Trastuzumab Deruxtecan Shows Promise in Metastatic Prostate Cancer Case

Key Insights

• A case study reports significant tumor reduction in a metastatic prostate cancer patient treated with trastuzumab deruxtecan (T-DXd) after failing multiple lines of therapy.
• The patient, who had HER2-positive prostate cancer, experienced a 57% reduction in tumor volume, including brain metastases, after four cycles of T-DXd.
• This outcome suggests T-DXd's potential in aggressive prostate cancer and emphasizes the importance of HER2 testing to identify candidates for targeted therapies.

A recent case study published in the Annals of Internal Medicine suggests that fam-trastuzumab deruxtecan-nxki (T-DXd) may offer a new treatment avenue for aggressive metastatic prostate cancer, particularly in patients with HER2-positive tumors. The study highlights a significant response in a patient who had exhausted other treatment options, showcasing the potential of targeted therapies in advanced prostate cancer.

Remarkable Response to T-DXd

The case report details a 60-year-old male with stage IV metastatic prostate cancer who had previously undergone multiple unsuccessful lines of therapy. After testing positive for HER2 expression via immunohistochemistry, the patient was treated off-label with T-DXd starting in February 2024. Following four cycles of T-DXd, the patient exhibited a 57% reduction in overall tumor volume, including a reduction in brain metastases. This response was particularly striking given the patient's prior lack of response to other treatments and the initial prognosis that suggested hospice care.

Clinical Improvement and Continued Treatment

As of November 2024, the patient was reported to be in good clinical condition and has continued to receive T-DXd treatment for 9 months. In contrast, the patient's previous three lines of treatment for advanced prostate cancer provided only 3 to 4 months of benefit each, underscoring the potential impact of T-DXd in this case.

Implications for HER2 Testing in Prostate Cancer

"This case highlights the promising potential of T-DXd in treating patients with prostate cancer, particularly aggressive types of disease," stated Dr. Maneesh Jain, an oncologist at the George Washington University School of Medicine and Health Sciences. He further emphasized the importance of routine HER2-expression testing in advanced prostate cancer, which could help identify more patients who might benefit from targeted therapies like T-DXd.

The findings suggest that HER2 testing could become a more routine practice in advanced prostate cancer to identify patients who may benefit from T-DXd treatment. This approach aligns with the broader trend toward personalized medicine, where treatment decisions are guided by the specific molecular characteristics of a patient's tumor.