HER2 Positive Breast Cancer / Trastuzumab SC / Breast Cancer · Phase 2 Trial

ATEMPT 2.0: Adjuvant T-DM1 vs TH

ClinicalTrials.gov · August 19, 2026

Preliminary Why this matters to you Expert discussion

Early or partial results. Treat as a signal, not a conclusion.

AI Summary

This is a Phase 2 clinical trial registration comparing adjuvant T-DM1 with trastuzumab SC plus paclitaxel in HER2-positive breast cancer. The study is currently recruiting and has not yet reported results; no outcome data are available to assess efficacy or safety.

What was studied

Phase 2, Interventional, Randomized, Parallel, Open label, Treatment purpose. Breast Cancer, HER2-positive Breast Cancer; age from 18 Years. Intervention: Arm A. T-DM1 followed by Trastuzumab SC; Arm B: Paclitaxel with Trastuzumab SC, followed by Trastuzu…. Compared with: Trastuzumab SC (Herceptin Hylecta) plus Paclitaxel. n = 500. 53 sites: United States.

Key findings

Safety

No comparator efficacy or safety data available from this source.

Who this may help

This trial is in early stages of recruitment and will inform whether T-DM1-based adjuvant therapy offers safety or efficacy advantages over trastuzumab SC with paclitaxel. Results should not yet be used to guide clinical practice.

Plain-language summary

Phase 2 interventional trial still recruiting with no results posted; designed to compare toxicity and disease-free survival in HER2-positive breast cancer but outcome data not yet available.

Study design

As stated by the source record.

MethodsPrimary outcome measures: Incidence of clinically relevant toxicities (CRT) (assessed at First 18 weeks of treatment); Disease Free Survival (DFS) (assessed at Time from randomization to first Disease Free Survival (DFS) event up to 72 mon…)

DesignPhase 2, Interventional, Randomized, Parallel, Open label, Treatment purpose

PopulationBreast Cancer, HER2-positive Breast Cancer; age from 18 Years

Sample size500

InterventionArm A. T-DM1 followed by Trastuzumab SC; Arm B: Paclitaxel with Trastuzumab SC, followed by Trastuzu…

ComparatorTrastuzumab SC (Herceptin Hylecta) plus Paclitaxel

Setting53 sites: United States

Reported figures

Quoted from the source exactly as published.

Planned enrollment500

Primary outcome measure 1Incidence of clinically relevant toxicities (CRT) at first 18 weeks of treatment

Primary outcome measure 2Disease Free Survival (DFS) from randomization up to 72 months

Study phasePHASE 2

Clinical bottom line

Caveats

This is a registry record with no posted results; all outcomes remain unknown.
Recruitment status is RECRUITING; final sample size and data maturity are undetermined.
Registry record does not report blinding, allocation method, or statistical analysis plan.
No comparator efficacy or safety data available from this source.

Evidence assessment

Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.

Study design

moderate

Phase 2 interventional design with planned randomization; two-arm comparison structure.

Directness

strong

Directly examines clinical outcomes (toxicity, DFS) in newly diagnosed HER2-positive breast cancer.

Consistency

insufficient

No results reported; consistency cannot be assessed from registry record alone.

Risk of bias

insufficient

Registry record does not describe blinding, allocation concealment, or other bias mitigation methods.

Sample adequacy

moderate

Estimated enrollment 500 participants; adequate for Phase 2 but actual accrual unknown.

What is missing. This record has no key findings. That is a gap in the analysis, not a judgement about the study.

Source abstract

Registry record from ClinicalTrials.gov (NCT04893109). This is a study registration, not published results. Lead sponsor: Dana-Farber Cancer Institute. Recruitment status: RECRUITING. Phase: PHASE2. Study type: INTERVENTIONAL. Enrollment: 500 participants (ESTIMATED). Conditions: Breast Cancer, HER2-positive Breast Cancer. Interventions: DRUG: trastuzumab-emtansine; DRUG: Trastuzumab SC; DRUG: Paclitaxel. Primary outcome measures: Incidence of clinically relevant toxicities (CRT) , First 18 weeks of treatment; Disease Free Survival (DFS) , Time from randomization to first Disease Free Survival (DFS) event up to 72 months. Brief summary: This research study is studying how well newly diagnosed breast cancer that has tested positive for a protein called HER2 responds using one of two different combination of HER2-directed therapies as a treatment after surgery. The name of the study drugs involved are: * Trastuzumab-emtansine (T-DM1, Kadcyla) * Trastuzumab SC (Herceptin Hylecta) * Paclitaxel

Follow from this

Taken from the source record, never inferred. Follow any of these and new work involving them reaches your briefing.

Dana-Farber Cancer InstituteHER2 Positive Breast CancerNCT04893109Trastuzumab SCBreast Cancertrastuzumab-emtansinePaclitaxel