Natalizumab: Tysabri and 1 biosimilar

1 biosimilar bill against Tysabri (J2323). On average they are paid ↑ 2.0% relative to the reference product per 1 MG in 4Q26.

Tysabri (reference)
Tyruko

Payment limit per 1 MG, last 8 quarters. Reference product as the thick navy line, biosimilars in teal and other colors.

All products

Product	Code	CMS description	Per 1 MG	vs. reference	CMS 8% add-on note	8 quarters
Tysabri	J2323	Natalizumab injection	$23.927	Reference	–
Tyruko	Q5134	Inj, tyruko, 1 mg	$24.397	↑ 2.0%	No

Payment limits are from the CMS 4Q26 file. Which products are grouped together comes from the site’s biosimilar groups list (reference/biosimilar_groups/2026-10-17T183707Z_d3109bb50c53.csv), checked by hand; it is not a CMS file. “CMS 8% add-on note” shows whether CMS’s notes say the 8% of reference product add-on was applied.

Medicare Part B usage

Natalizumab market in Medicare

$152.0M Medicare Part B spending, 2025 (preliminary)

21,691 claims in 2025 (preliminary); 6,782,989 billing units (1 mg each) in 2024

0.0% of 2025 claims were for biosimilars, vs. 0.0% in 2024

$34.7M spending so far in 2026 (Q1, preliminary)

Spending by product

Market share (share of claims)

Tysabri (reference)
Tyruko

Medicare Part B fee-for-service spending and claims by calendar year. Years marked “prelim.” come from CMS’s quarterly spending file and will be replaced when CMS publishes the yearly file. Market share is each product’s percent of the group’s claims that year; claims are used because the quarterly file has no dosage units. A product with no bar for a year is not in CMS’s file for that year.

By product

Product	Spending 2024	Units 2024	Spending per unit 2024	Spending 2025 (prelim.)	Claims 2025	Share of claims 2025	Spending 2026 (Q1)
Tysabri J2323	$158,815,402.00	6,782,989	$23.4137785	$152,041,606.46	21,691	100.0%	$34,713,828.80
Tyruko Q5134	–	–	–	–	–	–	–

Spending, units and claims are CMS figures; spending per unit is CMS’s own average for 2024. Units are billing units, which can differ between codes, so compare units only between codes billed per the same amount. Shares are this site’s calculation from CMS claims. CMS may count spending differently in its quarterly and yearly files, so treat changes between 2024 and 2025 with care.

Physician-billed use by state, 2024

From CMS’s Physician & Other Practitioners by Geography and Service file, which covers drugs billed by physicians and other practitioners, mostly in offices. Drugs billed by hospital outpatient departments are not in it. For these products it covers 49.7% of 2024 Medicare units. CMS leaves out a state’s row for a product when fewer than 11 patients received it, so small states may undercount.

Hover over a state to see its figure. Territories and states with no data are in the table.

Show 31 states and territories

State	Services (billing units)	Biosimilar share
New York	331,509	0.0%
Florida	302,714	0.0%
Texas	227,401	0.0%
North Carolina	219,620	0.0%
California	219,609	0.0%
Utah	203,514	0.0%
Illinois	191,700	0.0%
Alabama	144,600	0.0%
Tennessee	127,800	0.0%
Ohio	115,224	0.0%
Maryland	108,917	0.0%
Virginia	102,300	0.0%
Michigan	102,000	0.0%
South Carolina	90,900	0.0%
Pennsylvania	84,601	0.0%
New Jersey	80,700	0.0%
Georgia	79,200	0.0%
Minnesota	68,110	0.0%
Massachusetts	63,029	0.0%
Arizona	51,600	0.0%
Colorado	48,604	0.0%
Alaska	43,201	0.0%
Kansas	37,200	0.0%
Indiana	36,000	0.0%
Arkansas	32,400	0.0%
Nevada	30,002	0.0%
Connecticut	29,700	0.0%
Washington	25,204	0.0%
Oklahoma	24,300	0.0%
Wisconsin	24,000	0.0%
Rhode Island	22,200	0.0%

Sources: 2026-06-25_DSD_PTB_RY26_P06_V10_DYT24_HCPCS-260602.csv, 2026-05-21_MUP_PHY_R26_P05_V10_D24_Geo.csv.gz, 2026-07-23_qddptb_r2603_p06_v10_dqt2601_260722.csv (data.cms.gov).