Trastuzumab deruxtecan / Metastatic Breast Cancer / Durvalumab · Phase 1 Trial

A Phase 1b Study of T-DXd Combinations in HER2-low Advanced or Metastatic Breast Cancer

ClinicalTrials.gov · August 3, 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 1b registry record for DESTINY-Breast 08, a combination study of trastuzumab deruxtecan (T-DXd) with multiple agents in HER2-low metastatic breast cancer. No results are posted in this registry record; the trial is active and designed to assess safety, tolerability, pharmacokinetics, and preliminary anti-tumour activity.

What was studied

Phase 1, Interventional, Non Randomized, Parallel, Open label, Treatment purpose. Metastatic Breast Cancer; age from 18 Years. Intervention: Module 1: T-DXd + capecitabine; Module 2: T-DXd + durvalumab + paclitaxel; Module 3: T-DXd + capivasertib; Module 4: T-DXd + anastrozole; Module 5: T-DXd + fulvestrant. n = 138. 37 sites across 10 countries.

Key findings

Safety

Registry record only; no efficacy, safety, or outcome data are reported in this source. Primary outcomes are safety and tolerability; efficacy endpoint results are not yet available.

Who this may help

This study will characterise the safety profile and preliminary efficacy signals of T-DXd in combination regimens for HER2-low disease, an area with limited treatment options. Results will inform dose selection and combination strategy for future development.

Plain-language summary

This is a Phase 1b registry record with no posted results; it describes a planned safety and tolerability study of combination therapies in HER2-low metastatic breast cancer with no efficacy data yet reported.

Study design

As stated by the source record.

MethodsPrimary outcome measures: Occurrence of adverse events (AEs)- Part 1 (assessed at Up to follow-up period, approximately 24 months); Occurrence of serious adverse events (SAEs)- Part 1 (assessed at Up to follow-up period, approximately 24 months); Occurrence of adverse events (AEs)- Part 2 (assessed at Up to follow-up period, approximately 24 months); Occurrence of serious adverse events (SAEs)- Part 2 (assessed at Up to follow-up period, approximately 24 months)

DesignPhase 1, Interventional, Non Randomized, Parallel, Open label, Treatment purpose

PopulationMetastatic Breast Cancer; age from 18 Years

Sample size138

InterventionModule 1: T-DXd + capecitabine; Module 2: T-DXd + durvalumab + paclitaxel; Module 3: T-DXd + capivasertib; Module 4: T-DXd + anastrozole; Module 5: T-DXd + fulvestrant

Setting37 sites across 10 countries

Reported figures

Quoted from the source exactly as published.

Planned enrollment138

Study phasePhase 1b

Primary outcome measure (Part 1 & 2)Occurrence of adverse events and serious adverse events up to approximately 24 months follow-up

Clinical bottom line

Caveats

Registry record only; no efficacy, safety, or outcome data are reported in this source.
Recruitment status is 'Active Not Recruiting,' suggesting the study is ongoing but no results are posted.
Primary outcomes are safety and tolerability; efficacy endpoint results are not yet available.
No data on baseline characteristics, arm-specific allocations, or completion/follow-up rates are provided.

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

strong

Phase 1b interventional study with defined safety monitoring and multi-arm structure.

Directness

moderate

Study targets HER2-low metastatic breast cancer; primary focus is safety rather than efficacy.

Consistency

insufficient

Registry record only; no comparative efficacy data or consistency assessment possible.

Risk of bias

insufficient

No methodological detail on blinding, randomisation, or allocation concealment reported.

Sample adequacy

moderate

138 participants enrolled in Phase 1b dose-escalation; adequate for safety characterisation.

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 (NCT04556773). This is a study registration, not published results. Lead sponsor: AstraZeneca. Recruitment status: ACTIVE_NOT_RECRUITING. Phase: PHASE1. Study type: INTERVENTIONAL. Enrollment: 138 participants (ACTUAL). Conditions: Metastatic Breast Cancer. Interventions: DRUG: Trastuzumab deruxtecan; DRUG: Durvalumab; DRUG: Paclitaxel; DRUG: Capivasertib; DRUG: Anastrozole; DRUG: Fulvestrant; DRUG: Capecitabine. Primary outcome measures: Occurrence of adverse events (AEs)- Part 1 , Up to follow-up period, approximately 24 months; Occurrence of serious adverse events (SAEs)- Part 1 , Up to follow-up period, approximately 24 months; Occurrence of adverse events (AEs)- Part 2 , Up to follow-up period, approximately 24 months; Occurrence of serious adverse events (SAEs)- Part 2 , Up to follow-up period, approximately 24 months. Brief summary: DESTINY-Breast 08 will investigate the safety, tolerability, PK and preliminary anti-tumour activity of T-DXd in combination with other therapies in patients with Metastatic HER2-low Advanced or Metastatic Breast Cancer

Follow from this

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

NCT04556773Trastuzumab deruxtecanMetastatic Breast CancerDurvalumabAstraZenecaCapivasertibPaclitaxel