A 17-Gene Genomic Prostate Score Assay Provides Independent Information on Adverse Pathology in the Setting of Combined Multiparametric Magnetic Resonance Imaging Fusion Targeted and Systematic Prostate Biopsy.

PURPOSE: Multiparametric magnetic resonance imaging and biopsy based molecular tests such as the 17-gene Oncotype DX® Genomic Prostate Score™ assay are increasingly performed to improve risk stratification in men with clinically localized prostate cancer. The prostate score assay was previously shown to be a significant independent predictor of adverse pathology findings at radical prostatectomy in men diagnosed by systematic biopsies only. Therefore, we investigated the ability of the prostate score assay to predict adverse pathology findings in the setting of magnetic resonance imaging guided prostate biopsy. MATERIALS AND METHODS: We identified men diagnosed with NCCN® (National Comprehensive Cancer Network®) very low, low or intermediate risk prostate cancer who underwent simultaneous multiparametric magnetic resonance imaging fusion targeted and systematic prostate biopsy with subsequent radical prostatectomy within 6 months. Prostate score assay testing was performed on biopsy tissue with the highest Gleason score. The primary outcome of the study was adverse pathology findings, defined as Gleason score 4 + 3 or greater disease and/or pT3+ at radical prostatectomy. Independent predictors of adverse pathology findings were determined in a multivariable model to adjust for clinical parameters. RESULTS: A total of 134 men were eligible for primary analysis. On univariable analysis the UCLA score, magnetic resonance imaging, prostate score assay results and biopsy Gleason score were significant predictors of adverse pathology findings. After multivariable adjustment prostate score assay values remained a significant predictor of adverse pathology results (prostate score assay per 20 U OR 3.28, 95% CI 1.74-6.62, p <0.001). A wide and overlapping distribution of prostate score assay results was seen across PI-RADS® (Prostate Imaging Reporting and Data System) version 2 scores. CONCLUSIONS: The prostate score assay result is an independent predictor of adverse pathology findings in patients who were diagnosed with very low, low or intermediate risk prostate cancer in the setting of multiparametric magnetic resonance imaging fusion prostate biopsy. This assay can be useful as an independent technology or an adjunct technology to multiparametric magnetic resonance imaging to individualize risk stratification of low and intermediate risk prostate cancer.

A Biopsy-based 17-gene Genomic Prostate Score as a Predictor of Metastases and Prostate Cancer Death in Surgically Treated Men with Clinically Localized Disease.

BACKGROUND: A 17-gene biopsy-based reverse transcription polymerase chain reaction assay, which provides a Genomic Prostate Score (GPS-scale 0-100), has been validated as an independent predictor of adverse pathology and biochemical recurrence after radical prostatectomy (RP) in men with low- and intermediate-risk prostate cancer (PCa). OBJECTIVE: To evaluate GPS as a predictor of PCa metastasis and PCa-specific death (PCD) in a large cohort of men with localized PCa and long-term follow-up. DESIGN, SETTING, AND PARTICIPANTS: A retrospective study using a stratified cohort sampling design was performed in a cohort of men treated with RP within Kaiser Permanente Northern California. RNA from archival diagnostic biopsies was assayed to generate GPS results. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We assessed the association between GPS and time to metastasis and PCD in prespecified uni- and multivariable statistical analyses, based on Cox proportional hazard models accounting for sampling weights. RESULTS AND LIMITATIONS: The final study population consisted of 279 men with low-, intermediate-, and high-risk PCa between 1995 and 2010 (median follow-up 9.8 yr), and included 64 PCD and 79 metastases. Valid GPS results were obtained for 259 (93%). In univariable analysis, GPS was strongly associated with time to PCD, hazard ratio (HR)/20 GPS units=3.23 (95% confidence interval [CI] 1.84-5.65; p<0.001), and time to metastasis, HR/20 units=2.75 (95% CI 1.63-4.63; p<0.001). The association between GPS and both end points remained significant after adjusting for National Comprehensive Cancer Network, American Urological Association, and Cancer of the Prostate Risk Assessment (CAPRA) risks (p<0.001). No patient with low- or intermediate-risk disease and a GPS of<20 developed metastases or PCD (n=31). In receiver operating characteristic analysis of PCD at 10 yr, GPS improved the c-statistic from 0.78 (CAPRA alone) to 0.84 (GPS+CAPRA; p<0.001). A limitation of the study was that patients were treated during an era when definitive treatment was standard of care with little adoption of active surveillance. CONCLUSIONS: GPS is a strong independent predictor of long-term outcomes in clinically localized PCa in men treated with RP and may improve risk stratification for men with newly diagnosed disease. PATIENT SUMMARY: Many prostate cancers are slow growing and unlikely to spread or threaten a man's life, while others are more aggressive and require treatment. Increasingly, doctors are using new molecular tests, such as the17-gene Genomic Prostate Score (GPS), which can be performed at the time of initial diagnosis to help determine how aggressive a given patient's cancer may be. In this study, performed in a large community-based healthcare network, GPS was shown to be a strong predictor as to whether a man's prostate cancer will spread and threaten his life after surgery, providing information that may help patients and their doctors decide on the best course of management of their disease.

Association between a 17-gene genomic prostate score and multi-parametric prostate MRI in men with low and intermediate risk prostate cancer (PCa).

BACKGROUND: We aimed to directly compare results from multi-parametric prostate MRI (mpMRI) and a biopsy-based 17-gene RT-PCR assay providing a Genomic Prostate Score (GPS) among individuals who were candidates for active surveillance with low and intermediate risk prostate cancer (PCa). PATIENTS AND METHODS: We evaluated the association between GPS results (scale 0-100) and endorectal mpMRI findings in men with clinically localized PCa. MR studies were reviewed to a five-tier scale of increasing suspicion of malignancy. Mean apparent diffusion coefficient (ADC) was calculated from a single dominant lesion. Mean rank of the GPS (0-100) among MRI strata was compared with the Kruskal-Wallis test and Dunn's multiple comparison test. Spearman's correlation was performed to examine the association between mean ADC and scaled GPS. RESULTS: Of 186 patients who received GPS testing, 100 were identified who received mpMRI. Mean GPS results differed between mpMRI categories (p = 0.001); however a broad range was observed in all mpMRI categories. Among men with biopsy Gleason pattern 3+3, mean GPS results were not significantly different among MRI groups (p = 0.179), but GPS differences were seen among MRI categories for patients with pattern 3+4 (p = 0.010). Mean ADC was weakly associated with GPS (σ = -0.151). Stromal response (p = 0.015) and cellular organization (p = 0.045) gene group scores differed significantly by MRI findings, but no differences were seen among androgen signaling or proliferation genes. CONCLUSIONS: Although a statistically significant association was observed between GPS results and MRI scores, a wide range of GPS values were observed across imaging categories suggesting that mpMRI and genomic profiling may offer non- overlapping clinical insights.

Patient-specific Meta-analysis of 2 Clinical Validation Studies to Predict Pathologic Outcomes in Prostate Cancer Using the 17-Gene Genomic Prostate Score.

OBJECTIVE: To perform patient-specific meta-analysis (MA) of two independent clinical validation studies of a 17-gene biopsy-based genomic assay as a predictor of favorable pathology at radical prostatectomy. MATERIALS AND METHODS: Patient-specific MA was performed on data from 2 studies (732 patients) using the Genomic Prostate Score (GPS; scale 0-100) together with Cancer of the Prostate Risk Assessment (CAPRA) score or National Comprehensive Cancer Network (NCCN) risk group as predictors of the likelihood of favorable pathology (LFP). Risk profile curves associating GPS with LFP by CAPRA score and NCCN risk group were generated. Decision curves and receiver operating characteristic curves were calculated using patient-specific MA risk estimates. RESULTS: Patient-specific MA-generated risk profiles ensure more precise estimates of LFP with narrower confidence intervals than either study alone. GPS added significant predictive value to each clinical classifier. A model utilizing GPS and CAPRA provided the most risk discrimination. In decision-curve analysis, greater net benefit was shown when combining GPS with each clinical classifier compared with the classifier alone. The area under the receiver operating characteristic curve improved from 0.68 to 0.73 by adding GPS to CAPRA, and 0.64 to 0.70 by adding GPS to NCCN risk group. The proportion of patients with LFP >80% increased from 11% using NCCN risk group alone to 23% using GPS with NCCN. Using GPS with CAPRA identified the highest proportion-31%-of patients with LFP >80%. CONCLUSION: Patient-specific MA provides more precise risk estimates that reflect the complete body of evidence. GPS adds predictive value to 3 widely used clinical classifiers, and identifies a larger proportion of low-risk patients than identified by clinical risk group alone.

A Biopsy-based 17-gene Genomic Prostate Score Predicts Recurrence After Radical Prostatectomy and Adverse Surgical Pathology in a Racially Diverse Population of Men with Clinically Low- and Intermediate-risk Prostate Cancer.

BACKGROUND: Biomarkers that are validated in independent cohorts are needed to improve risk assessment for prostate cancer (PCa). OBJECTIVE: A racially diverse cohort of men (20% African American [AA]) was used to evaluate the association of the clinically validated 17-gene Genomic Prostate Score (GPS) with recurrence after radical prostatectomy and adverse pathology (AP) at surgery. DESIGN, SETTING, AND PARTICIPANTS: Biopsies from 431 men treated for National Comprehensive Cancer Network (NCCN) very low-, low-, or intermediate-risk PCa between 1990 and 2011 at two US military medical centers were tested to validate the association between GPS and biochemical recurrence (BCR) and to confirm the association with AP. Metastatic recurrence (MR) was also evaluated. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Cox proportional hazards models were used for BCR and MR, and logistic regression was used for AP. Central pathology review was performed by one uropathologist. AP was defined as primary Gleason pattern 4 or any pattern 5 and/or pT3 disease. RESULTS AND LIMITATIONS: GPS results (scale: 0-100) were obtained in 402 cases (93%); 62 men (15%) experienced BCR, 5 developed metastases, and 163 had AP. Median follow-up was 5.2 yr. GPS predicted time to BCR in univariable analysis (hazard ratio per 20 GPS units [HR/20 units]: 2.9; p<0.001) and after adjusting for NCCN risk group (HR/20 units: 2.7; p<0.001). GPS also predicted time to metastases (HR/20 units: 3.8; p=0.032), although the event rate was low (n=5). GPS was strongly associated with AP (odds ratio per 20 GPS units: 3.3; p<0.001), adjusted for NCCN risk group. In AA and Caucasian men, the median GPS was 30.3 for both, the distributions of GPS results were similar, and GPS was similarly predictive of outcome. CONCLUSIONS: The association of GPS with near- and long-term clinical end points establishes the assay as a strong independent measure of PCa aggressiveness. Tumor aggressiveness, as measured by GPS, and outcomes were similar in AA and Caucasian men in this equal-access health care system. PATIENT SUMMARY: Predicting outcomes in men with newly diagnosed prostate cancer is challenging. This study demonstrates that a new molecular test, the Genomic Prostate Score, which can be performed on a patient's original prostate needle biopsy, can predict the aggressiveness of the cancer and help men make decisions regarding the need for immediate treatment of their cancer.

The Impact of a Biopsy Based 17-Gene Genomic Prostate Score on Treatment Recommendations in Men with Newly Diagnosed Clinically Prostate Cancer Who are Candidates for Active Surveillance.

INTRODUCTION: The biopsy based 17-gene GPS was clinically validated to predict the likelihood of adverse surgical pathology in men with NCCN® very low, low or low-intermediate risk prostate cancer. We performed a prospective study to assess the impact of incorporating GPS into treatment recommendations in 3 high volume urology practices. METHODS: Men with newly diagnosed prostate cancer meeting specific NCCN criteria were prospectively enrolled in the trial. Biopsy tissue was analyzed. Urologists indicated treatment recommendations on questionnaires administered before and after GPS. The primary study objectives were to assess all changes in treatment modality and/or treatment intensity after GPS. RESULTS: A total of 158 men were included in analysis, including 35, 71 and 52 at NCCN very low, low and low-intermediate risk. Biological risk predicted by GPS differed from NCCN clinical risk alone in 61 men (39%). Overall 18% of recommendations between active surveillance and immediate treatment changed after GPS. The relative increase in recommendations for active surveillance was 24% (absolute change 41% to 51%). In 41 of 158 men (26%) modality and/or intensity recommendations changed after GPS, including 25, 14 and 2 in whom recommendation intensity decreased, increased and were equivocal, respectively. All changes were directionally consistent with GPS. The NCCN low risk group showed the greatest absolute recommendation change after GPS (37%). In 17 of 57 men (30%) the initial recommendation of radical prostatectomy was changed to active surveillance after GPS. Urologists indicated greater confidence and found that incorporating GPS was useful in 85% and 79% of cases, respectively, including when biological risk confirmed the clinical risk category. CONCLUSIONS: This study demonstrates that the 17-gene GPS influenced treatment recommendations among urologists and provided increased confidence in these recommendations in patients at NCCN very low to low-intermediate risk.

A guide for clinicians in the evaluation of emerging molecular diagnostics for newly diagnosed prostate cancer.

Prostate-specific antigen (PSA) screening is associated with a decline in prostate cancer-related mortality. However, screening has also led to overdiagnosis and overtreatment of clinically insignificant tumors. Recently, certain national guidelines (eg, US Preventive Services Task Force) have recommended against PSA screening, which may lead to a reverse-stage migration. Although many prostate tumors are indolent at presentation, others are aggressive and are appropriate targets for treatment interventions. Utilization of molecular markers may improve our ability to measure tumor biology and allow better discrimination of indolent and aggressive tumors at diagnosis. Many emerging commercial molecular diagnostic assays have been designed to provide more accurate risk stratification for newly diagnosed prostate cancer. Unfamiliarity with molecular diagnostics may make it challenging for some clinicians to navigate and interpret the medical literature to ascertain whether particular assays are appropriately developed and validated for clinical use. Herein, the authors provide a framework for practitioners to use when assessing new tissue-based molecular assays. This review outlines aspects of assay development, clinical and analytic validation and clinical utility studies, and regulatory issues, which collectively determine whether tests (1) are actionable for specific clinical indications, (2) measurably influence treatment decisions, and (3) are sufficiently validated to warrant incorporation into clinical practice.

Clinical validation of a PCR assay for the detection of EGFR mutations in non-small-cell lung cancer: retrospective testing of specimens from the EURTAC trial.

The EURTAC trial demonstrated that the tyrosine kinase inhibitor (TKI) erlotinib was superior to chemotherapy as first-line therapy for advanced non-small cell lung cancers (NSCLC) that harbor EGFR activating mutations in a predominantly Caucasian population. Based on EURTAC and several Asian trials, anti-EGFR TKIs are standard of care for EGFR mutation-positive NSCLC. We sought to validate a rapid multiplex EGFR mutation assay as a companion diagnostic assay to select patients for this therapy. Samples from the EURTAC trial were prospectively screened for EGFR mutations using a combination of laboratory-developed tests (LDTs), and tested retrospectively with the cobas EGFR mutation test (EGFR PCR test). The EGFR PCR test results were compared to the original LDT results and to Sanger sequencing, using a subset of specimens from patients screened for the trial. Residual tissue was available from 487 (47%) of the 1044 patients screened for the trial. The EGFR PCR test showed high concordance with LDT results with a 96.3% overall agreement. The clinical outcome of patients who were EGFR-mutation detected by the EGFR PCR test was very similar to the entire EURTAC cohort. The concordance between the EGFR PCR test and Sanger sequencing was 90.6%. In 78.9% of the discordant samples, the EGFR PCR test result was confirmed by a sensitive deep sequencing assay. This retrospective study demonstrates the clinical utility of the EGFR PCR test in the accurate selection of patients for anti-EGFR TKI therapy. The EGFR PCR test demonstrated improved performance relative to Sanger sequencing.

Analytic performance studies and clinical reproducibility of a real-time PCR assay for the detection of epidermal growth factor receptor gene mutations in formalin-fixed paraffin-embedded tissue specimens of non-small cell lung cancer.

BACKGROUND: Epidermal growth factor receptor (EGFR) gene mutations identify patients with non-small cell lung cancer (NSCLC) who have a high likelihood of benefiting from treatment with anti-EGFR tyrosine kinase inhibitors. Sanger sequencing is widely used for mutation detection but can be technically challenging, resulting in longer turn-around-time, with limited sensitivity for low levels of mutations. This manuscript details the technical performance verification studies and external clinical reproducibility studies of the cobas EGFR Mutation Test, a rapid multiplex real-time PCR assay designed to detect 41 mutations in exons 18, 19, 20 and 21. METHODS: The assay's limit of detection was determined using 25 formalin-fixed paraffin-embedded tissue (FFPET)-derived and plasmid DNA blends. Assay performance for a panel of 201 specimens was compared against Sanger sequencing with resolution of discordant specimens by quantitative massively parallel pyrosequencing (MPP). Internal and external reproducibility was assessed using specimens tested in duplicate by different operators, using different reagent lots, instruments and at different sites. The effects on the performance of the cobas EGFR test of endogenous substances and nine therapeutic drugs were evaluated in ten FFPET specimens. Other tests included an evaluation of the effects of necrosis, micro-organisms and homologous DNA sequences on assay performance, and the inclusivity of the assay for less frequent mutations. RESULTS: A >95% hit rate was obtained in blends with >5% mutant alleles, as determined by MPP analysis, at a total DNA input of 150 ng. The overall percent agreement between Sanger sequencing and the cobas test was 96.7% (negative percent agreement 97.5%; positive percent agreement 95.8%). Assay repeatability was 98% when tested with two operators, instruments, and reagent lots. In the external reproducibility study, the agreement was > 99% across all sites, all operators and all reagent lots for 11/12 tumors tested. Test performance was not compromised by endogenous substances, therapeutic drugs, necrosis up to 85%, and common micro-organisms. All of the assessed less common mutations except one (exon 19 deletion mutation 2236_2248 > AGAC) were detected at a similar DNA input level as that for the corresponding predominant mutation. CONCLUSION: The cobas EGFR Mutation Test is a sensitive, accurate, rapid, and reproducible assay.

Comparison of molecular testing methods for the detection of EGFR mutations in formalin-fixed paraffin-embedded tissue specimens of non-small cell lung cancer.

AIM: To conduct a methods correlation study of three different assays for the detection of mutations at EGFR gene in human formalin-fixed paraffin-embedded tumour (FFPET) specimens of non-small cell lung carcinomas (NSCLC). METHODS: We conducted a 2-site method comparison study of two european conformity (CE) in vitro diagnostic (IVD)-marked assays, the cobas EGFR Mutation Test and the Therascreen EGFR29 Mutation Kit, and 2× bidirectional Sanger sequencing. We blind-tested 124 NSCLC FFPET specimens with all three methods; the cobas test was performed at both sites. Positive (PPA) and negative percent agreements (NPA) were determined for the cobas test versus each of the other two methods. Specimens yielding discordant test results between methods were further tested using quantitative massively parallel pyrosequencing (MPP). RESULTS: PPA between cobas and Sanger was 98.8%; NPA was 79.3%. Overall there were seven discordant results. MPP confirmed an exon 19 deletion in two cases and L858R mutation in four cases. PPA between cobas and Therascreen was 98.9% and NPA was 100%. There was one discordant result. Reproducibility of the cobas test between the two sites was 99.2%. CONCLUSIONS: The invalid rates for the cobas test and Therascreen were lower than Sanger sequencing. The cobas and Therascreen assays showed a high degree of concordance, and both were more sensitive for the detection of exon 19 deletion and L858R mutations than Sanger. The cobas test was highly reproducible between the two testing sites, used the least amount of DNA input and was the only test with automated results reporting.

Comparison of testing methods for the detection of BRAF V600E mutations in malignant melanoma: pre-approval validation study of the companion diagnostic test for vemurafenib.

BACKGROUND: The cobas 4800 BRAF V600 Mutation Test is a CE-marked and FDA-approved in vitro diagnostic assay used to select patients with metastatic melanoma for treatment with the selective BRAF inhibitor vemurafenib. We describe the pre-approval validation of this test in two external laboratories. METHODS: Melanoma specimens were tested for BRAF V600 mutations at two laboratories with the: cobas BRAF Mutation Test; ABI BRAF test; and bidirectional direct sequencing. Positive (PPA) and negative (NPA) percent agreements were determined between the cobas test and the other assays. Specimens with discordant results were tested with massively parallel pyrosequencing (454). DNA blends with 5% mutant alleles were tested to assess detection rates. RESULTS: Invalid results were observed in 8/116 specimens (6·9%) with Sanger, 10/116 (8·6%) with ABI BRAF, and 0/232 (0%) with the cobas BRAF test. PPA was 97·7% for V600E mutation for the cobas BRAF test and Sanger, and NPA was 95·3%. For the cobas BRAF test and ABI BRAF, PPA was 71·9% and NPA 83·7%. For 16 cobas BRAF test-negative/ABI BRAF-positive specimens, 454 sequencing detected no codon 600 mutations in 12 and variant codon 600 mutations in four. For eight cobas BRAF test-positive/ABI BRAF-negative specimens, four were V600E and four V600K by 454 sequencing. Detection rates for 5% mutation blends were 100% for the cobas BRAF test, 33% for Sanger, and 21% for the ABI BRAF. Reproducibility of the cobas BRAF test was 111/116 (96%) between the two sites. CONCLUSIONS: It is feasible to evaluate potential companion diagnostic tests in external laboratories simultaneously to the pivotal clinical trial validation. The health authority approved assay had substantially better performance characteristics than the two other methods. The overall success of the cobas BRAF test is a proof of concept for future biomarker development.

Multisite analytic performance studies of a real-time polymerase chain reaction assay for the detection of BRAF V600E mutations in formalin-fixed, paraffin-embedded tissue specimens of malignant melanoma.

CONTEXT: A polymerase chain reaction-based companion diagnostic (cobas 4800 BRAF V600 Mutation Test) was recently approved by the US Food and Drug Administration to select patients with BRAF-mutant metastatic melanoma for treatment with the BRAF inhibitor vemurafenib. OBJECTIVES: (1) To compare the analytic performance of the cobas test to Sanger sequencing by using screening specimens from phase II and phase III trials of vemurafenib, and (2) to assess the reproducibility of the cobas test at different testing sites. DESIGN: Specimens from 477 patients were used to determine positive and negative percent agreements between the cobas test and Sanger sequencing for detecting V600E (1799T>A) mutations. Specimens were evaluated with a massively parallel pyrosequencing method (454) to resolve discordances between polymerase chain reaction and Sanger results. Reproducibility of the cobas test was assessed at 3 sites by using 3 reagent lots and an 8-member panel of melanoma samples. RESULTS: A valid cobas result was obtained for all eligible patients. Sanger sequencing had a failure rate of 9.2% (44 of 477). For the remaining 433 specimens, positive percent agreement was 96.4% (215 of 223) and negative percent agreement, 80% (168 of 210). Among 42 cobas mutation-positive/Sanger V600E-negative specimens, 17 were V600E positive and 24 were V600K positive by 454. The cobas test detected 70% of V600K mutations. In the reproducibility study, a correct interpretation was made for 100% of wild-type specimens and specimens with greater than 5% mutant alleles; V600E mutations were detected in 90% of specimens with less than 5% mutant alleles. CONCLUSIONS: The cobas test (1) had a lower assay failure rate than that of Sanger, (2) was more sensitive in detecting V600E mutations, (3) detected most V600K mutations, and (4) was highly reproducible.

Analytical performance of a real-time PCR-based assay for V600 mutations in the BRAF gene, used as the companion diagnostic test for the novel BRAF inhibitor vemurafenib in metastatic melanoma.

Melanomas frequently harbor BRAFV600 mutations. Vemurafenib (RG7204/PLX4032), a small-molecule inhibitor of mutant BRAF, has shown striking clinical efficacy in BRAFV600 mutant melanoma, creating the need for a well-validated companion diagnostic to select patients for treatment. We describe analytic performance characteristics of the cobas 4800 BRAF V600 Mutation Test, the test used to select patients for the pivotal vemurafenib trials. This real-time polymerase chain reaction assay was designed to detect the V600E (1799T>A) mutation DNA from formalin-fixed paraffin-embedded tissue samples. Sensitivity was assessed using blends of cell lines or tumor DNA, and tumor specimens with low levels of mutant alleles, as determined by 454 sequencing (a quantitative next-generation pyrosequencing method). A >96% hit rate was obtained across all specimen types with 5% mutant alleles at a DNA input of 125 ng, an amount readily obtained from one 5-µm section. The cobas test showed a higher sensitivity and specificity than direct bidirectional sequencing in a panel of 219 melanoma specimens. Cross reactivity with V600K and V600D was observed. Repeated testing of 5 specimens by 2 operators, using different instruments and reagent lots, yielded correct calls in 158/160 tests (98.8%). A set of 26 highly pigmented samples were identified that gave invalid test results. A simple 1:2 dilution resulted in a valid test result of 76% in such cases. The cobas test is a reproducible assay that detects some non-V600E mutations and is more accurate than direct sequencing in detecting BRAFV600E.

Survival in BRAF V600-mutant advanced melanoma treated with vemurafenib.

BACKGROUND: Approximately 50% of melanomas harbor activating (V600) mutations in the serine-threonine protein kinase B-RAF (BRAF). The oral BRAF inhibitor vemurafenib (PLX4032) frequently produced tumor regressions in patients with BRAF V600-mutant metastatic melanoma in a phase 1 trial and improved overall survival in a phase 3 trial. METHODS: We designed a multicenter phase 2 trial of vemurafenib in patients with previously treated BRAF V600-mutant metastatic melanoma to investigate the efficacy of vemurafenib with respect to overall response rate (percentage of treated patients with a tumor response), duration of response, and overall survival. The primary end point was the overall response rate as ascertained by the independent review committee; overall survival was a secondary end point. RESULTS: A total of 132 patients had a median follow-up of 12.9 months (range, 0.6 to 20.1). The confirmed overall response rate was 53% (95% confidence interval [CI], 44 to 62; 6% with a complete response and 47% with a partial response), the median duration of response was 6.7 months (95% CI, 5.6 to 8.6), and the median progression-free survival was 6.8 months (95% CI, 5.6 to 8.1). Primary progression was observed in only 14% of patients. Some patients had a response after receiving vemurafenib for more than 6 months. The median overall survival was 15.9 months (95% CI, 11.6 to 18.3). The most common adverse events were grade 1 or 2 arthralgia, rash, photosensitivity, fatigue, and alopecia. Cutaneous squamous-cell carcinomas (the majority, keratoacanthoma type) were diagnosed in 26% of patients. CONCLUSIONS: Vemurafenib induces clinical responses in more than half of patients with previously treated BRAF V600-mutant metastatic melanoma. In this study with a long follow-up, the median overall survival was approximately 16 months. (Funded by Hoffmann-La Roche; ClinicalTrials.gov number, NCT00949702.).

Analytical performance of a PCR assay for the detection of KRAS mutations (codons 12/13 and 61) in formalin-fixed paraffin-embedded tissue samples of colorectal carcinoma.

KRAS mutation testing is mandatory before prescribing anti-epidermal growth factor monoclonal antibodies in the treatment of advanced colorectal cancer. We describe the performance of a TaqMelt polymerase chain reaction (PCR) assay-the cobas® KRAS Mutation Test-designed to detect 19 mutations in codons 12, 13, and 61. The limit of detection was determined using DNA blends from cell lines, plasmids, and formalin-fixed paraffin-embedded tissue specimens. Assay performance was compared to Sanger sequencing using a panel of 188 specimens. Discordant specimens were subjected to next generation pyrosequencing (454). Assay repeatability was assessed using a panel of six specimens. A >95% correct mutation call rate was obtained in all specimen types with ~5% mutant alleles at DNA inputs of 0.8-6.3 ng per PCR reaction; 100% detection rate was observed at the recommended DNA input of 50 ng. The positive percent agreement with Sanger was 97.5% (79/81) for codons 12/13 and 85.7% (6/7) for codon 61. Negative percent agreement was 94.4% (101/107) for codon 12/13 and 99.4% (180/181) for codon 61. Nine of 10 discordant specimens yielded 454 results consistent with the cobas® results. With repeated testing, the assay showed a correct call rate of 100% (192/192) for all operators, instruments, reagent lots, and days tested. The cobas® test detects KRAS mutations in codons 12, 13, and 61 at a limit of detection of <5%. The PCR assay was more sensitive and specific than Sanger sequencing, and performance was highly reproducible. Test performance was not influenced by various endogenous interfering substances or common gut microbes.

Pharmacogenetic testing affects choice of therapy among women considering tamoxifen treatment.

BACKGROUND: Pharmacogenetic testing holds major promise in allowing physicians to tailor therapy to patients based on genotype. However, there is little data on the impact of pharmacogenetic test results on patient and clinician choice of therapy. CYP2D6 testing among tamoxifen users offers a potential test case of the use of pharmacogenetic testing in the clinic. We evaluated the effect of CYP2D6 testing in clinical practice to determine whether genotype results affected choice of hormone therapy in a prospective cohort study. METHODS: Women planning to take or currently taking tamoxifen were considered eligible. Participants were enrolled in an informational session that reviewed the results of studies of CYP2D6 genotype on breast cancer recurrence. CYP2D6 genotyping was offered to participants using the AmpliChip CYP450 Test. Women were classified as either poor, intermediate, extensive or ultra-rapid metabolizers. Results were provided to clinicians without specific treatment recommendations. Follow-up was performed with a structured phone interview 3 to 6 months after testing to evaluate changes in medication. RESULTS: A total of 245 women were tested and 235 completed the follow-up survey. Six of 13 (46%) women classified as poor metabolizers reported changing treatment compared with 11 of 218 (5%) classified as intermediate, extensive or ultra-rapid metabolizers (P < 0.001). There was no difference in treatment choices between women classified as intermediate and extensive metabolizers. In multi-variate models that adjusted for age, race/ethnicity, educational status, method of referral into the study, prior knowledge of CYP2D6 testing, the patients' CYP2D6 genotype was the only significant factor that predicted a change in therapy (odds ratio 22.8; 95% confidence interval 5.2 to 98.8). Genetic testing did not affect use of co-medications that interact with CYP2D6. CONCLUSIONS: CYP2D6 genotype testing led to changes in therapy among poor metabolizers, even in the absence of definitive data that an alternative medicine improved outcomes. Pharmacogenetic testing can affect choice of therapy, even in the absence of definitive data on clinical impact.

Hoxa9/hoxb3/hoxb4 compound null mice display severe hematopoietic defects.

OBJECTIVE: Members of the hox family of homeodomain-containing transcription factors, including hoxa9, hoxb3, and hoxb4 play an important role in the regulation of differentiation, proliferation and self-renewal of hematopoietic stem and progenitor cells. Lack-of-function studies using hoxa9, hoxb4, or hoxb3/hoxb4 null mice demonstrate that all these mutations compromise the repopulating ability of hematopoietic stem cells (HSC), implying similar functions of each of these genes in hematopoiesis. Because cross regulation and cooperativity are known features of hox proteins, we investigated mice with a compound deficiency in hoxa9, hoxb3 and hoxb4 (hoxa9/b3/b4) for evidence of synergy between these genes in hematopoiesis. MATERIALS AND METHODS: Hoxa9/b3/b4 were generated by mating the hoxb3/hoxb4 null mice with the hoxa9 null strain and HSC function was measured by competitive repopulating assay and by immunophenotype using fluorescence-activated cell sorting. RESULTS: Our findings demonstrate that the hoxa9/b3/b4 null mice are smaller in body weight, and display a marked reduction in spleen size and cellularity compared to control mice. The numbers of colony-forming unit (CFU)-granulocyte macrophage and CFU-spleen progenitor colonies were normal but hoxa9/b3/b4 null bone marrow contained increased numbers of immunophenotypic HSC (Lin(-), c-kit(+), Sca-1(+), CD150(+)). However the reconstitution defect in hoxa9 null HSC was not enhanced further in the hoxa9/b3/b4 null HSC. CONCLUSION: These findings demonstrate overlapping functions of hoxa9, hoxb3, and hoxb4 in hematopoietic cells, and emphasize an important role for these transcription factors for regulation of HSC proliferation. However, none of these hox proteins is absolutely essential for generation or maintenance of all major blood lineages.

Concurrent acute myeloid leukemia with inv(16)(p13.1q22) and chronic lymphocytic leukemia: molecular evidence of two separate diseases.

Acute myeloid leukemia (AML) occurring concurrently with or after untreated chronic lymphocytic leukemia (CLL) is rare. We report a case of a 59-year-old man who was evaluated for anemia, thrombocytopenia, and leukocytosis with circulating blasts. On the basis of the morphology and immunophenotyping results, a preliminary diagnosis of chronic myelomonocytic leukemia with concurrent CLL was considered. Subsequently, cytogenetic analysis of the leukemic blood specimen revealed inv(16)(p13.1q22) with secondary trisomy 22 in a sideline clone. Fluorescence in situ hybridization confirmed the CBFbeta rearrangement associated with inv(16) in myeloblasts and myelomonocytic cells, but not in CLL cells. Therefore, a final diagnosis of AML with inv(16) with concurrent CLL was made. After standard chemotherapy for AML, the patient achieved complete remission for both his AML and CLL. The unique aspects of this case include concomitant AML and CLL, which do not share clonality, complex cytogenetic abnormalities with trisomy 22 as a secondary abnormality associated with inv(16), and achievement of remission for both AML and CLL by AML chemotherapy regimen. This case also represents one of the rare instances where a diagnosis of AML can be established even when the blast percentage in the marrow and blood is less than 20%.

Analysis of HSC activity and compensatory Hox gene expression profile in Hoxb cluster mutant fetal liver cells.

Overexpression of Hoxb4 in bone marrow cells promotes expansion of hematopoietic stem cell (HSC) populations in vivo and in vitro, indicating that this homeoprotein can activate the genetic program that determines self-renewal. However, this function cannot be solely attributed to Hoxb4 because Hoxb4(-/-) mice are viable and have an apparently normal HSC number. Quantitative polymerase chain reaction analysis showed that Hoxb4(-/-) c-Kit+ fetal liver cells expressed moderately higher levels of several Hoxb cluster genes than control cells, raising the possibility that normal HSC activity in Hoxb4(-/-) mice is due to a compensatory up-regulation of other Hoxb genes. In this study, we investigated the competitive repopulation potential of HSCs lacking Hoxb4 alone, or in conjunction with 8 other Hoxb genes. Our results show that Hoxb4(-/-) and Hoxb1-b9 (-/-) fetal liver cells retain full competitive repopulation potential and the ability to regenerate all myeloid and lymphoid lineages. Quantitative Hox gene expression profiling in purified c-Kit+ Hoxb1-b9(-/-) fetal liver cells revealed an interaction between the Hoxa, b, and c clusters with variation in expression levels of Hoxa4,-a11, and -c4.Together, these studies show a complex network of genetic interactions between several Hox genes in primitive hematopoietic cells and demonstrate that HSCs lacking up to 30% of the active Hox genes remain fully competent.