Pan-cancer Analysis of CDK12 Alterations Identifies a Subset of Prostate Cancers with Distinct Genomic and Clinical Characteristics

BACKGROUND

CDK12 genomic alterations occur in several tumor types, but little is known about their oncogenic role and clinical significance.

OBJECTIVE

To describe the landscape of CDK12 alterations across solid cancers and the clinical features of CDK12-altered prostate cancer.

DESIGN, SETTING, AND PARTICIPANTS

A single-center retrospective study of 26743 patients across 25 solid tumor types who underwent tumor sequencing was performed. Clinicopathologic features and outcomes were assessed in prostate cancer.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

CDK12 alterations and their association with genomic characteristics are described. For prostate cancer patients, overall survival and time to castration resistance were assessed using univariable and multivariable Cox regression analysis.

RESULTS AND LIMITATIONS

CDK12 alterations were identified in 404/26743 patients (1.5%) overall, but were most frequent in prostate (100/1875, 5.3%) and ovarian cancer (43/1034, 4.2%), in which they were associated with a high prevalence of truncating variants and biallelic inactivation. CDK12 alterations defined a genomic subtype of prostate cancer with a unique copy-number alteration profile and involvement of distinct oncogenic pathway alterations, including cell-cycle pathway genes. CDK12-altered prostate cancer was associated with somewhat more aggressive clinical features and shorter overall survival (median 64.4 vs 74.9 mo; p=0.032) independent of standard clinical factors and tumor copy-number alteration burden (adjusted hazard ratio 1.80, 95% confidence interval 1.12-2.89; p=0.024). The study is limited by its retrospective nature.

CONCLUSIONS

CDK12 alteration is a rare event across solid cancers but defines a clinically distinct molecular subtype of prostate cancer associated with unique genomic alterations and slightly more aggressive clinical features.

PATIENT SUMMARY

CDK12 gene alterations occur rarely across tumor types, but more frequently in prostate cancer, where they are associated with genomic instability, cell-cycle pathway gene alterations, and somewhat worse clinical outcomes, warranting further investigation of therapeutic targeting of this disease subset.

Impact of clinical versus radiographic progression on clinical outcomes in metastatic castration-resistant prostate cancer

OBJECTIVES

Unequivocal clinical progression (UCP)-a worsening of clinical status with or without radiographic progression (RAD)-represents a distinct mode of disease progression in metastatic prostate cancer. We evaluated the prevalence, risk factors and the impact of UCP on survival outcomes.

METHODS

A post-hoc analysis of the COU-AA-302, a randomised phase 3 study of abiraterone plus prednisone (AAP) versus prednisone was performed. Baseline characteristics were summarised. Cox proportional-hazards model and Kaplan-Meier method were used for survival and time to event analyses, respectively. Iterative multiple imputation method was used for correlation between clinicoradiographic progression-free survival (crPFS) and overall survival (OS).

RESULTS

Of 736 patients with disease progression, 280 (38%) had UCP-only and 124 (17%) had UCP plus RAD. Prognostic index model high-risk group was associated with increased likelihood of UCP (p<0.0001). Median OS was 25.7 months in UCP-only and 33.0 months for RAD-only (HR 1.39; 95% CI 1.16 to 1.66; p=0.0003). UCP adversely impacted OS in both treatment groups. Lowest OS was seen in patients with prostate specific antigen (PSA)-non-response plus UCP-only progression (median OS 22.6 months (95% CI 20.7 to 24.4)). Including UCP events lowered estimates of treatment benefit-median crPFS was 13.3 months (95% CI 11.1 to 13.8) versus median rPFS of 16.5 months (95% CI 13.8 to 16.8) in AAP group. Finally, crPFS showed high correlation with OS (r=0.67; 95% CI 0.63 to 0.71).

CONCLUSIONS

UCP is a common and clinically relevant phenomenon in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with AAP or prednisone. UCP is prognostic and associated with inferior OS and post-progression survival. A combination of PSA-non-response and UCP identifies patients with poorest survival. When included in PFS analysis, UCP diminishes estimates of treatment benefit. Continued study of UCP in mCRPC is warranted.

Meeting report from the Prostate Cancer Foundation PSMA theranostics state of the science meeting

INTRODUCTION

The Prostate Cancer Foundation (PCF) convened a PCF prostate-specific membrane antigen (PSMA) Theranostics State of the Science Meeting on 18 November 2019, at Weill Cornell Medicine, New York, NY.

METHODS

The meeting was attended by 22 basic, translational, and clinical researchers from around the globe, with expertise in PSMA biology, development and use of PSMA theranostics agents, and clinical trials. The goal of this meeting was to discuss the current state of knowledge, the most important biological and clinical questions, and critical next steps for the clinical development of PSMA positron emission tomography (PET) imaging agents and PSMA-targeted radionuclide agents for patients with prostate cancer.

RESULTS

Several major topic areas were discussed including the biology of PSMA, the role of PSMA-targeted PET imaging in prostate cancer, the physics and performance of different PSMA-targeted PET imaging agents, the current state of clinical development of PSMA-targeted radionuclide therapy (RNT) agents, the role of dosimetry in PSMA RNT treatment planning, barriers and challenges in PSMA RNT clinical development, optimization of patient selection for PSMA RNT trials, and promising combination treatment approaches with PSMA RNT.

DISCUSSION

This article summarizes the presentations from the meeting for the purpose of globally disseminating this knowledge to advance the use of PSMA-targeted theranostic agents for imaging and treatment of patients with prostate cancer.

Prospective Multicenter Study of Circulating Tumor Cell AR-V7 and Taxane Versus Hormonal Treatment Outcomes in Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Androgen receptor splice variant 7 (AR-V7) detection in circulating tumor cells (CTCs) is associated with a low probability of response and short progression-free (PFS) and overall survival (OS) in men with metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide or abiraterone. However, it is unclear whether such men benefit from taxane chemotherapy.

PATIENTS AND METHODS

PROPHECY is a multicenter prospective blinded study of patients with poor-risk mCRPC starting abiraterone or enzalutamide and observed through subsequent progression and taxane chemotherapy. We assessed AR-V7 status using the Johns Hopkins modified AdnaTest CTC AR-V7 messenger RNA assay and the Epic Sciences CTC nuclear-localized AR-V7 protein assay before treatment. The primary objective was to validate the independent prognostic value of CTC AR-V7 status based on radiographic/clinical PFS. OS, confirmed prostate-specific antigen (PSA), and objective radiologic responses were secondary end points.

RESULTS

We enrolled 118 men with mCRPC treated with abiraterone or enzalutamide, 51 of whom received subsequent docetaxel or cabazitaxel. Pretreatment CTC AR-V7 status by the Johns Hopkins and Epic Sciences assays was independently associated with worse PFS (hazard ratio [HR], 1.7; 95% CI, 1.0 to 2.9 and HR, 2.1; 95% CI, 1.0 to 4.4, respectively) and OS (HR, 3.3; 95% CI, 1.7 to 6.3 and HR, 3.0; 95% CI, 1.4 to 6.3, respectively) and a low probability of confirmed PSA responses, ranging from 0% to 11%, during treatment with abiraterone or enzalutamide. At progression, subsequent CTC AR-V7 detection was not associated with an inferior PSA or radiographic response or worse PFS or OS with subsequent taxane chemotherapy after adjusting for CellSearch CTC enumeration and clinical prognostic factors.

CONCLUSION

Detection of AR-V7 in CTCs by two different blood-based assays is independently associated with shorter PFS and OS with abiraterone or enzalutamide, but such men with AR-V7-positive disease still experience clinical benefits from taxane chemotherapy.

Dickkopf-1 Can Lead to Immune Evasion in Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Metastatic castration-resistant prostate cancer (mCRPC) with low androgen receptor (AR) and without neuroendocrine signaling, termed double-negative prostate cancer (DNPC), is increasingly prevalent in patients treated with AR signaling inhibitors and is in need of new biomarkers and therapeutic targets.

METHODS

Candidate genes enriched in DNPC were determined using differential gene expression analysis of discovery and validation cohorts of mCRPC biopsies. Laboratory studies were carried out in human mCRPC organoid cultures, prostate cancer (PCa) cell lines, and mouse xenograft models. Epigenetic studies were carried out in a rapid autopsy cohort.

RESULTS

Dickkopf-1 (DKK1) expression is increased in DNPC relative to prostate-specific antigen (PSA)-expressing mCRPC in the Stand Up to Cancer/Prostate Cancer Foundation discovery cohort (11.2 v 0.28 reads per kilobase per million mapped reads; q < 0.05; n = 117) and in the University of Washington/Fred Hutchinson Cancer Research Center cohort (9.2 v 0.99 fragments per kilobase of transcript per million mapped reads; P < .0001). DKK1 expression can be regulated by activated Wnt signaling in vitro and correlates with activating canonical Wnt signaling mutations and low PSA mRNA in mCRPC biopsies (P < .05). DKK1 hypomethylation was associated with increased DKK1 mRNA expression (Pearson r = -0.66; P < .0001) in a rapid autopsy cohort (n = 7). DKK1-high mCRPC biopsies are infiltrated with significantly higher numbers of quiescent natural killer (NK) cells (P < .005) and lower numbers of activated NK cells (P < .0005). Growth inhibition of the human PCa model PC3 by the anti-DKK1 monoclonal antibody DKN-01 depends on the presence of NK cells in a severe combined immunodeficient xenograft mouse model.

CONCLUSION

These results support DKK1 as a contributor to the immunosuppressive tumor microenvironment of DNPC. These data have provided the rationale for a clinical trial targeting DKK1 in mCRPC (ClinicalTrials.gov identifier: NCT03837353).

Phase II trial of SM-88, a cancer metabolism based therapy, in non-metastatic biochemical recurrent prostate cancer

Background Androgen deprivation therapy (ADT) is a standard treatment for high-risk biochemically-recurrent, non-metastatic prostate cancer (BRPC) but is not curative and associated with toxicity. Racemetyrosine (SM-88) is an amino-acid analogue used with methoxsalen, phenytoin, and sirolimus (MPS) to enhance SM-88 activity. Method A phase 1b/2, open-label trial in BRPC and rising PSA. Patients were given daily SM-88 (230 mg BID), methoxsalen (10 mg), phenytoin (50 mg), and sirolimus (0.5 mg)). Outcome measures included changes in PSA, circulating tumor cells (CTCs) and imaging. Results 34 subjects were screened, 23 treated and 21 remained on study for ≥12 weeks. The median PSA was 6.4 ng/ml (range 1.7-80.1); doubling-time 6.2 months (range 1.4-36.6) and baseline testosterone 319.1 ng/ml (range 2.5-913.7). Median duration of therapy was 6.5 months (2.6-14.0). CTCs (median 48.5 cells/4 ml (range 15-268) at baseline) decreased a median of 65.3% in 18 of 19 patients. For patients who achieved an absolute CTC nadir count of <10 cells/4 ml (n = 10), disease control was 100% i.e. no metastases or PSA progression, while on trial (p = 0.005). PSA fell by ≥50% in 4.3% (1 subject). No patients developed metastatic disease while on treatment (metastases free survival =100%). There were no treatment-related adverse events (AEs) and quality of life was unchanged from baseline on the EORTC QLQ-C30 and QLQ-PR25. Testosterone levels rose slightly on SM-88 and were unrelated to efficacy or toxicity. Conclusions Use of SM-88 was associated with disease control while maintaining QOL. SM-88 may delay the need for ADT and the associated hormonal side effects. Larger trials are planned.Trial registration number, date of registration - NCT02796898, June 13, 2016.

Morphology-Predicted Large-Scale Transition Number in Circulating Tumor Cells Identifies a Chromosomal Instability Biomarker Associated with Poor Outcome in Castration-Resistant Prostate Cancer

Chromosomal instability (CIN) increases a tumor cell's ability to acquire chromosomal alterations, a mechanism by which tumor cells evolve, adapt, and resist therapeutics. We sought to develop a biomarker of CIN in circulating tumor cells (CTC) that are more likely to reflect the genetic diversity of patient's disease than a single-site biopsy and be assessed rapidly so as to inform treatment management decisions in real time. Large-scale transitions (LST) are genomic alterations defined as chromosomal breakages that generate chromosomal gains or losses of greater than or equal to10 Mb. Here we studied the relationship between the number of LST in an individual CTC determined by direct sequencing and morphologic features of the cells. This relationship was then used to develop a computer vision algorithm that utilizes CTC image features to predict the presence of a high (9 or more) versus low (8 or fewer) LST number in a single cell. As LSTs are a primary functional component of homologous recombination deficient cellular phenotypes, the image-based algorithm was studied prospectively on 10,240 CTCs in 367 blood samples obtained from 294 patients with progressing metastatic castration-resistant prostate cancer taken prior to starting a standard-of-care approved therapy. The resultant computer vision-based biomarker of CIN in CTCs in a pretreatment sample strongly associated with poor overall survival times in patients treated with androgen receptor signaling inhibitors and taxanes. SIGNIFICANCE: A rapidly assessable biomarker of chromosomal instability in CTC is associated with poor outcomes when detected in men with progressing mCRPC.

Pathogenic ATM Mutations in Cancer and a Genetic Basis for Radiotherapeutic Efficacy

BACKGROUND

Radiation therapy is one of the most commonly used cancer therapeutics but genetic determinants of clinical benefit are poorly characterized. Pathogenic germline variants in ATM are known to cause ataxia-telangiectasia, a rare hereditary syndrome notable for marked radiosensitivity. In contrast, somatic inactivation of ATM is a common event in a wide variety of cancers, but its clinical actionability remains obscure.

METHODS

We analyzed 20 107 consecutively treated advanced cancer patients who underwent targeted genomic sequencing as part of an institutional genomic profiling initiative and identified 1085 harboring a somatic or germline ATM mutation, including 357 who received radiotherapy (RT). Outcomes of irradiated tumors harboring ATM loss-of-function (LoF) mutations were compared with those harboring variants of unknown significance. All statistical tests were 2-sided.

RESULTS

Among 357 pan-cancer patients who received 727 courses of RT, genetic inactivation of ATM was associated with improved radiotherapeutic efficacy. The 2-year cumulative incidence of irradiated tumor progression was 13.2% vs 27.5% for tumors harboring an ATM LoF vs variant of unknown significance allele, respectively (hazard ratio [HR] = 0.51, 95% confidence interval [CI] = 0.34 to 0.77, P = .001). The greatest clinical benefit was seen in tumors harboring biallelic ATM inactivation (HR = 0.19, 95% CI = 0.06 to 0.60, P = .005), with statistically significant benefit also observed in tumors with monoallelic ATM inactivation (HR = 0.57, 95% CI = 0.35 to 0.92, P = .02). Notably, ATM LoF was highly predictive of outcome in TP53 wild-type tumors but not among TP53-mutant tumors.

CONCLUSIONS

We demonstrate that somatic ATM inactivation is associated with markedly improved tumor control following RT. The identification of a radio-sensitive tumor phenotype across multiple cancer types offers potential clinical opportunities for genomically guided RT.

Abstract A60: Evaluation of preanalytic variables in liquid biopsy tests for prostate cancer: Specimen acquisition and patient context factors that impact results

Cell-free DNA (cfDNA) and circulating tumor cell (CTC) enumeration and profiling serve as sources of tumor material to guide treatment decisions. Use of blood-based biomarker assays requires an understanding of factors outside the laboratory where the assay is performed that can influence the final reported result. The factors include preanalytical variables related to specimen acquisition, delivery and storage, and patient context variables. To address this question, our group activated an IRB-approved protocol to study the effect of variables associated with the factors mentioned above, including: (i) the order of blood being drawn in a single collection, (ii) collections done at different times of the day, (iii) collections repeated 1-14 days apart, (iv) patient fasting status, and (v) glucocorticoid use as an antiemetic. Our focus is on validated assays spanning different contexts of use in metastatic prostate cancer management, including: 1) a nuclear localized AR-V7 assay in circulating tumor cells (CTCs) as response indicator to androgen receptor (AR) signaling inhibitor vs. taxane based chemotherapy in the second line of therapy (Epic Sciences®, San Diego, CA); 2) a change in CTC number from any pretherapy value to zero post-therapy as a response indicator (CellSearch®, Menarini Silicon Biosystems); and 3) the detection of somatic mutations and copy number alterations in the AR pathway as resistance mechanism to abiraterone acetate in castration-resistant prostate cancer patients. Our pilot data currently include a cohort of 12 patients on which we aimed to study the effect of draw order on (i) the counts of CTC and ARV7 expression assessed by EpicScience® and (ii) the quality and quantity of cfDNA and mutation detected assessed by the analytically validated ThermFisher Oncomine® Pan-cancer cfDNA assay (Waltham, MA). Our initial analysis showed that the CTC and cfDNA results are mostly consistent across different draw orders, with slight variation at levels close to or below the limit of detection of the assay involved (such as 0.1% variant allele frequency of the ThermoFisher Oncomine® assay). We are expanding the sample size to further validate these results, perform additional statistical analysis, and include data from the Food and Drug Administration (FDA) cleared, CellSearch® CTC enumeration assay and MSK-ACCESS (Analysis of Circulating cfDNA to Examine Somatic Status), an ultrasensitive 129-gene cfDNA profiling assay that was developed internally at Memorial Sloan Kettering Cancer Center, recently approved by the New York State Department of Health, and launched in our Clinical Laboratory Improvement Amendment (CLIA)-certified molecular diagnostic laboratory. The results of this study will provide evidence to inform the design of preanalytical sample collection and inform how to use these tests in clinical practice.

Citation Format: Dana Tsui, Ethan S. Barnett, Kelli Bramlet, Joseph Schonhoft, Ruben Rizzi, Howard I. Scher. Evaluation of preanalytic variables in liquid biopsy tests for prostate cancer: Specimen acquisition and patient context factors that impact results [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A60.

Changes in ki-67 and cleaved caspase-3 (CC3) with short term androgen deprivation therapy (ADT) prior to prostatectomy as part of a trial in intermediate and high-risk prostate cancer (PC)

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Background: Ki-67 and CC3 are markers of cellular proliferation and apoptosis and have been associated with prognosis in localized PC. Testosterone suppression promotes a time-dependent modulation of these indices. We explored changes in Ki-67 and CC3 at different timepoints in a pilot trial using short-term ADT prior to radical prostatectomy (RP). Methods: Pts with intermediate and high-risk localized PC were randomized to receive a single dose of neoadjuvant degarelix (240 mg SC) either 4 ± 1 days (Cohort A) or 7 ± 1 days (Cohort B) prior to RP. Anatomically matched tumor foci from the pre-treatment diagnostic biopsy and the prostatectomy specimens were assessed by immunohistochemistry (IHC) for Ki-67, CC3, and PTEN expression. Results: 32 pts were randomized: 15 to Cohort A and 17 to Cohort B. Ki-67 and CC3 expression in the pre- and post-treatment samples for both cohorts are summarized in the table. A significant reduction in Ki-67 and increase in CC3 expression occurred in both cohorts (all p-values < 0.05). No difference was found when the absolute difference of Ki-67 expression was compared between Cohort A and Cohort B (p = 0.7). A significant reduction of Ki-67 and increase in CC3 expression occurred in pts independent of PTEN status. Conclusions: A reduction of Ki-67 and an increase in CC3 expression was achieved in both cohorts following a single dose of degarelix within 1 week of RP. Although loss of PTEN has been associated with androgen-independent progression, reduction of proliferation and increase in apoptosis levels were achieved independent of PTEN status in this small cohort. Further analyses are ongoing to correlate the pathologic findings with clinical outcomes. Clinical trial information: NCT01542021 . [Table: see text]

Circulating tumor cells (CTCs) with small-cell like pathology are prevalent in metastatic castration-resistant prostate cancer (mCRPC) and show selective pharmacodynamic reductions in patients treated with platinum but not ARSI or taxane

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Background: The increasing availability and earlier use of life prolonging drugs targeting the androgen receptor signaling axis (ARSI) has resulted in an increase in the frequency of late state tumors with “small cell/neuroendocrine (NESC) phenotypes” similar to small-cell lung cancer (SCLC). Definitive pathologic criteria to diagnose the “entity” are lacking, and the eligibility criteria across trials are inconsistent, limiting the ability to relate outcomes between studies. We hypothesized that an analytically valid assay for a rigorously defined “small-cell CTC” phenotype might serve as a unifying biomarker for the presence of NESC-like tumors in an individual for use in clinical trials. Methods: Using the WHO guidelines for small-cell diagnosis in tissue as reference, we defined an equivalent set of single-cell CTC criteria for defining a CTC with small-cell histology: a small and circular CD45-, CK+ cell with high N/C ratio lacking detectable nucleoli. Small-cell subtype pharmacodynamic changes were studied in 233 patients with progressing mCRPC about to start an AR signaling inhibitor ARSi (N=111), taxane (N=89), or platinum (N=33). Results: CTCs with small-cell morphology had lower AR protein expression compared with non-small-cell CTCs (P<0.0001) and increased with therapy line. The small-cell CTC subtype decreased in number from baseline to on-therapy in patients treated with platinum but not in those treated with ARSi or taxane (Table). Conclusions: Digital pathology analysis of CTCs defined a CTC subtype consistent with that of small-cell carcinoma that were only reduced in number with platinum-based therapy. The tracking of CTC subtypes after treatment with different drug classes may help assess drug activity in heavily treated patients that often have heterogeneous disease that of which may not be captured using standard measures of response. [Table: see text]

Evaluation of immune-related adverse events (irAE): Utilizing the patient-reported outcomes of the common terminology criteria for adverse events (PRO-CTCAE) in a phase II study of ipilimumab (ipi) in men with castration-sensitive prostate cancer (CSPC)

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Background: Incorporation of the PRO-CTCAE during chemotherapy is associated with fewer ER visits and improved survival. Limited data exist using this tool to capture irAE in immunotherapy trials. We collected select PRO-CTCAEs in a clinical trial evaluating an immune checkpoint inhibitor (ICI) in patients (pts) with CSPC. Methods: Cohort A (Coh A) enrolled de novo metastatic CSPC; Cohort B (Coh B) enrolled recurrent CSPC after radical prostatectomy (RP). Treatment consisted of 4 doses of ipi and 8 months of androgen deprivation therapy (ADT) in Coh A & B, and RP in Coh A. PRO-CTCAEs were collected at each ipi or ADT administration, and during follow-up. PRO-CTCAE items included abdominal pain, diarrhea, fatigue, anorexia, nausea, vomiting, rash and pruritus, with the correspondent attributes of frequency (freq), severity (sev), interference (int), and presence. Results: 16 pts were treated (Coh A: 7; Coh B: 9) with 181 matched pairs of PRO-CTCAE and CTCAE. The study was terminated early for an unfavorable risk:benefit ratio. PRO-CTCAE completion at required visits was 85.4% in Coh A and 98.1% in Coh B. Cohen’s kappa coefficients was lowest for pruritus (k = 0.10, slight agreement) and highest for rash (k = 0.64, moderate agreement). CTCAE captured diarrhea in 10 pts, 4 of whom received steroids. 75% (3/4) of pts receiving steroids graded diarrhea as ‘frequently’ or ‘almost constantly’ on the PRO-CTCAE while 66.7% (4/6) of those who did not receive steroids reported the same frequency. Conclusions: IrAE were more commonly reported and of higher grade by patients using the PRO-CTCAE as compared to clinician reporting, consistent with existing literature in non-ICI studies. Diarrhea as reported by the PRO-CTCAE did not associate with steroid use in this small trial. Further studies are needed to evaluate irAE using PRO-CTCAEs and the potential role in management of these toxicities. Clinical trial information: NCT02020070 . [Table: see text]

Prevalence and tissue concordance of BRCA2 copy number loss evaluated by single-cell, shallow whole genome sequencing of circulating tumor cells (CTCs) in castration-resistant prostate cancer (CRPC)

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Background: Genomic studies have shown that up to 25% of prostate cancer tissue specimens harbor alterations in DNA Damage Repair (DDR) genes, which may sensitize the tumor to poly ADP-ribose polymerase inhibitors (PARPi). Trials evaluating PARPi in patients with DDR deficiencies have shown varied response rates and differences regarding which genomic alterations predict for sensitivity to these agents, with the majority of objective responses seen in BRCA2-altered tumors. These results highlight the need to develop biomarker assays which can predict benefit from PARPi therapy. Tissue and cell-free DNA (cfDNA) have been the most utilized sources of tumor material for analysis in this setting, but success rates of obtaining sufficient tumor for analysis from bone are low and detecting tumor-derived copy number variants (CNVs) in cfDNA is challenging. Circulating tumor cells (CTCs) represent an alternate source of genetic information, for which assays are available to isolate and sequence individual cells in a manner that eliminates background noise from stroma and healthy cells, while capturing inter-cellular heterogeneity. Methods: Blood samples, collected from 138 progressing metastatic CRPC patients within 30 days of a pre-treatment biopsy intended for sequencing using MSK-IMPACT, were sent to EPIC Sciences for CTC analysis. Detected CTCs underwent single cell, low pass whole genome sequencing. Prevalence and concordance of BRCA2 copy-loss, regardless of whether single copy or homozygous, was compared in matched tissue and CTC samples. Results: BRCA2 copy-loss was identified in 21% (23/108) and 50% (58/115) of successfully sequenced tissue and CTC samples, respectively. In the 58 patients with CTC-detected BRCA2 loss, BRCA2 loss was detected in 36% (220/565) of the sequenced CTCs, representing a median of 46% (range 4-100%) of CTCs found in each individual sample. When both sequencing assays were successful, BRCA2 loss was detected in CTCs in 84% (16/19) of the tissue-positive cases, whereas tissue sequencing detected BRCA2 loss in 35% (16/46) of CTC-positive cases. Conclusions: Data from this study supports the notion that single-cell CTC sequencing can detect BRCA2 copy-loss at a high frequency, including cases that were negative in tissue, while also characterizing inter-cellular heterogeneity. Further studies will investigate whether CTC BRCA2 copy-loss can predict the likelihood of response to PARPi.

Clinical significance of CTC enumeration on the Epic Sciences platform in metastatic castration-resistant prostate cancer (mCRPC) patients treated with AR signaling inhibitors (ARSi)

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Background: Circulating Tumor Cell (CTC) number, enumerated using the analytically valid FDA cleared Cell Search (Menarini Silicon Biosystems) platform has been shown to be prognostic for survival pre- and post-therapy, and used as an aid to monitoring breast, colorectal and prostate cancers. The assay uses antibody-based capture and defines a CTC as an EpCAM+ and CD45- intact cell. In contrast, with the Epic sciences CTC detection platform red blood cells are first lysed and all nucleated cells deposited on pathology slides, fixed, and imaged. There is no affinity selection and CTCs for this analysis were defined in silico as any cytokeratin (CK)+, CD45- cell with an intact DAPI+ nucleus. Here we report the prognostic significance of the CK+ CTCs detected on the EPIC Sciences platform in mCRPC patients prior to treatment with an AR signaling inhibitor. Methods: A pre-treatment blood sample was collected from 181 unique patients with progressing mCRPC about to start an ARSI as 1st, 2nd or 3rd line therapy at MSKCC. CTCs were enumerated on the Epic Sciences platform and verified by a trained human technician. Results: At least 1 CTC was detected (median = 1, 0-711 CTCs/ml) in 134 (74%) of cases, with higher counts observed in patients with visceral or multiple osseous sites relative to those with lymph node only disease. Counts increased by line of therapy. The table shows the associated risk of death for CTCs modeled as a continuous variable. Conclusions: The results support the clinical validity of CTC number determined on the Epic Sciences platform as a significant baseline prognostic factor. In multivariate modeling CTC number was found to be the most significant blood-based predictor of poor OS with each doubling representing a 20% greater risk of death observed with adjustment for therapy line, LDH, PSA, and ALK. [Table: see text]

Platinum-Based Chemotherapy in Metastatic Prostate Cancer With DNA Repair Gene Alterations

PURPOSE

Alterations in DNA damage repair (DDR) genes occur in up to 25% of patients with metastatic castration-resistant prostate cancer (mCRPC) and may sensitize to platinum chemotherapy. We aimed to evaluate the efficacy of platinum-based chemotherapy in DDR-mutant (DDRmut) mCRPC.

METHODS

We assessed response to platinum chemotherapy based on DDR gene alteration status in men with mCRPC who underwent tumor and germline genomic profiling. Patients with deleterious alterations in a gene panel that included BRCA2, BRCA1, ATM, PALB2, FANCA, and CDK12 were considered DDRmut.

RESULTS

A total of 109 patients with mCRPC received platinum-based chemotherapy between October 2013 and July 2018. Sixty-four of 109 patients were taxane refractory and poly (ADP-ribose) polymerase inhibitor (PARPi) naïve. Within this subset, DDRmut was found in 16/64 patients (25%) and was associated with an increased likelihood of achieving a prostate-specific antigen (PSA) decline of 50% or more from baseline (PSA50; odds ratio, 7.0; 95% CI, 1.9 to 29.2). Time on platinum chemotherapy tended to be longer in the DDRmut group (median, 3.0 v 1.6 months; hazard ratio, 0.55, 95% CI, 0.29 to 1.24). No difference in survival was detected. Of 8 patients with DDRmut disease who received platinum-based therapy after a PARPi, 3/7 evaluable patients had radiographic partial response or stable disease, and 2/7 had a PSA50 response. None of 4 patients with ATM mutations had platinum responses regardless of prior PARPi exposure.

CONCLUSION

Patients with DDRmut disease had better response to platinum-based chemotherapy, suggesting that DDR status warrants prospective validation as a potential biomarker for patient selection. Responses to platinum chemotherapy were observed in BRCA-altered prostate cancer after PARPi progression. Additional studies are needed to determine the predictive role of individual genes on platinum sensitivity in the context of other clinical and genomic factors.

Oncogenic Genomic Alterations, Clinical Phenotypes, and Outcomes in Metastatic Castration-Sensitive Prostate Cancer

PURPOSE

The genomic underpinning of clinical phenotypes and outcomes in metastatic castration-sensitive prostate cancer is unclear.

EXPERIMENTAL DESIGN

In patients with metastatic castration-sensitive prostate cancer at a tertiary referral center, clinical-grade targeted tumor sequencing was performed to quantify tumor DNA copy number alterations and alterations in predefined oncogenic signaling pathways. Disease volume was classified as high volume (≥4 bone metastases or visceral metastases) versus low volume.

RESULTS

Among 424 patients (88% white), 213 (50%) had high-volume disease and 211 (50%) had low-volume disease, 275 (65%) had de novo metastatic disease, and 149 (35%) had metastatic recurrence of nonmetastatic disease. Rates of castration resistance [adjusted hazard ratio, 1.84; 95% confidence interval (CI), 1.40-2.41] and death (adjusted hazard ratio, 3.71; 95% CI, 2.28-6.02) were higher in high-volume disease. Tumors from high-volume disease had more copy number alterations. The NOTCH, cell cycle, and epigenetic modifier pathways were the highest-ranking pathways enriched in high-volume disease. De novo metastatic disease differed from metastatic recurrences in the prevalence of CDK12 alterations but had similar prognosis. Rates of castration resistance differed 1.5-fold to 5-fold according to alterations in AR, SPOP (inverse), and TP53, and the cell cycle, WNT (inverse), and MYC pathways, adjusting for disease volume and other genomic pathways. Overall survival rates differed 2-fold to 4-fold according to AR, SPOP (inverse), WNT (inverse), and cell-cycle alterations. PI3K pathway alterations were not associated with prognosis once adjusted for other factors.

CONCLUSIONS

This study identified genomic features associated with prognosis in metastatic castration-sensitive disease that may aid in molecular classification and treatment selection.

Analysis of the Prevalence of Microsatellite Instability in Prostate Cancer and Response to Immune Checkpoint Blockade

Importance

The anti-programmed cell death protein 1 (PD-1) antibody pembrolizumab is approved by the US Food and Drug Administration for the treatment of microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) solid tumors, but the prevalence of MSI-H/dMMR prostate cancer and the clinical utility of immune checkpoint blockade in this disease subset are unknown.

Objective

To define the prevalence of MSI-H/dMMR prostate cancer and the clinical benefit of anti-PD-1/programmed cell death 1 ligand 1 (PD-L1) therapy in this molecularly defined population.

Design, Setting, and Participants

In this case series, 1551 tumors from 1346 patients with prostate cancer undergoing treatment at Memorial Sloan Kettering Cancer Center were prospectively analyzed using a targeted sequencing assay from January 1, 2015, through January 31, 2018. Patients had a diagnosis of prostate cancer and consented to tumor molecular profiling when a tumor biopsy was planned or archival tissue was available. For each patient, clinical outcomes were reported, with follow-up until May 31, 2018.

Main Outcomes and Measures

Tumor mutation burden and MSIsensor score, a quantitative measure of MSI, were calculated. Mutational signature analysis and immunohistochemistry for MMR protein expression were performed in select cases.

Results

Among the 1033 patients who had adequate tumor quality for MSIsensor analysis (mean [SD] age, 65.6 [9.3] years), 32 (3.1%) had MSI-H/dMMR prostate cancer. Twenty-three of 1033 patients (2.2%) had tumors with high MSIsensor scores, and an additional 9 had indeterminate scores with evidence of dMMR. Seven of the 32 MSI-H/dMMR patients (21.9%) had a pathogenic germline mutation in a Lynch syndrome-associated gene. Six patients had more than 1 tumor analyzed, 2 of whom displayed an acquired MSI-H phenotype later in their disease course. Eleven patients with MSI-H/dMMR castration-resistant prostate cancer received anti-PD-1/PD-L1 therapy. Six of these (54.5%) had a greater than 50% decline in prostate-specific antigen levels, 4 of whom had radiographic responses. As of May 2018, 5 of the 6 responders (5 of 11 total [45.5%]) were still on therapy for as long as 89 weeks.

Conclusions and Relevance

The MSI-H/dMMR molecular phenotype is uncommon yet therapeutically meaningful in prostate cancer and can be somatically acquired during disease evolution. Given the potential for durable responses to anti-PD-1/PD-L1 therapy, these findings support the use of prospective tumor sequencing to screen all patients with advanced prostate cancer for MSI-H/dMMR. Because not all patients with the MSI-H/dMMR phenotype respond, further studies should explore mechanisms of resistance.

Association of circulating tumor cell chromosomal instability with worse outcomes in men with mCRPC treated with abiraterone or enzalutamide

183

Background: While AR-V7 is a known driver of hormonal resistance, most men with mCRPC lack AR-V7 detection and commonly experience cross-resistance to abiraterone and enzalutamide (abi/enza). Loss of AR dependence through neuroendocrine (NE) differentiation or chromosomal instability (CIN) may explain AR therapy cross-resistance in additional men. Methods: PROPHECY was a multicenter prospective study of men with poor risk mCRPC starting abi/enza. We assessed Epic CTC AR-V7, CIN and NE phenotypes before abi/enza and at progression. Radiographic/clinical progression free survival (PFS) and overall survival (OS) were associated with CIN (>3 CTCs) and NE (>3 CTCs) CTC phenotypes using the proportional hazards model adjusting for Cellsearch CTC, AR-V7, and clinical risk score. Results: 118 men with mCRPC starting on abi/enza were enrolled; 106 had evaluable CTCs for AR-V7, CIN, and NE on the Epic platform. Of these, 22.6% and 9.4% of men exhibited high CTC CIN and NE scores, respectively. High pre-treatment CIN and NE phenotypic scores were observed in 63 and 27% of AR-V7 (+) and in 17 and 7% of AR-V7 (-) men. CTC CIN phenotype but not NE phenotype was associated with a lower confirmed PSA response rate and OS (TABLE) with abi/enza, adjusting for CTC number, AR-V7 and risk score. Conclusions: A high chromosomal instability CTC phenotype is associated with worse outcomes in men with mCRPC treated with abi/enza and warrants further study as a prognostic or predictive biomarker. Clinical trial information: NCT02269982. [Table: see text]

Impact of upstream use of novel hormonal therapy on progression of patients (pts) to metastatic castration-resistant prostate cancer (mCRPC) in the United States (US)

92

Background: Novel hormonal therapies (nHTs) provide significant delay in disease progression in metastatic castration-sensitive prostate cancer (mCSPC) and non-metastatic (nm)CRPC. The impact of earlier use of these agents on the epidemiological burden of PC in the US was assessed. Methods: A disease stage transition model capturing pt flow through eight clinical states and tracking pt treatment history was used, with each nHT being used once. Progression-free survival (PFS) and overall survival (OS) data for each drug/regimen were derived from published sources where available. We analyzed scenarios 1) no nHTs and 2) with nHTs: (abiraterone acetate + prednisone [AAP], apalutamide [APA] and enzalutamide [ENZA] in high-risk mCSPC, and APA and ENZA in low-risk mCSPC and in high-risk nmCRPC). Resultant state progression parameters were compared, evaluating the impact of nHTs. The assumed nHT utilization was 17.2% in high-risk mCSPC, 7.1% in low-risk mCSPC, and 60.0% in high-risk nmCRPC. Results: For 2018, the model resulted in PC incidence of 240,150 and prevalence of 2,445,173; 49,450 pts progressed to mCRPC, 42% from PSA biochemical recurrence, 31% from mCSPC, and 27% from nmCRPC states. Longer PFS and OS afforded by novel treatments extended the mean time spent from 4.4 to 4.7 yrs in mCSPC and from 2.4 to 3.0 yrs in nmCRPC. This further resulted in reduction in inflow to mCRPC over 2019 – 2025 (table). Conclusions: Novel hormonal therapies are currently used earlier in PC, a trend anticipated to intensify. The disease model shows this change in the treatment paradigm to result in delaying progression to mCRPC and increasing OS in PC.[Table: see text]

Niraparib in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) and biallelic DNA-repair gene defects (DRD): Correlative measures of tumor response in phase II GALAHAD study

118

Background: Niraparib, a highly potent and selective poly (ADP-ribose) polymerase inhibitor (PARPi) received breakthrough designation by US FDA for treatment of pts with BRCA1,2 mutant mCRPC who progressed on taxane and androgen receptor-targeted therapy. Circulating tumor cells (CTC) detection associates with poor outcomes, with declining counts consistent with improved survival [1,2]. Methods: GALAHAD study assessed niraparib (300 mg daily) in pts with mCRPC+DRD (NCT02854436). Patients with non-measurable soft tissue disease by RECIST 1.1 were required to have a baseline CTC count ≥1 cell/7.5 mL blood. CTC response was defined as CTC conversion to <5 for pts with baseline CTC≥5 and CTC drop to 0 post-baseline for pts with ≥1 baseline CTC. Alkaline phosphatase (ALP) was collected at each monthly cycle. Results: For primary efficacy population of pts with BRCA1/2 mutations, the objective response rate (ORR) by RECIST 1.1 criteria was 41.4%. CTC response rates for this population were as high as ORR regardless of measurability (Table). Time to CTC response for each CTC responder will be shown. Radiographic progression-free survival (rPFS) durations were similar for patients with a measurable disease response and patients with CTC conversion. Median duration of treatment for responders of any type was 6.7mo (range: 2–27). DRD status, both BRCA and non- BRCA, for each responder will also be discussed. Trends in disease burden and markers of bone metabolism will also be quantitatively explored including 24% pts who were on treatment for at least one cycle who had ≥25% decreased unfractionated ALP from baseline. Conclusions: Niraparib showed clinical activity with CTC response and decline in ALP levels in mCRPC pts having biallelic BRCA mutations, which further supports its recent breakthrough designation. Clinical trial information: NCT02854436. [Table: see text]

AR-V7 and prediction of benefit with taxane therapy: Final analysis of PROPHECY

184

Background: We previously found that men with AR-V7 (+) poor risk mCRPC have a low chance of benefit with abiraterone or enzalutamide. The benefits of subsequent taxane chemotherapy based on AR-V7 status may help inform treatment decisions. Methods: We conducted a multicenter prospective study of men with poor risk mCRPC (PROPHECY, NCT02269982) starting Abi or Enza and subsequent taxane chemotherapy. AR-V7 status from CTCs was assessed before abi/enza and again before taxane chemotherapy using the Epic nuclear protein assay or the Johns Hopkins Adnatest assay. The primary endpoint was to test the association of AR-V7 with radiographic/ clinical progression free survival (PFS) and OS with taxane chemotherapy, using the proportional hazards model, adjusting for Cell Search enumeration and clinical risk score. Results: We enrolled 118 men with mCRPC starting Abi/Enza; of these, 51 were evaluable with CTC AR-V7 testing and received subsequent taxane chemotherapy. With 50 PFS events, see table for final results. While AR-V7 positivity was associated with worse outcomes overall, AR-V7 (+) patients had similar PFS, OS, and confirmed >50% PSA declines adjusting for CTC enumeration and clinical prognostic factors. Concordance between the two AR-V7 assays pre-taxane was 0.78 (kappa 0.46). AR-V7 positivity increased at progression on abi/enza, but not following taxane chemotherapy. Conclusions: Men with AR-V7 positive mCRPC have poor outcomes, but may benefit from taxane chemotherapy after progression on abi/enza. AR-V7 may provide a helpful predictive biomarker to guide treatment with a second AR inhibitor or a taxane. Clinical trial information: NCT02269982. [Table: see text]

Assessment of Adverse Events From the Patient Perspective in a Phase 3 Metastatic Castration-Resistant Prostate Cancer Clinical Trial

Importance

Standard adverse event (AE) reporting in oncology clinical trials has historically relied on clinician grading, which prior research has shown can lead to underestimation of rates of symptomatic AEs. Industry sponsors are beginning to implement in trials the National Cancer Institute's Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE), which was developed to allow patients to self-report symptomatic AEs and improve the quality of symptomatic AE detection.

Objectives

To evaluate the feasibility of implementing PRO-CTCAE in a prespecified correlative analysis of the phase 3 COMET-2 trial and enumerate statistically significant between-group differences in symptomatic AEs using PRO-CTCAE and the CTCAE.

Design, Setting, and Participants

This correlative study of 119 men in the randomized, double-blind, placebo-controlled phase 3 COMET-2 trial with metastatic castration-resistant prostate cancer who had undergone at least 2 prior lines of systemic treatment was conducted from March 2012 to July 2014. Participants completed PRO-CTCAE items using an automated telephone system from home prior to treatment and every 3 weeks during treatment. Statistical analysis was performed from May 2018 to June 2019.

Main Outcomes and Measures

The proportion of patients who completed expected PRO-CTCAE self-reports was computed as a measure of feasibility.

Results

Among the 119 men in the study (median age, 65 years [range, 44-80 years]), 534 of 587 (91.0%) expected PRO-CTCAE self-reports were completed, with consistently high rates of completion throughout participation. Rates of self-report adherence were similar between groups (cabozantinib s-maleate, 286 of 317 [90.2%]; and mitoxantrone hydrochloride-prednisone, 248 of 270 [91.9%]). Of 12 measured, patient-reported PRO-CTCAE symptomatic AEs, 4 reached statistical significance when comparing the proportion of patients with at least 1 postbaseline score greater than 0 between groups (differences ranged from 20.1% to 34.1% with higher proportions in the cabozantinib group; all P < .05), and use of a method for accounting for preexisting symptoms at baseline yielded 7 AEs with statistically significant differences between groups (differences ranged from 20.5% to 41.2% with higher proportions in the cabozantinib group; all P < .05). In the same analysis using investigator-reported CTCAE data, no statistically significant differences were found between groups for any symptomatic AEs.

Conclusions and Relevance

PRO-CTCAE data collection was feasible and improved the accuracy of symptomatic AE detection in a phase 3 cancer trial. This analysis adds to mounting evidence of the feasibility and value of patient-reported AEs in oncology, which should be considered for inclusion in cancer trials that incorporate AE evaluation.

Trial Registration

ClinicalTrials.gov identifier: NCT01522443.

Association Between New Unconfirmed Bone Lesions and Outcomes in Men With Metastatic Castration-Resistant Prostate Cancer Treated With Enzalutamide: Secondary Analysis of the PREVAIL and AFFIRM Randomized Clinical Trials

Importance

For men with metastatic castration-resistant prostate cancer (mCRPC) whose condition is responding to enzalutamide, new unconfirmed bone lesions detected at posttreatment scinitigraphy may reflect an osteoblastic reaction that represents healing, known as pseudoprogression, which can lead to premature discontinuation of therapy.

Objective

To determine the association between new unconfirmed lesions detected on a follow-up bone scintigram (bone scan) and outcomes in enzalutamide-treated men with mCRPC.

Design, Setting, and Participants

This post hoc, retrospective secondary analysis of 1672 enzalutamide-treated men from 2 phase 3, randomized mCRPC studies (PREVAIL and AFFIRM) before or after treatment with docetaxel was conducted from April 12, 2018, to July 25, 2019. Participants were men from the enzalutamide groups of the 2 studies with a decrease in prostate-specific antigen level at any time or with stable disease or soft-tissue disease responding to treatment based onradiologic findings.

Intervention

Enzalutamide, 160 mg once daily.

Main Outcomes and Measures

The clinical significance of new lesions detected on the first (early) or second (late) posttreatment bone scan, without an unfavorable change in prostate-specific antigen level or soft-tissue progression, was investigated. Associations of new unconfirmed lesions with radiographic progression-free survival, overall survival, decrease in prostate-specific antigen level, objective response in soft tissue, and quality of life were evaluated.

Results

Among the 643 men (median age, 72 years [range, 43-93 years]) in PREVAIL, early and late unconfirmed lesions were observed in 177 men (27.5%) with stable disease or disease responding to enzalutamide. Among the 404 men (median age, 70 years [range, 41-88 years]) in AFFIRM, early and late unconfirmed lesions were observed in 73 men (18.1%) with stable disease or disease responding to enzalutamide. In PREVAIL, men with new unconfirmed lesions had median radiographic progression-free survival (hazard ratio [HR], 1.37 [95% CI, 0.81-2.30]; P = .23) and median overall survival (HR, 1.25 [95% CI, 0.85-1.83]) in the chemotherapy-naive setting similar to men those of men without such new lesions. In AFFIRM, the median overall survival (HR, 1.94 [95% CI, 1.10-3.44]) was reduced among men with unconfirmed bone lesions, but the median radiographic progression-free survival was not reduced (HR, 1.21 [95% CI, 0.83-1.75]; P = .32). Quality of life over time was similar regardless of the presence of new unconfirmed lesions detected on a follow-up bone scan in either setting.

Conclusions and Relevance

These results suggest that new unconfirmed lesions detected on follow-up bone scans may represent pseudoprogression in men with mCRPC and are indicative of a favorable treatment response to enzalutamide. The detection of new unconfirmed bone lesions in men with mCRPC that responded to treatment with enzalutamide after docetaxel appears to be associated with worse overall survival and may represent true progression, thus highlighting the need for improved functional bone metastasis imaging.

Trial Registration

ClinicalTrials.gov Identifiers: NCT01212991 and NCT00974311.

Assessment of Adverse Events From the Patient Perspective in a Phase 3 Metastatic Castration-Resistant Prostate Cancer Clinical Trial

Importance

Standard adverse event (AE) reporting in oncology clinical trials has historically relied on clinician grading, which prior research has shown can lead to underestimation of rates of symptomatic AEs. Industry sponsors are beginning to implement in trials the National Cancer Institute's Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE), which was developed to allow patients to self-report symptomatic AEs and improve the quality of symptomatic AE detection.

Objectives

To evaluate the feasibility of implementing PRO-CTCAE in a prespecified correlative analysis of the phase 3 COMET-2 trial and enumerate statistically significant between-group differences in symptomatic AEs using PRO-CTCAE and the CTCAE.

Design, Setting, and Participants

This correlative study of 119 men in the randomized, double-blind, placebo-controlled phase 3 COMET-2 trial with metastatic castration-resistant prostate cancer who had undergone at least 2 prior lines of systemic treatment was conducted from March 2012 to July 2014. Participants completed PRO-CTCAE items using an automated telephone system from home prior to treatment and every 3 weeks during treatment. Statistical analysis was performed from May 2018 to June 2019.

Main Outcomes and Measures

The proportion of patients who completed expected PRO-CTCAE self-reports was computed as a measure of feasibility.

Results

Among the 119 men in the study (median age, 65 years [range, 44-80 years]), 534 of 587 (91.0%) expected PRO-CTCAE self-reports were completed, with consistently high rates of completion throughout participation. Rates of self-report adherence were similar between groups (cabozantinib s-maleate, 286 of 317 [90.2%]; and mitoxantrone hydrochloride-prednisone, 248 of 270 [91.9%]). Of 12 measured, patient-reported PRO-CTCAE symptomatic AEs, 4 reached statistical significance when comparing the proportion of patients with at least 1 postbaseline score greater than 0 between groups (differences ranged from 20.1% to 34.1% with higher proportions in the cabozantinib group; all P < .05), and use of a method for accounting for preexisting symptoms at baseline yielded 7 AEs with statistically significant differences between groups (differences ranged from 20.5% to 41.2% with higher proportions in the cabozantinib group; all P < .05). In the same analysis using investigator-reported CTCAE data, no statistically significant differences were found between groups for any symptomatic AEs.

Conclusions and Relevance

PRO-CTCAE data collection was feasible and improved the accuracy of symptomatic AE detection in a phase 3 cancer trial. This analysis adds to mounting evidence of the feasibility and value of patient-reported AEs in oncology, which should be considered for inclusion in cancer trials that incorporate AE evaluation.

Trial Registration

ClinicalTrials.gov identifier: NCT01522443.