Efavirenz

New data from CATALYST and MOMENTUM trials presented at American Diabetes Association’s (ADA) 86 th Scientific Sessions In the CATALYST trial, patients with hypercortisolism treated with Korlym exhibited clinically and statistically significant improvements in hemoglobin A1c (HbA1c) and clinically meaningful reductions in body weight, body mass index and waist circumference, with numerically greater benefit in those taking GLP-1 receptor agonists or tirzepatide Late-breaking data from the MOMENTUM trial confirm high prevalence of endogenous hypercortisolism in patients with type 2 diabetes and resistant hypertension REDWOOD CITY, Calif.--(BUSINESS WIRE)--Corcept Therapeutics Incorporated (NASDAQ: CORT), a commercial-stage company engaged in the discovery and development of medications to treat severe endocrinologic, oncologic, metabolic and neurologic disorders by modulating the effects of the hormone cortisol, today announced the presentation of new data from its CATALYST and MOMENTUM trials at the American Diabetes Association’s 86 th Scientific Sessions. The presentations underscore the critical role of hypercortisolism in difficult-to-control type 2 diabetes and resistant hypertension, and the potential of cortisol modulation treatment. The CATALYST trial screened 1,057 patients with difficult-to-control type 2 diabetes (HbA1c of 7.5 – 11.5 percent despite receiving multiple glucose-lowering medications) and found that 24 percent had hypercortisolism (cortisol levels of greater than 1.8 μg/dL in the 1 mg dexamethasone suppression test (DST)). In CATALYST’s treatment phase, 136 of the patients who had been found to have hypercortisolism were randomized 2:1 to receive either Korlym or placebo for 24 weeks. Patients who received Korlym exhibited a clinically meaningful and statistically significant reduction in HbA1c (1.3 percent, p-value: 10 percent) were hypokalemia, fatigue, nausea, vomiting, headache, peripheral edema, diarrhea and dizziness. The data presented at ADA described treatment outcomes in the 71 patients in CATALYST who were taking GLP-1 receptor agonists or the GLP-1/GIP agonist tirzepatide. In this group, patients who received Korlym exhibited numerically greater benefit than the overall study population with reductions in HbA1c (1.7 percent), body weight (6.1 kg), body mass index (2.0 kg/m 2 ) and waist circumference (6.5 cm), compared to patients who received placebo (all nominal p-values less than 0.04). “These new CATALYST data demonstrate the potential of cortisol modulation to improve critical metabolic parameters, even for patients who have poorly controlled type 2 diabetes despite treatment with powerful GLP-1 or GLP-1/GIP receptor agonists, such as semaglutide or tirzepatide. Excess cortisol disrupts the incretin system, impairs beta cell function, and induces insulin and incretin resistance, potentially limiting the effectiveness of these otherwise potent therapies. Screening for hypercortisolism and considering cortisol-directed treatment is a key part of managing type 2 diabetes in patients not responding to standard-of-care treatments,” said Lance Sloan, M.D., President, Texas Institute for Kidney and Endocrine Disorders. At ADA, Corcept also presented late-breaking data from its MOMENTUM trial, which screened 1,086 patients with resistant hypertension (as defined by the American Heart Association’s criteria ) and found that 27.3 percent of them had hypercortisolism . The prevalence of hypercortisolism was even higher in patients who had hemoglobin A1c (HbA1c) of 7.5 percent or higher and were taking 3 or more blood pressure medicines: 36.6 percent in CATALYST and 32.6 percent in MOMENTUM. “Data consistently show that hypercortisolism is an underlying driver of treatment resistant cardiometabolic disease, including in patients receiving best-in-class therapies like GLP-1s,” said Bill Guyer, PharmD, Corcept’s Chief Development Officer. “Data from CATALYST demonstrate that treatment with a cortisol modulator, such as Korlym, can be synergistic with GLP-1s or tirzepatide to help patients better control type 2 diabetes. It is our hope that this new research will lead to increased screening for hypercortisolism and improved treatment.” About CATALYST CATALYST is the largest and most rigorous trial ever conducted to determine the prevalence of hypercortisolism in patients with difficult-to-control type 2 diabetes and assess the effect of treating patients found to have hypercortisolism with a cortisol modulator. The initial prevalence phase of the trial screened 1,057 patients with difficult-to-control type 2 diabetes (i.e., patients with HbA1c greater than 7.5 percent despite receiving multiple glucose-lowering medications, including best-in-class therapies such as GLP-1 and GLP-1/GIP agonists) at 36 sites in the United States. Based on results from a standard 1-mg dexamethasone suppression test, 24 percent of the patients screened were found to have hypercortisolism and were eligible to enter the trial’s treatment phase, where they were randomized, 2:1, to receive either Korlym or placebo for 24 weeks. One hundred thirty-six patients enrolled in the treatment phase. About MOMENTUM MOMENTUM was the largest trial ever conducted to assess the prevalence of hypercortisolism in patients with resistant hypertension. A total of 1,086 patients were screened at 50 sites in the United States. All patients had resistant hypertension as defined by the American Heart Association’s criteria (systolic blood pressure greater or equal to 130 mmHg despite taking 3 or more blood-pressure lowering medications, including a diuretic, or taking 4 or more blood-pressure lowering medications). Using a simple, standardized 1-mg dexamethasone suppression test (DST), 27 percent of these patients were found to have hypercortisolism. About Hypercortisolism Hypercortisolism, also known as Cushing’s syndrome, is caused by excessive activity of the hormone cortisol. Symptoms vary, but most patients experience one or more of the following manifestations: hypertension, central obesity, elevated blood sugar and difficult-to-control type 2 diabetes, severe fatigue and weak muscles. Irritability, anxiety, depression and cognitive disturbances are common. Hypercortisolism can affect every organ system and can be fatal if not treated effectively. Cardiovascular events are the most common cause of death among patients with hypercortisolism. Recent research shows that endogenous hypercortisolism is more prevalent than previously believed. INDICATION KORLYM (mifepristone) is a cortisol receptor blocker indicated to control hyperglycemia secondary to hypercortisolism in adult patients with endogenous Cushing's syndrome who have type 2 diabetes mellitus or glucose intolerance and have failed surgery or are not candidates for surgery. Limitations of use: KORLYM should not be used in the treatment of patients with type 2 diabetes unless it is secondary to Cushing’s syndrome. IMPORTANT SAFETY INFORMATION BOXED WARNING: TERMINATION OF PREGNANCY Mifepristone is a potent antagonist of progesterone and cortisol via the progesterone and glucocorticoid (GR-II) receptors, respectively. The antiprogestational effects will result in the termination of pregnancy. Pregnancy must therefore be excluded before the initiation of treatment with Korlym and prevented during treatment and for one month after stopping treatment by the use of a nonhormonal medically acceptable method of contraception unless the patient has had a surgical sterilization, in which case no additional contraception is needed. Pregnancy must also be excluded if treatment is interrupted for more than 14 days in females of reproductive potential. CONTRAINDICATIONS Pregnancy; patients taking simvastatin or lovastatin and CYP3A substrates with narrow therapeutic ranges; patients receiving systemic corticosteroids for lifesaving purposes; women with a history of unexplained vaginal bleeding or endometrial hyperplasia with atypia or endometrial carcinoma; patients with known hypersensitivity to mifepristone or to any of the product components. WARNINGS AND PRECAUTIONS Adrenal insufficiency: Patients should be closely monitored for signs and symptoms of adrenal insufficiency. See full Prescribing Information for further management instructions. Hypokalemia: Hypokalemia should be corrected prior to treatment and monitored for during treatment. Measure serum potassium 1-2 weeks after starting or increasing the Korlym dose, and periodically thereafter. Mifepristone-induced hypokalemia should be treated with potassium supplementation based on severity. If hypokalemia persists despite potassium supplementation, consider adding mineralocorticoid antagonists. Vaginal bleeding and endometrial changes: Women may experience endometrial thickening or unexpected vaginal bleeding. Use with caution if the patient also has a hemorrhagic disorder or is on anticoagulant therapy. Women who experience vaginal bleeding during treatment should be referred to a gynecologist for further evaluation. QT interval prolongation: Avoid use with QT interval-prolonging drugs, or in patients with potassium channel variants resulting in a long QT interval. Exacerbation/Deterioration of Conditions Treated with Corticosteroids: For medical conditions in which chronic corticosteroid therapy is lifesaving, Korlym is contraindicated. Use of strong CYP3A inhibitors: Concomitant use increases mifepristone plasma levels. Use only when necessary and do not exceed a Korlym dose of 900 mg per day. The labeling contains warnings and precautions for Pneumocystis jiroveci Infection and potential effects of hypercortisolemia . See full Prescribing Information for further management instructions. ADVERSE REACTIONS Most common adverse reactions in Cushing’s syndrome (≥20%): nausea, fatigue, headache, decreased blood potassium, arthralgia, vomiting, peripheral edema, hypertension, dizziness, decreased appetite, and endometrial hypertrophy. DRUG INTERACTIONS Drugs metabolized by CYP3A: Administer drugs that are metabolized by CYP3A at the lowest dose when used with Korlym. CYP3A inhibitors: Caution should be used when Korlym is used with strong CYP3A inhibitors. Use only when necessary, and do not exceed a Korlym dose of 900 mg. CYP3A inducers: Do not use Korlym with CYP3A inducers. Drugs metabolized by CYP2C8/2C9: Use the lowest dose of CYP2C8/2C9 substrates when used with Korlym. Drugs metabolized by CYP2B6: Use of Korlym should be done with caution with bupropion and efavirenz. Hormonal contraceptives: Do not use with Korlym. DOSAGE AND ADMINISTRATION Obtain a negative pregnancy test prior to initiating treatment with Korlym in females of reproductive potential, or if treatment is interrupted for more than 14 days. Administer once daily orally with a meal. The recommended starting dose is 300 mg once daily. Renal impairment: Do not exceed 600 mg once daily. Mild-to-moderate hepatic impairment: Do not exceed 600 mg once daily. Do not use in severe hepatic impairment. Based on clinical response and tolerability, the dose may be increased in 300-mg increments to a maximum of 1200 mg once daily. Do not exceed 20 mg/kg per day. Concomitant use of Korlym with a strong CYP3A inhibitor resulted in a 38% increase in mean plasma concentration of mifepristone. For patients already being treated with a strong CYP3A inhibitor, start with a Korlym dose of 300 mg per day and titrate to a maximum of 900 mg per day if clinically indicated. When a strong CYP3A inhibitor is administered to patients already receiving Korlym, adjust the dose as follows: for patients receiving a daily dose of 600 mg, reduce dose to 300 mg. For patients receiving a daily dose of 900 mg, reduce dose to 600 mg. For patients receiving a daily dose of 1200 mg, reduce dose to 900 mg. Titrate if clinically indicated and do not exceed a Korlym dose of 900 mg in combination with a strong CYP3A inhibitor. USE IN SPECIFIC POPULATIONS Lactation: Mifepristone is present in human milk, however, there are no data on the amount of mifepristone in human milk, the effects on the breastfed infant, or the effects on milk production during long term use of mifepristone. About Corcept Therapeutics For over 25 years, Corcept has focused on cortisol modulation and its potential to treat patients with a wide variety of serious disorders, leading to the discovery of more than 1,000 proprietary selective cortisol modulators and glucocorticoid receptor antagonists. Corcept is conducting advanced clinical trials in patients with Cushing’s syndrome, solid tumors, ALS and liver disease. In 2012, the company introduced Korlym ® , the first medication approved by the U.S. Food and Drug Administration (FDA) for the treatment of patients with endogenous Cushing’s syndrome, and in 2026, the company introduced Lifyorli™, approved in combination with nab-paclitaxel, the first FDA-approved selective glucocorticoid receptor antagonist for adults with platinum-resistant ovarian cancer. Corcept is headquartered in Redwood City, California. For more information, visit Corcept.com . Forward-Looking Statements Statements in this press release, other than statements of historical fact, are forward-looking statements based on our current plans and expectations and are subject to risks and uncertainties that might cause our actual results to differ materially from any future results expressed or implied by such forward-looking statements. In this press release, forward-looking statements include statements concerning: the potential for cortisol modulation treatment to improve critical metabolic parameters, even for patients with poorly controlled type 2 diabetes despite treatment with powerful GLP-1 or GLP-1/GIP receptor agonists; and our hope that the findings from the CATALYST and MOMENTUM trials will lead to increased screening for hypercortisolism and improved treatment. A further description of risks and uncertainties can be found in our SEC filings, which are available at our website and the SEC’s website. These risks and uncertainties include, but are not limited to, those related to: our ability to operate our business; our efforts to study and develop Korlym, relacorilant, miricorilant, dazucorilant, nenocorilant and our other product candidates; those molecules’ clinical attributes; regulatory approvals, mandates, oversight and other requirements imposed on our products or our business by laws, regulations or discretion of government authorities; and the scope and protective power of our intellectual property. We disclaim any intention or duty to update forward-looking statements made in this press release. Contacts Investor inquiries: ir@corcept.com Media inquiries: communications@corcept.com

April 21, 2026 2:11 pm EDT IDVYNSO is approved for adults with virologically suppressed HIV-1 with no history of virologic treatment failure and no known substitutions associated with resistance to doravirine IDVYNSO is the first and only non-INSTI, tenofovir-free, once-daily, complete two-drug regimen to demonstrate non-inferior efficacy in a head-to-head Phase 3 trial versus three-drug regimen BIKTARVY®i (BIC/FTC/TAF) RAHWAY, N.J.--(BUSINESS WIRE)-- Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced today that the U.S. Food and Drug Administration (FDA) approved IDVYNSO™, a new, two-drug single-tablet regimen of 100 mg doravirine and 0.25 mg islatravir, for the treatment of HIV-1 infection in adults 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 virologic treatment failure and no known substitutions associated with resistance to doravirine. IDVYNSO is contraindicated when co-administered with drugs that are strong cytochrome P450 (CYP)3A enzyme inducers and lamivudine (3TC) or emtricitabine (FTC). Co-administration with these drugs may decrease the effectiveness of IDVYNSO. See additional selected safety information on the following pages. IDVYNSO (pronounced ihd-VIHN-soh) will be available in pharmacies after May 11. “Advances in HIV treatment mean more people living with HIV are living longer — a remarkable achievement,” said Carl Baloney, Jr., president and chief executive officer of AIDS United. “People aging with HIV face additional health challenges, including managing multiple chronic conditions and medications at the same time. It is essential that management of HIV considers these factors in addition to virologic suppression when choosing an HIV treatment regimen.” “IDVYNSO combines islatravir, a next-generation NRTI with multiple mechanisms of action, including translocation inhibition, with doravirine, an NNRTI with an established efficacy and safety profile. As the only two-drug, non-INSTI, tenofovir-free regimen, IDVYNSO expands therapeutic diversity beyond the currently available oral treatment options,” said Dr. Eliav Barr, senior vice president and chief medical officer, Merck Research Laboratories. “As the health needs of adults living with HIV change over time, IDVYNSO gives clinicians a new choice for HIV treatment. This approval marks an important new chapter in Merck’s long-standing commitment to research and discovery for people living with HIV.” IDVYNSO is a complete regimen; co-administration with other antiretroviral medications for treatment of HIV-1 infection is not recommended. Severe skin reactions, including Stevens-Johnson syndrome/toxic epidermal necrolysis, have been reported with doravirine-containing regimens. Drug Rash with Eosinophilia and Systemic Symptoms was reported with IDVYNSO. Concomitant use of IDVYNSO and certain other drugs may result in known or potentially significant drug interactions, some of which may lead to loss of therapeutic effect of IDVYNSO and possible development of resistance, or possible clinically significant adverse reactions from greater exposures of a component of IDVYNSO. See additional selected safety information on the following pages. “IDVYNSO is the first non-INSTI, tenofovir-free, two-drug regimen to demonstrate non-inferior efficacy to standard oral antiretroviral regimens, including BIKTARVY. This makes IDVYNSO a potential alternative for people with virologically suppressed HIV who may need to switch their treatment,” said Dr. Amy Colson, director of research at Community Resource Initiative, Boston, Massachusetts. Phase 3 studies supporting approval of IDVYNSO The efficacy and safety of IDVYNSO is supported by Week 48 data from two randomized, active-controlled, non-inferiority trials [Trial 052 (NCT05630755) and Trial 051 (NCT05631093)] in virologically-suppressed (HIV-1 RNA less than 50 copies per mL) adults living with HIV. Participants must have been stably suppressed on their baseline regimen for at least 3 months prior to trial entry and had no history of treatment failure. Across the two trials, a total of 708 participants received once-daily IDVYNSO; of these, 81 (11%) participants were aged 65 years and older, including 10 (1%) aged 75 years and older. In the double-blind Trial 052, participants were switched from BIKTARVY [bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF)] to IDVYNSO. A total of 513 participants were randomized (2:1) and were switched to once-daily IDVYNSO (n=342) or remained on BIC/FTC/TAF (n=171). At baseline, participants had a mean age of 48 years (range: 19 to 77), 21% of participants were female, 61% were White, 31% were Black/African American, and 6% were Asian. A total of 23% identified as Hispanic/Latino. In the open-label Trial 051, participants were switched from an oral ART (antiretroviral therapy) regimen to IDVYNSO. A total of 551 participants were randomized (2:1) and were switched to once-daily IDVYNSO (n=366) or remained on their baseline ART (bART) (n=185). Randomization was stratified by bART. At baseline, participants had a mean age of 50 years (range: 18 to 83), 40% of participants were female, 39% were White, 45% were Black/African American, and 5% were Asian. A total of 15% identified as Hispanic/Latino. At enrollment, 64% of the participants were receiving integrase strand transfer inhibitor (INSTI)-based regimens, 5% protease inhibitor (PI)-based regimens (including combinations with INSTI), and 30% were receiving other regimens. Efficacy profile of IDVYNSO IDVYNSO was non-inferior to BIC/FTC/TAF (in Trial 052) and bART (in Trial 051) as assessed by the proportion of participants with HIV-1 RNA ≥50 copies/mL at Week 48. In the double-blind Trial 052, results for the primary endpoint (HIV-1 RNA ≥50 copies/mL) showed that 1% of participants who were switched to IDVYNSO (n=342) had a viral load of ≥50 copies/mL at Week 48, compared to 1% who continued on BIC/FTC/TAF (n=171; treatment difference 0.9%, 95% CI, -1.9%, 2.9%). At Week 48, results from the secondary endpoint showed that 92% of participants who switched to IDVYNSO maintained viral suppression (HIV-1 RNA <50 copies/mL) compared to 94% of participants who continued receiving BIC/FTC/TAF. In the open-label Trial 051, results for the primary endpoint (HIV-1 RNA ≥50 copies/mL) showed that 1% of participants who were switched to IDVYNSO (n=366) had a viral load of ≥50 copies/mL at Week 48, compared to 5% who continued on bART (n=185; treatment difference -3.6%, 95% CI, -7.8%, -0.8%). At Week 48, results from the secondary endpoint showed that 96% of participants who switched to IDVYNSO maintained viral suppression (HIV-1 RNA <50 copies/mL) compared to 92% of participants who continued on bART. In both trials, treatment outcomes between treatment groups were similar across subgroups by age, sex and race, and in Trial 051, also by bART regimens. In participants aged 65 years and older who received IDVYNSO in both trials, no overall differences in safety or effectiveness were observed between these participants and younger participants, but greater sensitivity of some older individuals cannot be ruled out. Safety and tolerability profile of IDVYNSO The safety profile of IDVYNSO was generally comparable to BIC/FTC/TAF in Trial 052 and to oral bART regimens in Trial 051. In Trial 052, by Week 48, 3% in the IDVYNSO group and 2% in the BIC/FTC/TAF group had adverse events leading to discontinuation of study medication. In Trial 051, by Week 48, 0.5% in the IDVYNSO group and 2% in the bART group had adverse events leading to discontinuation of study medication. The most common adverse reactions (all grades) reported in greater than or equal to 2% of participants in any treatment group in Trials 052 and 051 through Week 48 were as follows: In Trial 052 (IDVYNSO vs BIC/FTC/TAF, respectively): diarrhea (1% vs 1%), dizziness (1% vs 0%), fatigue (1% vs 1%), abdominal distention (1% vs 0%), headache (1% vs 0%), weight increase (less than 1% vs 0%). In Trial 051 (IDVYNSO vs bART, respectively): diarrhea (3% vs 0%), dizziness (2% vs 1%), fatigue (2% vs 1%), abdominal distention (2% vs 0%), headache (2% vs 1%), weight increase (2% vs 0%). Trial participants taking IDVYNSO had minimal change in weight from baseline. The mean change in weight from baseline at Week 48 was -0.03 kg in the IDVYNSO group vs. 0.28 kg in the BIC/FTC/TAF group in Trial 052 and 0.94 kg in the IDVYNSO group vs. -0.15 kg in the bART group in Trial 051. Four of the six participants with adverse reactions of weight increased switched from a bART regimen containing efavirenz and/or tenofovir disoproxil fumarate in Trial 051. The Merck Access Program for IDVYNSO Merck offers support to individuals who are prescribed IDVYNSO, including information about individual insurance coverage and out-of-pocket costs, co-pay assistance for eligible, commercially insured individuals, and how individuals may access IDVYNSO through The Merck Access Program. For additional information, healthcare providers and individuals can call 1-877-709-4455 or visit merckaccessprogram-IDVYNSO.com. About IDVYNSO IDVYNSO is a fixed-dose combination of two medicines, doravirine with islatravir. Doravirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that inhibits HIV-1 replication by non-competitive inhibition of HIV-1 reverse transcriptase. Islatravir is a potent, next-generation nucleoside analog reverse transcriptase inhibitor (NRTI) that blocks HIV-1 replication by multiple mechanisms including: inhibition of reverse transcriptase translocation, resulting in immediate chain termination, and induction of structural changes in the viral DNA (delayed chain termination). Selected Safety Information for IDVYNSO Contraindications IDVYNSO 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 IDVYNSO. lamivudine (3TC) or emtricitabine (FTC) as significant decreases in islatravir-triphosphate (ISL-TP) concentrations may occur, which may decrease the effectiveness of IDVYNSO. (See Drug Interactions) Warnings and Precautions Severe skin reactions, including Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), have been reported during postmarketing experience with doravirine-containing regimens. In addition, Drug Rash with Eosinophilia and Systemic Symptoms (DRESS syndrome) was reported with IDVYNSO in a clinical trial. Discontinue IDVYNSO, and other medications associated with these reactions, immediately if a painful rash with mucosal involvement, a progressive severe rash, or a rash with constitutional symptoms, eosinophilia, lymphadenopathy, or other organ involvement develops. Close clinical monitoring, and appropriate therapy should be initiated. The concomitant use of IDVYNSO and certain other drugs may result in known or potentially significant drug interactions, some of which may lead to loss of therapeutic effect of IDVYNSO and possible development of resistance and possible clinically significant adverse reactions from greater exposures of a component of IDVYNSO. Consider the potential for drug interactions prior to and during IDVYNSO therapy, review concomitant medications during IDVYNSO therapy, and monitor for adverse reactions. (See Drug Interactions) Adverse Reactions The most common adverse reactions (incidence ≥ 2%, all grades in any treatment group) reported in virologically suppressed participants in the IDVYNSO treatment groups from 2 clinical trials, respectively, were: diarrhea (3% and 1%), dizziness (2% and 1%), fatigue (2% and 1%), abdominal distension (2% and 1%), headache (2% and 1%) and increased weight (2% and <1%). A single case of severe immune thrombocytopenia (platelet count nadir of 2 x10⁹/L) characterized by abrupt onset of subcutaneous hematoma, petechiae, and hematuria was reported in a participant 32 days after initiating IDVYNSO. The case resolved with discontinuation of IDVYNSO, in conjunction with treatments including corticosteroids and IVIG. Among all participants in Trials 052 and 051, there were no patterns of platelet decreases over time with IDVYNSO and no differences between treatment arms in mean change from baseline in platelet count. Drug Interactions IDVYNSO is a complete regimen; co-administration with other antiretroviral medications for treatment of HIV-1 infection is not recommended. Co-administration of IDVYNSO with a CYP3A inducer decreases doravirine plasma concentrations, which may reduce the efficacy of IDVYNSO. If IDVYNSO is co-administered with rifabutin, one tablet of doravirine should be taken approximately 12 hours after the dose of IDVYNSO. Co-administration of IDVYNSO with other moderate CYP3A inducers is not recommended. Co-administration of IDVYNSO and drugs that are inhibitors of CYP3A may result in increased plasma concentrations of doravirine. Co-administration of IDVYNSO is not recommended with deoxycytidine kinase (dCK) substrates (e.g., nucleoside antimetabolites) as they may reduce the exposure of islatravir-triphosphate or with adenosine deaminase (ADA) inhibitors (e.g., pentostatin) as they may increase the exposure of islatravir. (see Contraindications) Use in Specific Populations Clinical trials in virologically suppressed participants who received IDVYNSO included 81 (11%) participants aged 65 years and older, including 10 (1%) aged 75 years and older. Overall differences in response have not been identified between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. IDVYNSO does not have activity against hepatitis B virus (HBV). Patients with HBV coinfection who switch to IDVYNSO from an antiretroviral regimen with activity against HBV, and patients on IDVYNSO who are newly diagnosed with HBV coinfection, should be closely monitored and specific anti-HBV therapy should be considered, as clinically appropriate. Merck’s Commitment to HIV For 40 years, Merck has been committed to scientific research and discovery in HIV leading to scientific breakthroughs that have helped change HIV treatment. Our work has helped pioneer the development of new options across multiple drug classes to help those impacted by HIV. Today, we are developing a series of antiviral options designed to help people manage HIV and protect people from HIV. We are researching for real life and want to ensure people are not defined by HIV. Our work focuses on transformational innovations, collaborations with others in the global HIV community and access initiatives aimed at helping to end the HIV epidemic for everyone. About Merck’s HIV research Islatravir is under evaluation in multiple ongoing early and late-stage clinical trials in combination with other antiretrovirals for potential once-weekly treatments for HIV-1, with islatravir serving as the anchor medicine in these two-drug regimens. Islatravir in combination with Gilead’s lenacapavir is in Phase 3 development as a novel oral once-weekly treatment for HIV-1 [ISLEND-1 (NCT06630286) and ISLEND-2 (NCT06630299)], and islatravir in combination with our company’s investigational non-nucleoside reverse transcriptase inhibitor (NNRTI) ulonivirine (MK-8507) is in Phase 2b development [MK-8591B-060 (NCT06891066) and MK-8591B-062 (NCT07266831)] as an oral once-weekly treatment. MK-8527 is the company’s investigational, novel, once-monthly oral candidate for pre-exposure prophylaxis (PrEP) for HIV-1. In collaboration with the Gates Foundation, the Phase 3 EXPrESSIVE-10 trial (MK-8527-010, NCT07071623) is evaluating the safety and efficacy of MK-8527 as PrEP to reduce the risk of sexually acquired HIV-1 infection among women and adolescent girls in sub-Saharan Africa. The Phase 3 EXPrESSIVE-11 trial (MK-8527-011, NCT07044297) in 16 countries is evaluating the safety and efficacy of MK-8527 as PrEP to reduce the risk of sexually acquired HIV-1 infection among people likely to be exposed to HIV-1. Both trials are now enrolling. For an overview of Merck’s HIV treatment and prevention clinical development program, please click here. About Merck At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.merck.com and connect with us on X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn. Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA This news release of Merck & Co., Inc., Rahway, N.J., USA (the “company”) includes “forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs and expectations of the company’s management and are subject to significant risks and uncertainties. There can be no guarantees with respect to pipeline candidates that the candidates will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements. Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the company’s patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions. The company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2025 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov). Please see Prescribing Information for IDVYNSO™ (doravirine and islatravir) at https://www.merck.com/product/usa/pi_circulars/i/idvynso/idvynso_pi.pdf and Patient Information for IDVYNSO at https://www.merck.com/product/usa/pi_circulars/i/idvynso/idvynso_ppi.pdf. i IDVYNSO™ is a trademark of Merck & Co., Inc. BIKTARVY is a registered trademark of Gilead Sciences Ireland UC. Media Contacts: Melissa Moody (215) 407-3536 Deb Wambold (215) 779-2234 Investor Contacts: Damini Chokshi (732) 594-1577 Peter Dannenbaum (732) 594-1579