HCPCS code J9318 – Romidepsin injection, non-lyophilized

Key takeaways

HCPCS code J9318 describes non-lyophilized romidepsin injection, a solution that needs no reconstitution, billed per 0.1 mg administered.

One mg of romidepsin equals 10 units of J9318, so a 25.2 mg dose bills as 252 units.

Lyophilized romidepsin (Istodax) bills under J9319, not J9318. J2796 is a deleted romiplostim code and never applies to romidepsin.

Romidepsin’s FDA-labeled indication is cutaneous T-cell lymphoma after at least one prior systemic therapy. The PTCL indication was withdrawn in 2021, and FDA approval for it ended in May 2022.

Pair J9318 with chemotherapy infusion codes 96413 and 96415, and add JW or JZ on Medicare single-dose vial claims.

HCPCS code J9318: Definition and drug description

HCPCS code J9318 is defined by CMS as “injection, romidepsin, non-lyophilized, 0.1 mg,” with each billing unit representing 0.1 mg administered.

The code sits in the J9000-J9999 chemotherapy drug range of HCPCS Level II. It has been effective since October 1, 2021.

Romidepsin is a histone deacetylase (HDAC) inhibitor, given as an intravenous infusion over four hours. “Non-lyophilized” means the drug is a solution that needs no reconstitution, but it is diluted in 0.9% sodium chloride before infusion.

Amneal announced FDA approval of a romidepsin injection solution, 27.5 mg/5.5 mL in single-dose vials, in June 2026. Amneal’s product is non-lyophilized, so it bills under J9318 (Amneal’s own product information sheet lists NDC 70121-2250-01 under J9318). Confirm it against the current CMS file. Teva had earlier withdrawn its own romidepsin solution. Check which product your pharmacy stocks before you pick the code.

J9318, J9319 or J2796: Which romidepsin code applies?

The formulation in the vial decides the code, not the brand on the order. CMS split romidepsin into two codes in October 2021, both at 0.1 mg per unit.

J2796 shows up on romidepsin claims because the drug names look alike. Romiplostim treats immune thrombocytopenia, and from 2025 it bills under J2802 at 1 microgram per unit. A romidepsin line coded J2796 will deny as an invalid or deleted code.

Watch the unit change too. Under the old J9315, one unit meant 1 mg. Under J9318 and J9319, the same 1 mg is 10 units, so legacy charge masters often under-report the dose tenfold.

How to calculate billing units for HCPCS code J9318

Romidepsin dosing is based on body surface area (BSA). The Istodax label sets the CTCL dose at 14 mg/m², infused over four hours on days 1, 8 and 15 of a 28-day cycle.

1. Multiply the dose in mg/m² by the patient’s BSA in m² to get the mg administered.
2. Divide the mg administered by 0.1, or multiply by 10, to get J9318 units.
3. Subtract the administered mg from the vial content to find any discarded amount.
4. Convert the discarded mg to units the same way and report them on a JW line.

Worked example: A patient with a BSA of 1.8 m² receives 14 mg/m², which is 25.2 mg. That dose bills as 252 units of J9318. A 27.5 mg vial leaves 2.3 mg unused, so a second line reports 23 units with modifier JW. The vial splits between those two lines like this.

On the claim, the drug lines sit beside the infusion codes for the same session.

Bill the dose administered, not the vial size. The administration record must show the exact milligrams given, because that figure supports the unit count. Payer rules on partial units vary, so confirm rounding with each payer before you submit.

Covered indications and diagnosis codes

Romidepsin’s FDA-labeled indication is cutaneous T-cell lymphoma (CTCL) in adults who have received at least one prior systemic therapy. Bristol Myers Squibb withdrew the peripheral T-cell lymphoma (PTCL) indication in August 2021 (FDA formally withdrew approval in May 2022). A confirmatory trial did not meet its primary endpoint.

Most CTCL claims map to three ICD-10-CM categories. Code to the full number in the current tabular, including site and remission characters.

Some payer policies still list PTCL as an accepted diagnosis, often through compendia support. Others treat it as off-label. Read the patient’s plan policy before you schedule the first cycle.

Paired CPT codes for drug administration

J9318 reports the drug only, so the claim also needs an administration code. Romidepsin is an antineoplastic agent, which places its infusion in the chemotherapy administration codes.

Record the infusion start and stop times. Those times are what support the 96415 units, and auditors check them against the claim.

Medicare reimbursement for J9318

Medicare Part B generally pays physician-administered drugs at the Average Sales Price (ASP) plus 6%. CMS updates the payment limit for each code every quarter in the ASP pricing files.

Because the unit is only 0.1 mg, the per-unit payment limit looks small next to older 1 mg codes. Multiply the current limit by your unit count to estimate the line, then check it against the remittance. Strong revenue cycle management tracks these quarterly changes by payer.

NDC reporting requirements

Medicaid requires the 11-digit National Drug Code (NDC) on physician-administered drug claims, and many commercial payers do too. Report the NDC from the vial used, with its qualifier and quantity.

The NDC also proves the formulation. A lyophilized Istodax NDC on a J9318 line is a mismatch that payer edits catch, and the reverse applies to J9319.

Prior authorization requirements

Prior authorization for romidepsin depends on the payer. Original Medicare does not generally require it for Part B drugs, but Medicare Administrative Contractors (MACs) can set coverage criteria.

• Medicare Advantage: Most plans require prior authorization for infused oncology drugs. Criteria are set by the plan.
• Commercial insurers: Expect to send pathology confirming the CTCL subtype and records of prior systemic therapy.
• Medicaid: Rules are state-specific, and many state policies list romidepsin criteria by diagnosis.
• Original Medicare: No national prior authorization, but documentation must still meet MAC coverage criteria.

Check that the authorization names the right code. An approval written for J9319 may not cover a J9318 claim, even for the same patient.

Common claim denials and how to avoid them

Most J9318 denials trace back to the code, the units or the diagnosis. A short pre-submission check catches each of them, and denial management covers the appeal side.

JW and JZ modifiers for romidepsin vials

Medicare requires JW on any discarded amount from a single-dose container. Since July 1, 2023, it also requires JZ when no drug is discarded. CMS sets out both rules in its JW and JZ modifier FAQs.

• Dose uses the whole vial: One J9318 line with modifier JZ.
• Dose leaves drug in the vial: One J9318 line for the units given, plus a JW line for the units discarded.
• Record the waste: Note the vial size, the dose given, the amount discarded and the lot number.

Commercial payer policies on waste vary. Some follow the Medicare rule, while others do not pay for discarded drug at all.

Documentation requirements for compliant billing

The administration record is what supports every number on a J9318 claim. Keep these details in each infusion note:

• Diagnosis, with pathology confirming the CTCL subtype
• Prior systemic therapies, to show the label requirement is met
• Height, weight and calculated BSA on the day of treatment
• Ordered dose in mg/m² and total mg administered
• Product name, NDC, vial size and lot number
• Infusion start and stop times
• Amount discarded, if any

These records also support medical billing compliance if a MAC or payer reviews the claim later.

How Pabau cuts rework on J9318 claims

On many billing teams, a romidepsin claim passes through several manual steps. A biller copies the dose, works out the units and keys the claim into a separate portal. Each hand-off is a chance for the 10-units-per-mg conversion to slip.

In Pabau’s claims management software, each claim is checked for missing or invalid details before it leaves the system. A flagged claim links straight to the field that needs fixing. US claims then go to payers electronically through Claim.MD.

Prior authorizations are stored as cases and attached at booking, so the authorization follows the appointment to the claim. That matters for romidepsin, which runs on a fixed infusion schedule across each cycle.

You can also verify insurance eligibility before the visit and settle payments from electronic remittance advice files. A short-paid drug line shows up when the remittance posts, not months later.

Catch J9318 claim errors before submission

Pabau checks claim details before you send them, submits US claims electronically and settles payments from ERA files. Your team spends less time resubmitting oncology drug claims.

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Conclusion

With romidepsin, the code follows the vial. Romidepsin solution bills as J9318, lyophilized Istodax bills as J9319, and J2796 belongs to a different drug.

The trade-off is the small unit. At 0.1 mg per unit, every milligram becomes 10 units, and an old 1 mg habit under-bills the dose tenfold. Build that conversion into your pre-submission checklist once, so a denial isn’t the first place you find it.

Book a demo to see how Pabau checks claim details before submission and tracks each drug claim through to payment.

Continue your research

Pairing the infusion code? CPT code 96413 explains the first-hour chemotherapy infusion code billed with J9318.

Need guidance on denial codes and appeals? Denial management in healthcare covers CARC-based denial workflows and appeal strategies for drug claims.

Working through the 837P claim format? The 837 file explained details the segments where drug units and NDCs are reported.

Want fewer first-pass rejections? What makes a clean claim walks through the elements payers check before processing a drug code.

Browsing other drug codes? HCPCS Level II codes lists the J-code guides for other injectable and infused drugs.

Frequently asked questions