Updated results from the BEGONIA Phase Ib/II trial for the cohort of patients treated with datopotamab deruxtecan (Dato-DXd) plus Imfinzi (durvalumab) (Arm 7) showed that the combination demonstrated durable tumour responses and no new safety signals in patients with previously untreated advanced or metastatic triple-negative breast cancer (TNBC) with six months additional follow-up from the previous data cut-off.
These data will be presented today in a mini oral session at the European Society for Medical Oncology (ESMO) 2023 Congress in Madrid, Spain (379MO).
Datopotamab deruxtecan is a specifically engineered TROP2-directed DXd antibody drug conjugate (ADC) being jointly developed by AstraZeneca and Daiichi Sankyo.
Approximately 300,000 people worldwide are diagnosed annually with TNBC, the most aggressive breast cancer subtype.1-2 Less than half of patients with metastatic TNBC respond to current 1st-line treatment options which can include chemotherapy alone or in combination with an immunotherapy.2-4 Among patients with tumours that do respond to initial treatment, disease progression is common and rapid, often occurring within two years.2,4-6
Results showed that datopotamab deruxtecan plus Imfinzi, an anti-PD-L1 therapy, demonstrated a confirmed objective response rate (ORR) of 79% (n=49 of 62) including six complete responses (CRs) and 43 partial responses (PRs). Responses were observed regardless of PD-L1 expression level. Median progression-free survival (PFS) was 13.8 months (95% confidence interval [CI] 11-not calculable [NC]) and median duration of response (DoR) was 15.5 months (95% CI: 9.9-NC) with 11.7 months of follow-up.
Peter Schmid, MD, Barts Cancer Institute, London, United Kingdom, and investigator in the trial, said: "These results for datopotamab deruxtecan plus durvalumab in the first-line triple-negative breast cancer setting are highly encouraging, particularly the 79% objective response rate. This magnitude of response is especially notable given the majority of patients in this cohort have PD-L1-low tumours, representing a population for whom treatment has long been limited to standard chemotherapy."
Cristian Massacesi, Chief Medical Officer and Oncology Chief Development Officer, AstraZeneca, said: "Progress in the first-line advanced triple-negative breast cancer setting has been modest for years and new therapeutic strategies are needed to improve outcomes for patients with this aggressive breast cancer subtype. These updated results from the BEGONIA trial reinforce our confidence in the potential for datopotamab deruxtecan to become a new, important treatment modality in this setting as we eagerly await results from our ongoing Phase III triple-negative breast cancer programme."
Mark Rutstein, MD, Global Head, Oncology Clinical Development, Daiichi Sankyo, said: "Disease progression after initial treatment is a reality for patients with triple-negative breast cancer, underscoring the need for more durable treatment options. These findings showcase the potential of datopotamab deruxtecan in previously untreated advanced triple-negative breast cancer and, following the positive results of our TROPION-Breast01 Phase III trial, build on the growing body of evidence for the potential use of this TROP2-directed antibody drug conjugate, alone and in combinations, in several subtypes of breast cancer."
The safety profile of datopotamab deruxtecan in combination with Imfinzi was consistent with the known safety profiles of both agents. Grade 3 or higher treatment-emergent adverse events (TEAEs) occurred in 57% of patients. The most common Grade 3 or higher TEAEs were increased amylase (18%), stomatitis (11%), constipation (2%), fatigue (2%), vomiting (2%) and decreased appetite (2%). There were three interstitial lung disease (ILD) events adjudicated as drug-related by an independent committee including two Grade 2 events and one Grade 1 event.
In Arm 7 of the BEGONIA trial (n=62), the majority of patients (n=54) had tumours with low PD-L1 expression (tumour area positivity [TAP]
Summary of BEGONIA Arm 7 Efficacy Results
