Single-cell analyses of metastatic bone marrow in human neuroblastoma reveals microenvironmental remodeling and metastatic signature.

Neuroblastoma is an aggressive pediatric cancer with a high rate of metastasis to the BM. Despite intensive treatments including high-dose chemotherapy, the overall survival rate for children with metastatic neuroblastoma remains dismal. Understanding the cellular and molecular mechanisms of the metastatic tumor microenvironment is crucial for developing new therapies and improving clinical outcomes. Here, we used single-cell RNA-Seq to characterize immune and tumor cell alterations in neuroblastoma BM metastases by comparative analysis with patients without metastases. Our results reveal remodeling of the immune cell populations and reprogramming of gene expression profiles in the metastatic niche. In particular, within the BM metastatic niche, we observed the enrichment of immune cells, including tumor-associated neutrophils, macrophages, and exhausted T cells, as well as an increased number of Tregs and a decreased number of B cells. Furthermore, we highlighted cell communication between tumor cells and immune cell populations, and we identified prognostic markers in malignant cells that are associated with worse clinical outcomes in 3 independent neuroblastoma cohorts. Our results provide insight into the cellular, compositional, and transcriptional shifts underlying neuroblastoma BM metastases that contribute to the development of new therapeutic strategies.

Circulating and Imaging Biomarkers of Radium-223 Response in Metastatic Castration-Resistant Prostate Cancer.

PURPOSE: Radium-223 improves overall survival (OS) and reduces skeletal events in patients with bone metastatic castration-resistant prostate cancer (CRPC), but relevant biomarkers are lacking. We evaluated automated bone scan index (aBSI) and circulating tumor cell (CTC) analyses as potential biomarkers of prognosis and activity. PATIENTS AND METHODS: Patients with bone metastatic CRPC were enrolled on a prospective single-arm study of standard radium-223. 99mTc-MDP bone scan images at baseline, 2 months, and 6 months were quantitated using aBSI. CTCs at baseline, 1 month, and 2 months were enumerated and assessed for RNA expression of prostate cancer-specific genes using microfluidic enrichment followed by droplet digital polymerase chain reaction. RESULTS: The median OS was 21.3 months in 22 patients. Lower baseline aBSI and minimal change in aBSI (<+0.7) from baseline to 2 months were each associated with better OS (P = .00341 and P = .0139, respectively). The higher baseline CTC count of ≥5 CTC/7.5 mL was associated with worse OS (median, 10.1 v 32.9 months; P = .00568). CTCs declined at 2 months in four of 15 patients with detectable baseline CTCs. Among individual genes in CTCs, baseline expression of the splice variant AR-V7 was significantly associated with worse OS (hazard ratio, 5.20 [95% CI, 1.657 to 16.31]; P = .00195). Baseline detectable AR-V7, higher aBSI, and CTC count ≥5 CTC/7.5 mL continued to have a significant independent negative impact on OS after controlling for prostate-specific antigen or alkaline phosphatase. CONCLUSION: Quantitative bone scan assessment with aBSI and CTC analyses are prognostic markers in patients treated with radium-223. AR-V7 expression in CTCs is a particularly promising prognostic biomarker and warrants validation in larger cohorts.

The radiopharmaceutical radium-223 has immunomodulatory effects in patients and facilitates anti-programmed death receptor-1 therapy in murine models of bone metastatic prostate cancer.

BACKGROUND & PURPOSE: Radium-223 (Ra223) improves survival in metastatic prostate cancer (mPC), but its impact on systemic immunity is unclear, and biomarkers of response are lacking. We examined markers of immunomodulatory activity during standard clinical Ra223 and studied the impact of Ra223 on response to immune checkpoint inhibition (ICI) in preclinical models. MATERIALS & METHODS: We conducted a single-arm biomarker study of Ra223 in 22 bone mPC patients. We measured circulating immune cell subsets and a panel of cytokines before and during Ra223 therapy and correlated them with overall survival (OS). Using two murine mPC models-orthotopic PtenSmad4-null and TRAMP-C1 grafts in syngeneic immunocompetent mice-we tested the efficacy of combining Ra223 with ICI. RESULTS: Above-median level of IL-6 at baseline was associated with a median OS of 358 versus 947 days for below levels; p = 0.044, from the log-rank test. Baseline PlGF and PSA inversely correlated with OS (p = 0.018 and p = 0.037, respectively, from the Cox model). Ra223 treatment was associated with a mild decrease in some peripheral immune cell populations and a shift in the proportion of MDSCs from granulocytic to myeloid. In mice, Ra223 increased the proliferation of CD8+ and CD4+ helper T cells without leading to CD8+ T cell exhaustion in the mPC lesions. In one of the models, combining Ra223 and anti-PD-1 antibody significantly prolonged survival, which correlated with increased CD8+ T cell infiltration in tumor tissue. CONCLUSION: The inflammatory cytokine IL-6 and the angiogenic biomarker PlGF at baseline were promising outcome biomarkers after standard Ra223 treatment. In mouse models, Ra223 increased intratumoral CD8+ T cell infiltration and proliferation and could improve OS when combined with anti-PD-1 ICI.

Single-cell analysis of immune and stroma cell remodeling in clear cell renal cell carcinoma primary tumors and bone metastatic lesions.

BACKGROUND: Despite therapeutic advances, once a cancer has metastasized to the bone, it represents a highly morbid and lethal disease. One third of patients with advanced clear cell renal cell carcinoma (ccRCC) present with bone metastasis at the time of diagnosis. However, the bone metastatic niche in humans, including the immune and stromal microenvironments, has not been well-defined, hindering progress towards identification of therapeutic targets. METHODS: We collected fresh patient samples and performed single-cell transcriptomic profiling of solid metastatic tissue (Bone Met), liquid bone marrow at the vertebral level of spinal cord compression (Involved), and liquid bone marrow from a different vertebral body distant from the tumor site but within the surgical field (Distal), as well as bone marrow from patients undergoing hip replacement surgery (Benign). In addition, we incorporated single-cell data from primary ccRCC tumors (ccRCC Primary) for comparative analysis. RESULTS: The bone marrow of metastatic patients is immune-suppressive, featuring increased, exhausted CD8 + cytotoxic T cells, T regulatory cells, and tumor-associated macrophages (TAM) with distinct transcriptional states in metastatic lesions. Bone marrow stroma from tumor samples demonstrated a tumor-associated mesenchymal stromal cell population (TA-MSC) that appears to be supportive of epithelial-to mesenchymal transition (EMT), bone remodeling, and a cancer-associated fibroblast (CAFs) phenotype. This stromal subset is associated with poor progression-free and overall survival and also markedly upregulates bone remodeling through the dysregulation of RANK/RANKL/OPG signaling activity in bone cells, ultimately leading to bone resorption. CONCLUSIONS: These results provide a comprehensive analysis of the bone marrow niche in the setting of human metastatic cancer and highlight potential therapeutic targets for both cell populations and communication channels.

Genomic Tumor Correlates of Clinical Outcomes Following Organ-Sparing Chemoradiation Therapy for Bladder Cancer.

PURPOSE: There is an urgent need for biomarkers of radiation response in organ-sparing therapies. Bladder preservation with trimodality therapy (TMT), consisting of transurethral tumor resection followed by chemoradiation, is an alternative to radical cystectomy for muscle-invasive bladder cancer (MIBC), but molecular determinants of response are poorly understood. EXPERIMENTAL DESIGN: We characterized genomic and transcriptomic features correlated with long-term response in a single institution cohort of patients with MIBC homogeneously treated with TMT. Pretreatment tumors from 76 patients with MIBC underwent whole-exome sequencing; 67 underwent matched transcriptomic profiling. Molecular features were correlated with clinical outcomes including modified bladder-intact event-free survival (mBI-EFS), a composite endpoint that reflects long-term cancer control with bladder preservation. RESULTS: With a median follow-up of 74.6 months in alive patients, 37 patients had favorable long-term response to TMT while 39 had unfavorable long-term response. Tumor mutational burden was not associated with outcomes after TMT. DNA damage response gene alterations were associated with improved locoregional control and mBI-EFS. Of these alterations, somatic ERCC2 mutations stood out as significantly associated with favorable long-term outcomes; patients with ERCC2 mutations had significantly improved mBI-EFS [HR, 0.15; 95% confidence interval (CI), 0.06-0.37; P = 0.030] and improved BI-EFS, an endpoint that includes all-cause mortality (HR, 0.33; 95% CI, 0.15-0.68; P = 0.044). ERCC2 mutant bladder cancer cell lines were significantly more sensitive to concurrent cisplatin and radiation treatment in vitro than isogenic ERCC2 wild-type cells. CONCLUSIONS: Our data identify ERCC2 mutation as a candidate biomarker associated with sensitivity and long-term response to chemoradiation in MIBC. These findings warrant validation in independent cohorts.

Radical cystectomy versus trimodality therapy for muscle-invasive bladder cancer: a multi-institutional propensity score matched and weighted analysis.

BACKGROUND: Previous randomised controlled trials comparing bladder preservation with radical cystectomy for muscle-invasive bladder cancer closed due to insufficient accrual. Given that no further trials are foreseen, we aimed to use propensity scores to compare trimodality therapy (maximal transurethral resection of bladder tumour followed by concurrent chemoradiation) with radical cystectomy. METHODS: This retrospective analysis included 722 patients with clinical stage T2-T4N0M0 muscle-invasive urothelial carcinoma of the bladder (440 underwent radical cystectomy, 282 received trimodality therapy) who would have been eligible for both approaches, treated at three university centres in the USA and Canada between Jan 1, 2005, and Dec 31, 2017. All patients had solitary tumours less than 7 cm, no or unilateral hydronephrosis, and no extensive or multifocal carcinoma in situ. The 440 cases of radical cystectomy represent 29% of all radical cystectomies performed during the study period at the contributing institutions. The primary endpoint was metastasis-free survival. Secondary endpoints included overall survival, cancer-specific survival, and disease-free survival. Differences in survival outcomes by treatment were analysed using propensity scores incorporated in propensity score matching (PSM) using logistic regression and 3:1 matching with replacement and inverse probability treatment weighting (IPTW). FINDINGS: In the PSM analysis, the 3:1 matched cohort comprised 1119 patients (837 radical cystectomy, 282 trimodality therapy). After matching, age (71·4 years [IQR 66·0-77·1] for radical cystectomy vs 71·6 years [64·0-78·9] for trimodality therapy), sex (213 [25%] vs 68 [24%] female; 624 [75%] vs 214 [76%] male), cT2 stage (755 [90%] vs 255 [90%]), presence of hydronephrosis (97 [12%] vs 27 [10%]), and receipt of neoadjuvant or adjuvant chemotherapy (492 [59%] vs 159 [56%]) were similar between groups. Median follow-up was 4·38 years (IQR 1·6-6·7) versus 4·88 years (2·8-7·7), respectively. 5-year metastasis-free survival was 74% (95% CI 70-78) for radical cystectomy and 75% (70-80) for trimodality therapy with IPTW and 74% (70-77) and 74% (68-79) with PSM. There was no difference in metastasis-free survival either with IPTW (subdistribution hazard ratio [SHR] 0·89 [95% CI 0·67-1·20]; p=0·40) or PSM (SHR 0·93 [0·71-1·24]; p=0·64). 5-year cancer-specific survival for radical cystectomy versus trimodality therapy was 81% (95% CI 77-85) versus 84% (79-89) with IPTW and 83% (80-86) versus 85% (80-89) with PSM. 5-year disease-free survival was 73% (95% CI 69-77) versus 74% (69-79) with IPTW and 76% (72-80) versus 76% (71-81) with PSM. There were no differences in cancer-specific survival (IPTW: SHR 0·72 [95% CI 0·50-1·04]; p=0·071; PSM: SHR 0·73 [0·52-1·02]; p=0·057) and disease-free survival (IPTW: SHR 0·87 [0·65-1·16]; p=0·35; PSM: SHR 0·88 [0·67-1·16]; p=0·37) between radical cystectomy and trimodality therapy. Overall survival favoured trimodality therapy (IPTW: 66% [95% CI 61-71] vs 73% [68-78]; hazard ratio [HR] 0·70 [95% CI 0·53-0·92]; p=0·010; PSM: 72% [69-75] vs 77% [72-81]; HR 0·75 [0·58-0·97]; p=0·0078). Outcomes for radical cystectomy and trimodality therapy were not statistically different among centres for cancer-specific survival and metastasis-free survival (p=0·22-0·90). Salvage cystectomy was done in 38 (13%) trimodality therapy patients. Pathological stage in the 440 radical cystectomy patients was pT2 in 124 (28%), pT3-4 in 194 (44%), and 114 (26%) node positive. The median number of nodes removed was 39, the soft tissue positive margin rate was 1% (n=5), and the perioperative mortality rate was 2·5% (n=11). INTERPRETATION: This multi-institutional study provides the best evidence to date showing similar oncological outcomes between radical cystectomy and trimodality therapy for select patients with muscle-invasive bladder cancer. These results support that trimodality therapy, in the setting of multidisciplinary shared decision making, should be offered to all suitable candidates with muscle-invasive bladder cancer and not only to patients with significant comorbidities for whom surgery is not an option. FUNDING: Sinai Health Foundation, Princess Margaret Cancer Foundation, Massachusetts General Hospital.

Dissecting the immune suppressive human prostate tumor microenvironment via integrated single-cell and spatial transcriptomic analyses.

The treatment of low-risk primary prostate cancer entails active surveillance only, while high-risk disease requires multimodal treatment including surgery, radiation therapy, and hormonal therapy. Recurrence and development of metastatic disease remains a clinical problem, without a clear understanding of what drives immune escape and tumor progression. Here, we comprehensively describe the tumor microenvironment of localized prostate cancer in comparison with adjacent normal samples and healthy controls. Single-cell RNA sequencing and high-resolution spatial transcriptomic analyses reveal tumor context dependent changes in gene expression. Our data indicate that an immune suppressive tumor microenvironment associates with suppressive myeloid populations and exhausted T-cells, in addition to high stromal angiogenic activity. We infer cell-to-cell relationships from high throughput ligand-receptor interaction measurements within undissociated tissue sections. Our work thus provides a highly detailed and comprehensive resource of the prostate tumor microenvironment as well as tumor-stromal cell interactions.

A transcriptional metastatic signature predicts survival in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) is the most common type of kidney cancer in adults. When ccRCC is localized to the kidney, surgical resection or ablation of the tumor is often curative. However, in the metastatic setting, ccRCC remains a highly lethal disease. Here we use fresh patient samples that include treatment-naive primary tumor tissue, matched adjacent normal kidney tissue, as well as tumor samples collected from patients with bone metastases. Single-cell transcriptomic analysis of tumor cells from the primary tumors reveals a distinct transcriptional signature that is predictive of metastatic potential and patient survival. Analysis of supporting stromal cells within the tumor environment demonstrates vascular remodeling within the endothelial cells. An in silico cell-to-cell interaction analysis highlights the CXCL9/CXCL10-CXCR3 axis and the CD70-CD27 axis as potential therapeutic targets. Our findings provide biological insights into the interplay between tumor cells and the ccRCC microenvironment.

Human prostate cancer bone metastases have an actionable immunosuppressive microenvironment.

Bone metastases are devastating complications of cancer. They are particularly common in prostate cancer (PCa), represent incurable disease, and are refractory to immunotherapy. We seek to define distinct features of the bone marrow (BM) microenvironment by analyzing single cells from bone metastatic prostate tumors, involved BM, uninvolved BM, and BM from cancer-free, orthopedic patients, and healthy individuals. Metastatic PCa is associated with multifaceted immune distortion, specifically exhaustion of distinct T cell subsets, appearance of macrophages with states specific to PCa bone metastases. The chemokine CCL20 is notably overexpressed by myeloid cells, as is its cognate CCR6 receptor on T cells. Disruption of the CCL20-CCR6 axis in mice with syngeneic PCa bone metastases restores T cell reactivity and significantly prolongs animal survival. Comparative high-resolution analysis of PCa bone metastases shows a targeted approach for relieving local immunosuppression for therapeutic effect.

The effectiveness of systemic therapies after surgery for metastatic renal cell carcinoma to the spine: a propensity analysis controlling for sarcopenia, frailty, and nutrition.

OBJECTIVE: The effectiveness of starting systemic therapies after surgery for spinal metastases from renal cell carcinoma (RCC) has not been evaluated in randomized controlled trials. Agents that target tyrosine kinases, mammalian target of rapamycin signaling, and immune checkpoints are now commonly used. Variables like sarcopenia, nutritional status, and frailty may impact recovery from spine surgery and are considered when evaluating a patient's candidacy for such treatments. A better understanding of the significance of these variables may help improve patient selection for available treatment options after surgery. The authors used comparative effectiveness methods to study the treatment effect of postoperative systemic therapies (PSTs) on survival. METHODS: Univariable and multivariable Cox regression analyses were performed to determine factors associated with overall survival (OS) in a retrospective cohort of adult patients who underwent spine surgery for metastatic RCC between 2010 and 2019. Propensity score-matched (PSM) analysis and inverse probability weighting (IPW) were performed to determine the treatment effect of PST on OS. To address confounding and minimize bias in estimations, PSM and IPW were adjusted for covariates, including age, sex, frailty, sarcopenia, nutrition, visceral metastases, International Metastatic RCC Database Consortium (IMDC) risk score, and performance status. RESULTS: In total, 88 patients (73.9% male; median age 62 years, range 29-84 years) were identified; 49 patients (55.7%) had an intermediate IMDC risk, and 29 (33.0%) had a poor IMDC risk. The median follow-up was 17 months (range 1-104 months) during which 57 patients (64.7%) died. Poor IMDC risk (HR 3.2 [95% CI 1.08-9.3]), baseline performance status (Eastern Cooperative Oncology Group score 3 or 4; HR 2.7 [95% CI 1.5-4.7]), and nutrition (prognostic nutritional index [PNI] first tertile, PNI < 40.74; HR 2.69 [95% CI 1.42-5.1]) were associated with worse OS. Sarcopenia and frailty were not significantly associated with poor survival. PST was associated with prolonged OS, demonstrated by similar effects from multivariable Cox analysis (HR 0.55 [95% CI 0.30-1.00]), PSM (HR 0.53 [95% CI 0.29-0.93]), IPW (HR 0.47 [95% CI 0.24-0.94]), and comparable confidence intervals. The median survival for those receiving PST was 28 (95% CI 19-43) months versus 12 (95% CI 4-37) months for those who only had surgery (log-rank p = 0.027). CONCLUSIONS: This comparative analysis demonstrated that PST is associated with improved survival in specific cohorts with metastatic spinal RCC after adjusting for frailty, sarcopenia, and malnutrition. The marked differences in survival should be taken into consideration when planning for surgery.

A Subset of Localized Prostate Cancer Displays an Immunogenic Phenotype Associated with Losses of Key Tumor Suppressor Genes.

PURPOSE: A subset of primary prostate cancer expresses programmed death-ligand 1 (PD-L1), but whether they have a unique tumor immune microenvironment or genomic features is unclear. EXPERIMENTAL DESIGN: We selected PD-L1-positive high-grade and/or high-risk primary prostate cancer, characterized tumor-infiltrating lymphocytes with multiplex immunofluorescence, and identified genomic alterations in immunogenic and nonimmunogenic tumor foci. RESULTS: One quarter of aggressive localized prostate cancer cases (29/115) had tumor PD-L1 expression more than 5%. This correlated with increased density of CD8+ T cells, a large fraction coexpressing PD-1, versus absent PD-1 expression on sparse CD8 T cells in unselected cases. Most CD8+PD-1+ cells did not express terminal exhaustion markers (TIM3 or LAG3), while a subset expressed TCF1. Consistent with these CD8+PD-1+TCF1+ cells being progenitors, they were found in antigen-presenting cell niches in close proximity to MHC-II+ cells. CD8 T-cell density in immunogenic prostate cancer and renal cell carcinoma (RCC) was nearly identical. Shallow RB1 and BRCA2 losses, and deep deletions of CHD1, were prevalent, the latter being strongly associated with a dendritic cell gene set in The Cancer Genome Atlas. Tumor mutation burden was variable; neither high microsatellite instability nor CDK12 alterations were present. CONCLUSIONS: A subset of localized prostate cancer is immunogenic, manifested by PD-L1 expression and CD8+ T-cell content comparable with RCC. The CD8+ T cells include effector cells and exhausted progenitor cells, which may be expanded by immune checkpoint inhibitors (ICI). Genomic losses of RB1, BRCA2, and CHD1 may be drivers of this phenotype. These findings indicate that immunotherapies may be effective in biomarker-selected subpopulations of patients with localized prostate cancer.

GnRH agonist-associated pituitary apoplexy: a case series and review of the literature.

PURPOSE: To examine the clinical presentation and longitudinal outcome of Pituitary Apoplexy (PA) after gonadotropin-releasing hormone agonist (GnRHa) in a series of patients and compare to prior reports. METHODS: A retrospective chart review was performed on seven patients receiving GnRHa who developed PA. Prior reported cases were analyzed. RESULTS: Six men (median age 72 years) with prostate cancer and one woman (aged 22 years) undergoing oocyte donation presented with PA between 1990 and 2020. Most presented with within 24 h of the first dose, but two developed PA 1 to 5 months after GnRHa initiation. The main clinical manifestations were headache (100%), nausea and vomiting (86%). While no patients had a previously known pituitary tumor, all had imaging demonstrating sellar mass and/or hemorrhage at presentation. Among those surgically treated (5/7), 80% (4/5) of patients had pathologic specimens that stained positive for gonadotropins; the remaining patient's pathologic specimen was necrotic. At the time of PA, the most common pituitary dysfunction was hypocortisolism. Central adrenal insufficiency and central hypothyroidism were reversible in a subset. Pituitary imaging remained stable. CONCLUSIONS: This is the first report of a case series with PA after GnRHa administration with longitudinal follow-up. Although infrequent, PA can be life-threatening and should be suspected among patients receiving GnRHa, with or without a known pituitary adenoma, who develop acute headache, nausea and/or vomiting. Since hypopituitarism was reversible in a subset, ongoing pituitary function testing may be indicated.

Survival After Surgery for Renal Cell Carcinoma Metastatic to the Spine: Impact of Modern Systemic Therapies on Outcomes.

BACKGROUND: Modern medical management of metastatic renal cell carcinoma (RCC) includes therapies targeting tyrosine kinases, growth pathways (mammalian target of rapamycin (mTOR)), and immune checkpoints. OBJECTIVE: To test our hypothesis that patients with spinal metastases would benefit from postoperative systemic therapy despite presenting with disease that, in many cases, was resistant to prior systemic therapy. METHODS: This is an Institutional Review Board-approved clinical retrospective cohort analysis. A sample of adult patients with RCC metastatic to the spine who underwent operative intervention between January 2010 and December 2017 at 2 large academic medical centers was used in this study. RESULTS: We identified 78 patients with metastatic RCC in whom instrumented stabilization was performed in 79% and postoperative stereotactic radiosurgery was performed in 41% of patients. Of patients presenting with weakness or myelopathy, 93% noted postoperative improvement and 78% reported improvement in radicular and axial paraspinal pain severity. Increased overall survival (OS) (913 d (95% CI: 633-1975 d, n = 49) vs 222 d (95% CI: 143-1005 d, n = 29), P = .003) following surgery was noted in patients who received postoperative systemic therapy a median of 80 d (interquartile range 48-227 d) following the surgical intervention. CONCLUSION: Postoperative outcomes and palliation of symptoms for metastatic RCC without targeted therapies in this cohort are similar to those reported in earlier series prior to the adoption of these systemic therapies. We observed a significantly longer OS among patients who received modern systemic therapies postoperatively. These findings have implications for the preoperative evaluation of patients with systemic disease who may have been deemed poor surgical candidates prior to the availability of these systemic therapies.

Bone Health and Bone-Targeted Therapies for Prostate Cancer: ASCO Endorsement of a Cancer Care Ontario Guideline.

PURPOSE: In 2017, Cancer Care Ontario's Program in Evidence-Based Care released the Bone Health and Bone-Targeted Therapies for Prostate Cancer guideline. This guideline included recommendations across a relatively broad clinical spectrum within prostate cancer. Topics addressed ranged from management of osteoporotic fracture risk in nonmetastatic disease to management of men with castration-resistant prostate cancer metastatic to bone. ASCO has a policy and set of procedures for endorsing clinical practice guidelines that have been developed by other professional organizations. METHODS: The Bone Health and Bone-Targeted Therapies for Prostate Cancer guideline was reviewed for developmental rigor by methodologists. An ASCO Expert Panel then reviewed the content and the recommendations. RESULTS: The ASCO Expert Panel determined that the recommendations from the Bone Health and Bone-Targeted Therapies for Prostate Cancer guideline were clear, thorough, and based on the most relevant scientific evidence. ASCO wholly endorses the Bone Health and Bone-Targeted Therapies for Prostate Cancer guideline. RECOMMENDATIONS: The ASCO Expert Panel endorses all the original guideline recommendations as written and offers a series of discussion points to guide practice for clinicians as they manage bone-related risks within this patient population.

Performance of 18F-fluciclovine PET/MR in the evaluation of osseous metastases from castration-resistant prostate cancer.

PURPOSE: 18F-Fluciclovine is indicated for evaluation of suspected prostate cancer (PCa) biochemical recurrence. There are few studies investigating fluciclovine with PET/MR and none evaluated osseous metastases. Our aim was to assess the performance of 18F-fluciclovine PET/MR (fluciclovine-PET/MR) for detecting osseous metastases in patients with castration-resistant prostate cancer (CRPC). We also investigated possible correlations between SUVmax and ADCmean. METHODS: We evaluated 8 patients with CRPC metastatic to bones, some before and some after radium therapy, who underwent 13 fluciclovine-PET/MR studies. We analyzed the performance of radionuclide bone scan (RBS), MR alone, fluciclovine-PET alone, and fluciclovine-PET/MR in detecting osseous metastases. Lesion size, characteristics (early sclerotic, late sclerotic, mixed, lytic), SUVmax, and ADCmean were assessed. The reference standard was a combination of clinical information and correlation with both prior and follow-up imaging. RESULTS: Of 347 metastatic bony lesions in 13 studies, 238/347 (68%) were detected by fluciclovine-PET alone, 286/347 (82%) by RBS, 344/347 (99%) by MR alone, and 347/347 (100%) by fluciclovine-PET/MR. Fluciclovine-PET/MR and MR had the best performance (p < 0.001). There was no statistically significant difference between fluciclovine-PET/MR and MR alone (p = 0.25). Fluciclovine-PET had a lower detection rate especially with late sclerotic lesions (p < 0.001). There was a moderate inverse correlation between lesion SUVmax and ADCmean (r = - 0.49; p < 0.001). CONCLUSIONS: This study suggests that fluciclovine-PET/MR and MR have high sensitivity for detecting osseous metastases in CRPC. Fluciclovine-PET alone underperformed in detecting late sclerotic lesions. The inverse correlation between SUVmax and ADCmean suggests a possible relationship between tumor metabolism and cellularity.