# Medicare price per gram of monoclonal antibodies

ProteinIQ analysis supporting [How much do monoclonal antibodies cost?](https://www.proteiniq.io/guides/monoclonal-antibody-cost), completed October 6, 2026. Run `python analyze.py` in this directory (Python 3.13, standard library only) to regenerate `medicare-price-per-gram.csv`, `biosimilar-comparison.csv` and `summary.json`.

## Input

`raw/october-2026-medicare-part-b-payment-limit-file.csv` is the Section 508 CSV from the Centers for Medicare & Medicaid Services "October 2026 Medicare Part B Payment Limit Files" (final, posted September 17, 2026), downloaded on October 6, 2026 from https://www.cms.gov/files/zip/october-2026-medicare-part-b-payment-limit-files-final.zip (ZIP SHA-256 `a9b7afa80aae96c43cf84bf0b18648f1974429de2913e2e29d8342747174c417`; CSV SHA-256 `508fba376a29e09994d840f42abd3c4c2dab78e91b4d1256fdb064f2cc5d213f`). The limits apply from October 1 to December 31, 2026 and are based on second-quarter 2026 average sales price (ASP) data.

For most drugs, the payment limit is 106% of the manufacturer's average sales price, which is net of most discounts. For a biosimilar, it is the biosimilar's own ASP plus 6% (or 8%) of the reference product's ASP. Payment limits are therefore closer to what providers pay than list prices are, but they do not capture rebates outside the ASP definition or what any individual patient pays.

## Method

Each row's payment limit was divided by the milligrams in its billing unit (for example, 1 mg, 10 mg or 5 micrograms) and multiplied by 1,000 to give US dollars per gram.

Inclusion: every product in the file whose international nonproprietary name ends in -mab and that is billed by mass, including antibody-drug conjugates, bispecific antibodies and T-cell engagers, and antibody fragments. Each molecule is counted once, at its reference (originator) product's standard code, giving 108 molecules.

Exclusions from the main set: subcutaneous co-formulations with hyaluronidase where a standard code exists for the same antibody (J2351, J9024, J9062, J9144, J9277, J9289, J9311, J9356); the fixed-dose nivolumab and relatlimab combination (J9298); the COVID-19 tocilizumab code (Q0249) and hospital-specific tocilizumab biosimilar codes (Q0234, Q0237, Q0238); Fc-fusion proteins such as abatacept and aflibercept, which are not antibodies; and biosimilars, which are analyzed separately.

Each molecule was assigned one format (conventional full-length antibody, antibody-drug conjugate, bispecific, or fragment) and one primary therapy area by ProteinIQ, based on its main approved use. Therapy areas are a judgment call for drugs with several indications; the CSV records every assignment.

Biosimilars: for the ten reference antibodies with biosimilar codes in the file, we compared the reference product's price per gram with the median of its biosimilars. Ranibizumab (whose reference payment limit is below every biosimilar's) and natalizumab (one biosimilar, paid at parity) are listed in `biosimilar-comparison.csv` but left out of the summary.

## Limitations

Price per gram is not price per treatment. Antibodies given in large doses, such as lecanemab at 10 mg per kilogram every two weeks, have low prices per gram, whereas antibodies dosed in micrograms, such as blinatumomab, have extreme ones. The median is robust to these extremes; the mean is not and is not reported. Antibody-drug conjugate prices are per gram of the whole conjugate, including its drug payload. The file covers only drugs paid under Medicare Part B, so antibodies dispensed mainly through pharmacies under Part D, such as adalimumab and dupilumab, are absent.