68Ga-PSMA PET/CT-based metastasis-directed radiotherapy for oligometastatic prostate cancer recurrence after radical prostatectomy.

PURPOSE: The aim of this communication was to assess the efficacy of directed oligometastatic radiotherapy (RT) based on 68Ga-PSMA PET/CT in patients with prostate cancer (PCa) biochemical relapse (BCR) after primary treatment with curative intent. METHODS: This is a retrospective analysis of a monocentric cohort of PCa patients diagnosed with oligometastatic disease on 68Ga-PSMA PET/CT and treated with metastasis-directed RT. Inclusion criteria were: histologically proven PCa, BCR after primary treatment with curative intent, oligometastatic disease defined as ≤ 3 metastatic lesions. To evaluate the efficacy of the therapy, biochemical response defined as a decrease of > 50% of PSA (PSA50) was measured at 1 and 4 months. Patients were followed up until progression and start of androgen deprivation therapy (ADT). BCR-free survival and ADT-free survival were calculated. RESULTS: 20 patients met the inclusion criteria. Median PSA value: 1.4 ng/ml (IQR, 0.3-2.3 ng/ml). A total of 30 PSMA-positive lesions were treated: 18 lymph nodes (60%), nine bone (30%) and three visceral lesions (10%). Median follow-up was 15 months (range 4-33 months). Biochemical response at 1 and 4 months was found in 3/20 patients (15%) and 14/20 (70%), respectively. BCR-free survival rate at 1 year was 79% and 53% at 2 years. ADT-free survival at 2 years was 74%. CONCLUSION: This retrospective study suggests that metastasis-directed RT based on 68Ga-PSMA PET/CT may be a valuable treatment in patients with PCa oligometastatic disease, providing promising BCR-free survival rates and potentially postponing ADT for at least 2 years in 74% of the patients. Response assessment should not be measured before 4 months after treatment.

Value of the 68Ga-DOTATATE PET-CT in the diagnosis of endometriosis. A pilot study.

OBJECTIVE: The non-invasive diagnosis of endometriosis remains challenging. Recent data suggested that somatostatin might be involved in its pathogenesis. High sensitive visualization of somatostatin receptors expression is possible using PET-CT imaging after the administration of a 68Ga-labeled somatostatin analog (DOTATATE) that will bind to the somatostatin receptor sub-types 2 and 5. The aim of the present study was to assess the usefulness of 68Ga-DOTATATE PET-CT in the diagnosis of endometriosis. STUDY DESIGN: This is a prospective, single center pilot study. A pre operative 68Ga-DOTATATE PET-CT was performed in all of the patients who presented with suspected endometriosis and who were scheduled for a laparoscopy. Surgical endometriosis staging and histopathological analysis, including somatostatin receptors SST1, 2 and 5 immunohistochemistry (IHC) of removed specimens, were confronted to the results of the 68Ga-DOTATATE PET-CT. RESULTS: 12 patients were included in this study. 68Ga-DOTATATE PET-CT performed pre operatively showed increased pathologic uptake in four patients with a deep infiltrating endometriosis (DIE) recto-vaginal lesion and in another patient with an adenomyoma. Expression of SST1, 2 and 5 receptors in surgical specimens was confirmed by IHC in these five lesions. Neither superficial peritoneal endometriosis, nor ovarian endometrioma were found to show an increased pathologic uptake on 68Ga-DOTATATE PET-CT. IHC analysis confirmed that SST1, 2, and 5 receptors were not present in these lesions. CONCLUSION: The results observed in this small size series of patients seem to confirm expression of somatostatin receptors only in recto-vaginal DIE and focal adenomyosis lesions. The usefulness of 68Ga-DOTATATE PET-CT in the diagnosis of this entity is uncertain. Future research should concentrate on studying the role of somatostatin in the pathogenesis of DIE.

Molecular imaging as a tool to investigate heterogeneity of advanced HER2-positive breast cancer and to predict patient outcome under trastuzumab emtansine (T-DM1): the ZEPHIR trial.

BACKGROUND: Only human epidermal growth factor receptor (HER)2 status determined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) has been validated to predict efficacy of HER2-targeting antibody-drug-conjugate trastuzumab emtansine (T-DM1). We propose molecular imaging to explore intra-/interpatient heterogeneity in HER2 mapping of metastatic disease and to identify patients unlikely to benefit from T-DM1. PATIENTS AND METHODS: HER2-positive mBC patients with IHC3+ or FISH ≥ 2.2 scheduled for T-DM1 underwent a pretreatment HER2-positron emission tomography (PET)/computed tomography (CT) with (89)Zr-trastuzumab. [(18)F]2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT was performed at baseline and before T-DM1 cycle 2. Patients were grouped into four HER2-PET/CT patterns according to the proportion of FDG-avid tumor load showing relevant (89)Zr-trastuzumab uptake (>blood pool activity): patterns A and B were considered positive (>50% or all of the tumor load 'positive'); patterns C and D were considered negative (>50% or all of the tumor load 'negative'). Early FDG-PET/CT was defined as nonresponding when >50% of the tumor load showed no significant reduction of FDG uptake (<15%). Negative (NPV) and positive predictive values (PPV) of HER2-PET/CT, early FDG response and their combination were assessed to predict morphological response (RECIST 1.1) after three T-DM1 cycles and time-to-treatment failure (TTF). RESULTS: In the 56 patients analyzed, 29% had negative HER2-PET/CT while intrapatient heterogeneity (patterns B and C) was found in 46% of patients. Compared with RECIST1.1, respective NPV/PPV for HER2-PET/CT were 88%/72% and 83%/96% for early FDG-PET/CT. Combining HER2-PET/CT and FDG-PET/CT accurately predicted morphological response (PPV and NPV: 100%) and discriminated patients with a median TTF of only 2.8 months [n = 12, 95% confidence interval (CI) 1.4-7.6] from those with a TTF of 15 months (n = 25, 95% CI 9.7-not calculable). CONCLUSIONS: Pretreatment imaging of HER2 targeting, combined with early metabolic response assessment holds great promise for improving the understanding of tumor heterogeneity in mBC and for selecting patients who will/will not benefit from T-DM1. CLINICALTRIALSGOV IDENTIFIER: NCT01565200.