CT-Guided Bone Biopsies in Metastatic Castration-Resistant Prostate Cancer: Factors Predictive of Maximum Tumor Yield

Multiparametric bone MRI targeting aides lesion selection for CT-guided sclerotic bone biopsies in metastatic castrate resistant prostate cancer

BACKGROUND

Bone biopsies in metastatic castrate-resistant prostate cancer (mCRPC) patients can be challenging. This study's objective was to prospectively validate a multiparametric bone MRI (mpBMRI) algorithm to facilitate target lesion selection in mCRPC patients with sclerotic bone disease for subsequent CT-guided bone biopsies.

METHODS

20 CT-guided bone biopsies were prospectively performed between 02/2021 and 11/2021 in 17 mCRPC patients with only sclerotic bone disease. Biopsy targets were selected based on MRI, including diffusion-weighted (DWI) and T1-weighted VIBE Dixon MR images, allowing for calculation of the apparent diffusion coefficient (ADC) and the relative fat-fraction (rFF), respectively. Bone marrow with high DWI signal, ADC < 1100 µm2/s and rFF < 20% was the preferred biopsy target. Tumor content and NGS-feasibility was assessed by a pathologist. Prognostic routine laboratory blood parameters, target lesion size, biopsy tract length, visual CT density, means of HU, ADC and rFF were compared between successful and unsuccessful biopsies (p < 0.05 = significant).

RESULTS

Overall, 17/20 (85%) biopsies were tumor-positive and next-generation genomic sequencing (NGS) was feasible in 13/18 (72%) evaluated samples. Neither laboratory parameters, diameter, tract length nor visual CT density grading showed significant differences between a positive versus negative or NGS feasible versus non-feasible biopsy results (each p > 0.137). Lesion mean HU was 387 ± 187 HU in NGS feasible and 493 ± 218 HU in non-feasible biopsies (p = 0.521). For targets fulfilling all MRI selection algorithm criteria, 13/14 (93%) biopsies were tumor-positive and 10/12 (83%) provided NGS adequate tissue.

CONCLUSIONS

Multiparametric bone MRI can facilitate target lesion selection for subsequent CT-guided bone biopsy in mCPRC patients with sclerotic metastases.

TRIAL REGISTRATION

Committee for Clinical Research of the Royal Marsden Hospital registration number SE1220.

The diagnosis and treatment of castrate-sensitive oligometastatic prostate cancer: A review

BACKGROUND

Oligometastatic prostate cancer (OMPCa) is emerging as a transitional disease state between localized and polymetastatic disease. This review will assess the current knowledge of castrate-sensitive OMPCa.

METHODS

A review of the current literature was performed to summarize the definition and classification of OMPCa, assess the diagnostic methods and imaging modalities utilized, and to review the treatment options and outcomes. We further identify gaps in knowledge and areas for future research.

RESULTS

Currently there is no unified definition of OMPCa. National guidelines mostly recommend systemic therapies without distinguishing oligometastatic and polymetastatic disease. Next generation imaging is more sensitive than conventional imaging and has led to early detection of metastases at initial diagnosis or recurrence. While mostly retrospective in nature, recent studies suggest that treatment (surgical or radiation) of the primary tumor and/or metastatic sites might delay initiation of androgen deprivation therapy while increasing survival in selected patients.

CONCLUSIONS

Prospective data are required to better assess the incremental improvement in survival and quality of life achieved with various treatment strategies in patients with OMPCa.

Practical Utility of Liquid Biopsies for Evaluating Genomic Alterations in Castration-Resistant Prostate Cancer

Traditional tissue-based assessments of genomic alterations in castration-resistant prostate cancer (CRPC) can be challenging. To evaluate the real-world clinical utility of liquid biopsies for the evaluation of genomic alterations in CRPC, we preemptively collected available plasma samples and archival tissue samples from patients that were being treated for clinically confirmed CRPC. The cell-free DNA (cfDNA) and tumor tissue DNA were analyzed using the AlphaLiquid^®100-HRR panel. Plasma samples from a total of 87 patients were included in this study. Somatic mutations from cfDNA were detected in 78 (89.7%) patients, regardless of the presence of overt metastasis or concomitant treatment given at the time of plasma sample collection. Twenty-three patients were found to have known deleterious somatic or germline mutations in HRR genes from their cfDNA. Archival tissue samples from 33 (37.9%) patients were available for comparative analysis. Tissue sequencing was able to yield an NGS result in only 51.5% of the tissue samples. The general sensitivity of cfDNA for detecting somatic mutations in tissues was 71.8%, but important somatic/germline mutations in HRR genes were found to have a higher concordance (100%). Liquid biopsies can be a reasonable substitute for tissue biopsies in CRPC patients when evaluating genomic alterations.

Optimising CT-guided biopsies of sclerotic bone lesions in cancer patients

Objectives

Investigate the laboratory, imaging and procedural factors that are associated with a tumour-positive and/or NGS-feasible CT-guided sclerotic bone lesion biopsy result in cancer patients.

Methods

In total, 113 CT-guided bone biopsies performed in cancer patients by an interventional radiologist in one institution were retrospectively reviewed. Sixty-five sclerotic bone biopsies were eventually included and routine blood parameters and tumour marker levels were recorded. Non-contrast (NC) biopsy CTs (65), contrast-enhanced CTs (24), and PET/CTs (22) performed within four weeks of biopsy were reviewed; lesion location, diameter, lesion-to-cortex distance, and NC-CT appearance (dense-sclerosis versus mild-sclerosis) were noted. Mean NC-CT, CE-CT HU, and PET SUVmax were derived from biopsy tract and lesion segmentations. Needle diameter, tract length, and number of samples were noted. Comparisons between tumour-positive/negative and next-generation sequencing (NGS)-feasible/non-feasible biopsies determined significant (p < 0.05) laboratory, imaging, and procedural parameter differences.

Results

Seventy-four percent of biopsies were tumour-positive. NGS was feasible in 22/30 prostate cancer patients (73%). Neither laboratory blood parameters, PET/CT availability, size, nor lesion-to-cortex distance affected diagnostic yield or NGS feasibility (p > 0.298). Eighty-seven percent of mildly sclerotic bone (mean 244 HU) biopsies were positive compared with 56% in dense sclerosis (622 HU, p = 0.005) and NC-CT lesion HU was significantly lower in positive biopsies (p = 0.003). A 610 HU threshold yielded 89% PPV for tumour-positive biopsies and a 370 HU threshold 94% PPV for NGS-feasible biopsies. FDG-PET and procedural parameters were non-significant factors (each p > 0.055).

Conclusion

In cancer patients with sclerotic bone disease, targeting areas of predominantly mild sclerosis in lower CT-attenuation lesions can improve tumour tissue yield and NGS feasibility.

Key Points

• Areas of predominantly mild sclerosis should be preferred to areas of predominantly dense sclerosis for CT-guided bone biopsies in cancer patients.

• Among sclerotic bone lesions in prostate cancer patients, lesions with a mean HU below 370 should be preferred as biopsy targets to improve NGS feasibility.

• Laboratory parameters and procedure related factors may have little implications for CT-guided sclerotic bone biopsy success.

DNA-repair status should be assessed in treatment-emergent neuroendocrine prostate cancer before platinum-based therapy

OBJECTIVES

This study sought to provide contemporary data from a multi-institution with respect to DNA-repair genes (DRGs) status and its impact on effects of platinum-based chemotherapy in treatment-emergent neuroendocrine prostate cancer (t-NEPC), for which little data exist.

PATIENTS AND METHODS

All patients were retrospectively collected with eligible biopsied tissues for targeted next generation sequencing (NGS). The main outcomes were radiologic progression-free survival and overall survival according to Response Evaluation Criteria in Solid Tumors, version 1.1.

RESULTS

Among the 43 NEPC patients, 13/43 (30%) harbored homozygous deletions, deleterious mutations, or both in DRGs. Eleven patients (11/13, 85%) with DRGs aberrations had effective response, including 7 patients with BRCA1/2 defects and 2 with mismatch repair-deficient caused by MSH2 alterations. While significantly fewer responders (30%) were detected in patients without DRGs aberrations (odds ratio = 12.83, p = 0.003). Compared with patients without genomic DRGs aberrations, the hazard ratio (HR) for radiologic progression in those with DRGs defects was 0.42 (95% confidence interval [CI]: 0.19-0.93), and the HR for death was 0.65 (95% CI: 0.24-1.72). The most common adverse event of Grade 3 or 4 was anemia, as noted in 7 patients (16%).

CONCLUSION

The DRGs status is therapeutically meaningful in t-NEPC. Given the potential responses to platinum-based chemotherapy, our findings support the clinical use of NGS in t-NEPC patients to identify DRGs aberrations.

Multiparametric bone MRI can improve CT-guided bone biopsy target selection in cancer patients and increase diagnostic yield and feasibility of next-generation tumour sequencing

Objectives

To evaluate whether multiparametric bone MRI (mpBMRI) utilising a combination of DWI signal, ADC and relative fat-fraction (rFF) can identify bone metastases, which provide high diagnostic biopsy yield and next-generation genomic sequencing (NGS) feasibility.

Methods

A total of 150 CT-guided bone biopsies performed by interventional radiologists (3/2013 to 2/2021) at our centre were reviewed. In 43 patients, contemporaneous DWI and rFF images, calculated from 2-point T1w Dixon MRI, were available. For each biopsied lesion, a region of interest (ROI) was delineated on ADC and rFF images and the following MRI parameters were recorded: visual classification of DWI signal intensity (SI), mean, median, 10th and 90th centile ADC and rFF values. Non-parametric tests were used to compare values between tumour positive/negative biopsies and feasible/non-feasible NGS, with p-values < 0.05 deemed significant.

Results

The mpBMRI combination high DWI signal, mean ADC < 1100 µm²/s and mean rFF < 20% identified tumour-positive biopsies with 82% sensitivity, 80% specificity, a positive predictive value (PPV) of 93% (p = 0.001) and NGS feasibility with 91% sensitivity, 78% specificity and 91% PPV (p < 0.001). The single MRI parameters DWI signal, ADC and rFF failed to distinguish between tumour-positive and tumour-negative biopsies (each p > 0.082). In NGS feasible biopsies, mean and 90th centile rFF were significantly smaller (each p < 0.041). Single ADC parameters did not show significant difference regarding NGS feasibility (each p > 0.292).

Conclusions

MpBMRI utilising the combination of DWI signal, ADC and rFF can identify active bone metastases, which provide biopsy tissue with high diagnostic yield and NGS feasibility.

Key Points

• Multiparametric bone MRI with diffusion-weighted and relative fat-fraction images helps to identify active bone metastases suitable for CT-guided biopsy.

• Target lesions for CT-guided bone biopsies in cancer patients can be chosen with greater confidence.

• CT-guided bone biopsy success rates, especially yielding sufficient viable tissue for advanced molecular tissue analyses, can be improved.

Prior PSMA PET-CT Imaging and Hounsfield Unit Impact on Tumor Yield and Success of Molecular Analyses from Bone Biopsies in Metastatic Prostate Cancer

Simple Summary

Prostate cancer is currently the fifth leading cause of death in men worldwide. To personalize and guide treatment in prostate cancer, identification of druggable genomic alterations is of major importance. Prostate cancer often metastasizes solely or predominantly to the bones, with molecular analyses on bone biopsies challenging due to technical difficulties to identify and obtain biopsies from high tumor cell containing locations. In our retrospective analysis, we showed a significantly higher success rate in patients where biopsy location was selected by a prior PSMA PET-CT compared to solely CT or MRI. CT-guided biopsies in locations with low Hounsfield units (HUs) and deviation of HUs were associated with a higher proportion of successful histological and molecular biopsies. Based on these results, we designed a simple prediction model for daily clinical practice to increase the success rate of bone biopsies for molecular analyses in prostate cancer to guide precision medicine.

Abstract

Developing and optimizing targeted therapies in metastatic castration-resistant prostate cancer (mCRPC) necessitates molecular characterization. Obtaining sufficient tumor material for molecular characterization has been challenging. We aimed to identify clinical and imaging variables of imaging-guided bone biopsies in metastatic prostate cancer patients that associate with tumor yield and success in obtaining molecular results, and to design a predictive model: Clinical and imaging data were collected retrospectively from patients with prostate cancer who underwent a bone biopsy for histological and molecular characterization. Clinical characteristics, imaging modalities and imaging variables, were associated with successful biopsy results. In our study, we included a total of 110 bone biopsies. Histological conformation was possible in 84 of all biopsies, of which, in 73 of the 84, successful molecular characterization was performed. Prior use of PSMA PET-CT resulted in higher success rates in histological and molecular successful biopsies compared to CT or MRI. Evaluation of spine biopsies showed more often successful results compared to other locations for both histological and molecular biopsies (p = 0.027 and p = 0.012, respectively). Low Hounsfield units (HUs) and deviation (Dev), taken at CT-guidance, were associated with histological successful biopsies (p = 0.025 and p = 0.023, respectively) and with molecular successful biopsies (p = 0.010 and p = 0.006, respectively). A prediction tool combining low HUs and low Dev resulted in significantly more successful biopsies, histological and molecular (p = 0.023 and p = 0.007, respectively). Based on these results, we concluded that site selection for metastatic tissue biopsies with prior PSMA PET-CT imaging improves the chance of a successful biopsy. Further optimization can be achieved at CT-guidance, by selection of low HU and low Dev lesions. A prediction tool is provided to increase the success rate of bone biopsies in mCRPC patients, which can easily be implemented in daily practice.

Accelerating precision medicine in metastatic prostate cancer

Despite advances in prostate cancer screening and treatment, available therapy options, particularly in later stages of the disease, remain limited and the treatment-resistant setting represents a serious unmet medical need. Moreover, disease heterogeneity and disparities in patient access to medical advances result in significant variability in outcomes across patients. Disease classification based on genomic sequencing is a promising approach to identify patients whose tumors exhibit actionable targets and make more informed treatment decisions. Here we discuss how we can accelerate precision oncology to inform broader genomically-driven clinical decisions for men with advanced prostate cancer, drug development and ultimately contribute to new treatment paradigms.

Bone Biopsies: What Radiologists Need to Know

OBJECTIVE. The purpose of this article is to provide a step-by-step guide for bone imaging-guided percutaneous core needle biopsy, including the armamentarium available and the most recent advances. CONCLUSION. Bone imaging-guided percutaneous core needle biopsies are well-established, minimally invasive, cost-effective interventions for histologic characterization of bone lesions with an excellent safety profile and diagnostic outcomes; they play a crucial role in management of patients. Radiologists involved in the care of patients with bone lesions must be familiar with the various steps involved in such procedures and their role in patient management.

Clinical and genomic characterization of Low PSA Secretors: a unique subset of metastatic castration resistant prostate cancer

BACKGROUND

Metastatic disease burden out of proportion to serum PSA has been used as a marker of aggressive phenotype prostate cancer but is not well defined as a distinct subgroup. We sought to prospectively characterize the molecular features and clinical outcomes of Low PSA Secretors.

METHODS

Eligible metastatic castration resistant prostate cancer (mCRPC) patients without prior small cell histology underwent metastatic tumor biopsy with molecular characterization. Low PSA secretion was defined as serum PSA < 2, 5, or 10 ng/mL plus >5 metastases with radiographic progression at study entry. Clinical and molecular features were compared between low PSA vs. normal secretors in a post-hoc fashion.

RESULTS

183 patients were enrolled, including 15 (8%) identified as Low PSA Secretors using optimal PSA cut point of 5 ng/mL. Biopsies from Low PSA Secretors demonstrated higher t-SCNC and RB1 loss and lower AR transcriptional signature scores compared with normal secretors. Genomic loss of RB1 and/or TP53 was more common in Low PSA Secretors (80% vs. 41%). Overall survival (OS) was shorter in Low PSA Secretors (median OS = 26.7 vs. 46.0 months, hazard ratio = 2.465 (95% CI: 0.982-6.183). Progression-free survival (PFS) on post-biopsy treatment with AR-targeted therapy was shorter than with chemotherapy (median PFS 6.2 vs. 4.1 months).

CONCLUSIONS

Low PSA secretion in relation to metastatic tumor burden may be a readily available clinical selection tool for de-differentiated mCRPC with molecular features consistent with t-SCNC. Prospective validation is warranted.

Harnessing cell-free DNA: plasma circulating tumour DNA for liquid biopsy in genitourinary cancers

In the era of precision oncology, liquid biopsy techniques, especially the use of plasma circulating tumour DNA (ctDNA) analysis, represent a paradigm shift in the use of genomic biomarkers with considerable implications for clinical practice. Compared with tissue-based tumour DNA analysis, plasma ctDNA is more convenient to test, more readily accessible, faster to obtain and less invasive, minimizing procedure-related risks and offering the opportunity to perform serial monitoring. Additionally, genomic profiles of ctDNA have been shown to reflect tumour heterogeneity, which has important implications for the identification of resistant clones and selection of targeted therapy well before clinical and radiographic changes occur. Moreover, plasma ctDNA testing can also be applied to cancer screening, risk stratification and quantification of minimal residual disease. These features provide an unprecedented opportunity for early treatment of patients, improving the chances of treatment success.

68Ga-PSMA-Guided Bone Biopsies for Molecular Diagnostics in Patients with Metastatic Prostate Cancer

For individual treatment decisions in patients with metastatic prostate cancer (mPC), molecular diagnostics are increasingly used. Bone metastases are frequently the only source for obtaining metastatic tumor tissue. However, the success rate of CT-guided bone biopsies for molecular analyses in mPC patients is approximately only 40%. PET using ⁶⁸Ga prostate-specific membrane antigen (⁶⁸Ga-PSMA) is a promising tool to improve the harvest rate of bone biopsies for molecular analyses. The aim of this study was to determine the success rate of ⁶⁸Ga-PSMA-guided bone biopsies for molecular diagnostics in mPC patients. Methods: Within a prospective multicenter whole-genome sequencing trial (NCT01855477), 69 mPC patients underwent ⁶⁸Ga-PSMA PET/CT before bone biopsy. The primary endpoint was the success rate (tumor percentage ≥ 30%) of ⁶⁸Ga-PSMA-guided bone biopsies. At biopsy sites, ⁶⁸Ga-PSMA uptake was quantified using rigid-body image registration of ⁶⁸Ga-PSMA PET/CT and interventional CT. Actionable somatic alterations were identified. Results: The success rate of ⁶⁸Ga-PSMA-guided biopsies for molecular analyses was 70%. At biopsy sites categorized as positive, inconclusive, or negative for ⁶⁸Ga-PSMA uptake, 70%, 64%, and 36% of biopsies were tumor-positive (≥30%), respectively (P = 0.0610). In tumor-positive biopsies, ⁶⁸Ga-PSMA uptake was significantly higher (P = 0.008), whereas radiodensity was significantly lower (P = 0.006). With an area under the curve of 0.84 and 0.70, both ⁶⁸Ga-PSMA uptake (SUV_max) and radiodensity (mean Hounsfield units) were strong predictors for a positive biopsy. Actionable somatic alterations were detected in 73% of the sequenced biopsies. Conclusion: In patients with mPC, ⁶⁸Ga-PSMA PET/CT improves the success rate of CT-guided bone biopsies for molecular analyses, thereby identifying actionable somatic alterations in more patients. Therefore, ⁶⁸Ga-PSMA PET/CT may be considered for guidance of bone biopsies in both clinical practice and clinical trials.

Reduction of Radiation Dose and Scanning Time While Preserving Diagnostic Yield: A Comparison of Battery-Powered and Manual Bone Biopsy Systems

BACKGROUND AND PURPOSE

There is scarcity of data on the comparative efficacy between bone biopsy drill systems across various types of bone lesions. Our aim was to investigate differences in diagnostic yield, scanning time, and radiation dose between manual and battery-powered bone biopsy systems in CT-guided biopsies of lytic, sclerotic, and infectious bone lesions.

MATERIALS AND METHODS

This was a retrospective single-center institutional review board-approved study. A total of 585 CT-guided core needle biopsies were performed at 1 institution from May 2010 to February 2019. Classification of bone lesions, location, bone biopsy system, suspected origin of primary disease, final pathologic diagnosis, diagnostic yield, presence of crush artifacts, radiation dose, and scanning times were collected. For the battery-powered system, OnControl was used. For the manual drill system, Bonopty, Osteo-site, and Laurane drill systems were used. Comparisons in lytic and sclerotic lesions and suspected discitis/osteomyelitis were made using the Fisher exact test. Subgroup analysis of the drill systems for scanning time and radiation dose was performed by 1-way ANOVA.

RESULTS

Our patient cohorts consisted of a total of 585 patients with 422 lytic, 110 sclerotic, and 53 suspected infectious lesions. The mean age was 62 ± 13 years with a male/female ratio of 305:280 for all lesions. The diagnostic yield was 85.5% (362/422) for lytic, 82.7% (91/110) for sclerotic, 50.9% (27/53) for infectious lesions, and 82.1% (480/585) for all lesions. No statistical difference was found when comparing diagnostic yields of powered drills with the manual systems for lytic, sclerotic, and infectious lesions. However, in a subgroup analysis, radiation dose and scanning time were significantly lower for powered drill compared with manual drill systems in lytic (P = .001 for both) and sclerotic lesions (P = .028 and P = .012, respectively). No significant differences were seen between the drill systems for suspected infectious lesions.

CONCLUSIONS

Our findings demonstrate that there was no statistically significant difference in diagnostic yield when comparing battery-powered and manual bone biopsy systems for CT-guided bone biopsies; however, the use of the power drill system resulted in significantly reduced scanning time and radiation dose in lytic and sclerotic lesions.

68Ga-PSMA-PET/CT and Diffusion MRI Targeting for Cone-Beam CT-Guided Bone Biopsies of Castration-Resistant Prostate Cancer Patients

Introduction

Precision medicine expands the treatment options for metastatic castration-resistant prostate cancer (mCRPC) by targeting druggable genetic aberrations. Aberrations can be identified following molecular analysis of metastatic tissue. Bone metastases, commonly present in mCRPC, hinder precision medicine due to a high proportion of biopsies with insufficient tumor cells for next-generation DNA sequencing. We aimed to investigate the feasibility of incorporating advanced target planning and needle guidance in bone biopsies and whether this procedure increases biopsy tumor yield and success rate of molecular analysis as compared to the current standards, utilizing only CT guidance.

Materials and Methods

In a pilot study, ten mCRPC patients received ⁶⁸Ga-prostate-specific membrane antigen (PSMA)-PET/CT and diffusion-weighted MRI as biopsy planning images. These datasets were fused for targeting metastatic lesions with high tumor densities. Biopsies were performed under cone-beam CT (CBCT) guidance. Feasibility of target planning and needle guidance was assessed, and success of molecular analysis and tumor yield were reported.

Results

Fusion target planning and CBCT needle guidance were feasible. Nine out of ten biopsies contained prostate cancer cells, with a median of 39% and 40% tumor cells by two different sequencing techniques. Molecular analysis was successful in eight of ten patients (80%). This exceeds previous reports on CT-guided biopsies that ranged from 33 to 44%. In two patients, important druggable aberrations were found.

Discussion

A biopsy procedure using advanced target planning and needle guidance is feasible and can increase the success rate of molecular analysis in bone metastases, thereby having the potential of improving treatment outcome for patients with mCRPC.

Level of Evidence

Level 4, case series.

Feasibility of genomic profiling with next-generation sequencing using specimens obtained by image-guided percutaneous needle biopsy

Aims: The demand for specimen collection for genomic profiling is rapidly increasing in the era of personalized medicine. Percutaneous needle biopsy is recognized as minimally invasive, but the feasibility of comprehensive genomic analysis using next-generation sequencing (NGS) is not yet clear. The purpose of this study was to evaluate the feasibility of genomic analysis using NGS with specimens obtained by image-guided percutaneous needle biopsy with 18-G needles. Patients and methods: Forty-eight patients who participated in a clinical study of genomic profiling with NGS with the specimen obtained by image-guided needle biopsy were included. All biopsies were performed under local anesthesia, with imaging guidance, using an 18-G cutting needle. A retrospective chart review was performed to determine the rate of successful genomic analysis, technical success rate of biopsy procedure, adverse events, rate of success in pathological diagnosis, and cause of failed genomic analysis. Results: The success rate of genomic analysis was 79.2% (38/48). The causes of failure were unprocessed for DNA extraction due to insufficient specimen volume (6/10), insufficient DNA volume (2/10), and deteriorated DNA quality (2/10). The rate of successful genomic analysis excluding NGS analysis that failed for reasons unrelated to the biopsy procedures was 95.2% (40/42). Technical success of biopsy was achieved in all patients without severe adverse events. The rate of success in the pathological diagnosis was 97.9% (47/48). Conclusions: Image-guided needle biopsy specimens using an 18-G cutting needle yielded a successful NGS genomic analysis rate with no severe adverse events and could be an adoptable method for tissue sampling for NGS.

The Bone Microenvironment in Prostate Cancer Metastasis

The propensity of prostate cancer cells to seed the skeleton and then progress into clinically relevant metastatic tumors is widely recognized and a major cause of morbidity and mortality for patients. The natural history of prostate adenocarcinoma most frequently begins with a tumor diagnosed at a localized stage, which is successfully treated by surgical and/or radiation therapy modalities. A relevant percentage of patients are clinically cured but approximately 20-30% will develop biochemical signs of recurrence, which respond to the inhibition of androgen receptor (AR) signaling by hormone-deprivation and receptor antagonists, before the inevitable transition into castration-resistant prostate cancer (CRPC). This stage simultaneously presents with or is rapidly followed by secondary tumors, which involve the skeleton in more than 90% of cases (mCRPC). While generalization in clinical practice is always unwise, it is indisputable that bone-metastatic prostate cancer is virtually incurable. Decades of research have revealed that the tissue microenvironment provided by the bone marrow is as important as the cell-autonomous features of tumor cells in fostering the right conditions that lead to establishment and progression of metastatic tumors in the skeleton.

A comparison of prostate cancer bone metastases on 18F-Sodium Fluoride and Prostate Specific Membrane Antigen (18F-PSMA) PET/CT: Discordant uptake in the same lesion

Purpose

Prostate-Specific Membrane Antigen (PSMA) PET/CT has been introduced as a sensitive method for characterizing metastatic prostate cancer. The purpose of this study is to compare the spatial concordance of ¹⁸F-NaF PET/CT and ¹⁸F-PSMA-targeted PET/CT within prostate cancer bone metastases.

Methods

Prostate cancer patients with known bone metastases underwent PSMA-targeted PET/CT (¹⁸F-DCFBC or ¹⁸F-DCFPyL) and ¹⁸F-NaF PET/CT. In pelvic and spinal lesions detected by both radiotracers, regions-of-interest (ROIs) derived by various thresholds of uptake intensity were compared for spatial colocalization. Overlap volume was correlated with uptake characteristics and disease status.

Results

The study included 149 lesions in 19 patients. Qualitatively, lesions exhibited a heterogeneous range of spatial concordance between PSMA and NaF uptake from completely matched to completely discordant. Quantitatively, overlap volume decreased as a function of tracer intensity. and disease status, where lesions from patients with castration-sensitive disease showed higher spatial concordance while lesions from patients with castration-resistant disease demonstrated more frequent spatial discordance.

Conclusion

As metastatic prostate cancer progresses from castration-sensitive to castration-resistant, greater discordance is observed between NaF PET and PSMA PET uptake. This may indicate a possible phenotypic shift to tumor growth that is more independent of bone remodeling via osteoblastic formation.

Implementing a comprehensive translational oncology platform: from molecular testing to actionability

BACKGROUND

In order to establish the workflows required to implement a real-time process involving multi-omic analysis of patient samples to support precision-guided therapeutic intervention, a tissue acquisition and analysis trial was implemented. This report describes our findings to date, including the frequency with which mutational testing led to precision-guided therapy and outcome for those patients.

METHODS

Eligible patients presenting to Oregon Health and Science University Knight Cancer Institute were enrolled on the study. Patients with biopsy proven metastatic or locally advanced unresectable prostate cancer, breast cancer, pancreatic adenocarcinoma, or refractory acute myelogenous leukemia receiving standard of care therapy were eligible. Metastatic site biopsies were collected and analyzed using the Knight Diagnostic Lab GeneTrails comprehensive solid tumor panel (124 genes). CLIA certified genomic information was made available to the treating physician.

RESULTS

Between 1/26/2017 and 5/30/2018, 38 patients were enrolled, with 28 successfully undergoing biopsy. Of these, 25 samples yielded sufficient tumor for analysis. The median biopsy cellularity and number of cores collected were 70% (15-90%) and 5 (2-20), respectively. No procedure-related complications occurred. GeneTrails analysis revealed that 22 of 25 (88%) tumor samples harbored at least one potentially actionable mutation, and 18 (72%) samples harbored 2 or more potentially actionable mutations. The most common genetic alterations identified involved: DNA damage repair genes, cell cycle regulating genes, PIK3CA/Akt/mTOR pathway, and FGF gene family. To date, CLIA certified genomic results were used by treating physicians for precision-guided therapy in 5 (23%) patients.

CONCLUSION

We report the feasibility of real-time tissue acquisition and analysis to support a successful translational oncology platform. The workflow will provide the foundation to improve access and accrual to biomarker driven precision oncology trials.

Cell-free DNA profiling of metastatic prostate cancer reveals microsatellite instability, structural rearrangements and clonal hematopoiesis

BACKGROUND

There are multiple existing and emerging therapeutic avenues for metastatic prostate cancer, with a common denominator, which is the need for predictive biomarkers. Circulating tumor DNA (ctDNA) has the potential to cost-efficiently accelerate precision medicine trials to improve clinical efficacy and diminish costs and toxicity. However, comprehensive ctDNA profiling in metastatic prostate cancer to date has been limited.

METHODS

A combination of targeted and low-pass whole genome sequencing was performed on plasma cell-free DNA and matched white blood cell germline DNA in 364 blood samples from 217 metastatic prostate cancer patients.

RESULTS

ctDNA was detected in 85.9% of baseline samples, correlated to line of therapy and was mirrored by circulating tumor cell enumeration of synchronous blood samples. Comprehensive profiling of the androgen receptor (AR) revealed a continuous increase in the fraction of patients with intra-AR structural variation, from 15.4% during first-line metastatic castration-resistant prostate cancer therapy to 45.2% in fourth line, indicating a continuous evolution of AR during the course of the disease. Patients displayed frequent alterations in DNA repair deficiency genes (18.0%). Additionally, the microsatellite instability phenotype was identified in 3.81% of eligible samples (≥ 0.1 ctDNA fraction). Sequencing of non-repetitive intronic and exonic regions of PTEN, RB1, and TP53 detected biallelic inactivation in 47.5%, 20.3%, and 44.1% of samples with ≥ 0.2 ctDNA fraction, respectively. Only one patient carried a clonal high-impact variant without a detectable second hit. Intronic high-impact structural variation was twice as common as exonic mutations in PTEN and RB1. Finally, 14.6% of patients presented false positive variants due to clonal hematopoiesis, commonly ignored in commercially available assays.

CONCLUSIONS

ctDNA profiles appear to mirror the genomic landscape of metastatic prostate cancer tissue and may cost-efficiently provide somatic information in clinical trials designed to identify predictive biomarkers. However, intronic sequencing of the interrogated tumor suppressors challenges the ubiquitous focus on coding regions and is vital, together with profiling of synchronous white blood cells, to minimize erroneous assignments which in turn may confound results and impede true associations in clinical trials.

Bone and Soft-Tissue Biopsies: What You Need to Know

Percutaneous, image-guided musculoskeletal biopsy, due to its minimal invasive nature, when compared with open surgical biopsy, is a safe and effective technique which is widely used in many institutions as the primary method to acquire tissue and bone samples. Indications include histopathologic and molecular assessment of a musculoskeletal lesion, exclusion of malignancy in a bone/vertebral fracture, examination of bone marrow, and infection investigation. Preprocedural workup should include both imaging (for lesion assessment and staging) and laboratory (including coagulation tests and platelet count) studies. In selected cases, antibiotic prophylaxis should be administered before the biopsy. Core needle biopsy of musculoskeletal lesions has a diagnostic accuracy that ranges from 66 to 98% with higher diagnostic yield for lytic, large-size, malignant lesions and when multiple and long specimens are obtained. Reported complication rates range between 0 and 10% and usually do not exceed 5%, with a suggested threshold of 2%. The purpose of this review article is to illustrate the technical aspects, the indications, and the methodology of percutaneous image-guided bone biopsy that will assist the interventional radiologist to perform these minimal invasive techniques.

A two-drug combination simulation study for metastatic castrate resistant prostate cancer

BACKGROUND

Prostate cancer often evolves resistance to androgen deprivation therapy leading to a lethal metastatic castrate-resistant form. Besides androgen independence, subpopulations of the tumor are genetically heterogeneous. With the advent of tumor genome sequencing we asked which has the greater influence on reducing tumor size: genetic background, heterogeneity, or drug potency?

METHODS

A previously developed theoretical evolutionary dynamics model of stochastic branching processes is applied to compute the probability of tumor eradication with two targeted drugs. Publicly available data sets were surveyed to parameterize the model.

RESULTS

Our calculations reveal that the greatest influence on successful treatment is the genetic background including the number of mutations overcoming resistance. Another important criteria is the tumor size at which it is still possible to achieve tumor eradication, for example, 2-4 cm large tumors have at best a 10% probability to be eradicated when 50 mutations can confer resistance to each drug.

CONCLUSION

Overall, this study finds that genetic background and tumor heterogeneity are more important than drug potency in treating mCRPC. It also points toward identifying metastatic sites early using biochemical assays and/or dPET.

Genomic Hallmarks and Structural Variation in Metastatic Prostate Cancer

While mutations affecting protein-coding regions have been examined across many cancers, structural variants at the genome-wide level are still poorly defined. Through integrative deep whole-genome and -transcriptome analysis of 101 castration-resistant prostate cancer metastases (109X tumor/38X normal coverage), we identified structural variants altering critical regulators of tumorigenesis and progression not detectable by exome approaches. Notably, we observed amplification of an intergenic enhancer region 624 kb upstream of the androgen receptor (AR) in 81% of patients, correlating with increased AR expression. Tandem duplication hotspots also occur near MYC, in lncRNAs associated with post-translational MYC regulation. Classes of structural variations were linked to distinct DNA repair deficiencies, suggesting their etiology, including associations of CDK12 mutation with tandem duplications, TP53 inactivation with inverted rearrangements and chromothripsis, and BRCA2 inactivation with deletions. Together, these observations provide a comprehensive view of how structural variations affect critical regulators in metastatic prostate cancer.

Clinical and Genomic Characterization of Treatment-Emergent Small-Cell Neuroendocrine Prostate Cancer: A Multi-institutional Prospective Study

Purpose The prevalence and features of treatment-emergent small-cell neuroendocrine prostate cancer (t-SCNC) are not well characterized in the era of modern androgen receptor (AR)-targeting therapy. We sought to characterize the clinical and genomic features of t-SCNC in a multi-institutional prospective study. Methods Patients with progressive, metastatic castration-resistant prostate cancer (mCRPC) underwent metastatic tumor biopsy and were followed for survival. Metastatic biopsy specimens underwent independent, blinded pathology review along with RNA/DNA sequencing. Results A total of 202 consecutive patients were enrolled. One hundred forty-eight (73%) had prior disease progression on abiraterone and/or enzalutamide. The biopsy evaluable rate was 79%. The overall incidence of t-SCNC detection was 17%. AR amplification and protein expression were present in 67% and 75%, respectively, of t-SCNC biopsy specimens. t-SCNC was detected at similar proportions in bone, node, and visceral organ biopsy specimens. Genomic alterations in the DNA repair pathway were nearly mutually exclusive with t-SCNC differentiation ( P = .035). Detection of t-SCNC was associated with shortened overall survival among patients with prior AR-targeting therapy for mCRPC (hazard ratio, 2.02; 95% CI, 1.07 to 3.82). Unsupervised hierarchical clustering of the transcriptome identified a small-cell-like cluster that further enriched for adverse survival outcomes (hazard ratio, 3.00; 95% CI, 1.25 to 7.19). A t-SCNC transcriptional signature was developed and validated in multiple external data sets with > 90% accuracy. Multiple transcriptional regulators of t-SCNC were identified, including the pancreatic neuroendocrine marker PDX1. Conclusion t-SCNC is present in nearly one fifth of patients with mCRPC and is associated with shortened survival. The near-mutual exclusivity with DNA repair alterations suggests t-SCNC may be a distinct subset of mCRPC. Transcriptional profiling facilitates the identification of t-SCNC and novel therapeutic targets.

Bone biopsy protocol for advanced prostate cancer in the era of precision medicine

BACKGROUND

Metastatic biopsies are increasingly being performed in patients with advanced prostate cancer to search for actionable targets and/or to identify emerging resistance mechanisms. Due to a predominance of bone metastases and their sclerotic nature, obtaining sufficient tissue for clinical and genomic studies is challenging.

METHODS

Patients with prostate cancer bone metastases were enrolled between February 2013 and March 2017 on an institutional review board-approved protocol for prospective image-guided bone biopsy. Bone biopsies and blood clots were collected fresh. Compact bone was subjected to formalin with a decalcifying agent for diagnosis; bone marrow and blood clots were frozen in optimum cutting temperature formulation for next-generation sequencing. Frozen slides were cut from optimum cutting temperature cryomolds and evaluated for tumor histology and purity. Tissue was macrodissected for DNA and RNA extraction, and whole-exome sequencing and RNA sequencing were performed.

RESULTS

Seventy bone biopsies from 64 patients were performed. Diagnostic material confirming prostate cancer was successful in 60 of 70 cases (85.7%). The median DNA/RNA yield was 25.5 ng/μL and 16.2 ng/μL, respectively. Whole-exome sequencing was performed successfully in 49 of 60 cases (81.7%), with additional RNA sequencing performed in 20 of 60 cases (33.3%). Recurrent alterations were as expected, including those involving the AR, PTEN, TP53, BRCA2, and SPOP genes.

CONCLUSIONS

This prostate cancer bone biopsy protocol ensures a valuable source for high-quality DNA and RNA for tumor sequencing and may be used to detect actionable alterations and resistance mechanisms in patients with bone metastases. Cancer 2018;124:1008-15. © 2017 American Cancer Society.

Concordance between fine-needle aspiration and core biopsies for osseous lesions by lesion imaging appearance and CT attenuation

OBJECTIVES

To compare the concordance between fine-needle aspiration and core biopsies for osseous lesions by lesion imaging appearance and CT attenuation.

MATERIALS AND METHODS

Retrospective review of 215 FNAs of osseous lesions performed in conjunction with core biopsy at our institution over a 6-year period (2011-2016). FNAs were interpreted independently of core biopsies. We assessed if FNA in conjunction with core biopsy increased diagnostic accuracy compared to core biopsy alone. We also calculated the concordance between FNA and core biopsy by lesion appearance, lesion CT attenuation, lesion histology, lesion location and FNA needle gauge size.

RESULTS

Core biopsy alone provided the diagnosis in 207/215 cases (96.3%), however, the FNA provided the diagnosis in the remaining 8/215 cases (3.7%) where the core biopsy was non-diagnostic. There were 154 (71.6%) lytic lesions, 21 (9.8%) blastic lesions, 25 (11.6%) mixed lytic and blastic lesions and 15 (7.0%) lesions that were neither lytic nor blastic. The concordance between FNA and core biopsy for lytic osseous lesions (136/154 cases, 88.3%) was statistically significantly higher than that for blastic osseous lesions (13/21 cases, 61.9%) [P = 4.2 × 10^-3; 95% CI (0.02, 0.50)]. The concordance between FNA and core biopsy was higher for low-attenuation- (110/126) than high-attenuation (58/77) lesions (P = 0.028). The concordance between FNA and core biopsy was also higher for metastases (102/119 cases, 85.7%) than non-metastases (78/96, 81.3%) [P = 0.487; 95% CI (- 0.15, 0.065)]. There was no difference in the rate of concordance between FNA and core biopsy by lesion location or FNA needle gauge size (P > 0.05).

CONCLUSION

FNA with core biopsy increases diagnostic rate compared to core biopsy alone or FNA alone. The concordance between FNA and core biopsy is higher for lytic lesions than for blastic lesions; and higher for low-attenuation lesions than for high-attenuation lesions.