Evidence review: Open Peptide Project (verified against primary PubMed, ClinicalTrials.gov & FDA records) · Last checked 2026-10-27. ← Back to Evidence Library
Romidepsin (Istodax, FK228): what the evidence says
At a glance
What it is: a natural bicyclic depsipeptide from the bacterium Chromobacterium violaceum that inhibits histone deacetylases (HDACs). Approved as Istodax in Nov 2009. The current label lists only CTCL after at least one prior systemic therapy. R1, R2 UNVERIFIED the bacterial source and the 2021 date of the PTCL withdrawal (no primary source opened).
What the evidence says: Human in the Ro-CHOP phase 3 trial (previously untreated PTCL), adding romidepsin to CHOP did not significantly improve progression-free survival (12.0 vs 10.2 months, p = 0.054). R3 UNVERIFIED the single-arm CTCL trials behind approval (not opened).
Biggest risks: UNVERIFIED specific label warnings (not opened in full).
Rating
| Human Human evidence | Moderate: CTCL single-arm data; Ro-CHOP RCT negative R3 |
| Animal Animal / lab evidence | Not reviewed |
| Regulatory | FDA-approved R1 · not on FDA's 503A or 503B bulk-substance category lists and not on FDA's compounding safety-risk page R4, R5, R6 · not named by WADA R7 |
| Established human dose | Yes, label dose (see Study details) |
Evidence verdict: Cutaneous T-cell lymphoma: Moderate (approved on single-arm trials) · Peripheral T-cell lymphoma: failed phase 3 (indication withdrawn)
This page reports what studies used. It is not dosing advice.
Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source
About the evidence: approval rests on single-arm response data; the only big randomized trial was negative.
What is it?
Related pages: carfilzomib, bortezomib.
Does it work?
- Human Ro-CHOP: PFS 12.0 vs 10.2 months, not significant. R3
Is it safe?
- Unknown Safety details not reviewed for this draft.
Gray-market vials: extra risks
A gray-market vial has no quality control and no guarantee of identity, strength or sterility. We test retail vials blind under the Open Peptide Standard; see /tests/. A passing test covers one batch on one date and does not mean the compound is safe.
Is it legal?
- US: FDA-approved for CTCL, prescription; generic approved 2026. R1, R8, R2
- Compounding: not on FDA's 503A or 503B bulk-substance category lists and not on FDA's compounding safety-risk page. R4, R5, R6
- Sport: not named on WADA's 2026 Prohibited List. R7
Study details
Study details
These are amounts researchers used, not recommendations.
| Study | People / model | Route | Amount used | Follow-up | Reported | Citation |
|---|---|---|---|---|---|---|
| Ro-CHOP final 2024 | Untreated PTCL | IV + CHOP | Per study | Median 6 years | PFS 12.0 vs 10.2 months (p = 0.054) | PMID 38364196 |
Full reference list (PubMed, CT.gov, FDA and WADA checked Oct 27, 2026)
- R1 Drugs@FDA, Istodax (romidepsin), application NDA022393 (openFDA drugsfda record checked Oct 27, 2026). https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=NDA022393
- R2 Romidepsin injection prescribing information, label published Sep 4, 2025 (DailyMed, checked Oct 27, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=61894b77-f29c-4a81-ad85-bd3a698233a4
- R3 Camus V, et al. J Clin Oncol. 2024. PMID 38364196
- R4 FDA, 503A bulk drug substances categories list (updated May 14, 2026). https://www.fda.gov/media/94155/download
- R5 FDA, 503B bulk drug substances categories list (updated Mar 21, 2025). https://www.fda.gov/media/94164/download
- R6 FDA, Certain bulk drug substances for use in compounding that may present significant safety risks (content current Apr 22, 2026). https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
- R7 WADA. The 2026 Prohibited List, full list checked; compound not named. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf
- R8 Drugs@FDA, romidepsin generic, approved Jun 2, 2026, application ANDA219099 (openFDA drugsfda record checked Oct 27, 2026). https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=ANDA219099
Disclaimer
This page is for education and harm reduction, not medical advice or a recommendation to use Romidepsin (Istodax, FK228). This is a prescription medicine. Use it only under the care of a licensed clinician; do not buy it from research-chemical or gray-market sellers. Report problems to FDA MedWatch (https://www.fda.gov/safety/medwatch).