(UroToday.com) In the on-demand poster session of the European Society for Medical Oncology (ESMO) Annual Congress, Dr. Madan provided an assessment of a semi-automated method of assessing Sodium Fluoride (NaF) PET using a novel technology. This is particularly relevant given that current and emerging PET platforms are enhancing clinicians’ ability to evaluate metastatic lesions in mCRPC.
To do so, the authors examined 18 patients with mCRPC who were treated with enzalutamide with or without prostvac on a trial (NCT01867333). This trial demonstrated no difference between the two treatment approaches, allowing for collective analysis. Each patient had serial CT, Tc99, and NaF PET scans and was treated until radiographic progression (rPD) regardless of PSA.
Lesions detected on NaF were automatically detected and matched across timepoints using AIQ technology in keeping with a previously utilized methodology. The lesion-level response was categorized as completely responding, partially responding, stable, progressive disease, or new lesions (either completely new or return of a resolved lesion).
Among the 18 patients with mCRPC who were evaluated with serial NaF scans, the median PSA at study initiation was 8.2 ng/ml, the median age was 65 years, and the median time on treatment was 21 months. Of the 18 patients included, 14 ultimately had rPD based on conventional imaging. Over the study interval, the 18 included patients underwent a total of 67 serial NaF studies which were evaluated. 233 lesions completely resolved after starting treatment, of which 52 (22%) eventually returned while on therapy. In addition to these lesions, 394 new lesions were seen during treatment but 112 (28%) resolved. Fourteen of 18 pts (78%) had new lesions that ultimately improved after appearing.
Among the 14 patients who eventually had disease progression, there was an average of 11.7 new lesions compared to baseline. In the 4 patients who had stable Tc99 throughout treatment, there was an average of 9.8 new lesions seen on serial NaF.
These authors conclude that serial NaF PET-CT can illustrate dynamic changes in patients with mCRPC treated with enzalutamide. Further, interval development of lesions visible on NaF PET may not predict rPD seen on Tc99.