HIGHLIGHT
Prevymis

Prevymis

letermovir

Manufacturer:

Merck Sharp & Dohme

Distributor:

Zuellig Pharma
Full Prescribing Info
Contents
Letermovir.
Description
Active Ingredient: PREVYMIS tablets contain 240 mg of letermovir.
PREVYMIS concentrate for solution for infusion is a clear, preservative-free sterile solution and may contain a few small translucent or white particles in single-dose vials of either 240 mg or 480 mg per vial. Each 1 mL of solution contains 20 mg letermovir.
Chemistry: Letermovir has a molecular formula of C29H28F4N4O4 and a molecular weight of 572.55. The chemical name for letermovir is (4S)-2-{8-Fluoro-2-[4-(3-methoxyphenyl)piperazin-1-yl]-3-[2-methoxy-5-(trifluoromethyl)phenyl]-3,4-dihydroquinazolin-4-yl}acetic acid. Letermovir is very slightly soluble in water.
Excipients/Inactive Ingredients: PREVYMIS tablets contain the following inactive ingredients: microcrystalline cellulose, croscarmellose sodium, povidone 25, colloidal silicon dioxide, magnesium stearate and film-coated with a coating material containing the following inactive ingredients: lactose monohydrate, hypromellose 2910, titanium dioxide, triacetin, and iron oxide yellow. Carnauba wax is added as a polishing agent.
Each 1 mL of PREVYMIS concentrate for solution for infusion contains the following inactive ingredients: hydroxypropyl betadex (150 mg), sodium chloride (3.1 mg), sodium hydroxide (1.2 mg), and Water for Injection. The amount of sodium hydroxide may be adjusted to achieve a pH of approximately 7.5.
Action
Therapeutic Class: PREVYMIS is an antiviral drug.
Pharmacology: Mechanism of Action: PREVYMIS is an antiviral drug against CMV [see PHARMACOLOGY: Pharmacodynamics as follows].
Pharmacodynamics: Cardiac Electrophysiology: The effect of letermovir on doses up to 960 mg given IV on the QTc interval was evaluated in a randomized, single-dose, placebo- and active-controlled (moxifloxacin 400 mg oral) 4-period crossover thorough QT trial in 38 healthy subjects. Letermovir does not prolong QTc to any clinically relevant extent following the 960 mg IV dose, with plasma concentrations approximately 2-fold higher than the 480 mg IV dose.
Microbiology: Mechanism of Action: Letermovir inhibits the CMV DNA terminase complex, which is required for viral replication. Biochemical characterization and electron microscopy demonstrated that letermovir affects the formation of proper unit length genomes and interferes with virion maturation.
Antiviral Activity: The median EC50 value of letermovir against a collection of clinical CMV isolates in a cell-culture model of infection was 2.1 nM (range = 0.7 nM to 6.1 nM, n=74).
Viral Resistance: In Cell Culture: The CMV genes UL51, UL56, and UL89 encode subunits of CMV DNA terminase. CMV mutants with reduced susceptibility to letermovir have been selected in cell culture, and the substitutions map to pUL51 (P91S), pUL56 (C25F, S229F, V231A, V231L, N232Y, V236A, V236L, V236M, E237D, L241P, T244K, T244R, L254F, L257F, L257I, K258E, F261C, F261L, F261S, Y321C, C325F, C325R, C325W, C325Y, L328V, M329T, A365S, N368D, R369G, R369M, R369S), and pUL89 (N320H, D344E). EC50 values for recombinant CMV mutants expressing these substitutions are 1.6- to 9,300-fold higher than those for the wild-type reference virus.
In Clinical Studies: In a Phase 2b trial evaluating letermovir doses of 60, 120, or 240 mg/day or placebo for up to 84 days in 131 HSCT recipients, DNA sequence analysis of a select region of UL56 (amino acids 231 to 369) was performed on samples obtained from 12 letermovir-treated subjects who experienced prophylaxis failure and for whom samples were available for analysis. One subject (who received 60 mg/day) had a letermovir resistant genotypic variant (GV) (V236M).
In a Phase 3 trial (P001), DNA sequence analysis of the entire coding regions of UL56 and UL89 was performed on samples obtained from 40 letermovir-treated subjects in the FAS population who experienced prophylaxis failure and for whom samples were available for analysis. A total of 2 letermovir resistance-associated substitutions both mapping to pUL56 were detected in 2 subjects. One subject had the substitution V236M, and the other had E237G.
Cross Resistance: Cross resistance is not likely with drugs outside of this class. Letermovir is fully active against viral populations with substitutions conferring resistance to CMV DNA polymerase inhibitors (ganciclovir, cidofovir, and foscarnet). A panel of recombinant CMV strains with substitutions conferring resistance to letermovir was fully susceptible to cidofovir, foscarnet and ganciclovir with the exception of a recombinant strain with the pUL56 E237G substitution which confers a 2.1-fold reduction in ganciclovir susceptibility relative to wild-type.
Pharmacogenomics: The impact of genetic variants in the OATP1B1 gene SLCO1B1 (rs4149056, rs2306283, rs4149032) and UGT1A1 (rs4148323 and the promoter TA repeat variants) on the pharmacokinetics of letermovir was evaluated in 299 study participants. There was no clinically relevant impact of these variants on letermovir exposures.
Clinical Studies: Adult CMV-seropositive Recipients [R+] of an Allogeneic Hematopoietic Stem Cell Transplant: To evaluate PREVYMIS prophylaxis as a preventive strategy for CMV infection or disease in transplant recipients at high risk for CMV reactivation, the efficacy of PREVYMIS was assessed in a multicenter, double-blind, placebo-controlled Phase 3 trial (P001) in adult CMV-seropositive recipients [R+] of an allogeneic HSCT. Subjects were randomized (2:1) to receive either PREVYMIS at a dose of 480 mg once daily adjusted to 240 mg when co-administered with cyclosporine, or placebo. Randomization was stratified by investigational site and risk level for CMV reactivation at the time of study entry. Study drug was initiated after HSCT (Day 0-28 post-transplant) and continued through Week 14 post-transplant. Study drug was administered either orally or IV; the dose of PREVYMIS was the same regardless of the route of administration. Subjects were monitored through Week 24 post-transplant for the primary efficacy endpoint with continued follow-up through Week 48 post-transplant.
Among the 565 treated subjects, 373 subjects received PREVYMIS (including 99 subjects who received at least one IV dose) and 192 received placebo (including 48 subjects who received at least one IV dose). The median time to starting study drug was 9 days after transplantation. Thirty-seven percent (37%) of subjects were engrafted at baseline. The median age was 54 years (range: 18 to 78 years); 58% were male; 82% were White; 10% were Asian; 2% were Black or African; and 7% were Hispanic or Latino. At baseline, 50% of subjects received a myeloablative regimen, 52% were receiving cyclosporine, and 42% were receiving tacrolimus. The most common primary reasons for transplant were acute myeloid leukemia (38%), myeloblastic syndrome (15%), and lymphoma (13%). Twelve percent (12%) of subjects were positive for CMV DNA at baseline.
At baseline, 31% of subjects were in the high risk stratum as defined by one or more of the following criteria: Human Leukocyte Antigen (HLA)-related (sibling) donor with at least one mismatch at one of the following three HLA-gene loci: HLA-A, -B or -DR, haploidentical donor; unrelated donor with at least one mismatch at one of the following four HLA-gene loci: HLA-A, -B, -C and -DRB1; use of umbilical cord blood as stem cell source; use of ex vivo T-cell-depleted grafts; Grade 2 or greater Graft-Versus-Host Disease (GVHD), requiring systemic corticosteroids. The remaining 69% of subjects did not meet any of these high risk stratum criteria and were therefore included in the low risk stratum.
Efficacy: Clinically Significant CMV Infection: The primary efficacy endpoint of P001 was the incidence of clinically significant CMV infection through Week 24 post-transplant. Clinically significant CMV infection was defined as the occurrence of either CMV end-organ disease, or initiation of anti-CMV pre-emptive therapy (PET) based on documented CMV viremia (using the Roche COBAS AmpliPrep/COBAS TaqMan assay, LLoQ is 137 IU/mL, which is approximately 150 copies/mL) and the clinical condition of the subject. The Non-Completer=Failure (NC=F) approach was used, where subjects who discontinued from the study prior to Week 24 post-transplant or had a missing outcome at Week 24 post-transplant were counted as failures.
PREVYMIS demonstrated superior efficacy over placebo in the analysis of the primary endpoint, as shown in Table 1. The estimated treatment difference of -23.5% was statistically significant (one-sided p-value <0.0001). (See Table 1.)

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At Week 24 post-transplant, the Kaplan-Meier (K-M) event rate for clinically significant CMV infection was 18.9% in the PREVYMIS group compared to 44.3% in the placebo group (nominal two-sided stratified log-rank p-value<0.0001) (see Figure 1). Factors associated with clinically significant CMV infection between Week 14 and Week 24 post-transplant among PREVYMIS-treated subjects included high risk for CMV reactivation at baseline, having GVHD, and steroid use at any time after randomization.
Of the 373 subjects treated with PREVYMIS in P001, 56 (15.0%) subjects were 65 years of age or older. Safety and efficacy were similar across older and younger subjects. (See Figure 1.)

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Efficacy consistently favored PREVYMIS across subgroups including low and high risk strata for CMV reactivation, conditioning regimens, and concomitant immunosuppressive regimens. (See Figure 2.)

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Mortality: The K-M event rate for all-cause mortality in the letermovir vs. placebo groups was 12.1% vs. 17.2% at Week 24 post-transplant (nominal two-sided stratified log-rank p-value=0.0401), and 23.8% vs. 27.6% at Week 48 post-transplant (nominal two-sided stratified log-rank p-value=0.2117; see Figure 3).

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In a post-hoc analysis of all-cause mortality through Week 48 post-transplant, among subjects with clinically significant CMV infection through Week 24, the mortality rate in the letermovir vs. placebo groups was 21.1% vs. 33.8%; and among subjects without clinically significant CMV infection through Week 24, the mortality rate in the letermovir vs. placebo groups was 23.9% vs. 22.2%.
Pharmacokinetics: General Introduction: The pharmacokinetics of letermovir have been characterized following oral and IV administration in healthy subjects and HSCT recipients.
In healthy subjects, letermovir exposure increased in a greater than dose-proportional manner with both oral or IV administration following single and multiple doses of 240 mg and 480 mg. Letermovir was absorbed rapidly with a median time to maximum plasma concentration (Tmax) of 1.5 to 3.0 hours and declined in a biphasic manner. The geometric mean steady-state AUC and Cmax values were 71,500 ng·hr/mL and 13,000 ng/mL, respectively, with 480 mg once daily oral PREVYMIS. The post-absorption plasma concentration-time profile of letermovir following oral administration was similar to the profile observed with IV dosing. Letermovir clearance (CL) reached steady-state in 9 to 10 days with an accumulation ratio of 1.22 for AUC and 1.03 for Cmax.
In HSCT recipients, letermovir AUC was estimated using population pharmacokinetic analyses using Phase 3 data (see Table 2). Differences in exposure across treatment regimens are not clinically relevant; efficacy was consistent across the range of exposures observed in P001. (See Table 2.)

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Absorption: In healthy subjects, absolute bioavailability of letermovir was estimated to be approximately 94% over the dose range 240 mg to 480 mg based on population pharmacokinetic analyses. In HSCT recipients, bioavailability of letermovir was estimated to be approximately 35% with 480 mg once daily oral PREVYMIS administered without cyclosporine. The inter-individual variability for bioavailability was estimated to be approximately 37%.
Effect of Cyclosporine: In HSCT recipients, co-administration of cyclosporine increased plasma concentrations of letermovir. Bioavailability of letermovir was estimated to be approximately 85% with 240 mg once daily oral PREVYMIS co-administered with cyclosporine. If PREVYMIS is co-administered with cyclosporine, the recommended dose of PREVYMIS is 240 mg once daily [see Dosage Adjustment in Adults under DOSAGE & ADMINISTRATION].
Effect of Food: Relative to fasting conditions, oral administration of 480 mg single dose of PREVYMIS with a standard high fat and high calorie meal did not have any effect on the overall exposure (AUC) and resulted in approximately 30% increase in peak levels (Cmax) of letermovir. PREVYMIS may be administered orally with or without food [see General under DOSAGE & ADMINISTRATION].
Distribution: Based on population pharmacokinetic analyses, the mean steady-state volume of distribution is estimated to be 45.5 L following IV administration in HSCT recipients.
Letermovir is extensively bound (98.7%) to human plasma proteins in vitro. Blood to plasma partitioning of letermovir is 0.56 and independent of the concentration range (0.1 to 10 mg/L) evaluated in vitro.
In preclinical distribution studies, letermovir is distributed to organs and tissues with the highest concentrations observed in the gastrointestinal tract, bile duct and liver and low concentrations in the brain.
Elimination: The mean apparent terminal half-life for letermovir is approximately 12 hours with 480 mg IV PREVYMIS in healthy subjects.
Metabolism: The majority of drug-related component in plasma is unchanged parent (96.6%). No major metabolites are detected in plasma. Letermovir is partly eliminated by glucuronidation mediated by UGT1A1/1A3.
Excretion: Based on population pharmacokinetic analyses, letermovir steady-state CL is estimated to be 4.84 L/hr following IV administration in HSCT recipients. The inter-individual variability for CL is estimated to be 24.6%.
After oral administration of radio-labeled letermovir, 93.3% of radioactivity was recovered in feces. The majority of drug was excreted as unchanged parent with a minor amount (6% of dose) as an acyl-glucuronide metabolite in feces. Urinary excretion of letermovir was negligible (<2% of dose).
Specific Populations: Pediatric Population: The pharmacokinetics of letermovir in pediatric patients less than 18 years of age have not been evaluated.
Geriatric Population: Based on population pharmacokinetic analyses, there is no effect of age on letermovir pharmacokinetics. No dose adjustment is required based on age.
Gender: Based on population pharmacokinetic analyses, there is no difference in letermovir pharmacokinetics in females compared to males.
Weight: Based on population pharmacokinetic analyses, letermovir AUC is estimated to be 18.7% lower in subjects weighing 80-100 kg compared to subjects weighing 67 kg. This change is not clinically relevant.
Race: Based on population pharmacokinetic analyses, letermovir AUC is estimated to be 33.2% higher in Asians compared to Whites. This change is not clinically relevant.
Renal Impairment: Letermovir AUC was approximately 1.9- and 1.4-fold higher in subjects with moderate (eGFR greater than or equal to 30 to 59 mL/min/1.73 m2) and severe (eGFR less than 30 mL/min/1.73 m2) renal impairment, respectively, compared to healthy subjects. The changes in letermovir exposure due to renal impairment are not clinically relevant.
Hepatic Impairment: Letermovir AUC was approximately 1.6- and 3.8-fold higher in subjects with moderate (Child-Pugh Class B [CP-B], score of 7-9) and severe (Child-Pugh Class C [CP-C], score of 10-15) hepatic impairment, respectively, compared to healthy subjects. The changes in letermovir exposure in subjects with moderate hepatic impairment are not clinically relevant.
Clinically relevant increases in letermovir exposure are anticipated in patients with severe hepatic impairment or in patients with moderate hepatic impairment combined with moderate or severe renal impairment.
Drug Interaction Studies: Drug interaction studies were performed in healthy subjects with PREVYMIS and drugs likely to be co-administered or drugs commonly used as probes for pharmacokinetic interactions (see Table 3 and Table 4).
In vitro results indicate that letermovir is a substrate of OATP1B1/3, P-gp, UGT1A1, and UGT1A3. Inhibitors of OATP1B1/3 transporters may result in increases in letermovir plasma concentrations. If PREVYMIS is co-administered with cyclosporine (a potent OATP1B1/3 inhibitor), the recommended dose of PREVYMIS is 240 mg once daily [see Dosage Adjustment in Adults under DOSAGE & ADMINISTRATION]. Changes in letermovir plasma concentrations due to inhibition of P-gp/BCRP by itraconazole were not clinically relevant. Inhibition of UGTs is not anticipated to have a clinically relevant effect on letermovir plasma concentrations. Induction of drug enzymes (e.g., UGTs) and/or transporters (e.g., P-gp) by rifampin may result in clinically relevant decreases in letermovir plasma concentrations; therefore, co-administration of strong and moderate inducers with letermovir is not recommended [see Effects of Other Drugs on PREVYMIS under INTERACTIONS], Table 6, and Table 3. Although CYP3A, CYP2D6 and CYP2J2 were identified as enzymes capable of mediating the metabolism of letermovir in vitro, oxidative metabolism is considered to be a minor elimination pathway based on in vivo human data.
Letermovir is a time-dependent inhibitor and inducer of CYP3A in vitro. Co-administration of PREVYMIS with midazolam resulted in increased exposure of midazolam, indicating that the net effect of letermovir on CYP3A is moderate inhibition (see Table 4). Based on these results, co-administration of PREVYMIS with CYP3A substrates may increase the plasma concentrations of the CYP3A substrates [see CONTRAINDICATIONS, Risk of Adverse Reactions or Reduced Therapeutic Effect Due to Drug Interactions under PRECAUTIONS, Effects of PREVYMIS on Other Drugs, and Established and Other Potential Drug Interactions under INTERACTIONS] and Table 6. Letermovir is a reversible inhibitor of CYP2C8 in vitro. Physiologically based pharmacokinetic modeling predicts an increase in plasma concentrations of CYP2C8 substrates when co-administered with PREVYMIS [see Table 6 in Established and Other Potential Drug Interactions under INTERACTIONS]. Co-administration of PREVYMIS reduced the exposure of voriconazole, most likely due to the induction of voriconazole elimination pathways, CYP2C9 and CYP2C19. Co-administration of PREVYMIS with CYP2C9 and CYP2C19 substrates may decrease the plasma concentrations of the CYP2C9 and CYP2C19 substrates [see Table 6 in Established and Other Potential Drug Interactions under INTERACTIONS]. Letermovir is an inducer of CYP2B6 in vitro; the clinical relevance is unknown.
Letermovir inhibited efflux transporters P-gp, breast cancer resistance protein (BCRP), bile salt export pump (BSEP), multidrug resistance-associated protein 2 (MRP2), OAT3, and hepatic uptake transporter OATP1B1/3 in vitro. Co-administration of PREVYMIS with substrates of OATP1B1/3 transporters (e.g., atorvastatin, a known substrate of CYP3A, OATP1B1/3, and potentially BCRP) may result in a clinically relevant increase in plasma concentrations of OATP1B1/3 substrates [see Table 6 in Established and Other Potential Drug Interactions under INTERACTIONS]. There were no clinically relevant changes in plasma concentrations of digoxin, a P-gp substrate, or acyclovir, an OAT3 substrate, following co-administration with PREVYMIS in clinical studies (see Table 4). The effect of letermovir on BCRP, BSEP, and MRP2 substrates was not evaluated in clinical studies; the clinical relevance is unknown. (See Tables 3 and 4.)

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Toxicology: Animal Toxicology: General Toxicity: Testicular toxicity was noted only in rats at systemic exposures (AUC) ≥ 3-fold the exposures in humans at the RHD. This toxicity was characterized by seminiferous tubular degeneration, and oligospermia and cell debris in the epididymides, with decreased testicular and epididymides weights. The No-Observed Adverse Effect Level (NOAEL) for testicular toxicity in rats was observed at exposures (AUC) in rats similar to the exposures in humans at the RHD. This testicular toxicity appears to be species-specific; testicular toxicity was not observed in mice and monkeys at the highest doses tested at exposures up to 4-fold and 2-fold, respectively, the exposures in humans at the RHD. The relevance to humans is unknown. In the Phase 3 trial in HSCT recipients, there was no evidence of letermovir-related testicular toxicity [see Clinical Trials Experience under ADVERSE REACTIONS].
The toxicity profile of letermovir was generally similar in oral and intravenous studies in rats and monkeys, with the exception of vacuolation noted in the kidneys of rats administered IV letermovir formulated with 1500 mg/kg/day of the cyclodextrin excipient hydroxypropyl betadex. It is known that hydroxypropyl betadex can cause kidney vacuolation in rats when given intravenously at doses greater than 50 mg/kg/day {1}.
Carcinogenesis: Carcinogenicity studies with letermovir have not been conducted.
Mutagenesis: Letermovir was not genotoxic in a battery of in vitro or in vivo assays, including microbial mutagenesis assays, chromosomal aberration in Chinese Hamster Ovary cells, and in an in vivo mouse micronucleus study.
Reproduction: In the fertility and early embryonic development studies in the rat, there were no effects of letermovir on female fertility at the highest dose tested, 240 mg/kg/day (approximately 5-fold the AUC in humans at the RHD). In male rats, reduced sperm concentration, reduced sperm motility, and decreased fertility were observed at systemic exposures ≥ 3-fold the AUC in humans at the RHD [see previously mentioned Animal Toxicoloy: General Toxicity].
In male mice, there were no effects on testicular toxicity by histopathologic evaluation at systemic exposures approximately 4-fold the AUC in humans at the RHD.
In a study dedicated to investigate effects on the male reproductive system of mature monkeys administered letermovir, there was no evidence of testicular toxicity based on histopathologic evaluation, measurement of testicular size, blood hormone analysis (follicle stimulating hormone, inhibin B and testosterone) and sperm evaluation (sperm count, motility and morphology) at systemic exposures approximately 2-fold the AUC in humans at the RHD.
Development: Letermovir was administered orally to pregnant rats at 0, 10, 50 or 250 mg/kg/day from gestation days 6 to 17. Maternal toxicity (including decrease in body weight gain) was noted at 250 mg/kg/day (approximately 11-fold the AUC at the RHD); in the offspring, decreased fetal weight with delayed ossification, slightly edematous fetuses, and increased incidence of shortened umbilical cords and of variations and malformations in the vertebrae, ribs, and pelvis were observed. No maternal or developmental effects were noted at the dose of 50 mg/kg/day (approximately 2.5-fold the AUC at the RHD).
Letermovir was administered orally to pregnant rabbits at 0, 25, 75 or 225 mg/kg/day from gestation days 6 to 20. Maternal toxicity (including mortality and abortions) was noted at 225 mg/kg/day (approximately 2-fold the AUC at the RHD); in the offspring, an increased incidence of malformations and variations in the vertebrae and ribs were observed. No maternal or developmental effects were noted at the dose of 75 mg/kg/day (at less than the AUC at the RHD).
In the pre- and post-natal developmental study, letermovir was administered orally to pregnant rats at 0, 10, 45 or 180 mg/kg/day from gestation day 6 to lactation day 22. There was no developmental toxicity observed up to the highest exposure tested (2-fold the AUC at the RHD).
Indications/Uses
PREVYMIS is indicated for the prophylaxis of cytomegalovirus (CMV) infection and disease in adult CMV-seropositive recipients [R+] of an allogeneic hematopoietic stem cell transplant (HSCT).
Dosage/Direction for Use
General: PREVYMIS Tablets: Administer with or without food.
Swallow tablets whole. Do not divide, crush or chew.
PREVYMIS Concentrate for Solution for Infusion: PREVYMIS injection must be administered through a sterile 0.2 micron or 0.22 micron polyethersulfone (PES) in-line filter.
Administer by intravenous infusion via a peripheral catheter or central venous line over approximately 60 minutes.
Do not administer as an intravenous bolus injection.
PREVYMIS tablet and concentrate for solution for infusion may be used interchangeably at the discretion of the physician, and no dose adjustment is necessary.
Missed Dose: Instruct patients that if they miss a dose of PREVYMIS, they should take it as soon as they remember. If they do not remember until it is time for the next dose, instruct them to skip the missed dose and go back to the regular schedule. Instruct patients not to double their next dose or take more than the prescribed dose.
Recommended Dosage in Adults: The recommended dosage of PREVYMIS is 480 mg administered once daily.
PREVYMIS should be started after HSCT. PREVYMIS may be started on the day of transplant and no later than 28 days post-transplant. PREVYMIS may be started before or after engraftment. Continue PREVYMIS through 100 days post-transplant.
The safety and efficacy of letermovir use for more than 100 days has not been studied in clinical trials.
Dosage Adjustment in Adults: If PREVYMIS is co-administered with cyclosporine, the dosage of PREVYMIS should be decreased to 240 mg once daily [see Table 6 in Established and Other Potential Drug Interactions under INTERACTIONS].
If cyclosporine is initiated after starting PREVYMIS, the next dose of PREVYMIS should be decreased to 240 mg once daily.
If cyclosporine is discontinued after starting PREVYMIS, the next dose of PREVYMIS should be increased to 480 mg once daily.
If cyclosporine dosing is temporarily interrupted due to high cyclosporine levels, no dose adjustment of PREVYMIS is needed.
Pediatric Patients: Safety and efficacy of PREVYMIS have not been established in pediatric patients less than 18 years of age.
Geriatric Patients:
No dose adjustment of PREVYMIS is required based on age [see Use in Elderly under PRECAUTIONS].
Renal Impairment: No dose adjustment of PREVYMIS is required based on renal impairment [see Hepatic Impairment as follows, Renal Impairment under PRECAUTIONS].
Hepatic Impairment: No dose adjustment of PREVYMIS is required based on mild (Child-Pugh Class A) to moderate (Child-Pugh Class B) hepatic impairment. PREVYMIS is not recommended for patients with severe (Child-Pugh Class C) hepatic impairment.
PREVYMIS is not recommended in patients with moderate hepatic impairment combined with moderate or severe renal impairment [see Hepatic Impairment under PRECAUTIONS].
Preparation and Administration of Intravenous Solution: PREVYMIS concentrate for solution for infusion is supplied in 30 mL single-dose vials containing either 240 mg (12 mL per vial) or 480 mg (24 mL per vial). The preparation and administration instructions are the same for either dose.
PREVYMIS vials are for single use only. Discard any unused portion.
Preparation: PREVYMIS must be diluted prior to intravenous (IV) use.
Inspect vial contents for discoloration and particulate matter prior to dilution. PREVYMIS concentrate for solution for infusion is a clear, colorless solution and may contain a few product-related small translucent or white particles.
Do not use the vial if the solution is cloudy, discolored, or contains matter other than a few small translucent or white particles.
Do not use PREVYMIS injection with IV bags and infusion set materials containing polyurethane or the plasticizer diethylhexyl phthalate (DEHP). Materials that are phthalate-free are also DEHP-free.
Do not shake PREVYMIS vial.
Add one single-dose vial of PREVYMIS concentrate for solution for infusion to a 250 mL pre-filled IV bag containing either 0.9% sodium chloride or 5% dextrose and mix bag gently. Do not shake.
Once diluted, the solution of PREVYMIS is clear, and ranges from colorless to yellow. Variations of color within this range do not affect the quality of the product. The diluted solution should be inspected visually for particulate matter and discoloration prior to administration.
Discard if the diluted solution is cloudy, discolored, or contains matter other than a few small translucent or white particles.
Storage of Diluted Solution: The diluted solution can be stored for up to 24 hours at room temperature or up to 48 hours under refrigeration at 2°C to 8°C (36°F to 46°F).
This time includes storage of the diluted solution in the intravenous bag through the duration of infusion.
Administration: The diluted solution must be administered through a sterile 0.2 micron or 0.22 micron PES in-line filter.
Do not administer the diluted solution through a filter other than a sterile 0.2 micron or 0.22 micron PES in-line filter.
Administer as an intravenous infusion only. Do not administer as an intravenous push or bolus.
After dilution, administer PREVYMIS via intravenous infusion via peripheral or central venous catheter using a total time of approximately 60 minutes. Administer the entire contents of the IV bag.
Compatible Diluents, Drug Products, and Other Materials Used for Intravenous Administration: Compatible Diluents: PREVYMIS concentrate for solution for infusion is compatible with 0.9% sodium chloride and 5% dextrose solutions.
Compatible Drug Products: A study was conducted to evaluate physical compatibility of PREVYMIS concentrate for solution for infusion with injectable drug products. Compatibility was determined through visual observations, turbidity, and measurement of particulate matter. Compatible drug products are listed as follows.
PREVYMIS should not be co-administered through the same intravenous line (or cannula) with other drug products and diluent combinations except those listed as follows.
The following compatible drug products may be co-administered with PREVYMIS for injection when both drug products are in 0.9% Sodium Chloride via Y tubing only, as per the approved instructions of the respective drug products: Ampicillin sodium, Ampicillin sodium/Sulbactam sodium, Anti-thymocyte globulin, Caspofungin, Daptomycin, Fentanyl citrate, Fluconazole, Furosemide, Human insulin, Magnesium sulfate, Methotrexate, Micafungin.
The following compatible drug products may be co-administered with PREVYMIS for injection when both drug products are in 5% Dextrose via Y tubing only, as per the approved instructions of the respective drug products: Amphotericin B (lipid complex)*, Anidulafungin, Cefazolin sodium, Ceftaroline, Ceftriaxone sodium, Doripenem, Famotidine, Folic acid, Ganciclovir sodium, Hydrocortisone sodium succinate, Morphine sulfate, Norepinephrine bitartrate, Pantoprazole sodium, Potassium chloride, Potassium phosphate, Tacrolimus, Telavancin, Tigecycline.
* Amphotericin B (lipid complex) is compatible with PREVYMIS. However, Amphotericin B (liposomal) is incompatible [see Incompatible Diluents, Drug Products, and Other Materials Used for Intravenous Administration as follows].
Compatible IV Bags and Infusion Set Materials: PREVYMIS is compatible with the following IV bags and infusion set materials. Any IV bags or infusion set materials not listed as follows should not be used.
IV Bag Materials: Polyvinyl chloride (PVC), ethylene vinyl acetate (EVA) and polyolefin (polypropylene and polyethylene).
Infusion Set Materials: PVC, polyethylene (PE), polybutadiene (PBD), silicone rubber (SR), styrene-butadiene copolymer (SBC), styrene-butadiene-styrene copolymer (SBS), polystyrene (PS).
Plasticizers: Tris (2-Ethylhexyl) trimellitate (TOTM), butyl benzyl phthalate (BBP).
Catheters: Radiopaque polyurethane.
Incompatible Diluents, Drug Products, and Other Materials Used for Intravenous Administration: Incompatible Drug Products: PREVYMIS concentrate for solution for infusion is physically incompatible with amiodarone hydrochloride, amphotericin B (liposomal), aztreonam, cefepime hydrochloride, ciprofloxacin, cyclosporine, diltiazem hydrochloride, filgrastim, gentamicin sulfate, levofloxacin, linezolid, lorazepam, midazolam HCl, mycophenolate mofetil hydrochloride, ondansetron, palonosetron.
Incompatible IV Bags and Infusion Set Materials: PREVYMIS concentrate for solution for infusion is incompatible with diethylhexyl phthalate (DEHP) plasticizers and polyurethane-containing IV administration set tubing.
Overdosage
There is no experience with human overdosage with PREVYMIS. During Phase 1 clinical trials, 86 healthy subjects received doses ranging from 720 mg/day to 1440 mg/day of PREVYMIS for up to 14 days. The adverse reaction profile was similar to that of the clinical dose of 480 mg/day. There is no specific antidote for overdose with PREVYMIS. In case of overdose, it is recommended that the patient be monitored for adverse reactions and appropriate symptomatic treatment instituted.
It is unknown whether dialysis will result in meaningful removal of PREVYMIS from systemic circulation.
Contraindications
PREVYMIS is contraindicated in patients with hypersensitivity to letermovir or any of its inactive ingredients.
Pimozide: Concomitant administration of PREVYMIS may result in increased concentrations of pimozide due to inhibition of cytochrome P450 (CYP3A) by letermovir, leading to QT prolongation and torsades de pointes [see Risk of Adverse Reactions or Reduced Therapeutic Effect Due to Drug Interactions under PRECAUTIONS, and Effects of PREVYMIS on Other Drugs under INTERACTIONS].
Ergot alkaloids: Concomitant administration of PREVYMIS may result in increased concentrations of ergot alkaloids (ergotamine and dihydroergotamine) due to inhibition of CYP3A by letermovir, which may lead to ergotism [see Risk of Adverse Reactions or Reduced Therapeutic Effect Due to Drug Interactions under PRECAUTIONS, and Effects of PREVYMIS on Other Drugs under INTERACTIONS].
Cyclosporine with pitavastatin or simvastatin: Concomitant administration of PREVYMIS in combination with cyclosporine may result in significantly increased pitavastatin or simvastatin concentrations, which may lead to myopathy or rhabdomyolysis [see Risk of Adverse Reactions or Reduced Therapeutic Effect Due to Drug Interactions under PRECAUTIONS, and Effects of PREVYMIS on Other Drugs under INTERACTIONS].
Special Precautions
Risk of Adverse Reactions or Reduced Therapeutic Effect Due to Drug Interactions: The concomitant use of PREVYMIS and certain drugs may result in known or potentially significant drug interactions, some of which may lead to: Possible clinically significant adverse reactions from greater exposure of concomitant drugs or PREVYMIS; Significant decrease of concomitant drug plasma concentrations which may lead to reduced therapeutic effect of the concomitant drug.
See Table 6 for steps to prevent or manage these known or potentially significant drug interactions, including dosing recommendations [see CONTRAINDICATIONS, Effects of PREVYMIS on Other Drugs and Established and Other Potential Drug Interactions under INTERACTIONS].
PREVYMIS should be used with caution with drugs that are CYP3A substrates with narrow therapeutic ranges (e.g., alfentanil, fentanyl, and quinidine) as co-administration may result in increases in the plasma concentrations of CYP3A substrates. Close monitoring and/or dose adjustment of co-administered CYP3A substrates is recommended. [See Table 6, Effects of PREVYMIS on Other Drugs and Established and Other Potential Drug Interactions under INTERACTIONS].
The safety and efficacy of letermovir has been established in patients with a negative CMV DNA test result prior to initiation of prophylaxis. CMV DNA was monitored on a weekly basis until post-transplant Week 14, and subsequently bi-weekly until Week 24. In cases of clinically significant CMV DNAemia or disease, letermovir prophylaxis was stopped and standard-of-care pre-emptive therapy (PET) or treatment was initiated. In patients in whom letermovir prophylaxis was initiated and the baseline CMV DNA test was subsequently found to be positive, prophylaxis could be continued if PET criteria has not been met.
Renal Impairment: No dose adjustment of PREVYMIS is required based on renal impairment [see Renal Impairment and Hepatic Impairment under DOSAGE & ADMINISTRATION, and Hepatic Impairment as follows]. There are no data in patients with end-stage renal disease (CrCl less than 10 mL/min), including patients on dialysis.
In patients with moderate or severe renal impairment (CrCl less than 50 mL/min) receiving PREVYMIS concentrate for solution for infusion, accumulation of the intravenous vehicle, hydroxypropyl betadex, could occur. Serum creatinine levels should be closely monitored in these patients.
Hepatic Impairment: No dose adjustment of PREVYMIS is required based on mild (Child-Pugh Class A) to moderate (Child-Pugh Class B) hepatic impairment. PREVYMIS is not recommended for patients with severe (Child-Pugh Class C) hepatic impairment [see Hepatic Impairment under DOSAGE & ADMINISTRATION].
PREVYMIS is not recommended in patients with moderate hepatic impairment combined with moderate or severe renal impairment [see Hepatic Impairment under DOSAGE & ADMINISTRATION].
Use in Children: Safety and efficacy of PREVYMIS in patients below 18 years of age have not been established.
Use in Elderly: Safety and efficacy were similar across older and younger subjects in the Phase 3 trial in HSCT recipients.
Use In Pregnancy & Lactation
Pregnancy: No adequate human data are available to establish whether or not PREVYMIS poses a risk to pregnancy outcomes. Embryofetal toxicity was observed in rats and rabbits at maternally toxic systemic AUC exposures of approximately 11- and 2-fold, respectively, the AUC at the recommended human dose (RHD). In the rat pre-and post-natal development study, no developmental toxicity was observed up to the highest maternal systemic AUC exposure (approximately 2-fold the AUC at the RHD). For the purpose of calculating safety margins, the AUC at the RHD is defined as the mean AUC in HSCT recipients receiving 480 mg IV.
The background risk of major birth defects and miscarriage for the indicated population is unknown. The potential risk for humans is unknown. PREVYMIS should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.
Nursing Mothers: It is not known whether letermovir is present in human breast milk, affects human milk production, or has effects on the breastfed child.
When administered to lactating rats, letermovir was present in milk, without effects on growth and development in nursing pups.
The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for PREVYMIS and any potential adverse effects on the breastfed child from PREVYMIS or from the underlying maternal condition.
Fertility: There were no effects on female fertility in rats. Impairment of fertility was observed in male rats, but not in male mice or male monkeys. Testicular toxicity in rats appears to be species-specific, and the relevance to humans is unknown. In the Phase 3 trial in HSCT recipients, there was no evidence of letermovir-related testicular toxicity [see Clinical Trials Experience under ADVERSE REACTIONS].
Adverse Reactions
Clinical Trials Experience: Adults: Adult CMV-seropositive Recipients [R+] of an Allogeneic HSCT: The safety of PREVYMIS was evaluated in a Phase 3 randomized, double-blind, placebo-controlled trial (P001) in which 565 subjects were randomized and treated with PREVYMIS (N=373) or placebo (N=192) through Week 14 post-transplant and were followed for safety through Week 24 post-transplant.
Cardiac Adverse Events: The cardiac adverse event rate (regardless of investigator-assessed causality) was higher in subjects receiving PREVYMIS (13%) compared to subjects receiving placebo (6%). The most common cardiac adverse events were tachycardia (reported in 4% of PREVYMIS subjects and in 2% of placebo subjects) and atrial fibrillation (reported in 3% of PREVYMIS subjects and in 1% of placebo subjects). Among those subjects who experienced one or more cardiac adverse events, 85% of PREVYMIS and 92% of placebo subjects had events reported as mild or moderate in severity.
The most commonly reported adverse reactions occurring in at least 1% of subjects in the PREVYMIS group through Week 24 post-transplant and at a frequency greater than placebo were: nausea, diarrhea, and vomiting (Table 5). (See Table 5.)

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Hypersensitivity was reported as a non-serious adverse reaction with PREVYMIS in one subject.
Overall, similar proportions of subjects in each group discontinued study medication due to an adverse reaction (4.8% PREVYMIS vs. 3.6% placebo). The most frequently reported adverse reactions that led to discontinuation of PREVYMIS were nausea (1.6%), vomiting (0.8%), and abdominal pain (0.5%).
Laboratory Abnormalities: Overall, the percentage of subjects with potentially clinically significant changes in laboratory values (e.g., hematology, chemistry, renal, and hepatic function) was similar in the PREVYMIS and placebo groups. There were no differences in the incidence of or time to engraftment between the PREVYMIS and placebo groups.
Biomarkers of testicular toxicity were evaluated in male subjects in P001. The changes from baseline in male sex hormones (serum inhibin B, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone) were similar in the PREVYMIS and placebo groups.
Drug Interactions
Effects of Other Drugs on PREVYMIS: Letermovir is a substrate of organic anion-transporting polypeptide 1B1/3 (OATP1B1/3) and P-glycoprotein (P-gp) transporters and UDP-glucuronosyltransferase 1A1/3 (UGT1A1/3) enzymes. Co-administration of PREVYMIS with drugs that are inhibitors of OATP1B1/3 transporters may result in increases in letermovir plasma concentrations. If PREVYMIS is co-administered with cyclosporine (a potent OATP1B1/3 inhibitor), the recommended dose of PREVYMIS is 240 mg once daily [see Dosage Adjustment in Adults under DOSAGE & ADMINISTRATION].
Co-administration of PREVYMIS with strong and moderate inducers of transporters (e.g., P-gp) and/or enzymes (e.g., UGTs) is not recommended due to the potential for a decrease in letermovir plasma concentrations (see Table 6).
Rifampin co-administration resulted in an initial increase in letermovir plasma concentrations (due to OATP1B1/3 inhibition) that is not clinically relevant, followed by clinically relevant decreases in letermovir plasma concentrations with continued rifampin co-administration [see Table 3 in PHARMACOLOGY: Drug Interaction Studies under ACTIONS].
Effects of PREVYMIS on Other Drugs: Co-administration of PREVYMIS with midazolam results in increased midazolam plasma concentrations, indicating that letermovir is a moderate inhibitor of CYP3A. Co-administration of PREVYMIS with drugs that are CYP3A substrates may result in clinically relevant increases in the plasma concentrations of co-administered CYP3A substrates [see CONTRAINDICATIONS, and Risk of Adverse Reactions or Reduced Therapeutic Effect Due to Drug Interactions under PRECAUTIONS] and Table 6.
Letermovir is an inhibitor of OATP1B1/3 transporters. Co-administration of PREVYMIS with drugs that are substrates of OATP1B1/3 transporters may result in a clinically relevant increase in plasma concentrations of co-administered OATP1B1/3 substrates (see Table 6).
Established and Other Potential Drug Interactions: If dose adjustments of concomitant medications are made due to treatment with PREVYMIS, doses should be readjusted after treatment with PREVYMIS is completed.
When PREVYMIS is co-administered with cyclosporine, the combined effect on CYP3A substrates may be similar to a strong CYP3A inhibitor. Refer to the prescribing information for dosing of the CYP3A substrate with a strong CYP3A inhibitor.
When PREVYMIS is co-administered with cyclosporine, the combined effect on agents that are both CYP3A and OATP1B1/3 substrates may be different than when they are administered with PREVYMIS alone. Refer to the prescribing information for both the co-administered drug and for cyclosporine.
Table 6 provides a listing of established or potentially clinically significant drug interactions. The drug interactions described are based on studies conducted with PREVYMIS or are predicted drug interactions that may occur with PREVYMIS [see Risk of Adverse Reactions or Reduced Therapeutic Effect Due to Drug Interactions under PRECAUTIONS]. (See Table 6.)

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Click on icon to see table/diagram/image

Drugs without Clinically Significant Interactions with PREVYMIS: There was no clinically relevant interaction when PREVYMIS was co-administered with itraconazole, a P-gp/BCRP inhibitor.
There were no clinically relevant changes in plasma concentrations of digoxin, a P-gp substrate, and acyclovir, an OAT3 substrate, following co-administration with PREVYMIS in clinical studies.
The interaction between letermovir and the following drugs was evaluated in clinical studies: mycophenolate mofetil, fluconazole, posaconazole, and oral contraceptives. No dose adjustments are needed when PREVYMIS is used with these drugs.
Caution For Usage
Incompatibilities: See Incompatible Diluents, Drug Products, and Other Materials Used for Intravenous Administration under DOSAGE & ADMINISTRATION.
Storage
Store PREVYMIS tablets below 30°C.
Store PREVYMIS tablets in the original package until use.
Store PREVYMIS concentrate for solution for infusion vials below 30°C.
Store in the original carton to protect from exposure to light.
MIMS Class
ATC Classification
J05AX18 - letermovir ; Belongs to the class of other antivirals. Used as a direct acting antiviral in the systemic treatment of viral infections.
Presentation/Packing
FC tab 240 mg (yellow oval, debossed with "591" on one side and Merck logo on the other side) x 28's. Infusion conc (clear solution in a single-dose vial) 240 mg/12 mL x 1's. 480 mg/24 mL x 1's.
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