About this trial

This study is a single arm Phase 2 clinical trial where patients before their definitive surgery will be treated with trastuzumab deruxtecan (T-DXd) 5.4mg/kg intravenously every three weeks for up to six cycles. A mandatory biopsy at Cycle 2 Day 14 (+/- 4 days) of starting T-DXd will be performed for the RNA Disruption Index (RDI) score assessment that will be used to predict an effectiveness of study treatment. Depending on the RDI score results some patients will have imaging assessments performed at the end of Cycle 4 and if scans will show absence of remaining tumour they will stop study treatment and proceed to surgery after four cycles of treatment. Other patients will continue treatment until six cycles are completed.

Patient Profile

Patient with newly diagnosed early stage HER2-positive breast cancer with tumour size larger than 2cm

Where’s this trial being run?

Beaumont Hospital, Cork University Hospital, St James’s Hospital, St Vincents University Hospital, and University Hospital Limerick

Can I join this study / trial?

The first thing you do is to talk to your doctor and/or the cancer trials research team in your hospital. The contact details for the cancer trials research units in Ireland is here.

Why not Print this page and bring it with you. It will help your doctor and research team advise you.

For more detailed information


Here’s a list of questions you may have for your doctor or local cancer research team.

Summary Data

Name: SHAMROCK study
Number: 22-01
Full Title:

Single arm phase 2 trial of neoadjuvant trastuzumab deruxtecan (T-DXd) with response-directed definitive therapy in early stage HER2-positive breast cancer: a standard chemotherapy-sparing approach to curative-intent treatment – SHAMROCK study

Principal Investigator: Prof. Bryan Hennessy
Type: In-House

Cancer Trials Ireland

Recruitment Started: Global: 26-Oct-2023
Ireland: 26-Oct-2023
Global Recruitment Target: 80
Ireland Recruitment Target: 80