Can SPECT/CT Guidance Facilitate Personalized Dosing for Patients with Prostate Cancer?

Single-photon emission computed tomography (SPECT) could play a significant role in monitoring and altering regimens for the use of Lu-177-PSMA (Pluvicto, Novartis) in treating metastatic castration-resistant prostate cancer (mCRPC).

In a recent interview at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) conference in Chicago, Andrew Nguyen, MBBS, FRACP, AANMS, discussed findings from a new study that looked at the use of SPECT imaging and diagnostic computed tomography (CT) after weekly treatment with Lu-177-PSMA in 125 men with mCRPC. After the second dose in a six-week treatment plan, Dr. Nguyen and colleagues assessed imaging and prostate-specific antigen (PSA) levels to determine whether treatment should be continued or altered, according to the study.

Overall, the researchers said the use of early biomarkers to monitor treatment response led to 60 percent of patients having greater than 50 percent PSA reduction, a median PSA progression-free survival (PFS) of 6.1 months and a mean overall survival of 16.8 months.

For men who demonstrated a marked early reduction in PSA level and partial treatment response on SPECT imaging, they were allowed to cease treatment until PSA levels increased, necessitating re-treatment. Study findings revealed these patients had nearly double the median PSA-PFS (12.1 months) of patients who had a stable initial treatment response and proceeded to have the full six-week treatment course (6.1 months).

“These men could afford a treatment holiday with a mean of (6.1) months, potentially improving quality of life in men who may have treatment fatigue and side effects,” noted Dr. Nguyen, MBBS, FRACP, AANMS, a senior staff specialist in the Department of Theranostics and Nuclear Medicine at St. Vincent’s Hospital in Sydney, Australia.

(Editor’s note: For related content, see “Clarity Pharmaceuticals to Begin Phase 3 Trial for New PSMA PET Agent for Prostate Cancer,” “A Closer Look at Urinary Activity and PET Radiopharmaceuticals for Prostate Cancer Imaging” and “Deep Learning Network Shows Significant Potential for Prostate Cancer Detection on MRI.”)

For patients who had a rise in PSA level and progressive disease on SPECT imaging after initial treatment, Dr. Nguyen said they had limited PSA progression-free survival at 2.6 months. However, Dr. Nguyen pointed out that the opportunity to switch those who weren’t responding to initial treatment to alternative therapy led to “moderate” median survival of 11.2 months for this patient population.

“Identifying early disease progression using early response biomarkers may allow the opportunity for an alternative potentially effective treatment,” added Dr. Nguyen.

For more insights from Dr. Nguyen, watch the video below.