DELSTRIGO

1 INDICATIONS AND USAGE DELSTRIGO ® is indicated as a complete regimen for the treatment of HIV-1 infection in adults and pediatric patients weighing at least 35 kg: with no prior antiretroviral treatment history, OR to replace the current antiretroviral regimen in those who are virologically-suppressed (HIV-1 RNA less than 50 copies per mL) on a stable antiretroviral regimen with no history of treatment failure and no known substitutions associated with resistance to the individual components of DELSTRIGO [see Clinical Studies (14) ] . DELSTRIGO is a three-drug combination of doravirine (a non-nucleoside reverse transcriptase inhibitor [NNRTI]), lamivudine, and tenofovir disoproxil fumarate (both nucleoside analogue reverse transcriptase inhibitors) and is indicated as a complete regimen for the treatment of HIV-1 infection in adults and pediatric patients weighing at least 35 kg: with no antiretroviral treatment history, OR to replace the current antiretroviral regimen in those who are virologically-suppressed (HIV-1 RNA less than 50 copies per mL) on a stable antiretroviral regimen with no history of treatment failure and no known substitutions associated with resistance to the individual components of DELSTRIGO. ( 1 )

2 DOSAGE AND ADMINISTRATION Testing: Prior to or when initiating DELSTRIGO, test for HBV infection. Prior to or when initiating DELSTRIGO, and during treatment with DELSTRIGO, on a clinically appropriate schedule, assess serum creatinine, estimated creatinine clearance, urine glucose and urine protein in all patients. In patients with chronic kidney disease, also assess serum phosphorus . ( 2.1 ) Recommended dosage: One tablet taken orally once daily with or without food in adults and pediatric patients weighing at least 35 kg. ( 2.2 ) Renal impairment: Not recommended in patients with estimated creatinine clearance below 50 mL per minute. ( 2.3 ) Dosage adjustment with rifabutin: Take one tablet of DELSTRIGO once daily, followed by one tablet of doravirine 100 mg (PIFELTRO) approximately 12 hours after the dose of DELSTRIGO. ( 2.4 ) 2.1 Testing When Initiating and During Treatment with DELSTRIGO Prior to or when initiating DELSTRIGO, test patients for HBV infection [see Warnings and Precautions (5.2) ]. Prior to or when initiating DELSTRIGO, and during treatment with DELSTRIGO, on a clinically appropriate schedule, assess serum creatinine, estimated creatinine clearance, urine glucose, and urine protein in all patients. In patients with chronic kidney disease, also assess serum phosphorus [see Warnings and Precautions (5.3) ]. 2.2 Recommended Dosage DELSTRIGO is a fixed-dose combination product containing 100 mg of doravirine (DOR), 300 mg of lamivudine (3TC), and 300 mg of TDF. The recommended dosage of DELSTRIGO in adults and pediatric patients weighing at least 35 kg is one tablet taken orally once daily with or without food [see Clinical Pharmacology (12.3) ] . 2.3 Renal Impairment Because DELSTRIGO is a fixed-dose combination tablet and the dosage of lamivudine and TDF cannot be adjusted, DELSTRIGO is not recommended in patients with estimated creatinine clearance less than 50 mL/min [see Warnings and Precautions (5.3) and Use in Specific Populations (8.6) ] . 2.4 Dosage Adjustment with Rifabutin If DELSTRIGO is co-administered with rifabutin, take one tablet of DELSTRIGO once daily, followed by one tablet of doravirine 100 mg (PIFELTRO) approximately 12 hours after the dose of DELSTRIGO for the duration of rifabutin co-administration [see Drug Interactions (7.2) and Clinical Pharmacology (12.3) ].

5 WARNINGS AND PRECAUTIONS Severe skin reactions, including Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), have been reported during the postmarketing experience with doravirine-containing regimens. Discontinue DELSTRIGO, and other medications known to be associated with severe skin reactions, immediately if a painful rash with mucosal involvement or a progressive severe rash develops, and closely monitor clinical status. ( 5.1 ) New onset or worsening renal impairment: Prior to or when initiating DELSTRIGO, and during treatment with DELSTRIGO, on a clinically appropriate schedule, assess serum creatinine, estimated creatinine clearance, urine glucose, and urine protein in all patients. Avoid administering DELSTRIGO with concurrent or recent use of nephrotoxic drugs. ( 5.3 ) Bone loss and mineralization defects: Consider monitoring BMD in patients with a history of pathologic fracture or other risk factors of osteoporosis or bone loss. ( 5.5 ) Monitor for Immune Reconstitution Syndrome. ( 5.6 ) 5.1 Severe Skin Reactions Severe skin reactions, including Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), have been reported during the postmarketing experience with doravirine-containing regimens [see Adverse Reactions (6.2) ] . Discontinue DELSTRIGO, and other medications known to be associated with severe skin reactions, immediately if a painful rash with mucosal involvement or a progressive severe rash develops. Clinical status should be closely monitored, and appropriate therapy should be initiated. 5.2 Severe Acute Exacerbation of Hepatitis B in People with Concomitant HIV-1 and HBV All patients with HIV-1 should be tested for the presence of HBV before initiating antiretroviral therapy. Severe acute exacerbations of hepatitis B (e.g., liver decompensated and liver failure) have been reported in people with concomitant HIV-1 and HBV who have discontinued products containing lamivudine and/or TDF, and may occur with discontinuation of DELSTRIGO. Patients who are coinfected with HIV-1 and HBV who discontinue DELSTRIGO should be closely monitored with both clinical and laboratory follow-up for at least several months after stopping treatment with DELSTRIGO. If appropriate, initiation of anti-hepatitis B therapy may be warranted, especially in patients with advanced liver disease or cirrhosis, since post-treatment exacerbation of hepatitis may lead to hepatic decompensation and liver failure. 5.3 New Onset or Worsening Renal Impairment Renal impairment, including cases of acute renal failure and Fanconi syndrome (renal tubular injury with severe hypophosphatemia), has been reported with the use of TDF, a component of DELSTRIGO. DELSTRIGO should be avoided with concurrent or recent use of a nephrotoxic agent (e.g., high-dose or multiple nonsteroidal anti-inflammatory drugs [NSAIDs]) [see Drug Interactions (7.1) ] . Cases of acute renal failure after initiation of high-dose or multiple NSAIDs have been reported in patients living with HIV with risk factors for renal dysfunction who appeared stable on TDF. Some patients required hospitalization and renal replacement therapy. Alternatives to NSAIDs should be considered, if needed, in patients at risk for renal dysfunction. Persistent or worsening bone pain, pain in extremities, fractures, and/or muscular pain or weakness may be manifestations of proximal renal tubulopathy and should prompt an evaluation of renal function in at-risk patients. Prior to or when initiating DELSTRIGO, and during treatment with DELSTRIGO, on a clinically appropriate schedule, assess serum creatinine, estimated creatinine clearance, urine glucose and urine protein in all patients. In patients with chronic kidney disease, also assess serum phosphorus. Discontinue DELSTRIGO in patients who develop clinically significant decreases in renal function or evidence of Fanconi syndrome. The lamivudine and TDF components of DELSTRIGO are primarily excreted by the kidney. Discontinue DEL…

4 CONTRAINDICATIONS DELSTRIGO is contraindicated when co-administered with drugs that are strong cytochrome P450 (CYP)3A enzyme inducers as significant decreases in doravirine plasma concentrations may occur, which may decrease the effectiveness of DELSTRIGO [see Warnings and Precautions (5.4) , Drug Interactions (7.2) , and Clinical Pharmacology (12.3) ] . These drugs include, but are not limited to, the following: - the anticonvulsants carbamazepine, oxcarbazepine, phenobarbital, phenytoin - the androgen receptor inhibitor enzalutamide - the antimycobacterials rifampin, rifapentine - the cytotoxic agent mitotane - St. John's wort ( Hypericum perforatum) DELSTRIGO is contraindicated in patients with a previous hypersensitivity reaction to lamivudine. DELSTRIGO is contraindicated when co-administered with drugs that are strong cytochrome P450 (CYP)3A enzyme inducers as significant decreases in doravirine plasma concentrations may occur, which may decrease the effectiveness of DELSTRIGO. ( 4 ) DELSTRIGO is contraindicated in patients with a previous hypersensitivity reaction to lamivudine.

7 DRUG INTERACTIONS Because DELSTRIGO is a complete regimen, co-administration with other antiretroviral medications for treatment of HIV-1 infection is not recommended. ( 7.1 ) Consult the full prescribing information prior to and during treatment for important potential drug-drug interactions. ( 4 , 5.4 , 7 ) 7.1 Concomitant Use with Other Antiretroviral Medications Because DELSTRIGO is a complete regimen for the treatment of HIV-1 infection, co-administration with other antiretroviral medications for treatment of HIV-1 infection is not recommended. Information regarding potential drug-drug interactions with other antiretroviral medications is not provided. 7.2 Effect of Other Drugs on DELSTRIGO Co-administration of DELSTRIGO with a CYP3A inducer decreases doravirine plasma concentrations, which may reduce DELSTRIGO efficacy [see Contraindications (4) , Warnings and Precautions (5.4) , and Clinical Pharmacology (12.3) ] . Co-administration of DELSTRIGO and drugs that are inhibitors of CYP3A may result in increased plasma concentrations of doravirine. Table 6 shows the significant drug interactions with the components of DELSTRIGO. The drug interactions described are based on studies conducted with either DELSTRIGO or the components of DELSTRIGO as individual agents. Table 6: Drug Interactions with DELSTRIGO This table is not all-inclusive Concomitant Drug Class: Drug Name Effect on Concentration Clinical Comment ↑ = increase, ↓ = decrease All other drug-drug interactions shown are anticipated based on the known metabolic and elimination pathways. Androgen Receptors enzalutamide ↓ doravirine Co-administration is contraindicated with enzalutamide. At least a 4-week cessation period is recommended prior to initiation of DELSTRIGO. Anticonvulsants carbamazepine oxcarbazepine phenobarbital phenytoin ↓ doravirine Co-administration is contraindicated with these anticonvulsants. At least a 4-week cessation period is recommended prior to initiation of DELSTRIGO. Antimycobacterials rifampin The interaction between doravirine and the concomitant drug was evaluated in a clinical study. rifapentine ↓ doravirine Co-administration is contraindicated with rifampin or rifapentine. At least a 4-week cessation period is recommended prior to initiation of DELSTRIGO. rifabutin ↓ doravirine If DELSTRIGO is co-administered with rifabutin, one tablet of doravirine (PIFELTRO) should be taken approximately 12 hours after the dose of DELSTRIGO [see Dosage and Administration (2.4) ] . Cytotoxic Agents mitotane ↓ doravirine Co-administration is contraindicated with mitotane. At least a 4-week cessation period is recommended prior to initiation of DELSTRIGO. Hepatitis C Antiviral Agents ledipasvir/sofosbuvir sofosbuvir/velpatasvir ↑ tenofovir Monitor for adverse reactions associated with TDF. Herbal Products St. John's wort ↓ doravirine Co-administration is contraindicated with St. John's wort. At least a 4-week cessation period is recommended prior to initiation of DELSTRIGO. Other Agents sorbitol ↓ lamivudine Co-administration of single doses of lamivudine and sorbitol resulted in a sorbitol dose-dependent reduction in lamivudine exposures. When possible, avoid use of sorbitol-containing medicines with lamivudine-containing medicines. Co-administration of DELSTRIGO with drugs that reduce renal function or compete for active tubular secretion may increase serum concentrations of lamivudine, tenofovir, and/or other renally eliminated drugs. Some examples of drugs that are eliminated by active tubular secretion include, but are not limited to, acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs [see Warnings and Precautions (5.3) and Clinical Pharmacology (12.3) ] . No clinically significant changes in concentration were observed for doravirine when co-administered with the following agents: TDF, lamivudine, elbasvir and grazoprevir, ledipasvir and sofosbuvir, ritonavir, ket…

8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in individuals exposed to DELSTRIGO during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at 1-800-258-4263. Risk Summary There is insufficient prospective pregnancy data from the APR to adequately assess the risk of birth defects and miscarriage. Doravirine use in individuals during pregnancy has not been evaluated; however, lamivudine and TDF use during pregnancy has been evaluated in a limited number of individuals reported to the APR. Available data from the APR show no difference in the overall risk of major birth defects for lamivudine and TDF compared with the background rate for major birth defects of 2.7% in the U.S. reference population of the Metropolitan Atlanta Congenital Defects Program (MACDP) ( see Data ) . The rate of miscarriage is not reported in the APR. The estimated background rate of miscarriage in the clinically recognized pregnancies in the U.S. general population is 15-20%. Methodological limitations of the APR include the use of MACDP as the external comparator group. The MACDP population is not disease-specific, evaluates individuals and infants from the limited geographic area, and does not include outcomes for births that occurred at less than 20 weeks gestation. In animal reproduction studies, oral administration of lamivudine to pregnant rabbits during organogenesis resulted in embryolethality at systemic exposure (AUC) similar to the recommended clinical dose; however, no adverse development effects were observed with oral administration of lamivudine to pregnant rats during organogenesis at plasma concentrations (C max ) 35 times the recommended clinical dose. No adverse developmental effects were observed when doravirine and TDF were administered separately at doses/exposures ≥8 (doravirine) and ≥14 (TDF) times those of the recommended human dose (RHD) of DELSTRIGO ( see Data ). Data Human Data Lamivudine : The APR has received a total of over 13,000 prospective reports with follow-up data of possible exposure to lamivudine-containing regimens; over 5,900 reports in the first trimester; over 5,600 reports in the second trimester; and over 1,800 reports in the third trimester. Birth defects occurred in 170 of 5,472 (3.1%, 95% CI: 2.7% to 3.6%) live births for lamivudine-containing regimens (first trimester exposure); and 218 of 7,513 (2.9%, 95% CI: 2.5% to 3.3%) live births for lamivudine-containing regimens (second/third trimester exposure). Among pregnant mothers in the U.S. reference population, the background rate of birth defects is 2.7%. There was no association between lamivudine and overall birth defects observed in the APR. TDF : The APR has received a total of over 7,000 prospective reports with follow-up data of possible exposure to tenofovir disoproxil-containing regimens; over 5,100 reports in the first trimester; over 1,300 reports in the second trimester; and over 600 reports in the third trimester. Birth defects occurred in 113 of 4,576 (2.5%, 95% CI: 2.0% to 3.0%) live births for TDF-containing regimens (first trimester exposure); and 51 of 1,965 (2.6%, 95% CI: 1.9% to 3.4%) live births for TDF-containing regimens (second/third trimester exposure). Among pregnant mothers in the U.S. reference population, the background rate of birth defects is 2.7%. There was no association between tenofovir and overall birth defects observed in the APR. Animal Data Doravirine : Doravirine was administered orally to pregnant rabbits (up to 300 mg/kg/day on gestation days (GD) 7 to 20) and rats (up to 450 mg/kg/day on GD 6 to 20 and separately from GD 6 to lactation/postpartum day 20). No significant toxicological effects on embryo-fetal (rats and rabbits) or pre/post-natal (rats) development were observed at exposures (AUC) approximately 9 times (rats) and 8 times (rabbits) the exposure in humans at the RHD…

6 ADVERSE REACTIONS The following adverse reactions are discussed in other sections of the labeling: Severe Acute Exacerbation of Hepatitis B in people with concomitant HIV-1 and HBV [see Warnings and Precautions (5.2) ] New Onset or Worsening Renal Impairment [see Warnings and Precautions (5.3) ] Bone Loss and Mineralization Defects [see Warnings and Precautions (5.5) ] Immune Reconstitution Syndrome [see Warnings and Precautions (5.6) ] Most common adverse reactions (incidence greater than or equal to 5%, all grades) are dizziness, nausea, and abnormal dreams. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Merck Sharp & Dohme LLC at 1-877-888-4231 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. Adverse Reactions in Adults with No Antiretroviral Treatment History The safety assessment of DELSTRIGO is based on Week 96 data from two Phase 3, randomized, international, multicenter, double-blind, active-controlled trials. A total of 747 participants received doravirine either as the single entity in combination with other antiretroviral drugs as background regimens (n=383) or as the fixed-dose DELSTRIGO (n=364), and a total of 747 participants were randomized to control arms. In DRIVE-AHEAD (Protocol 021), 728 adult participants received either DELSTRIGO (n=364) or EFV/FTC/TDF once daily (n=364). By Week 96, 3% in the DELSTRIGO group and 7% in the EFV/FTC/TDF group had adverse events leading to discontinuation of study medication. Adverse reactions reported in greater than or equal to 5% of participants in any treatment group in DRIVE-AHEAD are presented in Table 1. Table 1: Adverse Reactions Frequencies of adverse reactions are based on all adverse events attributed to trial drugs by the investigator. (All Grades) Reported in ≥5% No adverse reactions of Grade 2 or higher (moderate or severe) occurred in ≥2% of participants treated with DELSTRIGO. of Participants in Any Treatment Group in Adults with No Antiretroviral Treatment History in DRIVE-AHEAD (Week 96) DELSTRIGO Once Daily N=364 EFV/FTC/TDF Once Daily N=364 Dizziness 7% 32% Nausea 5% 7% Abnormal Dreams 5% 10% Headache 4% 5% Insomnia 4% 5% Diarrhea 4% 6% Somnolence 3% 7% Rash Rash: includes rash, rash erythematous, rash generalized, rash macular, rash maculo-papular, rash papular, rash pruritic. 2% 12% The majority (66%) of adverse reactions associated with DELSTRIGO occurred at severity Grade 1 (mild). Neuropsychiatric Adverse Events For DRIVE-AHEAD, the analysis of participants with neuropsychiatric adverse events by Week 48 is presented in Table 2. The proportion of participants who reported one or more neuropsychiatric adverse events was 24% and 57% in the DELSTRIGO and EFV/FTC/TDF groups, respectively. A statistically significantly lower proportion of DELSTRIGO-treated participants compared to EFV/FTC/TDF-treated participants reported neuropsychiatric adverse events by Week 48 in the three pre-specified categories of dizziness, sleep disorders and disturbances, and altered sensorium. Table 2: DRIVE-AHEAD - Analysis of Participants with Neuropsychiatric Adverse Events All causality and all grade events were included in the analysis. (Week 48) DELSTRIGO Once Daily N=364 EFV/FTC/TDF Once Daily N=364 Treatment Difference (DELSTRIGO - EFV/FTC/TDF) Estimate (95% CI) The 95% CIs were calculated using Miettinen and Nurminen's method. Categories pre-specified for statistical testing were dizziness (p <0.001), sleep disorders and disturbances (p <0.001), and altered sensorium (p=0.033). Sleep disorders and disturbances Predefined using MedDRA preferred terms including: abnormal dreams, hyposomnia, initial insomnia, insomnia, nightmare, sleep disorder, somnambulism. 12% 26% -13.…