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Sandy Srinivas, MD
Sandy Srinivas, MD
Posted: Tuesday, February 27, 2024
A phase II randomized trial showed that diffusion-weighted magnetic resonance imaging (DWI) may help to predict bone metastasis and disease response in men with metastatic castration-resistant prostate cancer being treated with radium-223. Chris Parker, MD, of The Royal Marsden NHS Foundation Trust, London, and colleagues observed a heterogeneous response to treating patients with radium-223 and patients developing new bone metastases during treatment. These findings were published in the JNCI Cancer Spectrum.
“DWI is set to be a valuable tool in the clinic, particularly in patients with bone-only metastases, to document early response, early progression, and heterogenous response without the need for a confirmatory scan, thus enabling a more accurate tailoring of treatment,” said the study authors.
This study included men with metastatic castration-resistant prostate cancer and bone metastases. Eligible patients were randomly given 55 or 88 kBq/kg of radium-223 every 4 weeks for six cycles. Whole-body DWI was performed at baseline, at cycles 2 and 4, and after treatment to monitor the apparent diffusion coefficient. The primary endpoint was reaching a 30% increase in global median apparent diffusion coefficient for treatment to be considered beneficial.
A total of 133 lesions were evaluated in 36 patients, and 14 of the 36 evaluable patients had a disease response from the DWI. This finding suggests interpatient and intrapatient heterogeneity of response between both patients and between different metastases in the same patient. The mean administered activity of radium-223 per cycle was not associated with global MRI response (P = .216). However, the mean administered activity of radium-223 was associated with a DWI response using a five-target lesion evaluation (P = .007). In 26 of 36 patients (72%), new bone metastases, not present at baseline, were seen on DWI scans during radium-223 treatment. This finding suggests a lack of activity against micrometastases, according to the investigators.
Disclosure: For full disclosures of the study authors, visit academic.oup.com.
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