October 9, 2025 7:00 am EDT
RAHWAY, N.J.–(BUSINESS WIRE)–
Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced today that it will present new findings from its HIV treatment and prevention pipeline at the 20th European AIDS Conference (EACS 2025) taking place Oct.15-18, 2025, in Paris, France. The company’s presentations will include:
- An oral presentation of weight and body composition at Week 48 from the Phase 3 trial ( MK-8591A-052) comparing doravirine/islatravir [DOR/ISL (100mg/0.25mg)] vs. bictegravir/emtricitabine/tenofovir alafenamide i[BIC/FTC/TAF (50mg/200mg/25mg)] for the once-daily treatment of adults with virologically suppressed HIV-1 infection on antiretroviral therapy
- A poster presentation of fasting lipids and insulin resistance at Week 48 from two Phase 3 trials comparing DOR/ISL vs. baseline antiretroviral therapy ( MK-8591A-051) or BIC/FTC/TAF ( MK-8591A-052), for the once-daily treatment of adults with virologically suppressed HIV-1 infection on antiretroviral therapy
- An oral presentation of 96 weeks of safety and pharmacokinetics data from the Phase 2 trial ( NCT05052996) of the investigational once-weekly oral combination of islatravir in combination with lenacapavir (MK-8591D) for adults with virologically suppressed HIV-1 infection on BIC/FTC/TAF
- A poster presentation of MK-8527 Phase 1 safety and pharmacokinetics data in adults with moderate or severe renal impairment ( MK-8527-008); MK-8527 is Merck’s investigational once-monthly pill for HIV pre-exposure prophylaxis (PrEP)
“We are pleased to share new data from across our HIV pipeline at EACS 2025, including additional analyses from the Phase 3 program of the investigational once-daily, two-drug treatment regimen, DOR/ISL, which is currently under review with the U.S. Food and Drug Administration,” said Dr. Luisa Stamm, associate vice president and HIV section head at Merck Research Laboratories. “By advancing multiple investigational agents for daily and weekly treatments and monthly oral prevention, we aim to give individuals new and different ways to treat and prevent HIV.”
Select abstracts in the EACS 2025 program include:
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Abstract Title and Author
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Date and Time
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HIV TREATMENT
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Weight and Body Composition After Switch to Doravirine/Islatravir (100mg/0.25mg) Once Daily from BIC/FTC/TAF in Adults Living With HIV-1: Week 48 Results from a Randomized, Double-Blind Phase 3 Study. Orkin, C, et al.
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Oral Presentation
Thursday, October 16, 2025,
11:00 – 12:00
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Evaluation of Fasting Lipids and Insulin Resistance After Switch to Doravirine/Islatravir (100mg/0.25mg) Once Daily: Week 48 Results From Two Randomized Phase 3 Studies in Adults Living With HIV‑1. Calmy, A, et al.
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Moderated ePoster
Friday, October 17, 2025,
15:35 – 16:10
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Oral Weekly Islatravir Plus Lenacapavir in Virologically Suppressed People with HIV-1: 96 Week Outcomes from a Phase 2 Study. Colson, A, et al.
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Oral Presentation
Saturday, October 18, 2025
09:15 – 10:15
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Patient-Reported Outcomes From People With HIV-1 Receiving Once-Weekly Oral Islatravir in Combination With Lenacapavir: Phase 2 Week 48 Results. Eron, J, et al.
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ePoster
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HIV PREVENTION
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Pharmacokinetics and Safety of MK-8527 in Adults With Moderate or Severe Renal Impairment, Carstens, R, et al.
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ePoster
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This year at EACS, Merck will host a policy symposium “Ending the Epidemic in Europe: Policy Challenges and Opportunities” on Thursday, October 16, from 18:00 – 19:30 CEST. Merck will also host a medical symposium “Optimization of HIV Care” on Friday, Oct. 17, from 12:30 – 14:00 CEST. Both events will be open to all registered attendees.
For more details about Merck’s clinical development program in HIV treatment and prevention, click here.
Merck’s Commitment to HIV
For more than 35 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 their HIV and to help prevent HIV, with the goal of reducing the growing burden of infection worldwide. We want to ensure people are not defined by HIV, and 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.
Indications and usage for PIFELTRO® (doravirine) and DELSTRIGO® (doravirine, lamivudine, and tenofovir disoproxil fumarate) in the U.S.
PIFELTRO is indicated in combination with other antiretroviral (ARV) agents for the treatment of HIV-1 infection in adult patients with no prior ARV treatment history or to replace the current ARV regimen in those who are virologically suppressed (HIV-1 RNA less than 50 copies per mL) on a stable ARV regimen with no history of treatment failure and no known substitutions associated with resistance to doravirine.
DELSTRIGO is indicated as a complete regimen for the treatment of HIV-1 infection in adult patients with no prior ARV treatment history or to replace the current ARV regimen in those who are virologically suppressed (HIV-1 RNA less than 50 copies per mL) on a stable ARV regimen with no history of treatment failure and no known substitutions associated with resistance to the individual components of DELSTRIGO.
Selected Safety Information
Warning: Posttreatment Acute Exacerbation of Hepatitis B Virus (HBV) for DELSTRIGO
All patients with HIV-1 should be tested for the presence of HBV before initiating ARV therapy. Severe acute exacerbations of HBV have been reported in people with concomitant HIV-1 and HBV who have discontinued products containing lamivudine or tenofovir disoproxil fumarate (TDF), which are components of DELSTRIGO. Patients coinfected with HIV-1 and HBV who discontinue DELSTRIGO should be monitored with both clinical and laboratory follow-up for at least several months after stopping DELSTRIGO. If appropriate, initiation of anti-HBV therapy may be warranted.
Contraindications
PIFELTRO and DELSTRIGO are contraindicated when coadministered with drugs that are strong cytochrome P450 (CYP)3A enzyme inducers (including the anticonvulsants carbamazepine, oxcarbazepine, phenobarbital, and phenytoin; the androgen receptor inhibitor enzalutamide; the antimycobacterials rifampin and rifapentine; the cytotoxic agent mitotane; and the herbal product St. John’s wort (Hypericum perforatum)), as significant decreases in doravirine plasma concentrations may occur, which may decrease the effectiveness of DELSTRIGO and PIFELTRO.
DELSTRIGO is contraindicated in patients with a previous hypersensitivity reaction to lamivudine.
Warnings and Precautions
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. Discontinue PIFELTRO or 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.
New or Worsening Renal Impairment
Renal impairment, including cases of acute renal failure and Fanconi syndrome, have been reported with the use of TDF. DELSTRIGO should be avoided with concurrent or recent use of a nephrotoxic agent (e.g., high-dose or multiple NSAIDs). Cases of acute renal failure after initiation of high-dose or multiple NSAIDs have been reported in people living with HIV with risk factors for renal dysfunction who appeared stable on TDF.
Prior to or when initiating DELSTRIGO, and during treatment, 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. Discontinue DELSTRIGO if estimated creatinine clearance declines below 50 mL/min.
Bone Loss and Mineralization Defects
In clinical trials in adults living with HIV, TDF was associated with slightly greater decreases in bone mineral density (BMD) and increases in biochemical markers of bone metabolism. Serum parathyroid hormone levels and 1,25 Vitamin D levels were also higher. Cases of osteomalacia associated with proximal renal tubulopathy have been reported with the use of TDF. The effects of TDF-associated changes in BMD and biochemical markers on long-term bone health and future fracture risk in adults are unknown.
Immune Reconstitution Syndrome
Immune reconstitution syndrome can occur, including the occurrence of autoimmune disorders with variable time to onset, which may necessitate further evaluation and treatment.
Drug Interactions
Because DELSTRIGO is a complete regimen, coadministration with other antiretroviral medications for the treatment of HIV-1 infection is not recommended.
Coadministration of PIFELTRO with efavirenz, etravirine, or nevirapine is not recommended.
If DELSTRIGO is coadministered with rifabutin, take one tablet of DELSTRIGO once daily, followed by one tablet of doravirine (PIFELTRO) approximately 12 hours after the dose of DELSTRIGO.
If PIFELTRO is coadministered with rifabutin, increase PIFELTRO dosage to one tablet twice daily (approximately 12 hours apart).
Consult the full Prescribing Information prior to and during treatment for more information on potential drug-drug interactions.
Dosage and Administration/Specific Populations
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.
Adverse Reactions
The most common adverse reactions with DELSTRIGO (incidence ≥5%, all intensities) were dizziness (7%), nausea (5%), and abnormal dreams (5%). The most common adverse reactions with PIFELTRO (incidence ≥5%, all intensities) were nausea (7%), dizziness (7%), headache (6%), fatigue (6%), diarrhea (6%), abdominal pain (5%), and abnormal dreams (5%).
By week 96 in DRIVE-FORWARD, 2% of adult participants in the PIFELTRO group and 3% in the darunavir+ritonavir (DRV+r) group had adverse events leading to discontinuation of study medication.
By week 96 in DRIVE-AHEAD, 3% of adult participants in the DELSTRIGO group and 7% in the efavirenz (EFV)/emtricitabine (FTC)/TDF group had adverse events leading to discontinuation of study medication.
In DRIVE-FORWARD, mean changes from baseline at week 48 in LDL-cholesterol (LDL-C) and non-HDL-cholesterol (non-HDL-C) were pre-specified. LDL-C: -4.6 mg/dL in the PIFELTRO group vs 9.5 mg/dL in the DRV+r group. Non-HDL-C: -5.4 mg/dL in the PIFELTRO group vs 13.7 mg/dL in the DRV+r group. The clinical benefits of these findings have not been demonstrated.
In DRIVE-AHEAD, mean changes from baseline at week 48 in LDL-C and non-HDL-C were pre-specified. LDL-C: -2.1 mg/dL in the DELSTRIGO group vs 8.3 mg/dL in the EFV/FTC/TDF group. Non-HDL-C: -4.1 mg/dL in the DELSTRIGO group vs 12.7 mg/dL in the EFV/FTC/TDF group. The clinical benefits of these findings have not been demonstrated.
In DRIVE-SHIFT, mean changes from baseline at week 24 in LDL-C and non-HDL-C were pre-specified. LDL-C: -16.3 mg/dL in the DELSTRIGO group vs -2.6 mg/dL in the PI + ritonavir group. Non-HDL-C: -24.8 mg/dL in the DELSTRIGO group vs -2.1 mg/dL in the PI + ritonavir group. The clinical benefits of these findings have not been demonstrated.
In DRIVE-AHEAD, neuropsychiatric adverse events were reported in the three pre-specified categories of sleep disorders and disturbances, dizziness, and altered sensorium. Twelve percent of adult participants in the DELSTRIGO group and 26% in the EFV/FTC/TDF group reported neuropsychiatric adverse events of sleep disorders and disturbances; 9% in the DELSTRIGO group and 37% in the EFV/FTC/TDF group reported dizziness; and 4% in the DELSTRIGO group and 8% in the EFV/FTC/TDF group reported altered sensorium.
The safety of DELSTRIGO in virologically-suppressed adults was based on week 48 data from participants in the DRIVE-SHIFT trial. Overall, the safety profile in virologically-suppressed adult participants was similar to that in participants with no ARV treatment history.
Serum ALT and AST Elevations: In the DRIVE-SHIFT trial, 22% and 16% of participants in the immediate switch group experienced ALT and AST elevations greater than 1.25 X ULN, respectively, through 48 weeks on DELSTRIGO. For these ALT and AST elevations, no apparent patterns with regard to time to onset relative to switch were observed. One percent of participants had ALT or AST elevations greater than 5 X ULN through 48 weeks on DELSTRIGO. The ALT and AST elevations were generally asymptomatic, and not associated with bilirubin elevations. In comparison, 4% and 4% of participants in the delayed switch group experienced ALT and AST elevations of greater than 1.25 X ULN through 24 weeks on their baseline regimen.
Pregnancy/Breastfeeding
There is a pregnancy exposure registry that monitors pregnancy outcomes in individuals exposed to PIFELTRO or DELSTRIGO during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at 1-800-258-4263.
Inform individuals with HIV-1 infection of the potential risks of breastfeeding, including: (1) HIV-1 transmission (in HIV-1–negative infants), (2) developing viral resistance (in HIV-1–positive infants), and (3) serious adverse reactions in a breastfed infant similar to those seen in adults.
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, 2024 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 PIFELTRO (doravirine) at: https://www.merck.com/product/usa/pi_circulars/p/pifeltro/pifeltro_pi.pdf and Patient Information for PIFELTRO at: https://www.merck.com/product/usa/pi_circulars/p/pifeltro/pifeltro_ppi.pdf
Please see Prescribing Information for DELSTRIGO (doravirine, lamivudine, and tenofovir disoproxil fumarate) at: https://www.merck.com/product/usa/pi_circulars/d/delstrigo/delstrigo_pi.pdf and Patient Information for DELSTRIGO at: https://www.merck.com/product/usa/pi_circulars/d/delstrigo/delstrigo_ppi.pdf
i bictegravir/emtricitabine/tenofovir alafenamide (BIKTARVY) is a registered trademark of Gilead Sciences, Inc.
Source: Merck & Co., Inc.
