NOW APPROVED
for the treatment of
essential
thrombocythemia
Start at the source.
Take control
with BESREMi.
BESREMi is the first and only FDA-approved interferon indicated for adults with essential thrombocythemia (ET) and polycythemia vera (PV).1,2
Select an indication to learn more:
Patient support and resources
Helping eligible patients access BESREMi
and stay on track with personalized support
and stay on track with personalized support
References: 1. BESREMi. Package insert. PharmaEssentia Corporation; 2026. 2. Mesa R, Gill H, Zhang L, et al. Ropeginterferon alfa-2b in hydroxyurea-intolerant or hydroxyurea-refractory essential thrombocythaemia (SURPASS ET): a multicentre, open-label, randomised, active-controlled, phase 3 study. Lancet Haematol. 2025;12:3862-e875.
INDICATION
BESREMi is indicated for:
- The treatment of adults with polycythemia vera.
- The treatment of adults with essential thrombocythemia.
IMPORTANT SAFETY INFORMATION
WARNING: RISK OF SERIOUS DISORDERS
Interferon alfa products may cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. Patients should be monitored closely with periodic clinical and laboratory evaluations. Therapy should be withdrawn in patients with persistently severe or worsening signs or symptoms of these conditions. In many, but not all cases, these disorders resolve after stopping therapy.
CONTRAINDICATIONS
- Existence of or history of severe depression, suicidal ideation, or suicide attempt
- Hypersensitivity to interferons or any inactive ingredients
- Moderate or severe hepatic impairment
- History or presence of active serious or untreated autoimmune disease
- Immunosuppressed transplant recipients
WARNINGS AND PRECAUTIONS
- Depression and Suicide: Closely monitor patients for any symptoms of psychiatric disorders and, if needed, consider psychiatric consultation and treatment or dosage modifications as listed in the full prescribing information.
- Endocrine Toxicity: Do not use BESREMi in patients with active serious or untreated endocrine disorders associated with autoimmune disease. Evaluate thyroid function in patients who develop symptoms suggestive of thyroid disease during BESREMi therapy. Discontinue BESREMi in patients who develop endocrine disorders that cannot be adequately managed during treatment with BESREMi.
- Cardiovascular Toxicity: Patients with a history of cardiovascular disorders should be closely monitored for cardiovascular toxicity during BESREMi therapy. Avoid use of BESREMi in patients with severe or unstable cardiovascular disease or recent stroke or myocardial infarction.
- Decreased Peripheral Blood Counts: Monitor complete blood counts at baseline, during titration, and every 3-6 months during the maintenance phase.
- Pancreatitis/Colitis/Pulmonary Toxicity: Interrupt BESREMi treatment in patients with possible pancreatitis, colitis, or pulmonary toxicity and evaluate promptly. Consider discontinuation of BESREMi in patients with confirmed pancreatitis or who show signs or symptoms of serious ulcerative or hemorrhagic colitis, or who develop pulmonary infiltrates or pulmonary function impairment.
- Ophthalmologic Toxicity: Advise patients to have eye examinations before and during treatment. Discontinue BESREMi in patients who develop new or worsening eye disorders.
- Hyperlipidemia/Hepatotoxicity/Renal Toxicity: Monitor serum triglycerides, liver enzymes, hepatic function, and serum creatinine at baseline and during therapy. Avoid use of BESREMi in patients with eGFR <30 mL/min. Discontinue BESREMi in patients with persistently marked elevated triglycerides, evidence of hepatic decompensation, or if renal impairment develops during treatment.
- Dental and Periodontal Toxicity: Patients should have good oral hygiene and regular dental examinations.
- Dermatologic Toxicity: Consider discontinuation of BESREMi if clinically significant dermatologic toxicity occurs.
- Driving and Operating Machinery: BESREMi may impact the ability to drive and use machinery. Patients should not drive or use heavy machinery until they know how BESREMi affects their abilities. Patients who experience dizziness, somnolence, or hallucination during BESREMi therapy should avoid driving or using machinery.
- Embryo-Fetal Toxicity: Based on the mechanism of action, BESREMi can cause fetal harm when administered to a pregnant woman. Obtain a pregnancy test in females of reproductive potential prior to initiating treatment with BESREMi. Advise females of reproductive potential to use an effective method of contraception during treatment with BESREMi and for at least 8 weeks after the final dose. Advise women not to breastfeed during treatment and for 8 weeks after the final dose.
ADVERSE REACTIONS
The most common adverse reactions reported in >40% of patients with polycythemia vera were influenza-like illness, arthralgia, fatigue, pruritus, nasopharyngitis, and musculoskeletal pain.
The most common adverse reactions reported in >30% of patients with essential thrombocythemia were aspartate aminotransferase increased (44%), alanine aminotransferase increased (43%), and fatigue (31%).
DRUG INTERACTIONS
Patients on BESREMi who are receiving concomitant drugs which are CYP450 substrates with a narrow therapeutic index should be monitored to inform the need for dosage modification. Avoid use with myelosuppressive agents, narcotics, hypnotics, or sedatives, and monitor patients receiving the combination for effects of excessive CNS toxicity.
To report SUSPECTED ADVERSE REACTIONS, contact PharmaEssentia at 1-800-999-2449 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch
Please see full Prescribing Information, including Boxed Warning.