A new case report was published in Volume 12 of Oncoscience on October 9, 2025, titled "Metastatic breast cancer with leptomeningeal carcinomatosis treated with trastuzumab deruxtecan – a case report."

In this report, Cristiana Honrado Martins, José Miguel Rocha, Catarina Portela, Ricardo Fernandes, and Cláudia Caeiro from Hospital de Braga, ULS de Braga, describe a rare case of advanced HER2-positive breast cancer (BC) that had spread to the membranes surrounding the brain and spinal cord—a condition known as leptomeningeal carcinomatosis.

The patient, a 37-year-old woman, initially responded to standard treatment but experienced a relapse two years later.

At that point, her cancer had progressed to involve the central nervous system, severely affecting her neurological function.

Given the complexity of her condition and limited standard options, the medical team initiated off-label treatment with trastuzumab deruxtecan.

Trastuzumab deruxtecan, a targeted antibody-drug conjugate, was selected based on data from recent clinical trials and multidisciplinary discussions.

The patient began to improve after three treatment cycles.

Imaging showed a reduction in the size and extent of the cancer, and her neurological symptoms gradually improved, allowing her to regain independence in daily activities.

She continued on treatment for more than two years, during which the disease in her brain and spinal membranes remained stable.

This case illustrates the potential of antibody-drug conjugates like trastuzumab deruxtecan in treating breast cancers that reach the central nervous system.

It also underscores the need for personalised and flexible treatment approaches in oncology, especially in cases of advanced or treatment-resistant breast cancer.

Therapies like trastuzumab deruxtecan may become important tools for managing these types of tumours.

Source: Impact Journals LLC