What Is Darinaparsin? Definition and What Research Reports

Definition

Darinaparsin — also referred to in the literature by the research code ZIO-101 and marketed in Japan as DARVIAS injection — is a small-molecule organic arsenical, formed by conjugating a dimethylated arsenic species to glutathione, the naturally occurring tripeptide γ-glutamyl-cysteinyl-glycine. A 2009 review in Expert Opinion on Investigational Drugs described darinaparsin as a novel organic arsenical investigated for anticancer activity (PMID 19780704). It is a prescription oncology agent in the jurisdiction where it has been approved, not a dietary ingredient, supplement or research peptide. This page is for educational purposes only and is not medical advice; consult a licensed physician for any question about diagnosis, treatment or medication.

What Class of Molecule Is It, and Where Does It Come From?

Darinaparsin belongs to the arsenicals — a drug class whose best-known member is inorganic arsenic trioxide. Where arsenic trioxide is an inorganic salt, darinaparsin is organic: the arsenic atom carries two methyl groups and is bound to the sulfur of a glutathione molecule. It is manufactured synthetically; nothing about it is extracted from a natural source, although both of its structural components (dimethylated arsenic metabolites and glutathione) occur in mammalian biology.

That glutathione linkage is chemically meaningful rather than decorative. Researchers have reported that darinaparsin produces a cellular response distinguishable from that of arsenic trioxide, and the 2009 study describing that work found the compound active in an arsenic trioxide–resistant myeloma cell line (PMID 19417148). In other words, the organic form is not simply a repackaged version of the inorganic one in the models that have been examined.

Why the term appears in peptide reference lists

Darinaparsin is not a peptide therapeutic. It contains a tripeptide — glutathione — as part of its structure, and glutathione is itself a frequent subject in peptide and thiol-biochemistry literature. That structural overlap is the main reason the name surfaces alongside peptide terminology. Readers scanning peptide glossaries should file darinaparsin under "small-molecule conjugate containing a peptide fragment," not under peptide hormones, secretagogues or peptide analogues.

How the Term Is Used in the Research Literature

• As an oncology investigational agent. Most published uses of the word describe cancer-directed research, from cell-line work to registration trials.
• As a comparator to arsenic trioxide. Papers frequently position darinaparsin against the inorganic arsenical to ask whether the organic form behaves differently (PMID 19417148).
• As a mechanistic probe. One 2015 report identified darinaparsin as an inhibitor of hedgehog signaling while studying prostate tumor-initiating cells (PMID 25381261).
• As a combination partner in preclinical models. A 2023 study in Acta Pharmacologica Sinica reported that darinaparsin enhanced the sensitivity of small-cell lung cancer models to PARP inhibitors (PMID 36253561).

What the Published Literature Reports

Laboratory and animal work

Preclinical reports have covered several tumor types. A 2023 paper in the International Journal of Molecular Sciences examined cytotoxic effects of darinaparsin against human leukemia cells (PMID 36768603). The 2015 Molecular Cancer Therapeutics study reported inhibition of prostate tumor-initiating cells and of Du145 xenograft growth, and characterized the compound as a hedgehog signaling inhibitor (PMID 25381261). In a different direction, a 2013 radiation-oncology study described darinaparsin as a tumor radiosensitizer while reporting radioprotection and cell cycle arrest in intestinal epithelial cells (PMID 24210080) — a dual observation that researchers have used to argue for tissue-dependent effects.

Early-phase clinical studies

A phase I clinical trial published in Clinical Cancer Research in 2009 evaluated darinaparsin in patients with refractory solid tumors (PMID 19584162). A phase II study published in Investigational New Drugs assessed the compound in patients with advanced hepatocellular carcinoma (PMID 19565187). A separate 2013 case report in Frontiers in Pharmacology followed response and resistance to darinaparsin in a single patient with acute myeloid leukemia (PMID 23408639). These are early-phase and single-patient reports; they describe what was observed in specific study populations and are not generalizable statements about outcomes.

Peripheral T-cell lymphoma and first approval

The clinical program that led to marketing authorization focused on relapsed or refractory peripheral T-cell lymphoma (PTCL). An Asian phase 2 study published in Blood Advances in 2023 reported results for darinaparsin in patients with relapsed or refractory PTCL (PMID 36661315). A 2022 review in Drugs summarized the compound's first approval (PMID 36331780), and a 2023 Japanese pharmacology review described the pharmacological profile and clinical study results for the organic arsenic product DARVIAS injection 135 mg in relapsed or refractory PTCL (PMID 37673618). Approval status is jurisdiction-specific and this page does not attempt to summarize regulatory status outside the cited sources.

Quick Reference Table

Adverse Events: What Studies Report

Safety characterization for darinaparsin appears within its clinical trial reports rather than in standalone tolerability papers. Dose-finding and safety assessment were part of the phase I evaluation in refractory solid tumors (PMID 19584162), and safety outcomes were reported alongside efficacy in the Asian phase 2 study in relapsed or refractory peripheral T-cell lymphoma (PMID 36661315). The 2023 Japanese review covered the pharmacological profile and clinical study results underpinning the approved product (PMID 37673618), and the 2022 Drugs review summarized the evidence package associated with first approval (PMID 36331780). Because arsenicals as a class carry recognized organ-system monitoring requirements, the specific event rates, gradings and monitoring parameters belong to the prescribing information and the primary reports themselves, not to a glossary summary.

What Darinaparsin Is Not

• Not a peptide therapeutic. The glutathione tripeptide is a structural component, not the active pharmacological class.
• Not a research-use-only peptide product. Published work describes it as an investigational and, in one jurisdiction, approved oncology medicine (PMID 36331780).
• Not interchangeable with arsenic trioxide. Researchers reported a distinct cellular response and activity in an arsenic trioxide–resistant myeloma line (PMID 19417148).
• Not a general-wellness compound. Every cited human study was conducted in cancer populations.

Summary for Reference Use

In one line: darinaparsin is a synthetic organic arsenical built on a glutathione conjugate, studied principally in hematologic and solid tumor oncology, with a phase 2 dataset in relapsed or refractory peripheral T-cell lymphoma (PMID 36661315) supporting a first approval reviewed in 2022 (PMID 36331780). Anyone encountering the term in a peptide context should recognize the peptide element as the glutathione fragment only.

References

• Darinaparsin: First Approval (Drugs, 2022)
• Darinaparsin: a novel organic arsenical with promising anticancer activity (Expert Opinion on Investigational Drugs, 2009)
• Pharmacological profile and clinical study results of darinaparsin (DARVIAS injection 135 mg), an organic arsenic product, for relapsed or refractory peripheral T-cell lymphoma (Folia Pharmacologica Japonica, 2023)
• Darinaparsin (ZIO-101) enhances the sensitivity of small-cell lung cancer to PARP inhibitors (Acta Pharmacologica Sinica, 2023)
• Radioprotection and cell cycle arrest of intestinal epithelial cells by darinaparsin, a tumor radiosensitizer (International Journal of Radiation Oncology Biology Physics, 2013)
• Monitoring Response and Resistance to the Novel Arsenical Darinaparsin in an AML Patient (Frontiers in Pharmacology, 2013)
• Darinaparsin in patients with relapsed or refractory peripheral T-cell lymphoma: results of an Asian phase 2 study (Blood Advances, 2023)
• Darinaparsin inhibits prostate tumor-initiating cells and Du145 xenografts and is an inhibitor of hedgehog signaling (Molecular Cancer Therapeutics, 2015)
• A phase I clinical trial of darinaparsin in patients with refractory solid tumors (Clinical Cancer Research, 2009)
• Cytotoxic Effects of Darinaparsin, a Novel Organic Arsenical, against Human Leukemia Cells (International Journal of Molecular Sciences, 2023)
• Darinaparsin induces a unique cellular response and is active in an arsenic trioxide-resistant myeloma cell line (Molecular Cancer Therapeutics, 2009)
• Phase II study of darinaparsin in patients with advanced hepatocellular carcinoma (Investigational New Drugs, 2010)