Medications
Avapritinib (Ayvakit)
A once-daily tablet (Ayvakit) that blocks KIT and PDGFRA growth signals; it treats gastrointestinal stromal tumors (GIST) with a PDGFRA exon 18 change, advanced systemic mastocytosis, and indolent systemic mastocytosis.
How Medicare covers it
Part D (forms used at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.
| Coverage details | |
|---|---|
| Part B status | No avapritinib row in the CMS Part B Spending by Drug HCPCS file (RY26, data through 2024) — no J-code basis; coverage path is Part D. |
| Medicare Advantage | Most Medicare Advantage plans that include drug coverage (MAPD plans) use the same formulary-and-tier system; the plan's own drug list decides coverage and copay — check the plan's formulary. |
| Medicare Supplement (Medigap) | Medicare Supplement (Medigap) plans sold today do not include prescription drug coverage; drug coverage comes from Part D or an MAPD plan. |
What it treats
Ayvakit (avapritinib) treats three conditions in adults: (1) unresectable (cannot be removed by surgery) or metastatic gastrointestinal stromal tumor (GIST) harboring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation, including PDGFRA D842V mutations; (2) advanced systemic mastocytosis (AdvSM), which includes aggressive systemic mastocytosis (ASM), systemic mastocytosis with an associated hematological neoplasm (SM-AHN), and mast cell leukemia (MCL); and (3) indolent systemic mastocytosis (ISM). Ayvakit is not recommended for patients with AdvSM or ISM whose platelet counts are less than 50 x 10^9/L.
What it is for, in depth
Ayvakit is a targeted cancer and mast cell medicine for adults whose disease is driven by specific KIT or PDGFRA gene changes. For GIST — a tumor of the stomach or bowel wall — it is used when the tumor cannot be removed by surgery or has spread and carries a PDGFRA exon 18 mutation, including the D842V mutation that does not respond to older kinase inhibitors; patients are selected by testing the tumor for that mutation. It also treats systemic mastocytosis, a disorder in which too many mast cells build up in organs: the advanced forms (aggressive systemic mastocytosis, systemic mastocytosis with an associated blood neoplasm, and mast cell leukemia) and the slower indolent form. The dose differs by condition — 300 mg daily for GIST, 200 mg for advanced systemic mastocytosis, and 25 mg for indolent systemic mastocytosis — and treatment continues while it is helping and side effects are acceptable. It comes as tablets in 25 mg, 50 mg, 100 mg, 200 mg, and 300 mg strengths, taken once a day on an empty stomach.
How it works
Avapritinib is a tyrosine kinase inhibitor. It targets KIT D816V, PDGFRA, and PDGFRA D842 mutants, as well as several KIT exon 11, 11/17, and 17 mutants. In GIST and systemic mastocytosis, changes (mutations) in the KIT or PDGFRA genes switch these growth receptors on all the time, driving tumor cells and mast cells to multiply. By blocking those receptors, avapritinib slows or stops that growth signaling.
How it is taken
Ayvakit is taken by mouth once daily on an empty stomach, at least 1 hour before or 2 hours after a meal. The recommended dosage is 300 mg once daily for GIST, 200 mg once daily for advanced systemic mastocytosis, and 25 mg once daily for indolent systemic mastocytosis. Treatment continues until disease progression or unacceptable toxicity. It comes as 25 mg, 50 mg, 100 mg, 200 mg, and 300 mg tablets.
Common side effects
The most common adverse reactions depend on the condition treated. In GIST (20% or more): edema (swelling), nausea, fatigue/asthenia (weakness), cognitive impairment, vomiting, decreased appetite, diarrhea, increased lacrimation (tearing), abdominal pain, constipation, rash, dizziness, and hair color changes. In advanced systemic mastocytosis (20% or more): edema, diarrhea, nausea, and fatigue/asthenia. In indolent systemic mastocytosis (10% or more): eye edema, dizziness, peripheral edema, and flushing.
Serious warnings
Serious intracranial hemorrhage (bleeding inside the skull) may occur with Ayvakit; it occurred in 2.9% of patients with GIST or AdvSM in clinical trials and fatal events occurred in less than 1%, and Ayvakit must be permanently discontinued if intracranial hemorrhage of any grade occurs. Watch for risk factors such as a history of vascular aneurysm, prior intracranial hemorrhage or stroke, use of anticoagulant drugs, or low platelets, and seek immediate care for headache, nausea, vomiting, vision changes, or altered mental status. A broad spectrum of cognitive effects (such as memory impairment and confusion) can occur and may require holding, reducing, or stopping the drug depending on severity. Ayvakit can cause photosensitivity, so limit direct ultraviolet exposure during treatment. It can cause fetal harm (embryo-fetal toxicity).
Who should be careful
Ayvakit is not recommended for patients with AdvSM or ISM who have platelet counts below 50 x 10^9/L, because of the bleeding risk. Tell your doctor if you have a history of brain aneurysm, bleeding in the brain, stroke, low platelets, or if you take anticoagulant (blood thinner) drugs, because of the intracranial hemorrhage risk. Patients should be monitored for cognitive effects and should limit sun and ultraviolet exposure because of photosensitivity. Females and males of reproductive potential should use effective contraception because Ayvakit can cause fetal harm, and patients should not breastfeed during treatment. There are no contraindications listed in the label.
Major interactions
Avoid coadministration of Ayvakit with strong or moderate CYP3A inhibitors, which increase avapritinib levels and may increase the incidence and severity of adverse reactions; if a moderate CYP3A inhibitor cannot be avoided in patients with GIST or AdvSM, the Ayvakit dose is reduced. Avoid coadministration with strong or moderate CYP3A inducers, which decrease avapritinib levels and may decrease efficacy. Coadministration with hormonal contraceptives containing ethinyl estradiol may increase ethinyl estradiol exposure and its adverse reactions, and in patients with GIST the label's recommendations should be followed for CYP3A substrates with a narrow therapeutic range.
Cost and saving notes
If this drug is covered under your Medicare Part D plan and the cost is high, you can ask your plan for a tier exception to pay a lower cost share. If you have limited income, Extra Help (the Part D Low-Income Subsidy) can lower your Part D premiums and drug costs. In 2027, your total yearly out-of-pocket spending on covered Part D drugs is capped at $2,400, and you can spread those costs out in monthly payments through the Medicare Prescription Payment Plan.
Why it is in its tier
Avapritinib (Ayvakit) sits on Tier 5 in 96.91% of the plans that list it (5325 of 5495 listing plans). Tier 5 is the specialty tier — instead of a flat copay, patients usually pay a percentage of the drug's cost (coinsurance), which is why specialty drugs feel expensive even with coverage. The data-visible drivers: It is a brand-only product with no generic version in the formulary data, and the CMS dashboard puts its average Part D spending at about $292,553 per beneficiary for 2024 — among the highest-cost drugs in the program, which matches where plans place it. It is listed by 100.0% of Part D plans. The tier shown is the most common one; individual plans vary.
Sources
- AYVAKIT (AVAPRITINIB) TABLET, FILM COATED [BLUEPRINT MEDICINES CORPORATION] — DailyMed
- MedlinePlus — National Library of Medicine
- MedlinePlus — Avapritinib: MedlinePlus Drug Information
What official patient guides say
In daily life, avapritinib (Ayvakit) is one tablet routine you build around meals. You take it once a day, at about the same time each day, on an empty stomach — at least 1 hour before a meal or at least 2 hours after one — exactly as your prescription label directs. If you vomit after a dose, do not take another one; just go on with your regular schedule. If you miss a dose, take it as soon as you remember, unless your next dose is due in less than 8 hours, in which case skip it and never double up. Keep the tablets in their original container, tightly closed, at room temperature away from light, heat, and moisture, and out of children's reach. The medicine can make you dizzy, drowsy, or confused, so do not drive until you know how it affects you, and protect your skin from strong sunlight with clothing, sunglasses, and sunscreen during treatment and for a week after your last dose. Keep all doctor and lab appointments, and tell your doctor how you are feeling, because your dose may be lowered or paused if side effects become a problem.
Source: MedlinePlus — Avapritinib: MedlinePlus Drug Information
Part D formulary coverage
| Formulary summary | |
|---|---|
| Most common tier | 5 |
| Plans listing this drug | 5495 |
| Total Part D plans | 5495 |
| Share of plans listing it | 100 |
| Formularies listing it | 286 |
| Tier | Plans |
|---|---|
| Tier 1 | 123 plans |
| Tier 2 | 1 plans |
| Tier 4 | 46 plans |
| Tier 5 | 5325 plans |
Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.
What you pay
| With Medicare Part D | |
|---|---|
| Most common tier | Tier 5 |
| Typical copay | $0 — half of plans charge between $0 and $0 |
| Typical coinsurance | 26.0% of the price |
| Based on | 5237 plans that cover this drug · 2027 plan year |
A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.
Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-07
Similar medications
Other medications in the same FDA pharmacologic class (Kinase Inhibitor):
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Part D spending averages (2024)
| Brand name | Generic name | Total claims 2024 | Total spending 2024 | Total beneficiaries 2024 | Rank by beneficiaries 2024 |
|---|---|---|---|---|---|
| Ayvakit | Avapritinib | 4023 | 1.60027e+08 | 547 | 2065 |
Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30
Companies covering this drug
5,495 plans from 509 companies list this drug on a formulary for 2027. Search by company or plan name, or filter by tier. Cost sharing is the plan's published amount for this drug's tier in the initial coverage stage (1-month retail supply), where the plan publishes it; a blank means the plan does not publish it.
| Company | Plan | Tier | Copay | Coinsurance |
|---|
A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.
Coverage and costs change. Drug lists (formularies), tiers, and copays can change during the year and differ by plan. Always check with your insurance company or plan directly to confirm what is covered and what you will pay.
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