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Enasinib 50 mg

Enasidenib 50mg tablets – Everest Pharmaceuticals Ltd.

Approved for adults with relapsed or refractory acute myeloid leukemia (AML) with an IDH2 mutation, as detected by an FDA-approved test — the first FDA approval specifically for IDH2-mutated relapsed/refractory AML.

19.3%

Complete remission rate in relapsed/refractory IDH2-mutant AML (AG221-C-001 trial), with median CR duration of 8.2 months

9.3 mo

Median overall survival overall — extending to 19.7 months in patients who achieved complete remission

34%

Of transfusion-dependent patients became transfusion-independent following treatment

1st

First-in-class oral inhibitor of mutant IDH2 enzymes, and first FDA approval specifically for IDH2-mutated R/R AML

Confirm IDH2 mutation status

Requires a confirmed IDH2 mutation via an FDA-approved companion diagnostic (the RealTime IDH2 Assay) — IDH2 mutations occur in approximately 12% of AML patients, and this medication is specifically for relapsed or refractory disease in that subgroup.

Discuss differentiation syndrome recognition before starting

This is the signature risk of IDH2 inhibitor therapy — your care team should walk you through the warning signs (fever, breathlessness, rapid weight gain, swelling) and confirm a monitoring plan, especially in the first weeks of treatment.

Baseline electrolyte and kidney function assessment

Tumor lysis syndrome and electrolyte abnormalities (potassium, phosphorus, calcium) are recognized risks — baseline labs and a hydration/monitoring plan, especially around treatment initiation, are part of standard preparation.

Baseline liver function testing

Elevated bilirubin is among the most common laboratory abnormalities seen with this medication — baseline liver function tests help establish a comparison point for ongoing monitoring.

Important safety information — differentiation syndrome: IDH2-inhibitor-associated differentiation syndrome can be fatal if not recognized and treated promptly. Symptoms include fever, dyspnea, hypoxia, pulmonary infiltrates, renal impairment, and rapid weight gain or peripheral edema. This has occurred in 14% of patients treated with enasidenib in clinical trials. If suspected, corticosteroid treatment and hemodynamic monitoring should begin promptly, and enasidenib should not necessarily be discontinued unless severe symptoms persist after corticosteroid initiation. Tumor lysis syndrome and electrolyte abnormalities have also been reported.

Medical Oncologist Review

Board-certified oncologist · 12+ years in thoracic malignancies

“Enasidenib filled a genuine gap for relapsed or refractory AML patients with an IDH2 mutation — a population that previously had very limited targeted options. What I emphasize most with patients starting this medication is differentiation syndrome — it’s manageable with prompt corticosteroid treatment, and the data shows it doesn’t have to mean stopping the drug, but it absolutely requires the patient and care team recognizing the warning signs early, particularly new breathlessness or rapid weight gain in the first weeks.”

Content reviewed against FDA prescribing information, NCCN Guidelines v2.2024, and published Phase III trial data. Last updated June 2026.

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Questions to ask my healthcare provider

What questions should I ask my hematologist about starting enasidenib?

Here are key questions to bring to your hematologist — given that differentiation syndrome is the signature risk of this medication and can be serious if not recognized promptly, making sure you and your care team have a clear, shared plan for spotting it early is the most important piece of preparation before starting.

Before confirming enasidenib as your treatment

Has my IDH2 mutation been confirmed using an FDA-approved test, specifically the RealTime IDH2 Assay?
Is my AML considered relapsed or refractory, and what treatments have I already tried?
Why is enasidenib being recommended for me specifically, given my mutation and treatment history?
Are there clinical trials I should know about?

About differentiation syndrome — the most important conversation to have upfront

Can you walk me through exactly what differentiation syndrome looks like, in plain terms — what symptoms should I watch for?
Given that it can include fever, breathlessness, rapid weight gain, and swelling, how do I tell the difference between this and something less serious, like a normal cold or fatigue from my leukemia itself?
How early in treatment does this typically develop, and how closely will I be monitored during that window?
If differentiation syndrome develops, does it always mean stopping enasidenib, or can it usually be managed with steroids while I continue treatment?
Should I have a clear, written list of symptoms and a phone number to call immediately if I notice them, rather than waiting for a scheduled visit?

About tumor lysis syndrome and electrolyte monitoring

Will I need baseline and ongoing blood tests to monitor my electrolytes — potassium, phosphorus, calcium — and how often?
What symptoms of tumor lysis syndrome should prompt me to seek care urgently?
Will I need additional hydration or other preventive measures, especially around when I first start treatment?

About liver function monitoring

Will my liver function, including bilirubin, be checked regularly?
What would an abnormal result mean for my treatment plan?

About dosing and administration

The dose is 100mg once daily (two 50mg tablets) — should these be taken at the same time each day, and does food matter?
What should I do if I miss a dose or vomit shortly after taking it?
Should the tablets always be swallowed whole, never crushed or chewed?

About managing common side effects

Nausea, diarrhea, and decreased appetite seem to be common — is there anything that can help, especially in the first weeks?
At what point would these become severe enough to need a dose adjustment?

About monitoring response

How will we track whether enasidenib is working — through blood counts, bone marrow assessments, or both?
How soon might we expect to see signs of response, and what does “response” actually mean for someone in my specific situation?
I understand some patients who needed blood or platelet transfusions were able to stop needing them — is that a realistic goal for me?

About my specific situation

Does my age, overall health, or any other conditions affect how closely I’ll need to be monitored on this medication?
Am I a candidate for any other treatments, like a stem cell transplant, either alongside or after enasidenib?

About the longer road

If enasidenib stops working or isn’t tolerated well, what would be considered next?
Are there patient assistance programs through Bristol Myers Squibb if cost is a concern?

A practical tip: Because differentiation syndrome can develop relatively early and progress quickly if unrecognized, it’s worth asking your hematologist to give you a specific, written checklist of symptoms and exactly who to call, day or night, if you notice them — rather than relying on memory or waiting to see if symptoms pass on their own. Many centers treat this proactively with very low thresholds for evaluation precisely because early recognition makes such a meaningful difference in outcomes.

compare with other therapies

Compare enasidenib vs ivosidenib for IDH-mutated AML

This isn’t really an either-or comparison the way it might first appear — enasidenib and ivosidenib target two different mutated genes, so the actual decision is usually made by your specific mutation test result rather than a head-to-head efficacy choice between equivalent options.

Different target genes — this is the most important distinction

	Enasidenib (Idhifa)	Ivosidenib (Tibsovo)
Target	Mutant IDH2	Mutant IDH1
Mutation prevalence in AML	~12% (IDH2)	6-10% (IDH1)
FDA approval	August 2017, relapsed/refractory IDH2-mutant AML	February 2018, relapsed/refractory IDH1-mutant AML; May 2022, newly diagnosed IDH1-mutant AML in combination with azacitidine
Manufacturer	Bristol Myers Squibb (Celgene)	Servier

IDH1 and IDH2 are related but distinct enzymes in the same metabolic pathway, and a patient’s AML will typically carry a mutation in one or the other, not both — so in practice, your specific mutation testing result determines which drug is even an option for you, rather than choosing between two interchangeable alternatives.

Efficacy in the relapsed/refractory monotherapy setting — broadly comparable

	Enasidenib (AG221-C-001)	Ivosidenib (Phase 1 monotherapy)
ORR	40.3%	39.1%
CR rate	19.3%	—
Median OS	9.3 months	8.8 months
18-month OS	—	50.1%

These numbers land remarkably close together — both drugs, used as monotherapy in relapsed/refractory disease, show roughly 39-40% response rates and median survival in the 8-9 month range, suggesting comparable single-agent activity within their respective mutation populations.

A crucial difference — ivosidenib has been moved into frontline combination therapy

This is where the picture diverges meaningfully: long-term follow-up data from the AGILE trial reinforce ivosidenib plus azacitidine as a standard of care for newly diagnosed IDH1-mutated AML patients ineligible for intensive chemotherapy, with improved event-free survival, overall survival, and clinical responses compared with placebo plus azacitidine, along with better quality-of-life outcomes. AGILE is the only phase 3 study to date specifically designed to assess a targeted therapy in the frontline setting in patients with IDH1-mutated AML — meaning ivosidenib has a more developed, higher-quality evidence base specifically supporting its use earlier in treatment (newly diagnosed disease), not just in the relapsed/refractory setting where enasidenib’s primary approval still sits.

Side effects — overlapping differentiation syndrome risk, but a distinct QT prolongation signal for ivosidenib

The rate of IDH differentiation syndrome with ivosidenib was similar to that observed with enasidenib — meaning this remains the shared, defining risk across both drugs in this class, requiring the same vigilance we discussed for enasidenib.

But ivosidenib carries an additional, distinctive risk that enasidenib does not share to the same degree: treatment-related grade 3 or higher QT interval prolongation occurred in 7.8% of patients in ivosidenib’s pivotal trial, and QT prolongation was reported in 24.6% of patients overall (any grade). Participants may be at increased risk for QT prolongation when ivosidenib is combined with fluoroquinolone antibiotics, azole antifungal medications, or certain anti-nausea drugs (5-HT3 antagonists), requiring careful ECG and electrolyte monitoring, particularly in patients experiencing nausea, vomiting, or diarrhea.

This is a genuinely important, drug-specific monitoring difference: ivosidenib requires baseline and ongoing ECG monitoring that isn’t a defining feature of enasidenib’s safety profile in the same way.

A distinctive enasidenib-specific lab finding

Enasidenib-induced indirect hyperbilirubinemia occurred in 35% of patients, possibly due to off-target inhibition of the UGT1A1 enzyme responsible for bilirubin metabolism — this connects directly to the elevated bilirubin side effect we flagged on the Enasinib product page, and gives it a specific mechanistic explanation: it’s not necessarily liver damage in the traditional sense, but an off-target enzyme interaction affecting bilirubin processing specifically.

An intriguing biological wrinkle — IDH1 and IDH2 mutations may behave differently even with other drugs

Subanalyses of the venetoclax-azacitidine VIALE-A trial found survival benefit and remission rates were notably greater for patients with IDH2-mutated AML (median 27.5 vs 13 months with placebo-azacitidine) than for IDH1-mutated AML (median 10.2 vs 2.2 months with placebo-azacitidine), suggesting these mutation subclasses may be biologically distinct from each other in ways that extend beyond just which specific IDH inhibitor applies. This is a useful, more nuanced point — IDH1 and IDH2-mutated AML aren’t simply interchangeable versions of the same disease responding to interchangeable drugs; they may have meaningfully different biology and treatment response patterns across multiple drug classes, not just the targeted IDH inhibitors themselves.

Combination strategies — both being actively explored beyond monotherapy

Preclinical data confirms synergistic activity of IDH inhibitors plus venetoclax, and a study is evaluating ivosidenib or enasidenib in combination with induction and consolidation chemotherapy, followed by maintenance therapy, in newly diagnosed AML or high-risk MDS patients eligible for intensive chemotherapy with the corresponding IDH1 or IDH2 mutation — indicating active research interest in moving both drugs beyond their original relapsed/refractory monotherapy approval into earlier-line and combination settings.

Bottom line

Enasidenib and ivosidenib aren’t really competing for the same patient — your IDH1 versus IDH2 mutation status determines which one is even relevant to you. Where they can be meaningfully compared is in their evidence maturity and specific safety considerations: ivosidenib has a stronger, phase 3-validated frontline combination indication (with azacitidine) that enasidenib’s primary approval doesn’t currently match, but it comes with a distinctive QT prolongation risk requiring cardiac monitoring that isn’t as central to enasidenib’s safety profile. Differentiation syndrome remains a shared, defining risk across both drugs in this class, requiring the same careful early-treatment vigilance regardless of which one applies to your specific mutation. This is exactly the kind of detail worth confirming directly with your hematologist: which mutation you actually carry, and whether frontline combination therapy or relapsed/refractory monotherapy is the more relevant treatment scenario for your situation.

How does testing work

What is IDH2 mutation and how does enasidenib cause leukemia cells to differentiate?

This is one of the more conceptually elegant mechanisms in our entire conversation — IDH2 mutation doesn’t directly damage DNA the way many cancer-driving mutations do. Instead, it corrupts a normal metabolic enzyme so badly that it starts manufacturing a toxic byproduct that poisons the cell’s ability to read its own genetic instructions correctly, freezing leukemia cells in a permanently immature, dangerous state.

The basic biology — what IDH2 normally does

Isocitrate dehydrogenase 2 (IDH2) is a normal metabolic enzyme that lives inside the mitochondria, the energy-producing structures within cells. Its everyday job is part of the citric acid cycle (also called the Krebs cycle), a fundamental metabolic pathway that helps cells generate energy. Specifically, IDH2 normally converts a molecule called isocitrate into another molecule called alpha-ketoglutarate (α-KG) — a completely ordinary, essential step in healthy cellular metabolism that has nothing to do with cancer in its normal form.

What the IDH2 mutation actually does — a “neomorphic” mutation

This is where things get genuinely unusual compared to most cancer mutations we’ve discussed in this conversation. Most cancer-driving mutations either knock out a gene’s normal function (like a tumor suppressor losing its job) or lock a gene into being permanently overactive in its normal role (like BCR-ABL constantly signaling “grow”). The IDH2 mutation does neither of these things.

Mutated IDH2 proteins neomorphically synthesize 2-hydroxyglutarate — meaning the mutation doesn’t simply break the enzyme or make it work harder at its normal job. Instead, it gives the enzyme an entirely new, abnormal function it didn’t have before: instead of producing normal alpha-ketoglutarate, the mutated enzyme now produces a different molecule called 2-hydroxyglutarate (2-HG), sometimes referred to as an “oncometabolite” because of the damage it goes on to cause.

Why 2-hydroxyglutarate is so destructive — it sabotages epigenetic regulation

2-HG isn’t just a harmless metabolic byproduct — it actively interferes with a whole family of enzymes throughout the cell that depend on normal alpha-ketoglutarate to do their jobs correctly. Many of these affected enzymes are involved in epigenetic regulation — meaning they control which genes get “read” and used by the cell, by adding or removing chemical tags on DNA and the histone proteins DNA wraps around, without changing the underlying genetic code itself.

This results in DNA and histone hypermethylation, which leads to blocked cellular differentiation. In plain terms: 2-HG essentially jams the cell’s epigenetic “settings dial,” causing genes that should be active — particularly the genes responsible for guiding an immature blood cell precursor through its normal maturation process — to become silenced through excessive methylation. The cell’s instruction manual for “how to grow up into a mature, functioning blood cell” gets locked away and ignored.

Why this specifically causes leukemia — cells get stuck as immature blasts

In normal bone marrow, blood cell precursors are constantly maturing from immature stem cells into fully differentiated, functional red blood cells, white blood cells, and platelets. With IDH2-mutated cells, this maturation process gets frozen at an early, immature stage — these stuck cells are called myeloid blasts, and an overwhelming buildup of these non-functional, immature cells crowding out the bone marrow is the defining feature of acute myeloid leukemia.

This is a meaningfully different cancer mechanism than something like uncontrolled cell division alone — IDH2-mutated leukemia isn’t necessarily about cells dividing faster than normal; it’s about cells getting permanently trapped in a dysfunctional, immature, non-differentiated state, accumulating in the bone marrow and blood in a way that crowds out healthy blood cell production.

Medical disclaimer: This page is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Osimertinib is a prescription medication that must only be used under the supervision of a qualified oncologist. Clinical outcomes data is drawn from published Phase III trials; individual results vary. Always consult your healthcare provider and refer to the full prescribing information before making any treatment decisions. Emergency: call your local emergency services or poison control immediately if you experience serious adverse effects.