Publications by authors named "Gemma Fowler"

8 Publications

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Olaparib in patients with metastatic castration-resistant prostate cancer with DNA repair gene aberrations (TOPARP-B): a multicentre, open-label, randomised, phase 2 trial.

Lancet Oncol 2020 01 2;21(1):162-174. Epub 2019 Dec 2.

The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK. Electronic address:

Background: Metastatic castration-resistant prostate cancer is enriched in DNA damage response (DDR) gene aberrations. The TOPARP-B trial aims to prospectively validate the association between DDR gene aberrations and response to olaparib in metastatic castration-resistant prostate cancer.

Methods: In this open-label, investigator-initiated, randomised phase 2 trial following a selection (or pick-the-winner) design, we recruited participants from 17 UK hospitals. Men aged 18 years or older with progressing metastatic castration-resistant prostate cancer previously treated with one or two taxane chemotherapy regimens and with an Eastern Cooperative Oncology Group performance status of 2 or less had tumour biopsies tested with targeted sequencing. Patients with DDR gene aberrations were randomly assigned (1:1) by a computer-generated minimisation method, with balancing for circulating tumour cell count at screening, to receive 400 mg or 300 mg olaparib twice daily, given continuously in 4-week cycles until disease progression or unacceptable toxicity. Neither participants nor investigators were masked to dose allocation. The primary endpoint of confirmed response was defined as a composite of all patients presenting with any of the following outcomes: radiological objective response (as assessed by Response Evaluation Criteria in Solid Tumors 1.1), a decrease in prostate-specific antigen (PSA) of 50% or more (PSA50) from baseline, or conversion of circulating tumour cell count (from ≥5 cells per 7·5 mL blood at baseline to <5 cells per 7·5 mL blood). A confirmed response in a consecutive assessment after at least 4 weeks was required for each component. The primary analysis was done in the evaluable population. If at least 19 (43%) of 44 evaluable patients in a dose cohort responded, then the dose cohort would be considered successful. Safety was assessed in all patients who received at least one dose of olaparib. This trial is registered at ClinicalTrials.gov, NCT01682772. Recruitment for the trial has completed and follow-up is ongoing.

Findings: 711 patients consented for targeted screening between April 1, 2015, and Aug 30, 2018. 161 patients had DDR gene aberrations, 98 of whom were randomly assigned and treated (49 patients for each olaparib dose), with 92 evaluable for the primary endpoint (46 patients for each olaparib dose). Median follow-up was 24·8 months (IQR 16·7-35·9). Confirmed composite response was achieved in 25 (54·3%; 95% CI 39·0-69·1) of 46 evaluable patients in the 400 mg cohort, and 18 (39·1%; 25·1-54·6) of 46 evaluable patients in the 300 mg cohort. Radiological response was achieved in eight (24·2%; 11·1-42·3) of 33 evaluable patients in the 400 mg cohort and six (16·2%; 6·2-32·0) of 37 in the 300 mg cohort; PSA50 response was achieved in 17 (37·0%; 23·2-52·5) of 46 and 13 (30·2%; 17·2-46·1) of 43; and circulating tumour cell count conversion was achieved in 15 (53·6%; 33·9-72·5) of 28 and 13 (48·1%; 28·7-68·1) of 27. The most common grade 3-4 adverse event in both cohorts was anaemia (15 [31%] of 49 patients in the 300 mg cohort and 18 [37%] of 49 in the 400 mg cohort). 19 serious adverse reactions were reported in 13 patients. One death possibly related to treatment (myocardial infarction) occurred after 11 days of treatment in the 300 mg cohort.

Interpretation: Olaparib has antitumour activity against metastatic castration-resistant prostate cancer with DDR gene aberrations, supporting the implementation of genomic stratification of metastatic castration-resistant prostate cancer in clinical practice.

Funding: Cancer Research UK, AstraZeneca, Prostate Cancer UK, the Prostate Cancer Foundation, the Experimental Cancer Medicine Centres Network, and the National Institute for Health Research Biomedical Research Centres.
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http://dx.doi.org/10.1016/S1470-2045(19)30684-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6941219PMC
January 2020

Clinical Utility of Circulating Tumour Cell Androgen Receptor Splice Variant-7 Status in Metastatic Castration-resistant Prostate Cancer.

Eur Urol 2019 11 27;76(5):676-685. Epub 2019 Apr 27.

The Institute for Cancer Research, London, UK; The Royal Marsden NHS Foundation Trust, London, UK. Electronic address:

Background: Detection of androgen receptor splice variant-7 (AR-V7) mRNA in circulating tumour cells (CTCs) is associated with worse outcome in metastatic castration-resistant prostate cancer (mCRPC). However, studies rarely report comparisons with CTC counts and biopsy AR-V7 protein expression.

Objective: To determine the reproducibility of AdnaTest CTC AR-V7 testing, and associations with clinical characteristics, CellSearch CTC counts, tumour biopsy AR-V7 protein expression and overall survival (OS).

Design, Setting, And Participants: CTC AR-V7 status was determined for 227 peripheral blood samples, from 181 mCRPC patients with CTC counts (202 samples; 136 patients) and matched mCRPC biopsies (65 samples; 58 patients).

Outcome Measurements And Statistical Analysis: CTC AR-V7 status was associated with clinical characteristics, CTC counts, and tissue biopsy AR-V7 protein expression. The association of CTC AR-V7 status and other baseline variables with OS was determined.

Results And Limitations: Of the samples, 35% were CTC+/AR-V7+. CTC+/AR-V7+ samples had higher CellSearch CTC counts (median CTC; interquartile range [IQR]: 60, 19-184 vs 9, 2-64; Mann-Whitney test p<0.001) and biopsy AR-V7 protein expression (median H-score, IQR: 100, 63-148 vs 15, 0-113; Mann-Whitney test p=0.004) than CTC+/AR-V7- samples. However, both CTC- (63%) and CTC+/AR-V7- (62%) patients had detectable AR-V7 protein in contemporaneous biopsies. After accounting for baseline characteristics, there was shorter OS in CTC+/AR-V7+ patients than in CTC- patients (hazard ratio [HR] 2.13; 95% confidence interval [CI] 1.23-3.71; p=0.02); surprisingly, there was no evidence that CTC+/AR-V7+ patients had worse OS than CTC+/AR-V7- patients (HR 1.26; 95% CI 0.73-2.17; p=0.4). A limitation of this study was the heterogeneity of treatment received.

Conclusions: Studies reporting the prognostic relevance of CTC AR-V7 status must account for CTC counts. Discordant CTC AR-V7 results and AR-V7 protein expression in matched, same-patient biopsies are reported.

Patient Summary: Liquid biopsies that determine circulating tumour cell androgen receptor splice variant-7 status have the potential to impact treatment decisions in metastatic castration-resistant prostate cancer patients. Robust clinical qualification of these assays is required before their routine use.
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http://dx.doi.org/10.1016/j.eururo.2019.04.006DOI Listing
November 2019

EpCAM and EpCAM circulating tumor cells in metastatic prostate and breast cancer patients.

Oncotarget 2018 Nov 2;9(86):35705-35716. Epub 2018 Nov 2.

Department of Medical Cell BioPhysics, Faculty of Sciences and Technology, MIRA Institute, University of Twente, Enschede, The Netherlands.

The presence of high expressing epithelial cell adhesion molecule (EpCAM) circulating tumor cells (CTC) enumerated by CellSearch in blood of cancer patients is strongly associated with poor prognosis. This raises the question about the presence and relation with clinical outcome of low EpCAM expressing CTC (EpCAM CTC). In the EU-FP7 CTC-Trap program, we investigated the presence of EpCAM and EpCAM CTC using CellSearch, followed by microfiltration of the EpCAM CTC depleted blood. Blood samples of 108 castration-resistant prostate cancer patients and 22 metastatic breast cancer patients were processed at six participating sites, using protocols and tools developed in the CTC-Trap program. Of the prostate cancer patients, 53% had ≥5 EpCAM CTC and 28% had ≥5 EpCAM CTC. For breast cancer patients, 32% had ≥5 EpCAM CTC and 36% had ≥5 EpCAM CTC. 70% of prostate cancer patients and 64% of breast cancer patients had in total ≥5 EpCAM and/or EpCAM CTC, increasing the number of patients in whom CTC are detected. Castration-resistant prostate cancer patients with ≥5 EpCAM CTC had shorter overall survival versus those with <5 EpCAM CTC ( = 0.000). However, presence of EpCAM CTC had no relation with overall survival. This emphasizes the importance to demonstrate the relation with clinical outcome when presence of CTC identified with different technologies are reported, as different CTC subpopulations can have different relations with clinical outcome.
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http://dx.doi.org/10.18632/oncotarget.26298DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235023PMC
November 2018

Single-Cell Analyses of Prostate Cancer Liquid Biopsies Acquired by Apheresis.

Clin Cancer Res 2018 11 9;24(22):5635-5644. Epub 2018 Aug 9.

Division of Clinical Studies, The Institute of Cancer Research, London, United Kingdom.

Circulating tumor cells (CTCs) have clinical relevance, but their study has been limited by their low frequency. We evaluated liquid biopsies by apheresis to increase CTC yield from patients suffering from metastatic prostate cancer, allow precise gene copy-number calls, and study disease heterogeneity. Apheresis was well tolerated and allowed the separation of large numbers of CTCs; the average CTC yield from 7.5 mL of peripheral blood was 167 CTCs, whereas the average CTC yield per apheresis (mean volume: 59.5 mL) was 12,546 CTCs. Purified single CTCs could be isolated from apheresis product by FACS sorting; copy-number aberration (CNA) profiles of 185 single CTCs from 14 patients revealed the genomic landscape of lethal prostate cancer and identified complex intrapatient, intercell, genomic heterogeneity missed on bulk biopsy analyses. Apheresis facilitated the capture of large numbers of CTCs noninvasively with minimal morbidity and allowed the deconvolution of intrapatient heterogeneity and clonal evolution. .
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http://dx.doi.org/10.1158/1078-0432.CCR-18-0862DOI Listing
November 2018

Toward a real liquid biopsy in metastatic breast and prostate cancer: Diagnostic LeukApheresis increases CTC yields in a European prospective multicenter study (CTCTrap).

Int J Cancer 2018 11 19;143(10):2584-2591. Epub 2018 Sep 19.

Prostate Cancer Targeted Therapies Group, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Sutton, UK.

Frequently, the number of circulating tumor cells (CTC) isolated in 7.5 mL of blood is too small to reliably determine tumor heterogeneity and to be representative as a "liquid biopsy". In the EU FP7 program CTCTrap, we aimed to validate and optimize the recently introduced Diagnostic LeukApheresis (DLA) to screen liters of blood. Here we present the results obtained from 34 metastatic cancer patients subjected to DLA in the participating institutions. About 7.5 mL blood processed with CellSearch® was used as "gold standard" reference. DLAs were obtained from 22 metastatic prostate and 12 metastatic breast cancer patients at four different institutions without any noticeable side effects. DLA samples were prepared and processed with different analysis techniques. Processing DLA using CellSearch resulted in a 0-32 fold increase in CTC yield compared to processing 7.5 mL blood. Filtration of DLA through 5 μm pores microsieves was accompanied by large CTC losses. Leukocyte depletion of 18 mL followed by CellSearch yielded an increase of the number of CTC but a relative decrease in yield (37%) versus CellSearch DLA. In four out of seven patients with 0 CTC detected in 7.5 mL of blood, CTC were detected in DLA (range 1-4 CTC). The CTC obtained through DLA enables molecular characterization of the tumor. CTC enrichment technologies however still need to be improved to isolate all the CTC present in the DLA.
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http://dx.doi.org/10.1002/ijc.31752DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6637919PMC
November 2018

Circulating tumor cells, tumor-derived extracellular vesicles and plasma cytokeratins in castration-resistant prostate cancer patients.

Oncotarget 2018 Apr 10;9(27):19283-19293. Epub 2018 Apr 10.

Department of Medical Cell BioPhysics, MIRA Institute, University of Twente, Enschede, the Netherlands.

Purpose: The presence of Circulating Tumor Cells (CTCs) in Castration-Resistant Prostate Cancer (CRPC) patients is associated with poor prognosis. In this study, we evaluated the association of clinical outcome in 129 CRPC patients with CTCs, tumor-derived Extracellular Vesicles (tdEVs) and plasma levels of total (CK18) and caspase-cleaved cytokeratin 18 (ccCK18).

Experimental Design: CTCs and tdEVs were isolated with the CellSearch system and automatically enumerated. Cut-off values dichotomizing patients into favorable and unfavorable groups of overall survival were set on a retrospective data set of 84 patients and validated on a prospective data set of 45 patients. Plasma levels of CK18 and ccCK18 were assessed by ELISAs.

Results: CTCs, tdEVs and both cytokeratin plasma levels were significantly increased in CRPC patients compared to healthy donors (HDs). All biomarkers except for ccCK18 were prognostic showing a decreased median overall survival for the unfavorable groups of 9.2 vs 21.1, 8.1 vs 23.0 and 10.0 vs 21.5 months respectively. In multivariable Cox regression analysis, tdEVs remained significant.

Conclusions: Automated CTC and tdEV enumeration allows fast and reliable scoring eliminating inter- and intra- operator variability. tdEVs provide similar prognostic information to CTC counts.
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http://dx.doi.org/10.18632/oncotarget.25019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5922396PMC
April 2018

Circulating Cell-Free DNA to Guide Prostate Cancer Treatment with PARP Inhibition.

Cancer Discov 2017 09 27;7(9):1006-1017. Epub 2017 Apr 27.

The Institute of Cancer Research, London, United Kingdom.

Biomarkers for more precise patient care are needed in metastatic prostate cancer. We have reported a phase II trial (TOPARP-A) of the PARP inhibitor olaparib in metastatic prostate cancer, demonstrating antitumor activity associating with homologous recombination DNA repair defects. We now report targeted and whole-exome sequencing of serial circulating cell-free DNA (cfDNA) samples collected during this trial. Decreases in cfDNA concentration independently associated with outcome in multivariable analyses (HR for overall survival at week 8: 0.19; 95% CI, 0.06-0.56; = 0.003). All tumor tissue somatic DNA repair mutations were detectable in cfDNA; allele frequency of somatic mutations decreased selectively in responding patients (χ < 0.001). At disease progression, following response to olaparib, multiple subclonal aberrations reverting germline and somatic DNA repair mutations () back in frame emerged as mechanisms of resistance. These data support the role of liquid biopsies as a predictive, prognostic, response, and resistance biomarker in metastatic prostate cancer. We report prospectively planned, serial, cfDNA analyses from patients with metastatic prostate cancer treated on an investigator-initiated phase II trial of olaparib. These analyses provide predictive, prognostic, response, and resistance data with "second hit" mutations first detectable at disease progression, suggesting clonal evolution from treatment-selective pressure and platinum resistance. .
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http://dx.doi.org/10.1158/2159-8290.CD-17-0261DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6143169PMC
September 2017

DNA-Repair Defects and Olaparib in Metastatic Prostate Cancer.

N Engl J Med 2015 Oct;373(18):1697-708

From the Institute of Cancer Research (J.M., S.C., S.S., S.M., H.M., R.P.-L., D.N.R., A.O., N.T., G.B., N.P., P.F., A.G., I.F., C.P., G.S., D.B., J.G., Z.Z., C.T.W., R.F., R.R., B.E., G.F., D. Roda, W.Y., R.B., H.P., R.A., A.S., R.E., G.A., C.J.L., A.A., E.H., J.S.B.), the Royal Marsden NHS Foundation Trust (J.M., S.S., R.P.-L., A.O., N.T., D.B., Z.Z., R.F., D. Roda, R.E., G.A., J.S.B.), and University College London Hospital (U.M.), London, Queen's University, Belfast (S.J.), University of Leeds, Leeds (C.R.), Churchill Hospital, Oxford (A.P.), University of Liverpool, Liverpool (S.H.), Beatson West of Scotland Cancer Centre, Glasgow (R.J.), and Christie Hospital, Manchester (T.E.) - all in the United Kingdom; the University of Michigan, Ann Arbor (D. Robinson, Y.-M.W., X.C., L.P.K., F.Y.F., A.M.C.); Weill Cornell Medical College, New York (M.A.R.); and Thomas Jefferson University, Philadelphia (K.E.K.).

Background: Prostate cancer is a heterogeneous disease, but current treatments are not based on molecular stratification. We hypothesized that metastatic, castration-resistant prostate cancers with DNA-repair defects would respond to poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibition with olaparib.

Methods: We conducted a phase 2 trial in which patients with metastatic, castration-resistant prostate cancer were treated with olaparib tablets at a dose of 400 mg twice a day. The primary end point was the response rate, defined either as an objective response according to Response Evaluation Criteria in Solid Tumors, version 1.1, or as a reduction of at least 50% in the prostate-specific antigen level or a confirmed reduction in the circulating tumor-cell count from 5 or more cells per 7.5 ml of blood to less than 5 cells per 7.5 ml. Targeted next-generation sequencing, exome and transcriptome analysis, and digital polymerase-chain-reaction testing were performed on samples from mandated tumor biopsies.

Results: Overall, 50 patients were enrolled; all had received prior treatment with docetaxel, 49 (98%) had received abiraterone or enzalutamide, and 29 (58%) had received cabazitaxel. Sixteen of 49 patients who could be evaluated had a response (33%; 95% confidence interval, 20 to 48), with 12 patients receiving the study treatment for more than 6 months. Next-generation sequencing identified homozygous deletions, deleterious mutations, or both in DNA-repair genes--including BRCA1/2, ATM, Fanconi's anemia genes, and CHEK2--in 16 of 49 patients who could be evaluated (33%). Of these 16 patients, 14 (88%) had a response to olaparib, including all 7 patients with BRCA2 loss (4 with biallelic somatic loss, and 3 with germline mutations) and 4 of 5 with ATM aberrations. The specificity of the biomarker suite was 94%. Anemia (in 10 of the 50 patients [20%]) and fatigue (in 6 [12%]) were the most common grade 3 or 4 adverse events, findings that are consistent with previous studies of olaparib.

Conclusions: Treatment with the PARP inhibitor olaparib in patients whose prostate cancers were no longer responding to standard treatments and who had defects in DNA-repair genes led to a high response rate. (Funded by Cancer Research UK and others; ClinicalTrials.gov number, NCT01682772; Cancer Research UK number, CRUK/11/029.).
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http://dx.doi.org/10.1056/NEJMoa1506859DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5228595PMC
October 2015