Salivary toxicity from PSMA-targeted radiopharmaceuticals: What we have learned and where we are going.

Clinical trials of prostate-specific membrane antigen (PSMA) targeted radiopharmaceuticals have shown encouraging results. Some agents, like lutetium-177 [177Lu]Lu-PSMA-617 ([177Lu]Lu-PSMA-617), are already approved for late line treatment of metastatic castration-resistant prostate cancer (mCRPC). Projections are for continued growth of this treatment modality; [177Lu]Lu-PSMA-617 is being studied both in earlier stages of disease and in combination with other anti-cancer therapies. Further, the drug development pipeline is deep with variations of PSMA-targeting radionuclides, including higher energy alpha particles conjugated to PSMA-honing vectors. It is safe to assume that an increasing number of patients will be exposed to PSMA-targeted radiopharmaceuticals during the course of their cancer treatment. In this setting, it is important to better understand and mitigate the most commonly encountered toxicities. One particularly vexing side effect is xerostomia. In this review, we discuss the scope of the problem, inventories to better characterize and monitor this troublesome side effect, and approaches to preserve salivary function and effectively palliate symptoms. This article aims to serve as a useful reference for prescribers of PSMA-targeted radiopharmaceuticals, while also commenting on areas of missing data and opportunities for future research.

Low PSA radiographic disease progression on C11-choline PET.

Background: For men with prostate cancer, radiographic progression may occur without a concordant rise in prostate-specific antigen (PSA). Our study aimed to assess the prevalence of radiographic progression using C-11 choline positron emission tomography (PET) imaging in patients achieving ultra-low PSA values and to evaluate clinical outcomes in this patient population. Methods: In a single institution study, we reviewed the prospectively maintained Mayo Clinic C-11 Choline PET metastatic prostate cancer registry to identify patients experiencing radiographic disease progression (rDP) on C-11 choline PET scan while the PSA value was less than 0.5 ng/mL. Disease progression was confirmed by tissue biopsy or response to subsequent therapy. Clinicopathologic variables were abstracted by trained research personnel. Overall survival was estimated using the Kaplan-Meier method. Intergroup differences were assessed using the log-rank test. A univariate and multivariate Cox regression model was performed to investigate variables associated with poor survival after rDP. Results: A total of 1323 patients within the registry experienced rDP between 2011 and 2021, including 220 (16.6%) men with rDP occurring at low PSA level. A median (interquartile range [IQR]) of 54.7 (19.7-106.9) months elapsed between the time of prostate cancer diagnosis and low PSA rDP, during which 173 patients (78%) developed castration-resistant prostate cancer (CRPC). Sites of low PSA rDP included local recurrence (n = 17, 8%), lymph node (n = 90, 41%), bone (n = 94, 43%) and visceral metastases (n = 19, 9%). Biopsy at the time of rDP demonstrated small-cell or neuroendocrine features in 21% of patients with available tissue. Over a median (IQR) follow-up of 49.4 (21.3-95.1) months from the time of low PSA rDP, 46% (n = 102) of patients died. Factors associated with poorer survival outcomes include advanced age at rDP, CRPC status, bone and visceral metastasis (p value <0.05). Visceral metastases were associated with decreased overall survival (p = 0.009 by log-rank) as compared with other sites of rDP. Conclusions: Men with prostate cancer commonly experience metastatic progression at very low or even undetectable PSA levels. Periodic imaging, even at low absolute PSA values, may result in more timely identification of disease progression.

Genomic attributes of prostate cancer across primary and metastatic noncastrate and castrate resistant disease states: a next generation sequencing study of 183 patients.

Primary prostatic adenocarcinoma (pPC) undergoes genomic evolution secondary to therapy-related selection pressures as it transitions to metastatic noncastrate (mNC-PC) and castrate resistant (mCR-PC) disease. Next generation sequencing results were evaluated for pPC (n = 97), locally advanced disease (involving urinary bladder/rectum, n = 12), mNC-PC (n = 21), and mCR-PC (n = 54). We identified enrichment of TP53 alterations in high-grade pPC, TP53/RB1 alterations in HGNE disease, and AR alterations in metastatic and castrate resistant disease. Actionable alterations (MSI-H phenotype and HRR genes) were identified in approximately a fifth of all cases. These results help elucidate the landscape of genomic alterations across the clinical spectrum of prostate cancer.

Treatment modalities and survival outcomes in prostate cancer parenchymal brain metastasis.

BACKGROUND: Prostate cancer (PCa) parenchymal brain metastases are uncommon and troubling observations in the course of the disease. Our study aims to evaluate the prevalence of brain metastases among PCa patients while reporting various therapeutic modalities, clinical features, and oncological outcomes. METHODS: We retrospectively identified 34 patients with parenchymal brain metastasis out of 4575 patients using a prospectively maintained database that contains clinicopathologic characteristics of PCa patients between January 2012 and December 2021. Based on the three treatment modalities used, the patients were divided into three groups: stereotactic radiosurgery (SRS), whole brain radiotherapy (WBRT), and systemic therapy alone. The Kaplan-Meier curve was used to calculate overall survival [OS] probability and the Cox proportional hazards regression model was used to compare between groups. RESULTS: At the time of brain metastasis diagnosis, the median age was 66 years, the median (interquartile range [IQR]) prostate-specific antigen (PSA) was 2.2 (0.1-26.6) ng/ml and the median (IQR) months from initial PCa diagnosis to brain metastasis development was 70.8 (27.6-100.9). The median (IQR) primary Gleason score was 8 (7-9) and over a median (IQR) follow-up time of 2.2 (1.2-16.5) months, 76.5% (n = 26) of the patients died. Thirteen (38.2%) patients had solitary lesion, whereas 21 (61.8%) had ≥2 lesions. The lesions were supratentorial in 19 (55.9%) patients, infratentorial in six (17.6%), and both sides in nine (26.5%). Among all 34 patients, 10 (29.4%) were treated with SRS, seven (20.6%) with WBRT, and 17 (50%) with systemic therapy alone. OS varied greatly between the three treatment modalities (log-rank test, p = 0.049). Those who were treated with SRS and WBRT had better OS compared with patients who were treated with systemic therapy alone (hazard ratio: 0.37, 95% confidence interval: 0.16-0.86, p = 0.022). CONCLUSIONS: In our single-institutional study, we confirmed that PCa brain metastasis is associated with poor survival outcomes and more advanced metastatic disease. Furthermore, we found that SRS and WBRT for brain metastasis in patients with recurrent PCa appear to be associated with improved OS as compared with systemic therapy alone and are likely secondary to selection bias.

Early PSA decline after starting second-generation hormone therapy in the post-docetaxel setting predicts cancer-specific survival in metastatic castrate-resistant prostate cancer.

BACKGROUND: The objective of this study was to evaluate the prognostic value of early PSA decline following initiation of second-generation hormone therapy (2nd HT), namely abiraterone acetate or enzalutamide, in patients with taxane-refractory metastatic castrate-resistant prostate cancer (mCRPC) and evaluate utility of this metric in informing intensified surveillance/imaging protocols. METHODS: We retrospectively identified 75 mCRPC patients treated with 2nd HT following docetaxel failure (defined as PSA rise and radiographic progression). Patients were categorized patients into two cohorts based on the first PSA within 3 months after initiation of therapy: PSA reduction ≥50% (Group A) and PSA reduction <50% (Group B). The primary endpoint was cancer-specific mortality (CSM). The secondary endpoint was radiographic disease progression (rDP) on 2nd HT. In univariate and multivariate analyses, we investigated factors associated with rPD and CSM. RESULTS: We included 75 patients (52 in Group A, 23 in Group B) in the analytic cohort. Baseline clinico-demographic characteristics, including median age, primary Gleason score risk group, median pre-treatment PSA, disease burden, site of metastases, and pre-treatment ECOG score were not statistically different between the two groups. Median follow up time was 30 months and the median time to radiographic disease progression was 28.1 and 12.5 months (p = 0.002) in cohorts A and B, respectively. On univariate and multivariate analyses, both PSA reduction ≥50% and volume of metastatic disease were significantly associated with a decreased risk of radiographic disease progression (HR 0.41, 95% CI 0.21-0.80, p = 0.0113) as well as a decreased risk of cancer-specific mortality (HR 0.29, 95% CI 0.09-0.87, p = 0.0325). CONCLUSION: PSA reduction ≥50% within 3 months of starting 2nd HT was associated with significantly improved radiographic disease progression-free survival and 3-year cancer-specific mortality. This suggests using PSA 50%-decline metric in surveillance patients with on 2nd HT and identifies patients who require further evaluation with imaging.

Coping Mechanisms for Financial Toxicity Among Patients With Metastatic Prostate Cancer: A Survey-based Assessment.

PURPOSE: Assessments of financial toxicity among patients with metastatic prostate cancer are lacking. Using patient surveys, we sought to identify coping mechanisms and assess characteristics associated with lower financial toxicity. MATERIALS AND METHODS: Surveys were administered to all patients seen at a single center's Advanced Prostate Cancer Clinic over a 3-month period. Surveys included the COST-FACIT (COmprehensive Score for Financial Toxicity) and coping mechanism questionnaires. Patients with metastatic disease (lymph nodes, bone, visceral) were included for analysis. Coping mechanisms were compared between patients experiencing low (COST-FACIT >24) vs high (COST-FACIT ≤24) financial toxicity using Fisher's exact test. Multivariable linear regression was used to evaluate characteristics associated with lower financial toxicity. RESULTS: Overall, 281 patients met inclusion criteria of which 79 reported high financial toxicity. In multivariable analysis, characteristics associated with lower financial toxicity included older age (estimate: 0.36, 95%CI: 0.21-0.52), applying for patient assistance programs (estimate: 4.42, 95%CI: 1.72-7.11), and an annual income of at least $100,000 (estimate: 7.81, 95%CI: 0.97, 14.66). Patients with high financial toxicity were more likely to decrease spending on basic goods (35% vs 2.5%, P < .001) and leisure activities (59% vs 15%, P > .001), as well as use savings (62% vs 17%, P < .001) to pay for their treatment. CONCLUSIONS: In this cross-sectional study, patients with metastatic prostate cancer and high financial toxicity were more likely to decrease spending on basic goods and leisure activities and use savings to pay for care. Understanding the impact of financial toxicity on patients' lives is crucial to inform shared decision-making and interventions designed to mitigate financial toxicity in this population.

Addressing the need for more therapeutic options in neuroendocrine prostate cancer.

INTRODUCTION: Neuroendocrine prostate cancer (NEPC) is an aggressive form of prostate cancer frequently seen after prolonged treatment of castration resistant prostate cancer (CRPC). NEPC has become increasingly prevalent over the last 20 years, with a poor prognosis caused by a late diagnosis and limited treatment options. Recent advances in PET/CT imaging and targeted radioimmunotherapy are promising, but more research into additional treatment options is needed. AREAS COVERED: The aim of this review is to analyze the current imaging and treatment options for NEPC, and to highlight future potential treatment strategies. A Pubmed search for 'Neuroendocrine Prostate Cancer' was performed and relevant articles were reviewed. EXPERT OPINION: The recent FDA approval and success of 177 PSMA Lutetium in CRPC is promising, as 177 Lutetium could potentially be paired with a NEPC specific biomarker for targeted therapy. Recent laboratory studies pairing DLL3, which is overexpressed in NEPC, with 177 Lutetium and new PET agents have showed good efficacy in identifying and treating NEPC. The success of future development of NEPC therapies may depend on the availability of 177 Lutetium, as current supplies are limited. Further research into additional imaging and treatment options for NEPC is warranted.

Neuroendocrine prostate cancer (NEPC) is a rare form of prostate cancer. People with NEPC have typically had previous treatment for prostate cancer. NEPC is usually found after prostate cancer cells have spread outside of the prostate. NEPC may not produce typical prostate cancer markers such as prostate specific antigen (PSA). This can make detection of NEPC difficult. NEPC is difficult to treat because NEPC does not respond very well to typical prostate cancer medications. Because of this, people with NEPC typically have a shortened survival. Many researchers have been developing new ways to find and treat NEPC. New methods of imaging with PET/CT scans are better at detecting NEPC than standard imaging. Treatments that specifically target NEPC cells are currently being researched, but these treatments have not been used on any patients yet. This article describes these research efforts and recommends that more research should be done to find treatments for NEPC.

Metastasis-directed Therapy Without Androgen Deprivation Therapy in Solitary Oligorecurrent Prostate Cancer.

PURPOSE: As controversy remains regarding the role of metastasis-directed therapy in patients with oligometastatic prostate cancer, we sought to characterize outcomes of metastasis-directed therapy without concomitant androgen deprivation therapy in the specific subset of patients with a solitary metastatic lesion on C-11 choline positron emission tomography imaging whose primary tumor has already been treated. MATERIALS AND METHODS: We identified 124 consecutive prostate cancer patients from 2008 to 2018 with a solitary oligorecurrent metastatic lesion on positron emission tomography imaging who were treated with metastasis-directed therapy without androgen deprivation therapy from the Mayo Clinic C-11 choline registry. Metastasis-directed therapy consisted of either stereotactic body radiation therapy or surgical excision. RESULTS: Of these 124 patients, 67 were treated with surgery (median follow-up 54 months) and 57 patients were treated with stereotactic body radiation therapy (median follow-up 53 months). Of patients treated with surgery, 80.5% had >50% decline in prostate specific antigen at first follow-up, and the 3-year radiographic progression-free survival was 29%. Median time to initiation of systemic therapy in this cohort was 18.5 months (interquartile range 8.4-44.7 months). Meanwhile, for patients treated with stereotactic body radiation therapy, 40.3% had >50% decline in prostate specific antigen at first follow-up, and the 3-year radiographic progression-free survival was 17%. Similarly, median time to initiation of systemic therapy was 17.8 months (interquartile range 7.1-42.3 months). CONCLUSIONS: This study represents the first reported series of metastasis-directed therapy without androgen deprivation therapy in patients with solitary oligorecurrent metastatic prostate cancer. These results suggest that metastasis-directed therapy without androgen deprivation therapy can delay initiation of systemic therapy and highlight the need for further prospective study for select patients with solitary metastatic recurrences of prostate cancer.

Out-of-Pocket Cost Burden Associated With Contemporary Management of Advanced Prostate Cancer Among Commercially Insured Patients.

PURPOSE: Out-of-pocket costs represent an important component of financial toxicity and may impact patients' receipt of care. Herein, we evaluated patient-level factors associated with out-of-pocket costs for contemporary advanced prostate cancer treatment options. MATERIALS AND METHODS: We identified all commercially insured men receiving treatment for advanced prostate cancer between 2007 and 2019 within the OptumLabs Data Warehouse®. Patients were categorized into 3 treatment groups: androgen deprivation monotherapy, novel hormonal therapy, and nonandrogen systemic therapy. The primary outcome was out-of-pocket costs in the first year of treatment. The associations of treatment and patient variables with out-of-pocket costs were assessed using multivariable regression models. All costs were adjusted to reflect 2019 U.S. dollars using the Consumer Price Index. RESULTS: In a cohort of 13,409 men 81% (n = 10,926) received androgen deprivation monotherapy, 6% (n = 832) novel hormonal therapy, and 12% (n = 1,651) nonandrogen systemic therapy. Mean treatment-related out-of-pocket costs in the first year were $165, $4,236, and $994 for androgen deprivation monotherapy, novel hormonal therapy, and nonandrogen systemic therapy, respectively. The adjusted difference in annual treatment-related out-of-pocket costs for novel hormonal therapy and nonandrogen systemic therapy were $2,581 (95% CI: $1,923-$3,240) and $752 (95% CI: $600-$903) higher than androgen deprivation monotherapy, respectively. Patient characteristics associated (P < .05) with higher treatment-related out-of-pocket costs included older age (65-74 years), Black race, lower comorbidity scores, and lower household income. CONCLUSIONS: Patients receiving novel hormonal therapy for advanced prostate cancer had substantially higher treatment-related out-of-pocket costs. In addition to raising awareness among prescribers, these data support the inclusion of treatment associated financial toxicity in shared decision making for advanced prostate cancer and call attention to subgroups of patients particularly vulnerable to financial toxicity.

Tumor-Derived Extracellular Vesicles Predict Clinical Outcomes in Oligometastatic Prostate Cancer and Suppress Antitumor Immunity.

PURPOSE: SABR has demonstrated clinical benefit in oligometastatic prostate cancer. However, the risk of developing new distant metastatic lesions remains high, and only a minority of patients experience durable progression-free response. Therefore, there is a critical need to identify which patients will benefit from SABR alone versus combination SABR and systemic agents. Herein we provide, to our knowledge, the first proof-of-concept of circulating prostate cancer-specific extracellular vesicles (PCEVs) as a noninvasive predictor of outcomes in oligometastatic castration-resistant prostate cancer (omCRPC) treated with SABR. METHODS AND MATERIALS: We analyzed the levels and kinetics of PCEVs in the peripheral blood of 79 patients with omCRPC at baseline and days 1, 7, and 14 after SABR using nanoscale flow cytometry and compared with baseline values from cohorts with localized and widely metastatic prostate cancer. The association of omCRPC PCEV levels with oncological outcomes was determined with Cox regression models. RESULTS: Levels of PCEVs were highest in mCRPC followed by omCRPC and were lowest in localized prostate cancer. High PCEV levels at baseline predicted a shorter median time to distant recurrence (3.5 vs 6.6 months; P = .0087). After SABR, PCEV levels peaked on day 7, and median overall survival was significantly longer in patients with elevated PCEV levels (32.7 vs 27.6 months; P = .003). This suggests that pretreatment PCEV levels reflect tumor burden, whereas early changes in PCEV levels after treatment predict response to SABR. In contrast, radiomic features of 11C-choline positron emission tomography and computed tomography before and after SABR were not predictive of clinical outcomes. Interestingly, PCEV levels and peripheral tumor-reactive CD8 T cells (TTR; CD8+ CD11ahigh) were correlated. CONCLUSIONS: This original study demonstrates that circulating PCEVs can serve as prognostic and predictive markers to SABR to identify patients with "true" omCRPC. In addition, it provides novel insights into the global crosstalk, mediated by PCEVs, between tumors and immune cells that leads to systemic suppression of immunity against CRPC. This work lays the foundation for future studies to investigate the underpinnings of metastatic progression and provide new therapeutic targets (eg, PCEVs) to improve SABR efficacy and clinical outcomes in treatment-resistant CRPC.

Prognostic role of 11C-choline PET/CT scan in patients with metastatic castrate resistant prostate cancer undergoing primary docetaxel chemotherapy.

BACKGROUND: We sought to assess the prognostic utility of 11C-choline positron emission tomography/computed tomography (PET/CT) in patients with metastatic castrate resistant prostate cancer (mCRPC) undergoing primary docetaxel chemotherapy. METHODS: We performed a single institution retrospective analysis of 77 mCRPC patients who were treated with 6 cycles of docetaxel chemotherapy, and who also underwent 11C-choline PET/CT scans at baseline (before chemotherapy), mid-course (after 3 cycles), and posttherapy (after 6 cycles). We evaluated treatment response based on percent change in blood pool-corrected maximum standardized uptake value (SUVmax) of the target lesion on PET/CT, as well as percent change in serum prostate specific antigen (PSA). Logistic regression analysis was used to identify factors associated with complete treatment response. Progression free survival (PFS) analysis was performed using log-rank test and shown on Kaplan-Meier plot. RESULTS: Percent change in blood pool-corrected SUVmax on mid-course scan was a significant predictor of complete response (odds ratio [OR]: 0.98, 95% confidence interval [CI]: 0.96-0.99, p = .0003), whereas percent change in PSA was not (OR: 0.99, 95% CI: 0.99-1.01, p = .6025). 57 of 77 patients (74%) achieved ≥20% reduction in blood pool-corrected SUVmax on mid-course; these patients were 3.6 times more likely to achieve complete response after full 6 cycles of docetaxel chemotherapy, compared to patients with <20% reduction in blood pool-corrected SUVmax (OR: 3.56, 95% CI: 1.04-16.52, p = .0420). Median PFS in the complete response group was 35.1 months (95% CI: 26.0-52.7 months), compared to 9.4 months (95% CI: 6.9-13.0 months) in the incomplete response group (p = .0005). CONCLUSIONS: Our study showed that mid-course and posttherapy 11C-choline PET/CT evaluation for mCRPC patients undergoing primary docetaxel chemotherapy can predict full course treatment response and PFS, respectively. 11C-choline PET/CT imaging may provide valuable prognostic information to guide treatment choices for patients with mCRPC.

Phase II Evaluation of Stereotactic Ablative Radiotherapy (SABR) and Immunity in 11C-Choline-PET/CT-Identified Oligometastatic Castration-Resistant Prostate Cancer.

PURPOSE: Outcomes for resistant metastatic castration-resistant prostate cancer (CRPC) are poor. Stereotactic ablative radiotherapy (SABR) induces antitumor immunity in clinical and preclinical studies, but immunologic biomarkers are lacking. PATIENTS AND METHODS: Eighty-nine patients with oligometastatic CRPC were identified by 11C-Choline-PET (Choline-PET) from August 2016 to December 2019 and treated with SABR. Prespecified coprimary endpoints were 2-year overall survival (OS) and PSA progression. Secondary endpoints included 2-year SABR-treated local failure and 6-month adverse events. Correlative studies included peripheral blood T-cell subpopulations before and after SABR. RESULTS: 128 lesions in 89 patients were included in this analysis. Median OS was 29.3 months, and 1- and 2-year OS were 96% and 80%, respectively. PSA PFS was 40% at 1 year and 21% at 2 years. Local PFS was 84.4% and 75.3% at 1 and 2 years, respectively, and no grade ≥3 AEs were observed. Baseline high levels of tumor-reactive T cells (TTR; CD8+CD11ahigh) predicted superior local, PSA, and distant PFS. Baseline high levels of effector memory T cells (TEM; CCR7-CD45RA-) were associated with improved PSA PFS. An increase in TTR at day 14 from baseline was associated with superior OS. CONCLUSIONS: This is the first comprehensive effector T-cell immunophenotype analysis in a phase II trial before and after SABR in CRPC. Results are favorable and support the incorporation of immune-based markers in the design of future randomized trials in patients with oligometastatic CRPC treated with SABR.

Radium-223 in the Third-Line Setting in Metastatic Castration-Resistant Prostate Cancer: Impact of Concomitant Use of Enzalutamide on Overall Survival (OS) and Predictors of Improved OS.

INTRODUCTION: Radium-223 (Ra-223) has been recommended for bone-dominant metastatic castration-resistant prostate cancer (mCRPC). Second-generation hormone therapy in combination with Ra-223 in mCRPC has been utilized, yet its benefit has not been well elucidated. We investigated the potential survival benefit of concomitant enzalutamide with Ra-223 in the third-line setting and predictors of improved overall survival (OS). PATIENTS AND METHODS: We retrospectively identified 51 patients with bone-dominant mCRPC that were treated with Ra-223 in the postchemotherapy and post-hormone therapy setting, either alone (group A; n = 32) or with concomitant enzalutamide (group B; n = 19). The primary endpoint was to study the OS difference between groups A and B. The secondary endpoint was to identify predictors of improved OS with Ra-223 in the third-line setting. RESULTS: Mean age was 70.9 years, median baseline prostatic-specific antigen (PSA) was 23.1 ng/mL, alkaline phosphatase was 91 IU/L, and hemoglobin was 12.5 g/dL. There was no difference in median OS between groups A and B, at 20.4 versus 17.5 months, respectively (P = .5186). In univariate and multivariate analyses, only pre-Ra-223 PSA < 30 ng/mL and Eastern Cooperative Oncology Group performance status < 2 were associated with improved OS. CONCLUSION: In our study cohort, concomitant use of enzalutamide with Ra-223 in the mCRPC setting was not associated with improved OS. Only pretreatment PSA < 30 ng/mL and pretreatment Eastern Cooperative Oncology Group performance status < 2 were associated with improved OS. Further prospective studies are warranted.

11C-choline positron emission tomography/computed tomography for detection of disease relapse in patients with history of biochemically recurrent prostate cancer and prostate-specific antigen ≤0.1 ng/ml.

OBJECTIVES: The objective was to evaluate the diagnostic performance of surveillance11 C-choline positron emission tomography/computed tomography (PET/CT) for the detection of disease relapse in patients with a history of biochemically recurrent (BCR) prostate cancer (PCa) and prostate-specific antigen (PSA) ≤0.1 ng/ml. MATERIALS AND METHODS: We included patients who had been treated for BCR PCa and had a surveillance11 C-choline PET/CT at serum PSA ≤0.1 ng/ml. Positive surveillance PET/CT was defined as a study that identified a new tracer-avid lesion or new tracer uptake in a previously treated lesion or both. Findings were confirmed against a composite radiologic-pathologic gold standard. Time to recurrence association analyses were performed for disease relapse risk with the use of Cox proportional hazards regression. RESULTS: In total, 13 (12.1%) of the 107 patients had positive surveillance PET/CT scans, confirmed on pathologic assessment (n = 5) and subsequent imaging (n = 8). Among these 13 patients, ten had distant metastases, two had local recurrence, and one had both. Nine of the ten patients with metastases had oligometastatic disease defined as the presence of ≤3 metastases. Serum PSA became detectable again in only seven patients with positive surveillance PET/CT, after a mean interval from surveillance PET/CT of 292 days (range: 105-543 days). We identified an association of N stage with increased risk of recurrence (hazard ratio = 3.85; P = 0.036) although this was not significant after accounting for multiple testing. CONCLUSIONS: Surveillance11 C-choline PET/CT can detect early disease relapse at serum PSA ≤0.1 ng/ml in patients with a history of BCR PCa.

Patterns of Recurrence and Modes of Progression After Metastasis-Directed Therapy in Oligometastatic Castration-Sensitive Prostate Cancer.

PURPOSE: Metastasis-directed therapy (MDT) is increasingly used in castration-sensitive oligometastatic prostate cancer because it prolongs progression-free survival (PFS) and androgen deprivation free survival. Here we describe patterns of recurrence and identify modes of progression after MDT using SABR. METHODS AND MATERIALS: Two hundred fifty-eight patients with castration-sensitive oligometastatic prostate cancer (≤5 lesions at staging) were retrospectively identified from a multi-institutional database. Descriptive patterns of recurrence and modes of progression were reported. Other outcomes including median time to prostate-specific antigen (PSA) recurrence, time to next intervention, distant metastasis-free survival, overall survival, and biochemical PFS (bPFS) were reported. Survival analysis was performed using the Kaplan-Meier method, and multivariable analysis was performed. RESULTS: Median follow-up was 25.2 months, and 50.4% of patients received concurrent androgen deprivation. Median time to PSA recurrence was 15.7 months, time to next intervention was 28.6 months, distant metastasis-free survival was 19.1 months, and bPFS was 16.1 months. Two-year overall survival was 96.8%. On multivariable analysis, factors associated with bPFS included age (hazard ratio [HR], 1.03; P = .04), N1 disease at diagnosis (HR, 2.00; P = .02), M1 disease at diagnosis (HR, 0.44; P = .01), initial PSA at diagnosis (HR, 1.002; P = <.001), use of androgen deprivation therapy (HR, 0.41; P < .001), pre-SABR PSA (HR, 1.02; P = .01), and use of enhanced imaging for staging (HR, 2.81; P = .001). Patterns of progression favored an osseous component at recurrence; in patients initially treated to a bone lesion alone, the vast majority (86.5%) experienced a recurrence that included an osseous site. Patients treated initially to a nodal site alone tended to recur in a node only (64.5%); however, there was also a significant minority with an osseous component of recurrence at progression (32.3%). Modes of progressors were class I (patients with long term control [no recurrence ≥18 months after therapy]) occurring in 40.9%, class II (oligoprogressors [≤3 lesions at recurrence]) occurring in 36% (including 7.9% of patients with PSA recurrence but no metastatic disease), and class III (polyprogressors [>3 lesions]) occurring in 23.1% of patients. CONCLUSIONS: After MDT, the majority of patients have long-term control or oligoprogression (class I or II). Recurrence tended to occur in osseous sites. These findings, if validated, have implications for future integration of MDT and clinical trial design.

A Rare Case of Prostate-Specific Antigen-Producing Metastatic Parotid Adenocarcinoma Developing Androgen Receptor Resistance.

A 62-year-old man presented with a rising serum concentration of prostate-specific antigen (PSA) to 53.3 ng/mL (to convert to µg/L, multiply by 1) and a PSA doubling time of 2.6 months. Computed tomography, fluorodeoxyglucose-positron emission tomography, and C-11 choline positron emission tomography demonstrated a parotid mass with innumerable lytic bone lesions and diffuse metastatic disease to the neck and mediastinal lymph nodes. Mediastinal lymph node biopsy revealed salivary ductal adenocarcinoma that produced PSA and demonstrated androgen receptor sensitivity. The patient had a prolonged clinical benefit to first- and second-line hormone therapy, and his PSA levels correlated with treatment response, development of hormone resistance, and progression. In summary, urologists, pathologists, and primary care providers should be aware that a rising PSA level in the setting of a head and neck mass in a patient without a history of prostate cancer does not constitute a diagnosis of metastatic prostate adenocarcinoma and that other primary tumors should be considered and a broader imaging and pathologic evaluation is indicated.

Final Analysis of the Ipilimumab Versus Placebo Following Radiotherapy Phase III Trial in Postdocetaxel Metastatic Castration-resistant Prostate Cancer Identifies an Excess of Long-term Survivors.

BACKGROUND: The phase 3 trial CA184-043 evaluated radiotherapy to bone metastases followed by Ipilimumab or placebo in men with metastatic castrate-resistant prostate cancer (mCRPC) who had received docetaxel previously. In a prior analysis, the trial's primary endpoint (overall survival [OS]) was not improved significantly. OBJECTIVE: To report the final analysis of OS. DESIGN, SETTING, AND PARTICIPANTS: A total of 799 patients were randomized to receive a single dose of radiotherapy to one or more bone metastases followed by either Ipilimumab (n = 399) or placebo (n = 400). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: OS was analyzed in the intention-to-treat population. Prespecified and exploratory subset analyses based on Kaplan-Meier/Cox methodology were performed. RESULTS AND LIMITATIONS: During an additional follow-up of approximately 2.4 yr since the primary analysis, 721/799 patients have died. Survival analysis showed crossing of the curves at 7-8 mo, followed by persistent separation of the curves beyond that point, favoring the ipilimumab arm. Given the lack of proportional hazards, a piecewise hazard model showed that the hazard ratio (HR) changed over time: the HR was 1.49 (95% confidence interval 1.12, 1.99) for 0-5 mo, 0.66 (0.51, 0.86) for 5-12 mo, and 0.66 (0.52, 0.84) beyond 12 mo. OS rates were higher in the ipilimumab versus placebo arms at 2 yr (25.2% vs 16.6%), 3 yr (15.3% vs 7.9%), 4 yr (10.1% vs 3.3%), and 5 yr (7.9% vs. 2.7%). Disease progression was the most frequent cause of death in both arms. In seven patients (1.8%) in the ipilimumab arm and one (0.3%) in the placebo arm, the primary cause of death was reported as study drug toxicity. No long-term safety signals were identified. CONCLUSIONS: In this preplanned long-term analysis, OS favored ipilimumab plus radiotherapy versus placebo plus radiotherapy for patients with postdocetaxel mCRPC. OS rates at 3, 4, and 5 yr were approximately two to three times higher in the ipilimumab arm. PATIENT SUMMARY: After longer follow-up, survival favored the group of men who received ipilimumab, with overall survival rates being two to three times higher at 3 yr and beyond.