Localised non-metastatic sarcomatoid renal cell carcinoma: a 31-year externally verified study.

OBJECTIVE: To evaluate post-nephrectomy outcomes and predictors of cancer-specific survival (CSS) between patients with localised sarcomatoid renal cell carcinoma (sRCC) and those with Grade 4 RCC (non-sRCC), as most sRCC research focuses on advanced or metastatic disease with limited studies analysing outcomes of patients with localised non-metastatic sRCC. PATIENTS AND METHODS: A total of 564 patients with localised RCC underwent partial or radical nephrectomy between June 1988 to March 2019 for sRCC (n = 204) or World Health Organization/International Society of Urological Pathology Grade 4 non-sRCC (n = 360). The CSS at every stage between groups was assessed. Phase III ASSURE clinical trial data were used to externally validate the CSS findings. The Mann-Whitney U-test and chi-squared test compared outcomes and the Kaplan-Meier method evaluated CSS, overall survival (OS) and recurrence-free survival. Clinicopathological features associated with RCC death were evaluated using Cox proportional hazards regression. RESULTS: The median follow-up was 31.5 months. The median OS and CSS between the sRCC and Grade 4 non-sRCC groups was 45 vs 102 months and 49 vs 152 months, respectively (P < 0.001). At every stage, sRCC had worse CSS compared to Grade 4 non-sRCC. Notably, pT1 sRCC had worse CSS than pT3 Grade 4 non-sRCC. Negative predictors of CSS were sarcomatoid features, non-clear cell histology, positive margins, higher stage (pT3/pT4), and use of minimally invasive surgery (MIS). ASSURE external verification showed worse CSS in patients with sRCC (hazard ratio [HR] 1.63, 95% confidence interval [CI] 1.12-2.36; P = 0.01), but not worse outcomes in MIS surgery (HR 1.39, 95% CI 0.75-2.56; P = 0.30). CONCLUSIONS: Localised sRCC had worse CSS compared to Grade 4 non-sRCC at every stage. Negative survival predictors included positive margins, higher pathological stage, use of MIS, and non-clear cell histology. sRCC is an aggressive variant even at low stages requiring vigilant surveillance and possible inclusion in adjuvant therapy trials.

Evolving biological associations of upfront cytoreductive nephrectomy in metastatic renal cell carcinoma.

BACKGROUND: Systemic responses to cytoreductive nephrectomy (CN) in the management of metastatic renal cell carcinoma (mRCC) are variable and difficult to anticipate. The authors aimed to determine the association of CN with modifiable International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk factors and oncological outcomes. METHODS: Consecutive patients with mRCC referred for potential CN (2009-2019) were reviewed. The primary outcome was overall survival (OS); variables of interest included undergoing CN and the baseline number of modifiable IMDC risk factors (anemia, hypercalcemia, neutrophilia, thrombocytosis, and reduced performance status). For operative cases, the authors evaluated the effects of IMDC risk factor dynamics, measured 6 weeks and 6 months after CN, on OS and postoperative treatment disposition. RESULTS: Of 245 treatment-naive patients with mRCC referred for CN, 177 (72%) proceeded to surgery. The CN cases had fewer modifiable IMDC risk factors (P = .003), including none in 71 of 177 patients (40.1%); fewer metastases (P = .011); and higher proportions of clear cell histology (P = .012). In a multivariable analysis, surgical selection, number of IMDC risk factors, metastatic focality, and histology were associated with OS. Total risk factors changed for 53.8% and 57.2% of the patients from the preoperative period to 6 weeks and 6 months after CN, respectively. Adjusted for preoperative IMDC risk scores, an increase in IMDC risk factors at 6 weeks and 6 months was associated with adverse OS (hazard ratio [HR], 1.57; 95% confidence interval [CI], 1.13-2.19; P = .007; HR, 2.52; 95% CI, 1.74-3.65; P < .001). CONCLUSIONS: IMDC risk factors are dynamic clinical variables that can improve after upfront CN in select patients, and this suggests a systemic benefit of cytoreduction, which may confer clinically meaningful prognostic implications.

A qualitative framework of non-selection factors for cytoreductive nephrectomy.

PURPOSE: Cytoreductive nephrectomy (CN) benefits a subset of patients with metastatic renal cell carcinoma (mRCC), however proper patient selection remains complex and controversial. We aim to characterize urologists' reasons for not undertaking a CN at a quaternary cancer center. METHODS: Consecutive patients with mRCC referred to MSKCC urologists for consideration of CN between 2009 and 2019 were included. Baseline clinicopathologic characteristics were used to compare patients selected or rejected for CN. The reasons cited for not operating and the alternative management strategies recommended were extrapolated. Using an iterative thematic analysis, a framework of reasons for rejecting CN was designed. Kaplan-Meier estimates tested for associations between the reasons for not undertaking a CN and overall survival (OS). RESULTS: Of 297 patients with biopsy-proven mRCC, 217 (73%) underwent CN and 80 (27%) did not. Median follow-up of patients alive at data cut-off was 27.3 months. Non-operative patients were older (p = 0.014), had more sites of metastases (p = 0.008), harbored non-clear cell histology (p = 0.014) and reduced performance status (p < 0.001). The framework comprised seven distinct themes for recommending non-operative management: two patient-fitness considerations and five oncological considerations. These considerations were associated with OS; four of the oncological factors conferred a median OS of less than 12 months (p < 0.001). CONCLUSION: We developed a framework of criteria by which patients were deemed unsuitable candidates for CN. These new insights provide a novel perspective on surgical selection, could potentially be applicable to other malignancies and possibly have prognostic implications.

Dynamic transcription factor activity profiles reveal key regulatory interactions during megakaryocytic and erythroid differentiation.

The directed differentiation toward erythroid (E) or megakaryocytic (MK) lineages by the MK-E progenitor (MEP) could enhance the ex vivo generation of red blood cells and platelets for therapeutic transfusions. The lineage choice at the MEP bifurcation is controlled in large part by activity within the intracellular signal transduction network, the output of which determines the activity of transcription factors (TFs) and ultimately gene expression. Although many TFs have been implicated, E or MK differentiation is a complex process requiring multiple days, and the dynamics of TF activities during commitment and terminal maturation are relatively unexplored. Herein, we applied a living cell array for the large-scale, dynamic quantification of TF activities during MEP bifurcation. A panel of hematopoietic TFs (GATA-1, GATA-2, SCL/TAL1, FLI-1, NF-E2, PU.1, c-Myb) was characterized during E and MK differentiation of bipotent K562 cells. Dynamic TF activity profiles associated with differentiation towards each lineage were identified, and validated with previous reports. From these activity profiles, we show that GATA-1 is an important hub during early hemin- and PMA-induced differentiation, and reveal several characteristic TF interactions for E and MK differentiation that confirm regulatory mechanisms documented in the literature. Additionally, we highlight several novel TF interactions at various stages of E and MK differentiation. Furthermore, we investigated the mechanism by which nicotinamide (NIC) promoted terminal MK maturation using an MK-committed cell line, CHRF-288-11 (CHRF). Concomitant with its enhancement of ploidy, NIC strongly enhanced the activity of three TFs with known involvement in terminal MK maturation: FLI-1, NF-E2, and p53. Dynamic profiling of TF activity represents a novel tool to complement traditional assays focused on mRNA and protein expression levels to understand progenitor cell differentiation.

Dynamic transcription factor activity profiling in 2D and 3D cell cultures.

Live-cell assays to measure cellular function performed within 3D cultures have the potential to elucidate the underlying processes behind disease progression and tissue formation. Cells cultured in 3D interact and remodel their microenvironment and can develop into complex structures. We have developed a transcription factor (TF) activity array that uses bioluminescence imaging (BLI) of lentiviral delivered luminescent reporter constructs that allows for the non-invasive imaging of TF activity in both 2D and 3D culture. Imaging can be applied repeatedly throughout culture to capture dynamic TF activity, though appropriate normalization is necessary. We investigated in-well normalization using Gaussia or Renilla luciferase, and external well normalization using firefly luciferase. Gaussia and Renilla luciferase were each unable to provide consistent normalization for long-term measurement of TF activity. However, external well normalization provided low variability and accounted for changes in cellular dynamics. Using external normalization, dynamic TF activities were quantified for five TFs. The array captured expected changes in TF activity to stimuli, however the array also provided dynamic profiles within 2D and 3D that have not been previously characterized. The development of the technology to dynamically track TF activity within cells cultured in both 2D and 3D can provide greater understanding of complex cellular processes.

The Relationship Between Overactive Bladder and Nocturia.

Overactive bladder (OAB) syndrome is a major risk factor for the occurrence of nocturia. In OAB patients, nocturia is driven by low nocturnal bladder capacity. OAB medications would probably demonstrate better performance in populations with greater nocturia severity at baseline.

Outcomes for Atypical Tumor Recurrences Following Minimally Invasive Kidney Cancer Operations.

Background: We managed a cohort of patients treated with minimally invasive surgery (MIS) for a kidney tumor presenting with atypical tumor recurrence (ATR) involving port sites, intraperitoneal carcinomatosis, and nephrectomy bed/perinephric tumor implants. Objective: To determine the clinical characteristics, management, and oncologic outcomes for patients with localized renal cell carcinoma (RCC) who develop ATR following curative-intent MIS for partial or radical nephrectomy. Design setting and participants: The study cohort comprised patients from 1999 to 2021 with localized RCC managed at Memorial Sloan Kettering Cancer Center (New York, NY, USA) after MIS for partial or radical nephrectomy who developed ATR. Outcome measurements and statistical analysis: We collected data on clinicopathologic characteristics, treatments, time to ATR, and overall survival. Results and limitations: The median age of the 58 RCC patients was 61 yr. Forty-one patients (71%) were male, 26 (45%) had robot-assisted operations, and 39 (67%) had clear cell RCC. Twenty-nine patients had stage pT1 disease (50%) and ten (17%) had positive surgical margins. The most common ATR site was perinephric/nephrectomy bed implants (n = 28, 48%). Management included: surgical resection alone (n = 11, 19%), systemic therapy alone (n = 12, 21%), surgical resection and systemic therapy (n = 17, 29%), and palliative care (n = 8, 14%). At median follow-up of 59 mo (interquartile range [IQR] 28-92), the median time to ATR was 12 mo (IQR 5-28). Overall survival at 5 yr was 69.0% (95% confidence interval 57.4-83.1%) with only nine patients alive with no evidence of disease. Limitations include the potential for referral, detection, and selection biases, as well as uncertainty regarding the true incidence of ATR. Conclusions: ATR following MIS for partial or radical nephrectomy is an understudied, poor prognostic event which leads to a heavy treatment burden. Further investigation into its etiology and means of prevention is warranted. Patient summary: Patients experiencing recurrence of kidney cancer in an atypical site require a heavy treatment burden and have a guarded overall prognosis. Continued research is needed to determine the precise incidence of these recurrences and identify methods for mitigating them.

Systemic Immunological Determinants of Oncological Outcomes After Surgery for Localized Renal Cell Carcinoma.

INTRODUCTION & OBJECTIVES: In systemic therapy trials, a decreasing neutrophil-to-lymphocyte ratio (NLR) after treatment for metastatic renal cell carcinoma (RCC) has been associated with improved oncologic outcomes. Paradoxically, for patients with localized RCC treated with upfront surgery the opposite effect has been reported. We thus aimed to evaluate NLR dynamics on localized RCC recurrence. MATERIALS AND METHODS: Treatment naïve patients with localized RCC managed surgically between 2005 and 2020 were included. Preoperative NLR was calculated within 6-weeks prior to surgery and postoperative NLR was calculated between 4 and twelve-weeks after surgery. Patients were followed for disease recurrence, noting metastatic sites and postoperative infections. Cox regression were used to determine whether the relative change in postoperative NLR was associated with metastasis-free survival (MFS) and cancer-specific survival (CSS), adjusted for preoperative NLR. RESULTS: In the cohort of 3310 patients, 996 (30%) had postoperative NLR available. These patients generally had more advanced disease, with 100 developing metastases and 38 dying from kidney cancer. Median MFS follow-up was 4.4 years. Decreasing 2-month postoperative NLR was associated with non-statistically significant worse MFS and CSS (HR 0.79, 95% 0.50, 1.24, P = .3; HR 0.83, 95% C.I. 0.40, 1.73; P = .6). On sensitivity analysis, across all NLR measurements, with NLR as a time-dependent covariate, results were similar, with a declining NLR associated with adverse MFS (HR 0.85, 95% CI 0.69, 1.30, P-value = .10), though not meeting conventional levels of significance. CONCLUSION: In higher-risk localized RCC patients, postoperative NLR is not suitable as a biomarker for predicting recurrences.

NCCN Risk Reclassification in Black Men with Low and Intermediate Risk Prostate Cancer After Genomic Testing.

OBJECTIVES: To assess the utility of genomic testing in risk-stratifying Black patients with low and intermediate risk prostate cancer. METHODS: We retrospectively identified 63 Black men deemed eligible for active surveillance based on National Comprehensive Cancer Network (NCCN) guidelines, who underwent OncotypeDx Genomic Prostate Score testing between April 2016 and July 2020. Nonparametric statistical testing was used to compare relevant features between patients reclassified to a higher NCCN risk after genomic testing and those who were not reclassified. RESULTS: The median age was 66 years and median pre-biopsy PSA was 7.3. Initial risk classifications were: very low risk: 7 (11.1%), low risk: 24(38.1%), favorable intermediate risk: 31(49.2%), and unfavorable intermediate risk: 1 (1.6%). Overall, NCCN risk classifications after Genomic Prostate Score testing were significantly higher than initial classifications (P=.003, Wilcoxon signed-rank). Among patients with discordant risk designations, 28(28/40, 70%) were reclassified to a higher NCCN risk after genomic testing. A pre-biopsy prostate specific antigen of greater than 10 did not have significantly higher odds of HBR (OR:2.16 [95% CI: 0.64,7.59, P=.2). Of favorable intermediate risk patients, 20(64.5%) were reclassified to a higher NCCN risk. Ultimately, 18 patients underwent definitive treatment. CONCLUSIONS: Incorporation of genomic testing in risk stratifying Black men with low and intermediate-risk prostate cancer resulted in overall higher NCCN risk classifications. Our findings suggest a role for increased utilization of genomic testing in refining risk-stratification within this patient population. These tests may better inform treatment decisions on an individualized basis.

The Clinicopathologic and Molecular Landscape of Clear Cell Papillary Renal Cell Carcinoma: Implications in Diagnosis and Management.

BACKGROUND: Clear cell papillary renal cell carcinoma (CCPRCC) is a recently described tumor entity. Several questions remain about its epidemiology, molecular features, and clinical behavior. OBJECTIVE: To comprehensively evaluate clinicopathologic and molecular features of CCPRCC, and compare it with more common kidney cancer subtypes. DESIGN, SETTING, AND PARTICIPANTS: We identified 89 CCPRCC patients and compared their clinicopathologic features with 1120 localized clear cell renal cell carcinoma (ccRCC) and 129 type 1 papillary renal cell carcinoma (pRCC) patients. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Nonparametric statistical testing was used to compare relevant features between tumor types. Overall, cancer-specific survival (CSS) and metastasis-free survival estimates were calculated from initial diagnosis using the Kaplan-Meier method. Patients with ipsilateral multifocal disease were explored further. A subset of CCPRCC tumors underwent genomic analysis and were compared with other RCC subtypes. RESULTS AND LIMITATIONS: A higher proportion of female (45% vs 32%) and African-American (19% vs 3%) patients were observed in the CCPRCC cohort than in the ccRCC and pRCC cohorts. CCPRCC tumors also had increased odds of presenting with additional ipsilateral masses (odds ratio [OR]: 4.41 [confidence interval {CI}: 2.34, 8.15], p < 0.001) and bilateral disease (OR: 4.80 [CI: 2.40, 9.59], p < 0.001) compared with ccRCC tumors. On molecular analysis, CCPRCC tumors showed fewer somatic aberrations and a greater degree of mitochondrial DNA depletion. In multifocal CCPRCC tumors, histologic concordance among the different renal cell carcinoma masses was estimated at 44% (7/16), and none of the individuals presenting exclusively with CCPRCC tumors developed metastatic disease after 5 yr. In contrast, multifocal tumors with CCPRCC and other nonconcordant histologies were more likely to experience adverse outcomes (CSS, log rank p = 0.034). CONCLUSIONS: CCPRCC is characterized by distinct molecular and epidemiologic features that could be used to refine current diagnostic approaches. Although their clinical course is generally indolent, multifocal CCPRCC tumors represent a unique diagnostic challenge. In this context, single-mass biopsies could miss concomitant aggressive disease, with a potential negative impact on patient outcomes. Furthermore, high discordance rates in multifocal CCPRCC tumors have important clinical implications in management. PATIENT SUMMARY: We explored the molecular and clinical features of clear cell papillary renal cell carcinoma (CCPRCC) relative to other kidney cancer subtypes. While CCPRCC generally conveys a good prognosis, additional caution should be taken when it is diagnosed using biopsy if multiple kidney masses are present.

Prevalence and Landscape of Actionable Genomic Alterations in Renal Cell Carcinoma.

PURPOSE: We report our experience with next-generation sequencing to characterize the landscape of actionable genomic alterations in renal cell carcinoma (RCC). EXPERIMENTAL DESIGN: A query of our institutional clinical sequencing database (MSK-IMPACT) was performed that included tumor samples from 38,468 individuals across all cancer types. Somatic variations were annotated using a precision knowledge database (OncoKB) and the available clinical data stratified by level of evidence. Alterations associated with response to immune-checkpoint blockade (ICB) were analyzed separately; these included DNA mismatch repair (MMR) gene alterations, tumor mutational burden (TMB), and microsatellite instability (MSI). Data from The Cancer Genome Atlas (TCGA) consortium as well as public data from several clinical trials in metastatic RCC were used for validation purposes. Multiregional sequencing data from the TRAcking Cancer Evolution through Therapy (TRACERx) RENAL cohort were used to assess the clonality of somatic mutations. RESULTS: Of the 753 individuals with RCC identified in the MSK-IMPACT cohort, 115 showed evidence of targetable alterations, which represented a prevalence of 15.3% [95% confidence interval (CI), 12.7%-17.8%). When stratified by levels of evidence, the alterations identified corresponded to levels 2 (11.3%), 3A (5.2%), and 3B (83.5%). A low prevalence was recapitulated in the TCGA cohort at 9.1% (95% CI, 6.9%-11.2%). Copy-number variations predominated in papillary RCC tumors, largely due to amplifications in the MET gene. Notably, higher rates of actionability were found in individuals with metastatic disease (stage IV) compared with those with localized disease (OR, 2.50; 95% CI, 1.16-6.16; Fisher's P = 0.01). On the other hand, the prevalence of alterations associated with response to ICB therapy was found to be approximately 5% in both the MSK-IMPACT and TCGA cohorts and no associations with disease stage were identified (OR, 1.35; 95% CI, 0.46-5.40; P = 0.8). Finally, multiregional sequencing revealed that the vast majority of actionable mutations occurred later during tumor evolution and were only present subclonally in RCC tumors. CONCLUSIONS: RCC harbors a low prevalence of clinically actionable alterations compared with other tumors and the evidence supporting their clinical use is limited. These aberrations were found to be more common in advanced disease and seem to occur later during tumor evolution. Our study provides new insights on the role of targeted therapies for RCC and highlights the need for additional research to improve treatment selection using genomic profiling.

Putative Drivers of Aggressiveness in TCEB1-mutant Renal Cell Carcinoma: An Emerging Entity with Variable Clinical Course.

BACKGROUND: TCEB1-mutant renal cell carcinoma (RCC) is a rare variant of RCC with clear-cell features. Owing to its unique morphological and molecular features it has recently been proposed as a separate entity. Initial series suggested an indolent, early-stage phenotype. Here we expand our clinical cohort and describe a more detailed genomic analysis looking for potential drivers of aggressiveness. DESIGN, SETTING, AND PARTICIPANTS: We identified five new cases in our institutional sequencing cohort, four of whom were found to have high-stage disease (American Joint Committee on Cancer stage III/IV). Twelve previously reported cases were pooled for comparison purposes (Sato, The Cancer Genome Atlas, TRACERx Renal). OUTCOME MEASURES AND STATISTICAL ANALYSIS: We used our previously validated pipeline to analyze somatic mutations and copy number alterations (CNAs) in seven tumor samples with available data and estimated the number of cancer cells bearing each somatic mutation. The oncogenic potential of mutations was assessed using OncoKB and two other algorithms. Mann-Whitney U tests were used to evaluate differences in genomic markers between stage groups. RESULTS AND LIMITATIONS: All tumors showed biallelic inactivation of the TCEB1 gene according to a combination of somatic mutation and CNA analyses. Mutations were always found in residues involved in hydrophobic interactions with VHL. We found that high-stage tumors had additional oncogenic mutations (median 1, interquartile range [IQR] 1-1 vs 2, IQR 2-2; median difference 1, 95% confidence interval [CI] 1-1; p= 0.002) and showed whole-genome doubling events. They also seemed to have a higher burden of somatic CNAs (median fraction CNA genome 0.10, IQR 0.10-0.15 vs 0.63, IQR 0.58-0.68), however, this finding did not reach statistical significance (median difference 0.49, 95% CI 0.33-0.63; p=0.052). CONCLUSIONS: TCEB1-mutant RCC can show variable behavior ranging from very indolent to aggressive. Specific molecular events leading to high genomic instability seem to be associated with aggressiveness. This study expands the clinical spectrum of TCEB1-mutant RCC. PATIENT SUMMARY: We present four cases of aggressive TCEB1-mutant renal cell carcinoma, a rare type of kidney cancer. In-depth analysis of the genomes of these tumors revealed certain abnormalities that might explain this aggressive behavior.

Single-cell sequencing links multiregional immune landscapes and tissue-resident T cells in ccRCC to tumor topology and therapy efficacy.

Clear cell renal cell carcinomas (ccRCCs) are highly immune infiltrated, but the effect of immune heterogeneity on clinical outcome in ccRCC has not been fully characterized. Here we perform paired single-cell RNA (scRNA) and T cell receptor (TCR) sequencing of 167,283 cells from multiple tumor regions, lymph node, normal kidney, and peripheral blood of two immune checkpoint blockade (ICB)-naïve and four ICB-treated patients to map the ccRCC immune landscape. We detect extensive heterogeneity within and between patients, with enrichment of CD8A+ tissue-resident T cells in a patient responsive to ICB and tumor-associated macrophages (TAMs) in a resistant patient. A TCR trajectory framework suggests distinct T cell differentiation pathways between patients responding and resistant to ICB. Finally, scRNA-derived signatures of tissue-resident T cells and TAMs are associated with response to ICB and targeted therapies across multiple independent cohorts. Our study establishes a multimodal interrogation of the cellular programs underlying therapeutic efficacy in ccRCC.

Epidemiology, Risk Assessment, and Biomarkers for Patients with Advanced Renal Cell Carcinoma.

In the preceding two decades, several milestones have been reached in the management of patients with metastatic renal cell carcinoma (mRCC), including the development of novel targeted agents paralleling an increased understanding of the molecular biology of this disease process. Recently, a renewed enthusiasm for immunotherapy in the form of immune checkpoint blockade has resulted in significant strides in the treatment of mRCC. Despite these advances, treatment remains challenging for clinicians, and only modest survival benefits are observed with current treatment paradigms. The risk-stratification tools and investigated predictive and prognostic biomarkers in patients with mRCC are detailed in this review.

The Learning Curve for Magnetic Resonance Imaging/Ultrasound Fusion-guided Prostate Biopsy.

BACKGROUND: Magnetic resonance imaging/ultrasound-guided fusion biopsy (FBx) is more accurate at detecting clinically significant prostate cancer than conventional transrectal ultrasound-guided systematic biopsy. However, learning curves for attaining accuracy may limit the generalizability of published outcomes. OBJECTIVE: To delineate and quantify the learning curve for FBx by assessing the targeted biopsy accuracy and pathological quality of systematic biopsy over time. DESIGN, SETTING, AND PARTICIPANTS: We carried out a retrospective analysis of 173 consecutive men who underwent Artemis FBx with computer-template systematic sampling between July 2015 and May 2017. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The accuracy of targeted biopsy was determined by calculating the distance between planned and actual core trajectories stored on Artemis. Systematic sampling proficiency was assessed via pathological analysis of fibromuscular tissue in all cores and then comparing pathology elements from individual cores from men in the first and last tertiles. Polynomial linear regression models, change-point analysis, and piecewise linear regression were used to quantify the learning curve. RESULTS AND LIMITATION: A significant improvement in targeted biopsy accuracy occurred up to 98 cases (p<0.01). There was a significant decrease in fibromuscular tissue in the systematic biopsy cores up to 84 cases (p<0.01) and an improvement in pathological quality when comparing systematic cores from the first and third tertiles. Use of a different fusion platform may limit the generalizability of our results. CONCLUSIONS: There is a significant learning curve for targeted and systemic biopsy using the Artemis platform. Improvements in accuracy of targeted biopsy and better sampling for systematic biopsy can be achieved with greater experience. PATIENT SUMMARY: We define the learning curve for magnetic resonance imaging/ultrasound-guided fusion biopsy (FBx) using targeted biopsy accuracy and systematic core sampling quality as measures. Our findings underscore the importance of overcoming learning curves inherent to FBx to minimize patient discomfort and biopsy risk and improve the quality of care for accurate risk stratification, active surveillance, and treatment selection.