Prediction of early biochemical response after 177Lu-PSMA radioligand therapy with 68Ga-PSMA PET, a different perspective with quantitative parameters

Abstract

Objective In this study, our aim was to evaluate the relationship of the quantitative data obtained from pretreatment 68Ga prostate-specific membrane antigen (PSMA) PET-computerized tomography (PET/CT) with treatment response of the patients with the diagnosis of metastatic castrationresistant prostate cancer (mCRPC) who received 177Lu-PSMA radioligand therapy (RLT). MethodsThe patients who were given three or four cycles of 177Lu-PSMA RLT between January 2016 and June 2018 were evaluated retrospectively. Volumetric data; PSMA tumor volume (TV) and total lesion (TL) PSMA, were obtained from 68Ga-PSMA PET/CT for whole (PSMA-TV T and TL-PSMA T ). The distance between the two furthest lesions (D max ) was calculated. Posttreatment early prostate-specific antigen (PSA) values on the fourteenth day after treatment were obtained. According to the PSA responses, the patients were divided into two groups as progressed and nonprogressed. In univariate analysis, the relationship of PET quantitative data with biochemical response groups was evaluated with Mann-Whitney U test. Logistic regression was used in multivariate analysis.Results A total of 38 patients were included in the study. In univariate analysis, D max , PSMA-TV T and TL-PSMA T values were obtained at lower levels in the progressed group. In multivariate analysis, only D max was found to be a prognostic factor in predicting early biochemical response. Conclusion D max is the most prognostic parameter in predicting the early biochemical response in patients with mCRPC; high total tumor volume and burden are also parameters that give us an idea about the response to treatment. The success rate will be higher if 177Lu-PSMA RLT treatment is planned for patients with higher tumor volume and spread.

Predictive and prognostic potential of pretreatment 68Ga-PSMA PET tumor heterogeneity index in patients with metastatic castration-resistant prostate cancer treated with 177Lu-PSMA

“…This finding was in contrast to the results of a study by A. Aksu et al. that found that D max was a prognostic parameter for the prediction of early BCR after 177Lu-PSMA therapy ( 36 ). In addition, Fadi Khreish et al.…”

“…They found that SUV min , SUV mean , and kurtosis as RFs and baseline values of hemoglobin and C-reactive protein (CRP), and Eastern Cooperative Oncology Group (ECOG) performance status scale as clinical parameters had a significant impact on OS. Their results were in contrast to other studies that found that conventional PET parameters such as SUV parameters had no predictive value for OS (41)(42)(43).…”

“…We found no significant relationship between BCR and D max , total PSMA-TV, PSMA-TV max , PSMA-TV mean , TL-PSMA max , TL-PSMA mean , total TL-PSMA, and TLR. This finding was in contrast to the results of a study by A. Aksu et al that found that D max was a prognostic parameter for the prediction of early BCR after 177Lu-PSMA therapy (36). In addition, Fadi Khreish et al found that 68Ga-PSMA PET/CTderived TLR could be used as a predictor for PFS after 177Lu-PSMA therapy (37).…”