Prostate-specific Membrane Antigen Positron Emission Tomography-detected Disease Extent and Overall Survival of Patients with High-risk Nonmetastatic Castration-resistant Prostate Cancer: An International Multicenter Retrospective Study

Previously, we demonstrated that prostate-specific membrane antigen positron emission tomography (PSMA-PET) revealed distant metastases in 109/200 patients (39% distant nodes, 24% bone, and 6% visceral organ) with nonmetastatic castration-resistant prostate cancer (nmCRPC) and high-risk features (International Society of Urological Pathology score ≥4 and/or prostate-specific antigen doubling time ≤10 mo) without metastases by conventional imaging. However, the impact of disease extent determined by PSMA-PET on patient outcomes is unknown. We followed these 200 patients for a median of 43 mo after PSMA-PET and retrospectively assessed the association between patient characteristics, PSMA-PET findings, treatment management, and outcomes using a Kaplan-Meier model and Cox multivariable regressions. Among assessed disease characteristics, polymetastatic disease (five or more distant lesions on PET) was independently associated with shorter overall survival (OS; median 61 mo vs not reached; hazard ratio [95% confidence interval], 1.81 [1.00-3.27]; p = 0.050) and time to new metastases (median 38 vs 60 mo; 1.80 [1.10-2.96]; p = 0.019), and initial pN1 status with shorter OS (55 mo vs not reached; 1.94 [1.12-3.37]; p = 0.019). Following PSMA-PET, locoregional salvage therapies were used most commonly in no/local disease (58%), and androgen receptor signaling inhibitors were used in distant metastatic disease (51%). PSMA-PET provides additional risk stratification for patients with nmCRPC. Polymetastatic disease (five or more distant lesions) is associated with worse outcomes. PATIENT SUMMARY: A novel sensitive imaging technology, called prostate-specific membrane antigen positron emission tomography (PSMA-PET), allows doctors to detect the spread of prostate cancer, known as distant metastases, earlier and more accurately than in the past. In our study, PSMA-PET detected none to many metastases in patients who were considered free of distant metastasis by conventional imaging. These findings predicted outcomes and were used to select appropriate treatment.

Actinium-225 Prostate-specific Membrane Antigen Theranostics: Will α Beat β?

Optimisation of prostate-specific membrane antigen (PSMA) based radioligand therapy (RLT) requires a focus on prospective trials.

A role of PSMA PET/CT in multimodality imaging approach in adenoid cystic carcinoma

Adenoid cystic carcinoma is a rare disease and characterised by slow but unrelenting local progression and risk of haematogenous metastases. We present a case of locally unresectable disease where PSMA PET/CT provided complementary staging and early treatment response assessment.

Mechanistic Insights for Optimizing PSMA Radioligand Therapy

PSMA radioligand therapy is a promising new class of therapy for prostate cancer. Heterogeneity of PSMA expression is an important factor explaining variability in clinical results. The ability to visualize the target with theranostics provides unique mechanistic insights. Potential clinically applicable strategies to improve patient selection and optimize therapeutic efficacy are discussed.See related article by Current et al., p. 2946.

Prognostic biomarkers in men with metastatic castration-resistant prostate cancer receiving [177Lu]-PSMA-617

PURPOSE

We analysed quantitative biomarkers derived from both baseline whole-body imaging and blood serum to identify prognostic markers in patients treated within the lutetium-177 prostate-specific membrane antigen (LuPSMA) phase 2 trial.

METHODS

PET image analysis was carried out using whole-body segmentation quantifying molecular tumour volume (SUV > 3 threshold for PSMA, SUV > liver+2sd for fluorodeoxyglucose (FDG) including SUVmax and SUVmean. For baseline bone scans, EXINI bone scan index (BSI) was used to calculate the percentage of involved bone. Baseline alkaline phosphatase (ALP), lactate dehydrogenase (LDH), prostate specific antigen (PSA) and PSA doubling time were also used in this analysis. We used univariate cox regression analysis and log-rank comparison with optimised cut-offs to find suitable biomarkers prognostic of overall survival from time of enrolment.

RESULTS

This analysis identified FDG-positive tumour volume (FDGvol; HR 2.6; 95% CI, 1.4-4.8), mean intensity of PSMA-avid tumour uptake (PSMAmean; HR 0.89; 95% CI, 0.8-0.98), bone scan index (BSI; HR 2.3; 95% CI, 1.2-4.4), ALP (HR 1.1; 95% CI, 1-1.2) and LDH (HR 1.2; 95% CI, 1-1.5) as biomarkers prognostic of overall survival.

CONCLUSIONS

In addition to established biomarkers, both FDG and PSMA PET/CT parameters have prognostic significance for survival in men undergoing LuPSMA therapy.

Characteristics and outcomes of therapy-related myeloid neoplasms after peptide receptor radionuclide/chemoradionuclide therapy (PRRT/PRCRT) for metastatic neuroendocrine neoplasia: a single-institution series

PURPOSE

Peptide receptor radionuclide/chemoradionuclide therapy (PRRT/PRCRT) is an effective therapy for metastatic neuroendocrine neoplasia (NEN), but therapy-related myeloid neoplasms (t-MN) remain of concern. The study reviewed the clinicopathological features and outcomes of patients who developed t-MN.

METHODS

Retrospective analysis of all patients diagnosed with t-MN by 2016 WHO classification, from a cohort of 521 patients who received PRRT/PRCRT over a 12-year period. Molecular next-generation sequencing using an in-house 26-gene panel was performed.

RESULTS

Twenty-five of 521 (4.8%) patients were diagnosed with t-MN, including six acute myeloid leukaemia (AML) and 19 myelodysplastic syndrome (MDS). The median time from first cycle PRRT/PRCRT to diagnosis of t-MN was 26 months (range 4-91). Twenty-two of 25 (88%) patients had grade 1-2 pancreatic or small bowel NEN with moderate metastatic liver burden. Six patients (24%) had prior chemotherapy. Median number of PRRT cycles = 5 (22/25 (88%) with concomitant radiosensitising chemotherapy). All 25 patients achieved disease stabilisation (68%) or partial response (32%) on RECIST 1.1 at 3 months post-PRRT. At t-MN diagnosis, all patients presented with thrombocytopenia (median nadir 33 × 10⁹/L, range 3-75) and 17 (68%) remained NEN progression-free. Marrow genetic analysis revealed unfavourable karyotype in 16/25 (66%) patients with tumour protein 53 (TP53) mutation in nine (36%). Azacitidine therapy was utilised in ten eligible patients, while four received induction chemotherapy for AML. The median overall survival from first PRRT was 62 months (19-94), but from t-MN diagnosis was only 13 months (1-56), with death due primarily to haematological disease progression.

CONCLUSIONS

The diagnosis of t-MN after PRRT/PRCRT is an infrequent but serious complication with poor overall survival. Most patients present with thrombocytopenia; unfavourable genetic mutations have a poor response to t-MN treatment. Prospective data are needed to explore potential pre-existing genetic factors and predictive biomarkers to minimise the risk of t-MN.

Preoperative Positron Emission Tomography for Node-Positive Head and Neck Cutaneous Squamous Cell Carcinoma

Objectives

Surgery is the primary treatment modality for node-positive cutaneous squamous cell carcinoma of the head and neck with no distant disease (HNcSCC-M0). The role of preoperative positron emission tomography/computed tomography (PET/CT) scan for these patients is unclear. We compared preoperative PET/CT with final histopathology among patients undergoing lymphadenectomy and/or parotidectomy for HNcSCC-M0.

Study Design

Case series with chart review.

Setting

Single Australian center.

Subjects and Methods

Investigation included disease parameters and preoperative CT and PET/CT findings of 64 patients with node-positive HNcSCC without distant metastatic disease. Fisher’s exact test was used to test for a difference in the proportion of patients with chronic lymphocytic leukemia between the false- and true-negative PET/CT subgroups.

Results

Of 64 patients who underwent PET/CT prior to surgery for node-positive HNcSCC-M0, 56 underwent a neck dissection and 30, a parotidectomy. Of these, 13 neck dissections and 2 parotidectomies were performed in the absence of FDG-avid (18F-fludeoxyglucose) nodes in these nodal fields. The PET/CT positive predictive value of the neck was 91.1%. The negative predictive values in the neck and parotid regions were 60%. Of the false-negative subgroup, 66.7% had chronic lymphocytic leukemia, compared with 11.1% of the true-negative subgroup ( P = .09). Based on PET/CT findings, surgical plans according to preoperative CT were changed for 6.25% of patients.

Conclusion

Use of PET/CT for surgical candidates with node-positive HNcSCC-M0 has high specificity and positive predictive value with relatively low sensitivity and negative predictive value. A statistical trend toward a higher rate of chronic lymphocytic leukemia among patients with false-negative results is suggested.

Gallium-68 DOTA-TATE Positron Emission Tomography/Computed Tomography: Scintigraphic Changes of Adrenal Glands Following Management of Ectopic Cushing's Syndrome by Steroidogenesis Inhibitors

In the era of emerging functional imaging techniques, an understanding of the effects of hormonal therapies on the scintigraphic appearance of endocrine organs is desirable to minimize the erroneous scan interpretation. The mechanisms by which changes in the scintigraphic appearance of endocrine organs occur however sometimes remain ambiguous. This case demonstrates the gallium-68 (Ga-68) DOTA-TATE positron emission tomography/computed tomography (CT) appearance of adrenal glands following management with steroidogenesis inhibitors. The potential mechanisms underlying this change are discussed. A 17-year-old boy with adrenocorticotropic hormone (ACTH) dependent Cushing's syndrome secondary to ectopic ACTH secretion underwent pre- and post-metyrapone and dexamethasone treatment Ga-68 DOTA-TATE scans 4 months apart. Pretreatment, both adrenals demonstrated normal symmetrical prominent Ga-68 DOTA-TATE uptake and normal CT appearance. The posttherapy scan revealed marked symmetrical suppression of Ga-68 DOTA-TATE uptake, but with bilateral adrenal hypertrophy on CT.