Prediction of plasma ctDNA fraction and prognostic implications of liquid biopsy in advanced prostate cancer

No consensus strategies exist for prognosticating metastatic castration-resistant prostate cancer (mCRPC). Circulating tumor DNA fraction (ctDNA%) is increasingly reported by commercial and laboratory tests but its utility for risk stratification is unclear. Here, we intersect ctDNA%, treatment outcomes, and clinical characteristics across 738 plasma samples from 491 male mCRPC patients from two randomized multicentre phase II trials and a prospective province-wide blood biobanking program. ctDNA% correlates with serum and radiographic metrics of disease burden and is highest in patients with liver metastases. ctDNA% strongly predicts overall survival, progression-free survival, and treatment response independent of therapeutic context and outperformed established prognostic clinical factors. Recognizing that ctDNA-based biomarker genotyping is limited by low ctDNA% in some patients, we leverage the relationship between clinical prognostic factors and ctDNA% to develop a clinically-interpretable machine-learning tool that predicts whether a patient has sufficient ctDNA% for informative ctDNA genotyping (available online: https://www.ctDNA.org ). Our results affirm ctDNA% as an actionable tool for patient risk stratification and provide a practical framework for optimized biomarker testing.

Prognostic Value of Nivolumab Clearance in Non-Small Cell Lung Cancer Patients for Survival Early in Treatment

INTRODUCTION

Immune checkpoint inhibitors improved survival of advanced stage non-small cell lung cancer patients, but the overall response rate remains low. A biomarker that identifies non-responders would be helpful to allow treatment decisions. Clearance of immune checkpoint inhibitors is related to treatment response, but its prognostic potential early in treatment remains unknown. Our primary aim was to investigate the prognostic potential of nivolumab clearance for overall survival early in treatment. Our secondary aim was to evaluate the performance of nivolumab clearance as prognostic biomarker.

PATIENTS AND METHODS

Individual estimates of nivolumab clearances at first dose, 6 and 12 weeks after treatment initiation were obtained via nonlinear mixed-effects modelling. Prognostic value of nivolumab clearance was estimated using univariate Cox regression at first dose and for the ratios between 6 and 12 weeks to first dose. The performance of nivolumab clearance as biomarker was assessed by calculating sensitivity and specificity.

RESULTS

During follow-up of 75 months, 69 patients were included and 865 died. Patients with a nivolumab clearance ≥ 7.3 mL/h at first dose were more likely to die compared to patients with a nivolumab clearance < 7.3 mL/h at first dose (hazard ratio [HR] = 3.55, 955 CI 1.75-7.20). The HRs of dose nivolumab clearance ratios showed similar results with a HR of 3.93 (955 CI 1.66-9.32) for 6 weeks to first-dose clearance ratio at a 0.953 cut-point and a HR of 2.96 (955 CI 1.32-6.64) for 12 weeks to first-dose clearance ratio at a cut-point of 0.814. For nivolumab clearance at all early time points, sensitivity was high (≥ 0.95) but specificity was low (0.11-0.29).

CONCLUSION

Nivolumab clearance is indicative of survival early in treatment. Our results encourage to further assess the prognostic potential of immunotherapy clearance.

Clinical Pharmacokinetics and Pharmacodynamics of the Next Generation Androgen Receptor Inhibitor-Darolutamide

Darolutamide is a next-generation androgen receptor signaling inhibitor (ARSI) currently approved for the treatment of nonmetastatic castration-resistant prostate cancer (nmCRPC) and metastatic hormone sensitive prostate cancer (mHSPC). Studies suggest that darolutamide also has the potential to be used to treat other stages of prostate cancer (PC), suggesting that its indications will broaden in the near future. Since ARSIs show similar efficacy for the treatment of PC, pharmacokinetic properties of these drugs and patient characteristics could help physicians decide which drug to select. This review provides an overview of the pharmacokinetic and pharmacodynamic properties of darolutamide. One of the most important pharmacological advantages of darolutamide is its low brain distribution and therefore limited seizure potential and central nervous system adverse effects. In addition, darolutamide has little drug-drug interaction potential and is unlikely to alter the exposure of other cytochrome P450 or P-glycoprotein substrates. Nevertheless, it may significantly increase the exposure of breast cancer resistant protein (BCRP) substrates. The limited solubility and bioavailability of darolutamide increases when taken together with food, regardless of the fat content. Darolutamide is excessively metabolized by oxidation and glucuronidation and excreted in the urine and feces. For this reason, dose reduction is required in patients with moderate and severe renal or severe hepatic impairment. Although no exposure-response relationship was observed with darolutamide, less advanced stages of PC showed better PSA response on treatment. Overall, darolutamide has some advantageous pharmacological properties that may lead to its preferred use, when broader registered, in selected patients across different disease stages.

Early on-treatment changes in circulating tumor DNA fraction and response to enzalutamide or abiraterone in metastatic castration-resistant prostate cancer

PURPOSE

Androgen receptor pathway inhibitors (ARPI) are standard of care for treatment-naive metastatic castration-resistant prostate cancer (mCRPC), but rapid resistance is common. Early identification of resistance will improve management strategies. We investigated whether changes in circulating tumor DNA (ctDNA) fraction during ARPI treatment are linked with mCRPC clinical outcomes.

EXPERIMENTAL DESIGN

Plasma cell-free DNA was collected from 81 patients with mCRPC at baseline and after 4-weeks of first-line ARPI treatment during two prospective multi-centre observational studies (NCT02426333;NCT02471469). CtDNA fraction was calculated from somatic mutations in targeted sequencing and genome copy number profiles. Samples were classified into detected vs. undetected ctDNA. Outcome measurements were progression-free survival (PFS) and overall survival (OS). Non-durable treatment response was defined as PFS ≤ 6 months.

RESULTS

CtDNA was detected in 48/81 (59%) baseline and 29/81 (36%) 4-week samples. CtDNA fraction for samples with detected ctDNA was lower at 4-weeks vs. baseline (median 5.0% vs. 14.5%, P=0.017). PFS and OS was shortest for patients with persistent ctDNA at 4 weeks (univariate hazard ratio 4.79 (95%CI, 2.62-8.77) and 5.49 (95%CI, 2.76-10.91), respectively), independent of clinical prognostic factors. For patients exhibiting change from detected to undetected ctDNA by 4-weeks, there was no significant PFS difference versus patients with baseline undetected ctDNA. CtDNA change had a positive predictive value of 88% and negative predictive value of 92% for identifying non-durable responses.

CONCLUSIONS

Early changes in ctDNA% are strongly linked to duration of first-line ARPI treatment benefit and survival in mCRPC and may inform early therapy switches or treatment intensification.

On-treatment plasma ctDNA fraction and treatment outcomes in metastatic castration-resistant prostate cancer

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Background: Androgen receptor pathway inhibitors (ARPI) are standard of care for treatment-naive metastatic castration-resistant prostate cancer (mCRPC), but primary or rapidly acquired resistance is common. Early identification of resistant disease is critical for improving management strategies. We investigated whether on-treatment changes in plasma ctDNA fraction (ctDNA%; the proportion of cell-free DNA that is tumor-derived) associate with ARPI treatment outcomes. Methods: We collected serial plasma cell-free DNA from 81 patients with mCRPC: at baseline and following 4 weeks of treatment during two prospective multi-center observational studies (NCT02426333; NCT02471469). CtDNA% was calculated by integrating deep targeted and shallow whole-genome sequencing. Samples were dichotomized at above and below 1%, and designated as high or low ctDNA%, respectively. Outcome measurements were radiographic and/or clinical progression-free survival (rcPFS) and overall survival (OS). Non-durable responses were defined as rcPFS < 6 months, excluding patients with PSA progression alone (n = 3) or treatment cessation for toxicity (n = 4). Results: Median follow-up was 27.4 months (IQR 17.7-34.9). CtDNA% was high in 47/81 (58%) patients at baseline and 29/81 (36%) patients at 4 weeks. The median ctDNA% for patients with high ctDNA was 15.0% (IQR 4.9-43.8%) at baseline and 5.0% (IQR 2.0-20.6%) at 4 weeks. High baseline ctDNA% was prognostic for rcPFS and OS (Table). RcPFS and OS was shortest for patients that retained high ctDNA% at 4 weeks. However, patients converting from high to low ctDNA% at 4 weeks did not experience different outcomes to patients with low ctDNA at both timepoints. ctDNA% associations with rcPFS and OS were independent of established clinical prognostic factors. 23/27 (85%) patients experiencing non-durable responses had high ctDNA% at baseline and 4 weeks. Only 3/47 patients (6%) experiencing durable responses had high ctDNA% at both timepoints. Sensitivity and specificity for predicting non-durable response was 85% and 94%, respectively. Conclusions: Early changes in ctDNA% are strongly linked to duration of first-line ARPI treatment benefit in mCRPC and may have utility for informing clinical trials testing early therapy switches in patients unlikely to experience durable disease responses. Clinical trial information: NCT02426333; NCT02471469. [Table: see text]

RNA Biomarkers as a Response Measure for Survival in Patients with Metastatic Castration-Resistant Prostate Cancer

Treatment evaluation in metastatic castration-resistant prostate cancer is challenging. There is an urgent need for biomarkers to discriminate short-term survivors from long-term survivors, shortly after treatment initiation. Thereto, the added value of early RNA biomarkers on predicting progression-free survival (PFS) and overall survival (OS) were explored. The RNA biomarkers: KLK3 mRNA, miR-375, miR-3687, and NAALADL2-AS2 were measured in 93 patients with mCRPC, before and 1 month after start of first-line abiraterone acetate or enzalutamide treatment, in two prospective clinical trials. The added value of the biomarkers to standard clinical parameters in predicting PFS and OS was tested by Harell's C-index. To test whether the biomarkers were independent markers of PFS and OS, multivariate Cox regression was used. The best prediction model for PFS and OS was formed by adding miR-375 and KLK3 (at baseline and 1 month) to standard clinical parameters. Baseline miR-375 and detectable KLK3 after 1 month of therapy were independently related to shorter PFS, which was not observed for OS. In conclusion, the addition of KLK3 and miR-375 (at baseline and 1 month) to standard clinical parameters resulted in the best prediction model for survival assessment.

The effect of chemotherapy on the exposure-response relation of abiraterone in metastatic castration-resistant prostate cancer

Aims

To assess whether the exposure–response relation for abiraterone is different in pre‐chemotherapy patients compared to post‐chemotherapy patients with metastatic castration‐resistant prostate cancer (mCRPC).

Methods

Data were collected from three clinical studies in mCRPC patients treated with abiraterone acetate. Cox regression analysis was used to determine the relation between abiraterone exposure and survival (progression‐free survival [PFS] and overall survival [OS]). An interaction term was used to test whether chemotherapy pretreatment was an effect modifier. To investigate the effect of the previously defined exposure threshold of 8.4 ng/mL on survival, Kaplan–Meier analysis was used.

Results

In total, 98 mCRPC patients were included, of which 78 were pre‐chemotherapy and 20 were post‐chemotherapy patients. Chemotherapy pretreatment in mCRPC setting appears to be an effect modifier. In pre‐chemotherapy patients, no significant association between abiraterone exposure and survival was observed (HR 0.68 [95% CI 0.42–1.10], P = .12 and HR 0.85 [95% CI 0.46–1.60], P = .61, PFS and OS, respectively) and no longer survival was seen for patients with an abiraterone exposure above the predefined threshold. In contrast, a significant association was seen in post‐chemotherapy patients (HR 0.30 [95% CI 0.12–0.74], P = .01 and HR 0.38 [95% CI 0.18–0.82] P = .01, PFS and OS, respectively), with an increased survival when exposed above this threshold.

Conclusion

Chemotherapy pretreatment in mCRPC setting modifies the abiraterone exposure–response relation. No relation between abiraterone exposure and survival was seen for pre‐chemotherapy patients. Therefore, potentially lower doses can be used in this setting to prevent overtreatment and reduce financial toxicity.

Liquid biopsy reveals KLK3 mRNA as a prognostic marker for progression free survival in patients with metastatic castration-resistant prostate cancer undergoing first-line abiraterone acetate and prednisone treatment

Circulating RNAs extracted from liquid biopsies represent a promising source of cancer‐ and therapy‐related biomarkers. We screened whole blood from patients with metastatic castration‐resistant prostate cancer (mCRPC) following their first‐line treatment with abiraterone acetate and prednisone (AA‐P) to identify circulating RNAs that may correlate with progression‐free survival (PFS). In a prospective multicenter observational study, 53 patients with mCRPC were included after they started first‐line AA‐P treatment. Blood was drawn at baseline, 1, 3, and 6 months after treatment initiation. The levels of predefined circulating RNAs earlier identified as being upregulated in patients with mCRPC (e.g., microRNAs, long noncoding RNAs, and mRNAs), were analyzed. Uni‐ and multivariable Cox regression and Kaplan–Meier analyses were used to analyze the prognostic value of the various circulating RNAs for PFS along treatment. Detectable levels of kallikrein‐related peptidase 3 (KLK3) mRNA at baseline were demonstrated to be an independent prognostic marker for PFS (201 vs 501 days, P = 0.00054). Three months after AA‐P treatment initiation, KLK3 could not be detected in the blood of responding patients, but was still detectable in 56% of the patients with early progression. Our study confirmed that KLK3 mRNA detection in whole blood is an independent prognostic marker in mCRPC patients receiving AA‐P treatment. Furthermore, the levels of circulating KLK3 mRNA in patients receiving AA‐P treatment might reflect treatment response or early signs of progression.

Prognostic Value of Novel Liquid Biomarkers in Patients with Metastatic Castration-Resistant Prostate Cancer Treated with Enzalutamide: A Prospective Observational Study

BACKGROUND

Several treatment options were recently added for metastatic castration-resistant prostate cancer (mCRPC). However, response to therapy is variable, and biomarkers that can guide treatment selection and response evaluation are lacking. Circulating RNAs are a promising source of biomarkers. We explored messenger RNAs (mRNAs), microRNAs (miRNAs), and long noncoding RNAs (lncRNAs) as potential biomarkers in liquid biopsies of patients with mCRPC treated with enzalutamide.

METHODS

Forty patients were included in this prospective multicenter observational study. Whole blood was drawn at baseline and 1, 3, and 6 months after start of therapy. Four mRNAs, 6 miRNAs, and 5 lncRNAs were analyzed by quantitative PCR. RNA levels in 30 healthy individuals were used as controls. RNA expression data were analyzed by Kaplan-Meier and Cox regression analyses, and the primary end point was progression-free survival. Clinical factors were included in the multivariable Cox regression analysis.

RESULTS

Levels of 2 miRNAs, miR-375 and miR-3687, and 1 lncRNA, N-acetylated alpha-linked acidic dipeptidase like 2 antisense RNA 2 (NAALADL2-AS2), were more than 2-fold higher in patients with mCRPC compared with healthy volunteers. Patients with higher levels of miR-375 or miR-3687 showed a shorter time to progression. Patients with higher levels of NAALADL2-AS2 showed a longer time to progression. In the multivariable Cox regression analysis, higher miR-375, miR-3687 and serum prostate-specific antigen concentrations were shown to be independent predictors for shorter time to progression.

CONCLUSIONS

We identified miR-3687 as a novel prognostic marker for response in patients with CRPC treated with enzalutamide, and we confirmed the prognostic value of miR-375.

A Systematic Review and Meta-Analysis on the Predictive Value of Cell-Free DNA–Based Androgen Receptor Copy Number Gain in Patients With Castration-Resistant Prostate Cancer

PURPOSE

It has been suggested that androgen receptor copy number gain ( AR gain) detected in cell-free DNA (cfDNA) can predict treatment response to androgen receptor signaling inhibitors (ARSIs) in patients with castration-resistant prostate cancer (CRPC). But it is unclear whether cfDNA-based AR gain is a true resistance mechanism to ARSIs or mainly a reflection of the tumor burden. In this systematic review, we aim to summarize current literature and comment on the potential of cfDNA-based AR gain as a predictive biomarker to guide therapy choices.

METHODS

A literature search was conducted in PubMed/Medline, Cochrane, Embase, and Web of Science databases. Sixteen articles published before November 2019 were selected for the meta-analysis, representing more than 1,000 patients. By using a random effects model, the progression-free survival (PFS) and overall survival (OS) were compared between patients with and without cfDNA-based AR gain who had been treated with ARSIs or with taxane chemotherapy.

RESULTS

Upon treatment with ARSIs, the PFS (hazard ratio [HR], 2.33; 95% CI, 2.00 to 2.72; P < .0001) and the OS (HR, 3.83; 95% CI, 3.11 to 4.70; P < .0001) were worse for patients with cfDNA-based AR gain, independent of the line and type of ARSIs. The OS and PFS in patients treated with first-line docetaxel or second-line or third-line cabazitaxel seemed to be unaffected by AR gain, despite a higher disease burden in patients with AR gain. AR gain was associated with reduced response with later lines of docetaxel.

CONCLUSION

In patients with CRPC, cfDNA-based AR gain is associated with a worse response to ARSIs. The effect on patients who are receiving taxane chemotherapy seems to be dependent on the type and line, although data are limited. Future prospective studies are essential to assess the true potential of cfDNA-based AR gain as a minimally invasive biomarker to guide therapy choice.

Abstract 1413: Exploring the prognostic value of microRNAs and drug exposure in patients with metastatic castration resistant prostate cancer treated with abiraterone: a prospective observational study

Background Abiraterone acetate is registered for treatment of metastatic prostate cancer, including those with castration-resistant disease (mCRPC). Although it improves overall survival and progression free survival (PFS), treatment response differs between patients. Biomarkers to predict treatment response are lacking. Liquid biopsies containing microRNAs (miRNAs) are a promising source of prognostic biomarkers in mCRPC patients. Furthermore, the exposure to abiraterone in plasma is highly variable and subtherapeutic exposure might contribute to the variability in response to therapy. We explored the prognostic value of microRNAs and drug exposure in mCRPC patients treated with abiraterone.

Methods In a prospective multi-center observational study, 53 patients with mCRPC were included who started pre-chemotherapy abiraterone treatment. Blood was drawn at baseline, 1, 3 and 6 months after start of treatment. The following predefined miRNAs were selected; miR-21, miR-141, miR-200a, miR-200c, miR-375, miR-3687 and abiraterone concentrations were measured. MiRNA-levels in 30 healthy individuals served as controls. Relative miRNA-levels were calculated by the ΔΔCt method. If the geometric mean of a miRNA was more than 2-fold higher in patients versus healthy controls, they were included for survival analysis. Ctrough levels after 1, 3 and 6 months of therapy were measured. The average Ctrough level per patient was used for further analysis. The prognostic value of miRNAs and drug exposure for PFS (radiographic, biochemical or clinical progression) was analyzed with Kaplan-Meier (KM) analysis and tested with a log-rank test. Cut-off values for miRNAs in KM analysis were calculated using maximally selected rank statistics and for the relation with abiraterone Ctrough the earlier defined threshold of 8.4ng/ml was used.

Results Of the miRNAs analyzed, miR-375 was more than 2-fold higher in mCRPC patients versus healthy controls. Patients with more than 2.16 fold higher miR-375 compared to healthy controls showed a trend towards shorter PFS, median 352 vs. 456 days (p=0.076). No PFS benefit was shown for patients with a mean abiraterone Ctrough concentration ≥8.4ng/ml compared to patients below this threshold, median 411 vs. 409 days (p=0.81).

Conclusion High levels of miR-375 might be a prognostic biomarker for PFS in patients with mCRPC treated with abiraterone. The prognostic value of this miRNA should be further explored in a larger cohort of patients. Additionally, the functionality of miR-375 should be further elucidated. The beneficial effect of higher abiraterone exposure levels could not be confirmed in this study for this patient population.

Citation Format: Emmy Boerrigter, Guillemette E. Benoist, Inge M. van Oort, Gerald W. Verhaegh, Onno van Hooij, Levi Groen, Frank Smit, Irma M. Oving, Pieter de Mol, Tineke J. Smilde, Diederik M. Somford, Niven Mehra, Jack A. Schalken, Nielka P. van Erp. Exploring the prognostic value of microRNAs and drug exposure in patients with metastatic castration resistant prostate cancer treated with abiraterone: a prospective observational study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1413.

[Drug-facilitated sexual assault; frequently used substances, symptoms and toxicological investigation]

Drug-facilitated sexual assault (DFSA) is a term used to describe incidents of sexual assault in which the victim is incapacitated and/or unable to provide consent to the sexual act as a result of drug or alcohol consumption. There are two types: 'proactive' in which the victim is covertly administered an incapacitating or disinhibiting substance by an assailant for the purpose of sexual assault; and 'opportunistic' in which a perpetrator engages in sexual activity with a victim who is profoundly intoxicated by his or her actions, to the point of near or actual unconsciousness. Alcohol is the drug most commonly found in alleged sexual assault cases. It is followed by non-opiate analgesics, illicit drugs and benzodiazepines. The possibility of DFSA should be considered in sexual assault cases. If there is suspicion, drug and alcohol screening has to be done as soon as possible because delay may lead to false-negative results.