Use of immune checkpoint inhibitors (ICIs) after prior ICI in metastatic renal cell carcinoma (mRCC): Results from a multicenter collaboration

5077

Background: Several ICIs are used in first and subsequent lines of therapy for mRCC, either alone or in combination with another ICI or targeted therapy (TT). There are no data on the efficacy and safety of using an ICI in patients who have already received an ICI in a prior line of therapy. Methods: We reviewed patients with mRCC at 8 institutions who received 2 separate lines of ICI therapy (ICI-1, ICI-2), including as a single-agent and/or combination with other agents. The primary outcomes were overall response rate (ORR) and time to progression (TTP) with ICI-1 and ICI-2. Immune-related adverse events (irAEs) were graded using CTCAEv5.0. Results: 65 patients were included. Median age at diagnosis of mRCC was 60 years (range 30-86) and the majority had clear cell RCC (n=56, 86%). Median follow-up was 3.5 years (95% CI 2.9-4.4). Median lines at which ICI-1 and ICI-2 were received were 1 (1-6) and 3 (2-8) respectively. Reasons for discontinuing ICI-1 were disease progression (n=47, 72%), toxicity (n=15, 23%) or other (n=3, 5%). Therapies received at ICI-2 were single-agent ICI (n=26, 40%), or combinations of ICI with another ICI (n=20, 31%), TT (n=11, 17%) or other agent (n=8, 12%). Responses to ICI-1 and ICI-2 are shown in the Table; ORR to ICI-2 was significantly lower than to ICI-1 (23% vs. 36%, p=0.044). Amongst those who responded to ICI-2 (n=14), 7 (50%) received single-agent ICI, and the remainder received ICI in combination with another ICI (n=4, 29%) or TT (n=3, 21%); 7 patients (50%) had previously responded to ICI-1. The ORR to ICI-2 was higher in responders to ICI-1 (32%) compared to those with SD (17%) or PD (15%) to ICI-1. Median TTP (mTTP) at ICI-2 was shorter compared to ICI-1 (5.3 months vs. 8.5 months, Wilcoxon p=0.024). 29 patients (45%) experienced an irAE with ICI-2; 8 (12%) and 3 (5%) had a grade 3 or 4 irAE respectively, with 3 (30%) of these patients having previously had ≥grade 3 irAE to ICI-1. There were no treatment-related deaths. Conclusions: The ORR to ICI-2 was 23%, which is comparable to that seen with ICI after prior TT. Responses were seen even amongst those receiving single-agent ICI at ICI-2 and the likelihood of response to ICI-2 was higher if a patient had previously responded to ICI-1. No increase in toxicity with ICI-2 was apparent. Additional data from prospective studies are needed to determine whether sequential ICI has a role in treatment of mRCC. [Table: see text]

Overall survival (OS) with docetaxel (D) vs novel hormonal therapy (NHT) with abiraterone (A) or enzalutamide (E) after a prior NHT in patients (Pts) with metastatic prostate cancer (mPC): Results from a real-world dataset

5537

Background: NHT (A and E) are approved first-line (1L) treatment (Rx) for mPC. After progression on NHT, Rx include either alternate NHT or D. However, OS from a randomized trial comparing NHT vs D after progression on 1L NHT has not been reported. Methods: Pts data were extracted from the Flatiron Health EHR-derived de-identified database. Inclusion: diagnosis of mPC; 1L Rx with single agent A or E only, single-agent Rx with alternate NHT (E or A) or D in second line (2L). Exclusion: > 180 days between date of diagnosis of mPC and date of next visit to ensure Pts were actively engaged in care at data-providing site; Rx with NHT in non-metastatic setting, any prior exposure to D. OS was compared using Cox proportional hazards model stratified by Rx propensity score. Each Pts’ probability of receiving D (rather than NHT) was modeled via a random forest based on Pts and disease characteristics which may drive treatment selection. These included pre-2L Rx ECOG scores, PSA, LDH, ALPH, Hb, age, ICD codes for liver metastasis, diabetes, neuropathy, and heart failure; insurance payer, year of start of 2L Rx, time on 1 L NHT, Gleason score, PSA at the original diagnosis of mPC. Subgroup analyses included 1L Rx duration < 12 mos. Results: 1165 Pts between 2/5/2013 to 9/27/2019 were eligible. Median follow up 8 mos (range 0.1-64.5). Median OS after 1L A was higher with E as compared to D (15.7 vs. 9.4 mos). Median OS after 1L E was higher with A as compared to D (13.3 vs. 9.7 mos) (table). Propensity distributions were overlapping among Rx arms and showed only modest imbalance. In 2L, D had a worse adjusted hazard ratio of 1.29 and 1.35 as compared to E and A respectively (p < 0.05). Similar results were seen with 1L Rx duration of < 12 mos (p < 0.05). Conclusions: These hypothesis-generating data provide real-world OS estimates with 2L D & NHT in mPC. In propensity-stratified analyses, mPC Pts who progressed on NHT had a worse OS with 2L D as compared to alternate NHT. Results were consistent in unadjusted analysis & subgroup analyses of 1L Rx < 12 mos. Results are subject to residual confounding and missingness. After prospective validation these data may aid in Rx sequencing, Pts counselling, and design of future clinical trials in this setting. [Table: see text]

Genomic alterations associated with the progression from castration-sensitive to castration-resistant metastatic prostate cancer based on machine learning analysis of cell-free DNA genomic profile

e17596

Background: Metastatic castration-sensitive prostate cancer (mCSPC) eventually progresses to metastatic castration-resistant prostate cancer (mCRPC), which has few treatment options and carries a poor prognosis. We hypothesize that there are specific genomic alterations (GAs) associated with the progression from mCSPC to mCRPC. Methods: Patients (Pts) with mCSPC and mCRPC undergoing next-generation sequencing of cell-free DNA by a CLIA certified lab (G360, Guardant Health Inc., Redwood City, CA) as a part of routine care were retrospectively identified. Principal components analysis, an unsupervised ML algorithm, was used for data exploration and visualization. A combination of feature selection and supervised machine learning classification algorithms were used to identify genes associated with mCRPC. Gene Ontology enrichment analysis was used to identify pathways enriched for mCRPC-associated GAs. Patterns of mCRPC-associated GAs at a gene- and pathway-level were identified by Bayesian networks fitted using an exact structure learning algorithm. Results: 154 Pts with mCSPC and 187 Pts with mCRPC were included. A set of 16 GAs that robustly distinguished mCRPC from mCSPC (PPV = 94%, specificity = 91%) using supervised machine learning algorithms. These GAs, primarily amplifications, corresponded to AR, MAPK signaling, PI3K signaling, G1/S cell cycle, and receptor tyrosine kinases (RTKs). Positive statistical dependencies were observed between genes in these pathways. At a pathway-level, the presence of G1/S GAs in mCRPC samples increased the likelihood of harboring GAs in RTK, MAPK, and PI3K signaling. Limitations: The retrospective nature of our study means that unknown exposures could act as confounding variables, however this is representative of real-world clinical settings. Although the strength of this study is inclusion of clinically annotated patient samples, the limitation is that patients with mCSPC and mCRPC were unmatched. Conclusions: These results provide evidence that progression from mCSPC to mCRPC is associated with stereotyped concomitant gain-of-function in the RTK, PI3K, MAPK, and G1/S pathways in addition to AR. Upon external validation, these hypothesis generating data may warrant further investigation into combinatorial therapies that target these pathways.

Mini-Review: Cabozantinib in the Treatment of Advanced Renal Cell Carcinoma and Hepatocellular Carcinoma

Cabozantinib is an oral, tyrosine-kinase inhibitor with potent activity against VEGFR2 and MET, along with multiple other tyrosine kinases involved in cancer development and progression. Herein, we will focus on preclinical and clinical studies leading to the approval of cabozantinib in advanced renal cell carcinoma and hepatocellular carcinoma. Covered studies include NCT01100619, CABOSUN, METEOR, NCT00940225 and the CELESTIAL trial. Finally, we review future directions of cabozantinib development by highlighting some ongoing clinical trials.

Cabozantinib real-world effectiveness in the first through fourth-line settings for the treatment of metastatic renal cell carcinoma (mRCC): Results from the International mRCC Database Consortium (IMDC)

639

Background: Cabozantinib (Cabo) is approved for mRCC patients based on the METEOR and CABOSUN trials. The real-world effectiveness of Cabo in mRCC patients in the first- (1L), second- (2L), third- (3L) and fourth-line (4L) settings requires characterization. Methods: This retrospective analysis included mRCC patients who were treated with Cabo and stratified using IMDC risk groups. Overall response rate (ORR), time to treatment failure (TTF), and overall survival (OS) were calculated. Results: A total of 413 patients (82.6% with clear cell and 17.4% non-clear cell) were identified. The median age was 57 years. Overall, 63% of patients had a Karnofsky performance status score of >80 and 82.6% had prior nephrectomy. 23.1%, 75.4% and 88.3% of patients received immunotherapy as a prior line of treatment, before receiving Cabo in the 2L, 3L and 4L settings, respectively. For patients treated with 1L PD(L)1 combination or monotherapy (n=31), 2nd line Cabo had ORR of 20.8%, median TTF of 5.4 months and median OS of 17.4 months. When segregated into IMDC favorable, intermediate, and poor risk groups, the median OS was 34.8 months (95% CI 5.52-NR), 18.0 months (12.3-35.6) and 9.8 months (7.4-20.8), p=0.0088, respectively for 2L Cabo; and 31.5 months (23.6-39.3), 20.5 months (10.1-21.8), and 6.9 months (4.1-10.9), p=<0.0001), respectively for 3L Cabo. Conclusions: The ORR and TTF of Cabo were maintained from the 1L to the 4L therapy settings. In the 2L and 3L settings, the IMDC criteria appropriately stratified patients into favorable, intermediate and poor risk groups for OS. Cabo has activity after first line immunotherapy.[Table: see text]

Association of serum iron and response to immune checkpoint inhibitors (ICIs) in metastatic clear cell renal cell carcinoma (mccRCC)

723

Background: ICIs have improved survival in mRCC patients (pts), yet response rates (RR) to these treatments are variable. Biomarkers predictive of response to ICIs may improve outcomes for mccRCC pts. Genes that promote tumor-specific iron accumulation such as hepcidin (HAMP) or transferrin (TF) are significantly correlated with decreased overall survival in clear cell RCC (TCGA-KIRC). Iron deficiency in cancer patients is positively correlated with tumor stage and inversely proportional to treatment response (PMID: 23567147). Here, we investigate whether serum iron profile may be associated with response to ICIs in mccRCC pts. Methods: Clinical data was obtained from an mRCC registry at the Huntsman Cancer Institute, University of Utah. Analyses were limited to mccRCC pts who had serum iron studies within 6 months before initiating an ICI and had been assessed for RR. ICIs included nivolumab + ipilimumab, atezolizumab, or nivolumab alone. Responses were defined as complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD) by RECIST criteria. Clinical benefit (CB) was defined as CR + PR + SD. Descriptive statistics were used to assess associations between iron stores and response to ICIs and IMDC criteria. Results: 36 pts met all aforementioned eligibility criteria (29 were of IMDC intermediate risk, 7 were of IMDC poor risk). 5 pts received a first-line ICI, and the remaining 31 pts received ICIs as salvage therapy. Pts with CB had a significantly higher median serum iron level compared to those with no CB (59 vs 38.5 ug/dL; p=0.024). Furthermore, pts with normal transferrin saturation (TSAT %) were more likely to derive CB from ICIs (p=0.048). No association was found between serum ferritin (a marker of inflammation and tissue iron) and response to ICIs. Conclusions: In this hypothesis-generating study, increased serum iron, and TSAT levels within the normal range are associated with an increased likelihood of response to ICIs in pts with mccRCC. Once validated, these results may establish serum iron profile as a predictive marker of response to ICIs, in addition to providing the rationale for ruling out iron deficiency before starting ICIs.

Outcomes of patients with pancreatic-only oligometastatic renal cell carcinoma (RCC)

681

Background: Patients (pts) with RCC and oligometastatic pancreas metastases are treated with pancreatectomy, stereotactic body radiation therapy (SBRT), or systemic therapy. The optimal approach is not clear. We aimed to evaluate the comparative efficacy of the modalities in terms of progression-free survival (PFS) and overall survival (OS). Methods: This IRB-approved, multi-institutional, retrospective study evaluated pts with pancreatic-only RCC metastasis without concurrent metastases elsewhere. Data on pt demographics, tumor characteristics, treatment, and outcomes were collected. PFS and OS in pts treated with pancreatectomy vs. systemic therapy were compared by log rank tests. Results: Fifty-one pts from 9 institutions were included. All had clear cell RCC; 50 pts had nephrectomy; 30 pts (58.8%) and 18 pts (35.3%) had IMDC favorable and intermediate risk, respectively. Median time from RCC diagnosis to oligometastatic disease was 120 months (mo) (range: 0, 175). As initial treatment, 23 (45%) pts had pancreatectomy (mostly partial); 25 (49%) had systemic therapy (VEGFR TKI and/or immunotherapy); 1 had SBRT; 2 had other treatments. Too few pts had SBRT for comparison. With a median follow-up of 25 mo (2, 68), median PFS for the population was 25 mo (17, 42 95% CI). Median PFS was 36 mo (8, 43 95% CI) for surgery pts and 22 mo (17, NR 95% CI) for systemic therapy pts; this was not statistically significant (NS), p = 0.3. Median OS for the population was 121 mo (100, NR 95% CI). With a median follow-up of 51 mo (2, 217), OS was 121 mo (100, NR 95% CI) for surgery pts and not reached (64, NR 95% CI) for systemic therapy pts; NS, p = 0.52. Conclusions: In this retrospective series, RCC pts with oligometastatic pancreatic-only disease had similar PFS and OS outcomes from initial pancreatectomy or systemic therapy. RCC pts with pancreas-only metastases represent a unique patient population and studies informing the underlying biology are needed to optimize clinical management.

Identification of genomic aberrations associated with overall survival in metastatic clear cell renal cell carcinoma (mccRCC)

745

Background: Tumor comprehensive genomic profiling (CGP) in addition to risk stratification by IMDC criteria may aid in improving risk stratification. The objective of this study was to assess the prognostic impact of somatic mutations in addition to IMDC risk criteria. Methods: All patients with mccRCC treated with first line with VEGFR-TKI with CGP data available through a CLIA certified lab were included. Kaplan-Meier methodology and Cox proportional hazard ratios were used to test the association of overall survival with genomic alterations present in at least 7% of the population in this dataset. Genomic data were correlated with outcome by univariate analysis and subsequent multivariate testing, integrating genomic data with IMDC risk criteria. Results: A total of 58 patients met eligibly. The presence of any mutation in VHL, PBRM1, and MLL2 were prognostic in terms of overall survival (Table). The mutation status for these three prognostic genes was added to the IMDC risk model to test for the prognostic correlation. The mutations status of these 3 genes significantly correlated with overall survival (VHL: 0.32 [95% CI 0.11-0.95], PBRM1: 0.36 [0.14-0.96], and MLL2: 7.60 [1.35-24.6]) independent of the IMDC risk criteria. Conclusions: In mccRCC, VHL, PBRM1, and MLL2 mutations each predict overall survival independent of IMDC criteria. Further studies are warranted to assess alterations with low prevalence in this data set. Upon external validation, these data provide the rationale for integration of mutation status of these three genes in to the IMDC risk criteria.[Table: see text]

Synchronous Versus Metachronous Metastatic Disease: Impact of Time to Metastasis on Patient Outcome-Results from the International Metastatic Renal Cell Carcinoma Database Consortium

BACKGROUND

Patients with metastatic renal cell carcinoma (mRCC) may present with primary metastases (synchronous disease) or develop metastases during follow-up (metachronous disease). The impact of time to metastasis on patient outcome is poorly characterised.

OBJECTIVE

To characterise overall survival (OS) and time to treatment failure (TTF) based on time to metastasis in mRCC patients treated with targeted therapy (tyrosine kinase inhibitors [TKIs]).

DESIGN, SETTING, AND PARTICIPANTS

We used the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) to compare synchronous (metastases within ≤3 mo of initial diagnosis of cancer) versus metachronous disease (evaluated by >3-12 mo, >1-2 yr, >2-7 yr, and >7 yr intervals).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

OS and TFF were assessed using Kaplan-Meier curves. Cox multivariable regressions analyses (MVAs) were adjusted for baseline factors.

RESULTS AND LIMITATIONS

Of 7386 patients with mRCC treated with first-line TKIs, 3906 (53%) and 3480 (47%) had synchronous and metachronous metastasis, respectively. More patients with synchronous versus metachronous disease had higher T stage (T1-2: 19% vs 34%), N1 disease (21% vs 6%), presence of sarcomatoid differentiation (15.8% vs 7.9%), Karnofsky performance status <80 (25.9% vs 15.1%), anaemia (62.5% vs 42.3%), elevated neutrophils (18.9% vs 10.9%), elevated platelets (21.6% vs 11.4%), bone metastases (40.4% vs 29.8%), and IMDC poor risk (40.6% vs 11.3%). Synchronous versus metachronous disease by intervals >3-12 mo, >1-2 yr, >2-7 yr, and >7 yr correlated with poor TTF (5.6 mo vs 7.3, 8.0, 10.8, and 13.3 mo, p <  0.0001) and poor OS (median 16.7 mo vs 23.8, 30.2, 34.8, and 41.7 mo, p <  0.0001). In MVAs, the adjusted hazard ratios (95% confidence intervals) were 1.00 (reference), 0.98 (0.90-1.06), 0.81 (0.73-0.91), 0.74 (0.68-0.81), and 0.60 (0.54-0.67), respectively, for OS (p <  0.0001), and 1.00 (reference), 0.99 (0.92-1.06), 0.98 (0.90-1.07), 0.83 (0.77-0.89), and 0.66 (0.60-0.72), respectively, for TTF (p <  0.0001). Data were collected retrospectively.

CONCLUSIONS

Timing of metastases after initial RCC diagnosis may impact the outcomes from targeted therapy in mRCC.

PATIENT SUMMARY

We looked at the impact of the timing of metastatic outbreak on survival outcomes in kidney cancer patients treated with targeted therapy. We found that the longer time to metastatic development was associated with improved outcome.

Genomic landscape of metastatic hormone sensitive prostate cancer (mHSPC) vs. metastatic castration-refractory prostate cancer (mCRPC) by circulating tumor DNA (ctDNA)

5043

Background: mCRPC carries a poor prognosis, and targeted therapies have had minimal success in mCRPC. Novel genomic targets could improve drug development. To date, large ctDNA studies in metastatic prostate cancer have been descriptive with limited or no clinical annotation. Herein, we hypothesize that profiles of genomic alterations (GAs) in ctDNA not only differ significantly between, but can also be used to predict mCRPC vs. mHSPC. These findings could help identify new drug targets for mCRPC treatment. Methods: Men with mHSPC or mCRPC who underwent NGS of ctDNA using G360 (Guardant Health Inc.) at the Huntsman Cancer Institute were included. Men were classified as mCRPC or mHSPC (patients with current or no prior ADT). G360 detects somatic mutations in selected exons of 73 genes, amplifications in 18 genes, and selected fusions in 6 genes. Two-sided students t-test was used to compare the %cfDNA and total GAs. The Chi squared test was used to compare the frequency of each GA. Machine learning (ML) algorithms were trained on GAs and benchmarked by cross-validated performance. GAs contributing to mCRPC vs. mHSPC classification were measured by ML feature importance (e.g. odds ratios, regression coefficients). Results: Of the 259 men included, 119 men had mHSPC and 140 had mCRPC. Men with mCRPC had more GAs (4.5 vs. 1.86, p<0.0001) and higher %cfDNA (9.56% vs. 5.02%, p=0.02). In mHSPC, there was no significant difference in the number of GAs or %cfDNA between men on ADT and those who hadn’t yet started ADT. ML algorithms used GAs to predict mCRPC with 78.1% sensitivity, 64.0% specificity, 76.7% PPV, 65.1% NPV, and 70.3% overall accuracy. mCRPC was enriched with GAs in AR, ARID1A, BRAF, BRCA2, CCNE1, CTNNB1, EGFR, FGFR1, KIT, MET, MYC, PDGFRB, PIK3CA, and TP53. Of note, many of these genes are involved in MAP/ERK signaling. Conclusions: Men with mCRPC have more GAs, higher %cfDNA, and enrichment of GAs in the MAP/ERK pathway compared to men with mHSPC. The distinct GAs seen in mCRPC represent novel therapeutic targets, especially in the MAP/ERK pathway. We also show that machine learning can differentiate mHSPC and mCRPC based on GAs detected in ctDNA.

TM1-5 Optimising observation strategies for incidentally discovered intracranial meningiomas

Objectives

Develop a model to identify incidental meningiomas at risk of observation failure.

Design

Retrospective study (2007–2015).

Subjects

385 patients. Mean age 62.6 years.

Methods

Observation failure was defined as: new symptoms, MRI progression (absolute growth rate 2 cm3/year or absolute growth rate 1 cm3/year +relative growth rate 30%/year) or loss of treatment options. A prognostic model was developed using MRI and patient comorbidity.

Results

Over a median of 36 months, 44 (10.9%) meningiomas failed observation. Median time to failure was 33 months. Model parameters were based on statistical and clinical considerations and included: increasing tumour size (HR=2.17 [95% CI=1.53–3.09], p<0.001), peritumoural signal change (HR=1.58 [95% CI=0.65–3.85], p=0.313), FLAIR/T2 hyperintense meningiomas (HR=10.6 [95% CI=5. 39–21.0], p<0.001) and proximity to neurovascular structures (HR=1.38 [95% CI=0.74–2.56], p=0.314). Patients were stratified based on the model into low, medium and high-risk groups and rates of failed observation at 5 years were 3%, 28% and 75% respectively. Low-risk patients had small meningiomas, free of all risk factors. After 5 years of follow-up the probability of failure plateaued in all risk groups. Older patients with comorbidities were 15-times more likely to die than to receive intervention at 5 years following diagnosis, regardless of risk group.

Conclusions

Most meningiomas remain clinically and radiologically stable. Stratifying follow-up according to risk-group has the potential to reduce the cost to healthcare.

A Genome-wide association study of metastatic prostate cancer

160

Background: There are no biomarkers currently used in clinical practice that can predict which men will develop metastatic prostate cancer (mPrCa). Germline genetic variants that are highly associated with metastatic disease could be used for such prediction and may be identifiable from genome-wide association analyses (GWAS) conducted in appropriately scaled mPrCa case-control datasets. Methods: 451 mPrCa cases sequentially sampled from University of Utah/Huntsman Cancer Institute clinics were genotyped on the Illumina OmniExpress SNP platform and population-matched via principal components analysis to 1043 controls from dbGaP study phs000733 genotyped on the Illumina 5M SNP platform. The mPrCa cases and controls were analyzed via genome-wide association to identify SNPs highly associated with mPrCa. The dataset was then merged and re-analyzed with 176 lethal prostate cancer cases (identified in the Utah SEER Tumor Registry with a linked Utah death certificate including prostate cancer as a cause of death) in an attempt to identify a larger number of potential candidate SNPs associated with metastatic or lethal prostate disease. Results: The GWAS of mPrCa cases identified 4 significant SNPs at the 8q24.21 locus (p < 5e-8), as well as 9 SNPs in 6 previously unreported regions (5q14.1, 6p24.1, 8q21.3, 15q13.3, 15q22.2, and 17q25.1) with suggestive evidence for association (p < 1e-6). In addition, 30 SNPs with nominal evidence (p < 0.001) in the mPrCa-only GWAS appeared with more extreme p-values when the 176 lethal subjects were included in the analysis, and may be appropriate candidate variants to test in external datasets. Conclusions: In this case-control GWAS study of 627 men with mPrCa or lethal PrCa, germline SNPs at the 8q24.21 locus and 6 previously unreported regions may be associated with mPrCa. These findings should be validated in external datasets of men with mPrCa.

Receipt of systemic therapy in older versus younger patients (pts) with metastatic renal cell carcinoma (mRCC)

580

Background: More than half of pts diagnosed with mRCC are age 65 or older. However, older pts are often under-accrued/under-represented in clinical trials, partly due to concerns about their ability to tolerate systemic therapy (Rx). Given this, efficacy data from the registration trials may not apply to older pts. Herein, we investigate whether older patients with mRCC are less likely to receive various lines of systemic Rx than their younger counterparts. Methods: Clinical data was obtained from a prospectively maintained mRCC registry at the Huntsman Cancer Institute, University of Utah. Older pts were defined as ≥65 yrs at initiation of first-line systemic Rx for mRCC. Univariate analyses of the lines of systemic Rx received were performed using the Chi-squared test. Comparison of ordered categorical variables was made with the Wilcoxon rank sum test. Results: 264 pts who received first-line Rx for mRCC between 2004-2018 were included, and 108 of them were older pts. For older pts, median age at first-line Rx was 71.1 years and 78.7% had clear cell histology, whereas, the median age for younger pts was 53.4 years and 75.6% had clear cell histology. There was no difference in the baseline IMDC risk categories in older vs. younger pts (p = 0.907). A similar proportion of older and younger pts received at least two lines of systemic Rx (66.9% vs. 62.4%, p = 0.532). Furthermore, when analyzed across all lines of treatment, there was no difference in the number of systemic Rx between older and younger pts (p = 0.593). The median OS was similar in both groups: older 30 months (95% CI 21-44 months) vs. younger 34 months (95% CI 30-46 months) (p = 0.639). Conclusions: Older pts with mRCC receive a similar number of systemic Rx as their younger counterparts, and have similar survival outcomes. These findings can inform clinicians when selecting first and salvage-line treatment for older pts, and warrant proportionate accrual and representation of older pts in clinical trials.

DNA Damage Repair (DDR) Mutations and the Utility of High-Risk Genetics Clinics in Metastatic Castration-Refractory Prostate Cancer (mCRPC)

Germline pathogenic variants (PVs) in DNA-repair genes have garnered increasing attention in metastatic prostate cancer, and more patients are having somatic and germline DNA testing performed. Interpretation of germline DNA testing is a novel challenge for many clinicians, and the results of germline DNA-repair gene testing have significant implications for men with advanced prostate cancer and their children and siblings. Here, we report the case of a man with metastatic castration-refractory prostate cancer and a pathogenic, germline BRCA2 variant. We discuss the significance of his referral to a high-risk genetics clinic and the unique targeted therapy that he responded to.

Treatment of metastatic renal cell carcinoma in older patients: A network meta-analysis

INTRODUCTION

More than half of patients diagnosed with renal cell carcinoma (RCC) are age 65 or older. However, older patients are often unable to meet eligibility criteria for clinical trial enrollment due to multiple factors, such as comorbidities and polypharmacy, which leads to under-representation of this population in clinical trials. Given this, efficacy data from the registration trials may not apply to older patients. Our objective was to evaluate the efficacy of first-line and salvage-line treatment in older patients, and compare efficacy between older and younger patients with metastatic RCC (mRCC).

METHODS

Pivotal phase three clinical trials for first-line and salvage-line treatments were included if they reported overall survival (OS) or progression-free survival (PFS) results stratified by age (</≥65 years). The meta-analysis of OS and PFS stratified by age </≥65 years was conducted in the context of Bayesian hierarchical log-linear models with both within and between study variance components.

RESULTS

In the first-line setting, data suggests that Nivolumab plus Ipilimumab is the most efficacious treatment for older patients (PFS hazard ratio (HR) 0.55, 95% confidence interval (CI) 0.23-1.45, probability best 39.7%). In the salvage-line setting, Cabozantinib is likely the most efficacious therapy for older patients (PFS HR 0.15, 95% CI 0.08-0.28, probability best 77.2%). Evidence suggests that the majority of first-line treatments have worse efficacy in older patients compared to younger patients.

CONCLUSION

For older patients, first-line Nivolumab plus Ipilimumab and salvage-line Cabozantinib may offer the best survival outcomes. Most first-line drugs for mRCC have inferior performance in older patients compared to their younger counterparts.

Independent assessment of TP53 and PTEN as predictors of response to enzalutamide (ENZ) or abiraterone acetate (AA) in men with metastatic castration-resistant prostate cancer (mCRPC)

351

Background: Alterations in androgen receptor signaling are well-established mechanisms of resistance to medical castration. Pre-clinical studies suggest that alterations to key tumor suppressor genes, such as TP53 or PTEN, may also be associated with development of androgen independence as an alternate mechanism of castration-resistance. Previous studies have shown that TP53 inactivation and PTEN loss are predictive of response to novel androgen axis inhibitors. Here, we independently assess whether TP53 and PTEN genomic alterations are predictive of response to ENZ and AA in men with mCRPC. Methods: Clinical data and samples were analyzed from a prospective prostate cancer registry at the University of Utah (Salt Lake City, UT). Next-generation sequencing (NGS) was performed on predominantly primary tumor tissue for 343 somatic and germline genetic alterations using FoundationOne. Primary endpoints were progression-free survival (PFS) and overall survival (OS). Patients with mCRPC who were treated with any line AA or enzalutamide were included. We performed a univariate analysis to assess the predictive value of TP53 and PTEN. Only patients treated with single-agent therapy were included. Results: Of 141 men with prostate cancer and NGS available, 56 were included. Most patients were treated with abiraterone (n = 50), and only 6 with enzalutamide. 28.6% had PTEN loss and 35.7% had a TP53 mutation. OS and PFS did not differ significantly according to PTEN or TP53 status. Median OS was 40.9 months and not reached for men with and without TP53 mutation (HR 1.85, p = 0.31). Median PFS was 7.5 months and 9.5 months for men with and without TP53 mutation (HR 1.18, p = 0.60). Median PFS was 7.2 months and 9.5 months for men with and without PTEN loss (HR 1.15, p = 0.66). Median OS for PTEN was not mature enough to analyze. Conclusions: In our independent cohort, neither TP53 mutation nor PTEN loss is predictive of response to androgen-directed therapy in men with mCRPC patients. However, this is a relatively small retrospective sample with few events. These results should be considered exploratory only.

CEREBRAL VASCULITIS HISTOPATHOLOGY IN RELAPSING POLYCHONDRITIS

Central nervous system (CNS) involvement in relapsing polychondritis (RPC) is rare and presumed to be the result of either a vasculitic or an encephalitic process, although there is little in the way of histopathological evidence for these. Understanding the underlying pathological process is important because cognitive decline can be halted or reversed with tailored immunosuppression.

We describe here the histopathological features of RPC with CNS involvement in a 65-year-old gentleman that presented with rapidly progressive cognitive decline, fevers and ataxia over six weeks. He had bilateral auricular inflammation with cartilage destruction, but relative lobe sparing, ocular inflammation, and a symmetrical small-joint polyarthropathy.

The cerebrospinal fluid showed lymphocytic pleocytosis. Diffuse sub-cortical white matter abnormalities were seen on magnetic resonance imaging. A clinical diagnosis of RPC was made on the basis of McAdam criteria.

Routinely stained histological brain sections showed scattered foci of vasculitis associated with multinucleated giant cells (MNGC), T-lymphocytes, neutrophils and eosinophils. The leptomeninges were oedematous and thickened by an increase in loose collagenous tissue, vascular proliferation and inflammatory infiltrate of neutrophils, lymphocytes and plasma cells. PAS staining did not reveal any infective organisms. Auricular histology showed central erosion of the cartilage and mild non-specific inflammation of the skin consistent with clinical impression of RPC.

In the context of the clinical diagnosis, our findings help further refine the histopathological understanding of RPC involving the CNS, suggesting a vasculitic rather than encephalitic process. Our histology also showed giant perivascular multinucleated cells as part of the vasculitic process, and this not been described before in the literature.