Clinical Implications of Tucatinib Approval in Europe 

Thomas Bachelot, MD, PhD: The clinical implications of the approval of tucatinib are quite important, because, as you know, it is the first drug that was developed specifically—it was not developed for this originally, but in the clinical trial this was the case—to include patients with active brain metastases. This drug and trial is the only 1 to have done that. We have a strong rationale to use this combination for patients with active brain metastases. We did not have any randomized studies that had those kind of patients included, so the evidence is very strong; the trial presents strong evidence to use tucatinib for those patients because the data have shown that utilization of this triplet combination—with tucatinib, trastuzumab, and capecitabine—improves the overall survival rate for these patients.

Patients who have a progressive disease, especially patients with brain metastases that did not receive capecitabine before, will be candidates to use this triplet combination. We are very excited about that. Furthermore, even for patients with no brain metastases who have been progressing on T-DM1 [trastuzumab emtansine], this triplet combination can improve overall survival. It will be our first choice for those patients.

Volkmar Mueller, MD: After the approval, tucatinib is going to be the standard treatment after trastuzumab, pertuzumab, and T-DM1 [trastuzumab emtansine], and not only in Germany. We updated our German guidelines at the end of February 2021, and we prefer tucatinib, trastuzumab, and capecitabine as a treatment regimen after the failure of T-DM1 [trastuzumab emtansine].

The landscape is shifting. You might know that trastuzumab, pertuzumab, and T-DM1 [trastuzumab emtansine] are also used in the treatment of early diseases as neoadjuvant and postneoadjuvant treatments, so we are going to have a lot of patients who already had this treatment who might receive this combination with tucatinib in the first-line setting to treat metastatic disease.

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