FDA Fast-Tracks Oral Arsenic Trioxide Agent for Rare AML Subtype

The FDA has awarded fast track designation to QTX-2101, an investigational oral arsenic trioxide therapy, for the treatment of patients with acute promyelocytic leukemia (APL).¹

Agents granted this designation enter the FDA’s program intended to facilitate the development and expedite the review of novel agents for treatment of serious conditions. Also known as AML-M3, APL is a rare, aggressive subtype of acute myeloid leukemia (AML) characterized by the PML-RARA gene fusion.²

Therapeutic advances have shifted the prognosis of this once highly lethal disease to a largely curable malignancy, with current treatments typically incorporating anthracycline-based chemotherapy or intravenous (IV) arsenic trioxide (Trisenox). However, the frequent and lengthy infusion requirements associated with IV treatment may place substantial demands on patients and clinics, potentially disrupting daily life and straining healthcare delivery systems.

QTX-2101, an oral capsule formulation of arsenic trioxide, aims to overcome the limitations of IV arsenic trioxide by simplifying treatment administration while maintaining precise dosing and stability.

“While survival rates in APL are favorable, treatment-related burden and tolerability remain significant challenges,” said Shaad Abedin, MD, chief medical officer at Quetzal Therapeutics, in a news release.³ “Our oral capsule formulation is designed to address key limitations of [IV] arsenic trioxide, with the goal of making treatment more accessible and manageable for patients and providers.”

Clinical Development of QTX-2101

The designation follows the recent December 2025 launch of an ongoing, global, randomized phase 3 trial of QTX-2101. This trial is evaluating the efficacy, safety, and pharmacokinetics of QTX-2101 against standard-of-care therapy in patients with newly diagnosed APL.³

The initiation of this study builds upon earlier favorable assessments of the agent’s pharmacokinetic and safety profile in prior phase 1 studies (NCT03048344; NCT04996030). According to findings from one of the studies published in Blood Advances, QTX-2101 demonstrated similar pharmacokinetics to IV arsenic trioxide, potentially supporting clinical equivalence between the 2 formulations.⁴

The study also reported an encouraging safety profile that was consistent with previous reports. The agent was well tolerated by patients at the 15 mg dose level, with most adverse events being low grade.

“The [pharmacokinetics] and safety data generated from this study support further development of [QTX-2101] in APL,” wrote study authors Ravandi et al in the publication.⁴ “Although this study was not designed or powered to formally demonstrate bioequivalence, the comparable exposures observed along with clinical outcomes reported with other formulations of [arsenic trioxide] demonstrate that oral [QTX-2101] can be expected to provide equivalent efficacy to [arsenic trioxide] IV and would significantly reduce the treatment burden for patients, allowing for an all-oral treatment regimen for APL.”

REFERENCES

1. QTX-2101 awarded FDA fast track designation for the treatment of acute promyelocytic leukemia. News release. Quetzal Therapeutics. January 29, 2026. Accessed February 2, 2026. https://tinyurl.com/md34r7pk

2. Ali H, Durugu SR, Agrawal S, et al. Epidemiology and survival outcomes of acute promyelocytic leukemia in adults: A SEER database analysis. Blood. 2024;144(Supplement 1):5943-5943. doi:10.1182/blood-2024-202192

3. Quetzal Therapeutics launches phase III clinical trial of oral QTX-2101 for acute promyelocytic leukemia (APL). News release. Quetzal Therapeutics. December 3, 2025. Accessed February 2, 2026. https://tinyurl.com/4fs36mbm

4. Ravandi F, Rangaraju S, Kantarjian H, et al. A pharmacokinetic and safety study of oral arsenic trioxide in patients with acute promyelocytic leukemia. Blood Adv. 2025;9(9):2136-2143. doi:10.1182/bloodadvances.2024015453