial lung disease [ see Warnings and Precautions (5.11) ]
• Increased risk of calcineurin inhibitor-induced HUS/TTP/TMA [ see Warnings and Precautions (5.13) ]
• Embryo-fetal toxicity [ see Warnings and Precautions (5.15) ]
• Male infertility [ see Warnings and Precautions (5.16) ] The most common (≥30%) adverse reactions observed with sirolimus in clinical studies for organ rejection prophylaxis in recipients of renal transplantation are: peripheral edema, hypertriglyceridemia, hypertension, hypercholesterolemia, creatinine increased, constipation, abdominal pain, diarrhea, headache, fever, urinary tract infection, anemia, nausea, arthralgia, pain, and thrombocytopenia. The most common (≥20%) adverse reactions observed with sirolimus in the clinical study for the treatment of LAM are: stomatitis, diarrhea, abdominal pain, nausea, nasopharyngitis, acne, chest pain, peripheral edema, upper respiratory tract infection, headache, dizziness, myalgia, and hypercholesterolemia. The following adverse reactions resulted in a rate of discontinuation of >5% in clinical trials for renal transplant rejection prophylaxis: creatinine increased, hypertriglyceridemia, and TTP. In patients with LAM, 11% of subjects discontinued due to adverse reactions, with no single adverse reaction leading to discontinuation in more than one patient being treated with sirolimus. Prophylaxis of organ rejection in patients receiving renal transplants: Most common adverse reactions (incidence ≥30%) are peripheral edema, hypertriglyceridemia, hypertension, hypercholesterolemia, creatinine increased, abdominal pain, diarrhea, headache, fever, urinary tract infection, anemia, nausea, arthralgia, pain, and thrombocytopenia ( 6 ). Lymphangioleiomyomatosis: Most common adverse reactions (incidence ≥20%) are stomatitis, diarrhea, abdominal pain, nausea, nasopharyngitis, acne, chest pain, peripheral edema, upper respiratory tract infection, headache, dizziness, myalgia, and hypercholesterolemia ( 6.6 ). To report SUSPECTED ADVERSE REACTIONS, contact Greenstone LLC Professional Information Services at 1-877-446-3679 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch

6.1 Clinical Studies Experience in Prophylaxis of Organ Rejection Following Renal Transplantation The safety and efficacy of sirolimus oral solution for the prevention of organ rejection following renal transplantation were assessed in two randomized, double-blind, multicenter, controlled trials [ see Clinical Studies (14.1) ]. The safety profiles in the two studies were similar. The incidence of adverse reactions in the randomized, double-blind, multicenter, placebo-controlled trial (Study 2) in which 219 renal transplant patients received sirolimus oral solution 2 mg/day, 208 received sirolimus oral solution 5 mg/day, and 124 received placebo is presented in Table 1 below. The study population had a mean age of 46 years (range 15 to 71 years), the distribution was 67% male, and the composition by race was: White (78%), Black (11%), Asian (3%), Hispanic (2%), and Other (5%). All patients were treated with cyclosporine and corticosteroids. Data (≥ 12 months post-transplant) presented in the following table show the adverse reactions that occurred in at least one of the sirolimus treatment groups with an incidence of ≥20%. The safety profile of the tablet did not differ from that of the oral solution formulation [ see Clinical Studies (14.1) ]. In general, adverse reactions related to the administration of sirolimus were dependent on dose/concentration. Although a daily maintenance dose of 5 mg, with a loading dose of 15 mg, was shown to be safe and effective, no efficacy advantage over the 2 mg dose could be established for renal transplant patients. Patients receiving 2 mg of sirolimus oral solution per day demonstrated an overall better safety profile than did patients receiving 5 mg of sirolimus oral solution per day. Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in one clinical trial of a drug cannot be directly compared with rates in the clinical trials of the same or another drug and may not reflect the rates observed in practice. TABLE 1: ADVERSE REACTIONS OCCURRING AT A FREQUENCY OF ≥20% IN AT LEAST ONE OF THE SIROLIMUS TREATMENT GROUPS IN A STUDY OF PROPHYLAXIS OF ORGAN REJECTION FOLLOWING RENAL TRANSPLANTATION (%) AT ≥ 12 MONTHS POST-TRANSPLANTATION (STUDY 2) Patients received cyclosporine and corticosteroids. ––– Sirolimus Oral Solution––– 2 mg/day 5 mg/day Placebo Adverse Reaction (n = 218) (n = 208) (n = 124) Peripheral edema 54 58 48 Hypertriglyceridemia 45 57 23 Hypertension 45 49 48 Hypercholesterolemia 43 46 23 Creatinine increased 39 40 38 Constipation 36 38 31 Abdominal pain 29 36 30 Diarrhea 25 35 27 Headache 34 34 31 Fever 23 34 35 Urinary tract infection 26 33 26 Anemia 23 33 21 Nausea 25 31 29 Arthralgia 25 31 18 Thrombocytopenia 14 30 9 Pain 33 29 25 Acne 22 22 19 Rash 10 20 6 Edema 20 18 15 The following adverse reactions were reported less frequently (≥3%, but <20%)

• Body as a Whole – Sepsis, lymphocele, herpes zoster, herpes simplex.
• Cardiovascular – Venous thromboembolism (including pulmonary embolism, deep venous thrombosis), tachycardia.
• Digestive System – Stomatitis.
• Hematologic and Lymphatic System – Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), leukopenia.
• Metabolic/Nutritional – Abnormal healing, increased lactic dehydrogenase (LDH), hypokalemia, diabetes mellitus.
• Musculoskeletal System – Bone necrosis.
• Respiratory System – Pneumonia, epistaxis.
• Skin – Melanoma, squamous cell carcinoma, basal cell carcinoma.
• Urogenital System – Pyelonephritis, decline in renal function (creatinine increased) in long-term combination of cyclosporine with sirolimus [ see Warnings and Precautions (5.8) ], ovarian cysts, menstrual disorders (including amenorrhea and menorrhagia). Less frequently (<3%) occurring adverse reactions included: lymphoma/post-transplant lymphoproliferative disorder, mycobacterial infections (including M. tuberculosis ), pancreatitis, cytomegalovirus (CMV), and Epstein-Barr virus. Increased Serum Cholesterol and Triglycerides The use of sirolimus in renal transplant patients was associated with increased serum cholesterol and triglycerides that may require treatment. In Studies 1 and 2, in de novo renal transplant patients who began the study with fasting, total serum cholesterol <200 mg/dL or fasting, total serum triglycerides <200 mg/dL, there was an increased incidence of hypercholesterolemia (fasting serum cholesterol >240 mg/dL) or hypertriglyceridemia (fasting serum triglycerides >500 mg/dL), respectively, in patients receiving both sirolimus 2 mg and sirolimus 5 mg compared with azathioprine and placebo controls. […]

Sirolimus is known to be a substrate for both cytochrome P-450 3A4 (CYP3A4) and p-glycoprotein (P-gp). Inducers of CYP3A4 and P-gp may decrease sirolimus concentrations whereas inhibitors of CYP3A4 and P-gp may increase sirolimus concentrations.

• Avoid concomitant use with strong CYP3A4/P-gp inducers or strong CYP3A4/P-gp inhibitors that decrease or increase sirolimus concentrations ( 7.4 , 12.3 ).
• Therapeutic drug monitoring and dose reduction for sirolimus should be considered when sirolimus is co-administered with cannabidiol ( 5.21 , 7.5 ).
• See full prescribing information for complete list of clinically significant drug interactions ( 12.3 ).

7.1 Use with Cyclosporine Cyclosporine, a substrate and inhibitor of CYP3A4 and P-gp, was demonstrated to increase sirolimus concentrations when co-administered with sirolimus. In order to diminish the effect of this interaction with cyclosporine, it is recommended that sirolimus be taken 4 hours after administration of cyclosporine oral solution (MODIFIED) and/or cyclosporine capsules (MODIFIED). If cyclosporine is withdrawn from combination therapy with sirolimus, higher doses of sirolimus are needed to maintain the recommended sirolimus trough concentration ranges [ see Dosage and Administration (2.2) , Clinical Pharmacology (12.3) ].

7.2 Strong Inducers and Strong Inhibitors of CYP3A4 and P-gp Avoid concomitant use of sirolimus with strong inducers (e.g., rifampin, rifabutin) and strong inhibitors (e.g., ketoconazole, voriconazole, itraconazole, erythromycin, telithromycin, clarithromycin) of CYP3A4 and P-gp. Alternative agents with lesser interaction potential with sirolimus should be considered [ see Warnings and Precautions (5.20) , Clinical Pharmacology (12.3) ].

7.3 Grapefruit Juice Because grapefruit juice inhibits the CYP3A4-mediated metabolism of sirolimus, it must not be taken with sirolimus [ see Clinical Pharmacology (12.3) ].

7.4 Weak and Moderate Inducers or Inhibitors of CYP3A4 and P-gp Exercise caution when using sirolimus with drugs or agents that are modulators of CYP3A4 and P-gp. The dosage of sirolimus and/or the co-administered drug may need to be adjusted [ see Clinical Pharmacology (12.3) ].

• Drugs that could increase sirolimus blood concentrations: Bromocriptine, cimetidine, cisapride, clotrimazole, danazol, diltiazem, fluconazole, letermovir, protease inhibitors (e.g., HIV and hepatitis C that include drugs such as ritonavir, indinavir, boceprevir, and telaprevir), metoclopramide, nicardipine, troleandomycin, verapamil
• Drugs and other agents that could decrease sirolimus concentrations: Carbamazepine, phenobarbital, phenytoin, rifapentine, St. John's Wort ( Hypericum perforatum )
• Drugs with concentrations that could increase when given with sirolimus: Verapamil

7.5 Cannabidiol The blood levels of sirolimus may increase upon concomitant use with cannabidiol. When cannabidiol and sirolimus are co-administered, closely monitor for an increase in sirolimus blood levels and for adverse reactions suggestive of sirolimus toxicity. A dose reduction of sirolimus should be considered as needed when sirolimus is co-administered with cannabidiol [ see Dosage and Administration (2.5) , Warnings and Precautions (5.21) ].

• Pregnancy: Based on animal data can cause fetal harm ( 5.15 , 8.1 ).
• Lactation: Potential for serious adverse effects in breastfed infants based on mechanism of action ( 8.2 ).
• Females and Males of Reproductive Potential: May impair fertility ( 8.1 , 8.3 , 13.1 ).

8.1 Pregnancy Risk Summary Based on animal studies and the mechanism of action, sirolimus can cause fetal harm when administered to a pregnant woman [ see Data , Clinical Pharmacology (12.1) ]. There are limited data on the use of sirolimus during pregnancy; however, these data are insufficient to inform a drug-associated risk of adverse developmental outcomes. In animal studies, sirolimus was embryo/fetotoxic in rats at sub-therapeutic doses [ see Data ]. Advise pregnant women of the potential risk to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2–4% and 15–20%, respectively. Data Animal Data Sirolimus crossed the placenta and was toxic to the conceptus. In rat embryo-fetal development studies, pregnant rats were administered sirolimus orally during the period of organogenesis (Gestational Day 6–15). Sirolimus produced embryo-fetal lethality at 0.5 mg/kg (2.5-fold the clinical dose of 2 mg, on a body surface area basis) and reduced fetal weight at 1 mg/kg (5-fold the clinical dose of 2 mg). The no observed adverse effect level (NOAEL) for fetal toxicity in rats was 0.1 mg/kg (0.5-fold the clinical dose of 2 mg). Maternal toxicity (weight loss) was observed at 2 mg/kg (10-fold the clinical dose of 2 mg). The NOAEL for maternal toxicity was 1 mg/kg. In combination with cyclosporine, rats had increased embryo-fetal mortality compared with sirolimus alone. In rabbit embryo-fetal development studies, pregnant rabbits were administered sirolimus orally during the period of organogenesis (Gestational Day 6–18). There were no effects on embryo-fetal development at doses up to 0.05 mg/kg (0.5-fold the clinical dose of 2 mg, on a body surface area basis); however, at doses of 0.05 mg/kg and above, the ability to sustain a successful pregnancy was impaired (i.e., embryo-fetal abortion or early resorption). Maternal toxicity (decreased body weight) was observed at 0.05 mg/kg. The NOAEL for maternal toxicity was 0.025 mg/kg (0.25-fold the clinical dose of 2 mg). In a pre- and post-natal development study in rats, pregnant females were dosed during gestation and lactation (Gestational Day 6 through Lactation Day 20). An increased incidence of dead pups, resulting in reduced live litter size, occurred at 0.5 mg/kg (2.5-fold the clinical dose of 2 mg/kg on a body surface area basis). At 0.1 mg/kg (0.5-fold the clinical dose of 2 mg), there were no adverse effects on offspring. Sirolimus did not cause maternal toxicity or affect developmental parameters in the surviving offspring (morphological development, motor activity, learning, or fertility assessment) at 0.5 mg/kg, the highest dose tested.

8.2 Lactation Risk Summary It is not known whether sirolimus is present in human milk. There are no data on its effects on the breastfed infant or milk production. The pharmacokinetic and safety profiles of sirolimus in infants are not known. Sirolimus is present in the milk of lactating rats. There is potential for serious adverse effects from sirolimus in breastfed infants based on mechanism of action [ see Clinical Pharmacology (12.1) ] . The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for sirolimus and any potential adverse effects on the breastfed child from sirolimus.

8.3 Females and Males of Reproductive Potential Contraception Females should not be pregnant or become pregnant while receiving sirolimus. Advise females of reproductive potential that animal studies have been shown sirolimus to be harmful to the developing fetus. Females of reproductive potential are recommended to use highly effective contraceptive method. Effective contraception must be initiated before sirolimus therapy, during sirolimus therapy, and for 12 weeks after sirolimus therapy has been stopped [ see Warnings and Precautions (5.15) , Use in Specific Populations (8.1) ]. Infertility Based on clinical findings and findings in animals, male and female fertility may be compromised by the treatment with sirolimus [ see Adverse Reactions (6.7) , Nonclinical Toxicology (13.1) ]. Ovarian cysts and menstrual disorders (including amenorrhea and menorrhagia) have been reported in females with the use of sirolimus. Azoospermia has been reported in males with the use of sirolimus and has been reversible upon discontinuation of sirolimus in most cases.

8.4 Pediatric Use Renal Transplant The safety and efficacy of sirolimus in pediatric patients <13 years have not been established. The safety and efficacy of sirolimus oral solution and sirolimus tablets have been established for prophylaxis of organ rejection in renal transplantation in children ≥13 years judged to be at low- to moderate-immunologic risk. Use of sirolimus oral solution and sirolimus tablets in this subpopulation of children ≥13 years is supported by evidence from adequate and well-controlled trials of sirolimus oral solution in adults with additional pharmacokinetic data in pediatric renal transplantation patients [ see Clinical Pharmacology (12.3) ]. Safety and efficacy information from a controlled clinical trial in pediatric and adolescent (<18 years of age) renal transplant patients judged to be at high-immunologic risk, defined as a history of one or more acute rejection episodes and/or the presence of chronic allograft nephropathy, do not support the chronic use of sirolimus oral solution or tablets in combination with calcineurin inhibitors and corticosteroids, due to the higher incidence of lipid abnormalities and deterioration of renal function associated with these immunosuppressive regimens compared to calcineurin inhibitors, without increased benefit with respect to acute rejection, graft survival, or patient survival [ see Clinical Studies (14.6) ]. Lymphangioleiomyomatosis The safety and efficacy of Sirolimus in pediatric patients <18 years have not been established.

8.5 Geriatric Use Clinical studies of sirolimus oral solution or tablets did not include sufficient numbers of patients ≥65 years to determine whether they respond differently from younger patients. Data pertaining to sirolimus trough concentrations suggest that dose adjustments based upon age in geriatric renal patients are not necessary. Differences in responses between the elderly and younger patients have not been identified. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, or cardiac function, and of concomitant disease or other drug therapy.

8.6 Patients with Hepatic Impairment The maintenance dose of sirolimus should be reduced in patients with hepatic impairment [ see Dosage and Administration (2.7) , Clinical Pharmacology (12.3) ].

8.7 Patients with Renal Impairment Dosage adjustment is not required in patients with renal impairment [ see Dosage and Administration (2.8) , Clinical Pharmacology (12.3) ].

Sirolimus inhibits T-lymphocyte activation and proliferation that occurs in response to antigenic and cytokine (Interleukin [IL]-2, IL-4, and IL-15) stimulation by a mechanism that is distinct from that of other immunosuppressants. Sirolimus also inhibits antibody production. In cells, sirolimus binds to the immunophilin, FK Binding Protein-12 (FKBP-12), to generate an immunosuppressive complex. The sirolimus:FKBP-12 complex has no effect on calcineurin activity. This complex binds to and inhibits the activation of the mammalian target of rapamycin (mTOR), a key regulatory kinase. This inhibition suppresses cytokine-driven T-cell proliferation, inhibiting the progression from the G 1 to the S phase of the cell cycle. Mammalian target of rapamycin (mTOR) inhibitors such as sirolimus have been shown in vitro to inhibit production of certain growth factors that may affect angiogenesis, fibroblast proliferation, and vascular permeability. Studies in experimental models show that sirolimus prolongs allograft (kidney, heart, skin, islet, small bowel, pancreatico-duodenal, and bone marrow) survival in mice, rats, pigs, and/or primates. Sirolimus reverses acute rejection of heart and kidney allografts in rats and prolongs the graft survival in presensitized rats. In some studies, the immunosuppressive effect of sirolimus lasts up to 6 months after discontinuation of therapy. This tolerization effect is alloantigen-specific. In rodent models of autoimmune disease, sirolimus suppresses immune-mediated events associated with systemic lupus erythematosus, collagen-induced arthritis, autoimmune type I diabetes, autoimmune myocarditis, experimental allergic encephalomyelitis, graft-versus-host disease, and autoimmune uveoretinitis. Lymphangioleiomyomatosis involves lung tissue infiltration with smooth muscle-like cells that harbor inactivating mutations of the tuberous sclerosis complex (TSC) gene (LAM cells). Loss of TSC gene function activates the mTOR signaling pathway, resulting in cellular proliferation and release of lymphangiogenic growth factors. Sirolimus inhibits the activated mTOR pathway and thus the proliferation of LAM cells.