# Single-arm trial

Source: https://onco.cc/terms/single-arm/  
OnCo record `single-arm` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A trial where everyone gets the new drug and there is no comparison group; success is judged by the share of tumours that shrink and for how long. Fast and small, it underpinned accelerated approvals for larotrectinib, sotorasib, tarlatamab and most CAR-T products, but it cannot show that patients live longer.

## Summary

Single-arm phase 2 trials with objective response rate and duration of response as endpoints supported accelerated approvals for a series of targeted drugs in rare or heavily pretreated populations (larotrectinib, sotorasib, tarlatamab, most CAR-T products) where randomisation was impractical or considered unethical. Their weaknesses are patient selection, lack of a comparator for time-to-event endpoints, and susceptibility to response-evaluable population definitions; the FDA increasingly asks for a randomised confirmatory trial to be under way at approval and has issued guidance on when single-arm data suffice. External or synthetic control arms are attempts to add a comparator after the fact.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: single-arm; single arm; single-arm trial; single-arm phase 2; single-arm study; uncontrolled; non-randomised; nonrandomized; non-randomized; one-arm; open-label single-arm; basket cohort; expansion cohort; phase 2 cohort; expansion cohorts; single-arm studies; single-arm trials

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Single-arm_study_design
- FDA guidance: clinical trial considerations to support accelerated approval of oncology therapeutics: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/clinical-trial-considerations-support-accelerated-approval-oncology-therapeutics

## Connected records

- terms: [Accelerated approval](https://onco.cc/terms/accelerated-approval/), [AMNOG (Germany, 2011)](https://onco.cc/terms/amnog/), [Basket trial](https://onco.cc/terms/basket-trial/), [Basket, umbrella, and platform trials](https://onco.cc/terms/basket-umbrella-platform/), [Blinding (double-blind, open-label, placebo-controlled)](https://onco.cc/terms/double-blind/), [China Drug Administration Law (2019) and expedited pathways](https://onco.cc/terms/china-drug-administration-law/), [Clinical equipoise](https://onco.cc/terms/clinical-equipoise/), [Duration of response (DoR) and disease control rate (DCR)](https://onco.cc/terms/duration-of-response-term/), [External and synthetic control arms](https://onco.cc/terms/external-control-arm/), [Objective response rate (ORR)](https://onco.cc/terms/orr/), [Phase 1, 2 and 3 trials](https://onco.cc/terms/trial-phases/), [Pivotal (registrational) trial](https://onco.cc/terms/pivotal-trial/), [Surrogate endpoint validation: which stand-ins have earned trust](https://onco.cc/terms/surrogate-validation/), [Umbrella trial](https://onco.cc/terms/umbrella-trial/), [Why trials fail: underpowered, wrong endpoint, control arm drift, subgroup fishing, crossover](https://onco.cc/terms/trial-failure-modes/)
- fronts: [Drug Discovery Platforms](https://onco.cc/fronts/drug-discovery/)
- trials: [ARROW (thyroid cohorts)](https://onco.cc/trials/arrow-thyroid/), [Ivermectin with balstilimab or pembrolizumab in metastatic triple-negative breast cancer (Cedars-Sinai phase 1/2)](https://onco.cc/trials/nct05318469/), [L-MIND](https://onco.cc/trials/l-mind/), [NAVIGATE](https://onco.cc/trials/navigate/), [NMTRC003/003B (DFMO maintenance)](https://onco.cc/trials/nmtrc003/), [PATHFINDER 2](https://onco.cc/trials/pathfinder-2/), [Phase III Clinical Study of VC004 in Patients With Localized Advanced/ Metastatic Solid Tumors](https://onco.cc/trials/nct06658353/), [ROAR (anaplastic thyroid cancer cohort)](https://onco.cc/trials/roar-atc/)
- drugs: [Ivermectin](https://onco.cc/drugs/ivermectin/)
- key papers: [A phase 2a clinical study on the safety and efficacy of individualized dosed mebendazole in patients with advanced gastrointestinal cancer](https://onco.cc/key-papers/paper-mansoori-mebendazole-gi-cancer-phase-2a-sci-rep-2021/)

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