TROPION-Breast01, decision support with HER2DX

Datopotamab deruxtecan shows superior safety profile in advanced breast cancer

By Elizabeth Donald

New safety data from the TROPION-Breast01 trial (N=711) highlight the benefits of datopotamab deruxtecan (Dato-DXd) over traditional chemotherapy in treating pretreated, inoperable, or metastatic HR+/HER2– breast cancer. The study underscored Dato-DXd’s favourable safety profile and potential as a preferred treatment option. The trial compared Dato-DXd with the investigator’s choice of chemotherapy (ICC). Results revealed that the median treatment duration was significantly longer for patients receiving Dato-DXd (6.7 months) compared with those on ICC (4.1 months), indicating sustained tolerability. Importantly, the rate of severe (grade 3 or higher) treatment-related adverse events (TRAEs) was substantially lower with Dato-DXd (21%) versus ICC (45%).

Adverse events of special interest (AESIs) with Dato-DXd included stomatitis/oral mucositis in 56% of patients, ocular events in 40%, and drug-related interstitial lung disease in 3%. Most AESIs were low grade and manageable. For instance, oral mucositis and ocular events were primarily mild (grade 1) and effectively controlled with toxicity management guidelines, resulting in minimal dose interruptions (1% and 3%) and rare discontinuations (0.3% each). Notably, over half of the ocular events were dry eye conditions, detected through mandatory eye exams.

By contrast, ICC was associated with a higher incidence of high-grade neutropenia (31%), leading to more frequent dose interruptions (17%) and reductions (13%). This comparison highlights Dato-DXd’s superior safety profile, with fewer severe adverse events.

The TROPION-Breast01 findings support Dato-DXd as a favourable treatment option for advanced HR+/HER2– breast cancer, providing a promising alternative for patients and healthcare providers

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HER2DX's predictive power in early-stage HER2-positive breast cancer treatment

Recent advances in breast cancer treatment have been spotlighted in two pivotal studies focusing on the efficacy of the HER2DX genomic test, which uses the expression of 27 genes to predict treatment outcomes for patients with HR+ early breast cancer. These investigations underscore the test's potential to facilitate disease management by providing critical insights into chemotherapy response and long-term prognosis.

Study 1: HER2DX pCR score and MRI response

The first study, presented by Tomás Pascual (Hospital Clinic Barcelona, Spain) and colleagues, evaluated the HER2DX pathologic complete response (pCR) score in predicting pCR to anti-HER2 neoadjuvant chemotherapy. Conducted with 147 patients at the Hospital Clinic Barcelona, the study compared the predictive accuracy of the HER2DX pCR likelihood score with that of magnetic resonance imaging (MRI) response. Results indicated that the HER2DX pCR score is a robust predictor of pCR, with an area under the receiver operating characteristics curve of 0.813, compared with just 0.655 for MRI, and was predictive regardless of whether patients had an MRI response to chemotherapy.

The study's findings are significant, showing that HER2DX can guide treatment decisions more effectively than MRI alone

Patients with high HER2DX pCR scores had notably higher pCR rates, suggesting that this genomic test can help oncologists tailor therapies more precisely, potentially improving outcomes and minimising unnecessary treatments.

Study 2: Prospective HER2DX clinical decision impact study

The second study, presented by Olga Martínez-Sáez (Hospital Clinic, Barcelona Spain), was an update from the first prospective clinical decision impact study of HER2DX at the Hospital Clinic of Barcelona. This ongoing observational study involves 128 patients and aims to assess how HER2DX impacts clinical practice. Notably, the study examines changes in treatment plans before and after HER2DX testing.

Results show that HER2DX significantly influences clinical decisions, with 34% of patients having their treatment plans escalated and 66% experiencing de-escalation based on test results. The study also highlights an increase in physician confidence in treatment decisions, from an average rating of 3.8 to 4.6 post-HER2DX testing.

Implications for practice

Professor Diana Lüftner discusses predicting treatment response with the HER2DX genomic test and how this might be applied in the context of the ELEANOR trial. View transcript

The studies together demonstrate HER2DX's potential in managing early-stage HER2-positive breast cancer. By providing a genomic perspective, HER2DX enables more personalised treatment approaches, aligning therapeutic strategies with individual patient profiles, explained Martínez-Sáez. This precision not only enhances the likelihood of positive outcomes but also reduces the physical and emotional burden of overtreatment.