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Nearly all breast cancer deaths result from metastatic disease. Despite this, the genomic events that drive metastatic recurrence are poorly understood. We performed whole-exome and shallow whole-genome sequencing to identify genes and pathways preferentially mutated or copy-number altered in metastases compared with the paired primary tumors from which they arose. Seven genes were preferentially mutated in metastases — MYLK, PEAK1, SLC2A4RG, EVC2, XIRP2, PALB2, and ESR1 — 5 of which are not significantly mutated in any type of human primary cancer. Four regions were preferentially copy-number altered: loss of STK11 and CDKN2A/B, as well as gain of PTK6 and the membrane-bound progesterone receptor, PAQR8. PAQR8 gain was mutually exclusive with mutations in the nuclear estrogen and progesterone receptors, suggesting a role in treatment resistance. Several pathways were preferentially mutated or altered in metastases, including mTOR, CDK/RB, cAMP/PKA, WNT, HKMT, and focal adhesion. Immunohistochemical analyses revealed that metastases preferentially inactivate pRB, upregulate the mTORC1 and WNT signaling pathways, and exhibit nuclear localization of activated PKA. Our findings identify multiple therapeutic targets in metastatic recurrence that are not significantly mutated in primary cancers, implicate membrane progesterone signaling and nuclear PKA in metastatic recurrence, and provide genomic bases for the efficacy of mTORC1, CDK4/6, and PARP inhibitors in metastatic breast cancer.

To determine the feasibility of liquid biopsy for monitoring of patients with advanced melanoma, cell-free DNA was extracted from plasma for 25 Stage III/IV patients, most (84.0%) having received previous therapy. DNA concentrations ranged from 0.6 to 390.0 ng/ml (median = 7.8 ng/ml) and were positively correlated with tumor burden as measured by imaging (Spearman rho = 0.5435, p = .0363). Using ultra-deep sequencing for a 61-gene panel, one or more mutations were detected in 12 of 25 samples (48.0%), and this proportion did not vary significantly for patients on or off therapy at the time of blood draw (52.9% and 37.5% respectively; p = .673). Sixteen mutations were detected in eight different genes, with the most frequent mutations detected in BRAF, NRAS, and KIT. Allele fractions ranged from 1.1% to 63.2% (median = 29.1%). Among patients with tissue next-generation sequencing, nine of 11 plasma mutations were also detected in matched tissue, for a concordance of 81.8%.

Key Points Acquired aplastic anemia is a T-cell–mediated autoimmune bone marrow aplasia, without a known etiologic trigger. Clonal expansion of CD8+ effector T lymphocytes can occur following vaccination and accompany graft dysfunction or aplastic anemia relapse.

Context.— Next-generation sequencing is a high-throughput method for detecting genetic abnormalities and providing prognostic and therapeutic information for patients with cancer. Oncogenic fusion transcripts are among the various classifications of genetic abnormalities present in tumors and are typically detected clinically with fluorescence in situ hybridization (FISH). However, FISH probes only exist for a limited number of targets, do not provide any information about fusion partners, cannot be multiplex, and have been shown to be limited in specificity for common targets such as ALK. Objective.— To validate an anchored multiplex polymerase chain reaction–based panel for the detection of fusion transcripts in a university hospital–based clinical molecular diagnostics laboratory. Design.— We used 109 unique clinical specimens to validate a custom panel targeting 104 exon boundaries from 17 genes involved in fusions in solid tumors. The panel can accept as little as 100 ng of total nucleic acid from PreservCyt-fixed tissue, and formalin-fixed, paraffin-embedded specimens with as little as 10% tumor nuclei. Results.— Using FISH as the gold standard, this assay has a sensitivity of 88.46% and a specificity of 95.83% for the detection of fusion transcripts involving ALK, RET, and ROS1 in lung adenocarcinomas. Using a validated next-generation sequencing assay as the orthogonal gold standard for the detection of EGFR variant III (EGFRvIII) in glioblastomas, the assay is 92.31% sensitive and 100% specific. Conclusions.— This multiplexed assay is tumor and fusion partner agnostic and will provide clinical utility in therapy selection for patients with solid tumors.

Molecular profiling of glioblastoma has revealed complex cytogenetic, epigenetic, and molecular abnormalities that are necessary for diagnosis, prognosis, and treatment. Our neuro-oncology group has developed a data-driven, institutional consensus guideline for efficient and optimal workup of glioblastomas based on our routine performance of molecular testing. We describe our institution’s testing algorithm, assay development, and genetic findings in glioblastoma, to illustrate current practices and challenges in neuropathology related to molecular and genetic testing. We have found that coordination of test requisition, tissue handling, and incorporation of results into the final pathologic diagnosis by the neuropathologist improve patient care. Here, we present analysis of O 6 -methylguanine-DNA-methyltransferase promoter methylation and next-generation sequencing results of 189 patients, obtained utilizing our internal processes led by the neuropathology team. Our institutional pathway for neuropathologist-driven molecular testing has streamlined the management of glioblastoma samples for efficient return of results for incorporation of genomic data into the pathological diagnosis and optimal patient care.

PURPOSE Tumor-only genomic profiling (TGP) is increasingly advocated for all patients with cancer given the possible therapeutic implications. It is critical to develop clinical algorithms to identify and address potentially actionable germline findings identified by TGP. METHODS A multidisciplinary team analyzed publicly available data for genes in which mutations are implicated in germline cancer susceptibility and established a pipeline to automate clinical referral for evaluation of TGP findings. RESULTS A total of 2,308 patients underwent TGP, with 81 patients (3.5%) identified by the automatic referral pipeline; 37 patients (1.6%) were referred outside the pipeline based on concerns by the molecular geneticist, pathologist, or oncologist regarding genotype-phenotype correlation. Thirty-one patients (38%) and 17 patients (46%) underwent germline testing from the automatic pipeline and other referrals, respectively, and of these patients, 23 (72%) and four (24%) had confirmed germline pathogenic variants (GPVs), respectively. The majority of confirmed GPVs were in automatic referral genes, with BRCA2 being most common (confirmed GPVs in 11 [85%] of 13 patients tested), followed by PALB2 (five [67%] of six patients), BRCA1 (two [40%] of five patients), MSH6 (two of three patients), and MLH1 (two of two patients). Forty-eight percent of confirmed GPVs were found in tumors known to be associated with germline mutations in the gene. Germline testing was not performed in 50 (62%) of 81 patients identified by automatic referral as a result of poor patient health or death (30%), lack of follow-up (30%), and patient refusal (30%). CONCLUSION Of patients undergoing TGP, 5% had somatic findings triggering referral, and implementation of an automatic referral pipeline based solely on gene versus other clinical or molecular features resulted in a 74% germline confirmation. However, only 41% of referred patients underwent germline testing. Systems-based approaches are needed to identify carriers of actionable germline cancer susceptibility mutations identified by TGP.

Purpose: The expanding number of targeted therapeutics for non–small cell lung cancer (NSCLC) necessitates real-time tumor genotyping, yet tissue biopsies are difficult to perform serially and often yield inadequate DNA for next-generation sequencing (NGS). We evaluated the feasibility of using cell-free circulating tumor DNA (ctDNA) NGS as a complement or alternative to tissue NGS. Experimental Design: A total of 112 plasma samples obtained from a consecutive study of 102 prospectively enrolled patients with advanced NSCLC were subjected to ultra-deep sequencing of up to 70 genes and matched with tissue samples, when possible. Results: We detected 275 alterations in 45 genes, and at least one alteration in the ctDNA for 86 of 102 patients (84%), with EGFR variants being most common. ctDNA NGS detected 50 driver and 12 resistance mutations, and mutations in 22 additional genes for which experimental therapies, including clinical trials, are available. Although ctDNA NGS was completed for 102 consecutive patients, tissue sequencing was only successful for 50 patients (49%). Actionable EGFR mutations were detected in 24 tissue and 19 ctDNA samples, yielding concordance of 79%, with a shorter time interval between tissue and blood collection associated with increased concordance (P = 0.038). ctDNA sequencing identified eight patients harboring a resistance mutation who developed progressive disease while on targeted therapy, and for whom tissue sequencing was not possible. Conclusions: Therapeutically targetable driver and resistance mutations can be detected by ctDNA NGS, even when tissue is unavailable, thus allowing more accurate diagnosis, improved patient management, and serial sampling to monitor disease progression and clonal evolution. Clin Cancer Res; 22(23); 5772–82. ©2016 AACR.

Importance The clinical implications of adding plasma-based circulating tumor DNA next-generation sequencing (NGS) to tissue NGS for targetable mutation detection in non–small cell lung cancer (NSCLC) have not been formally assessed. Objective To determine whether plasma NGS testing was associated with improved mutation detection and enhanced delivery of personalized therapy in a real-world clinical setting. Design, Setting, and Participants This prospective cohort study enrolled 323 patients with metastatic NSCLC who had plasma testing ordered as part of routine clinical management. Plasma NGS was performed using a 73-gene commercial platform. Patients were enrolled at the Hospital of the University of Pennsylvania from April 1, 2016, through January 2, 2018. The database was locked for follow-up and analyses on January 2, 2018, with a median follow-up of 7 months (range, 1-21 months). Main Outcomes and Measures The number of patients with targetable alterations detected with plasma and tissue NGS; the association between the allele fractions (AFs) of mutations detected in tissue and plasma; and the association of response rate with the plasma AF of the targeted mutations. Results Among the 323 patients with NSCLC (60.1% female; median age, 65 years [range, 33-93 years]), therapeutically targetable mutations were detected inEGFR,ALK,MET,BRCA1,ROS1, RET, ERBB2,orBRAFfor 113 (35.0%) overall. Ninety-four patients (29.1%) had plasma testing only at the discretion of the treating physician or patient preference. Among the 94 patients with plasma testing alone, 31 (33.0%) had a therapeutically targetable mutation detected, thus obviating the need for an invasive biopsy. Among the remaining 229 patients who had concurrent plasma and tissue NGS or were unable to have tissue NGS, a therapeutically targetable mutation was detected in tissue alone for 47 patients (20.5%), whereas the addition of plasma testing increased this number to 82 (35.8%). Thirty-six of 42 patients (85.7%) who received a targeted therapy based on the plasma result achieved a complete or a partial response or stable disease. The plasma-based targeted mutation AF had no correlation with depth of Response Evaluation Criteria in Solid Tumors response (r = −0.121;P = .45). Conclusions and Relevance Integration of plasma NGS testing into the routine management of stage IV NSCLC demonstrates a marked increase of the detection of therapeutically targetable mutations and improved delivery of molecularly guided therapy.

Comprehensive genomic profiling of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) cases have enabled the detection and differentiation of driver and subclonal mutations, informed risk prognostication, and defined targeted therapies. These insights into disease biology, and management have made multigene-acquired mutation testing a critical part of the diagnostic assessment of patients with sporadic MDS and AML. More recently, our understanding of the role of an increasing number of inherited genetic factors on MDS/AML risk and management has rapidly progressed. In recognition of the growing impact of this field, clinical guidelines and disease classification systems for both MDS and AML have recently incorporated familial MDS/AML predisposition syndromes into their diagnostic algorithms. In this perspective piece, we contemplate the advantages, disadvantages, and barriers that would need to be overcome to incorporate inherited MDS/AML genetic testing into the upfront molecular diagnostic work-up of every MDS/AML patient. For centers already performing panel-based tumor-only testing, including genes associated with familial forms of MDS/AML (e.g., RUNX1, CEBPA, GATA2, TP53), we advocate optimizing these tests to detect all types of germline variants in these genes and moving toward upfront paired tumor/germline testing to maximize detection and streamline patient care.

BACKGROUND Tissue specimens are typically considered optimal for molecular testing; however, in the current era of personalized medicine, cytopathology specimens are increasingly recognized as potential sources for molecular testing. This is often accomplished by using cell block specimens and/or fine-needle aspiration (FNA) smear preparations. In this study, the authors investigated the feasibility, performance, and quality of “residual” FNA rinse and body effusion fluids used for next-generation sequencing (NGS). METHODS Sequence data were generated from 17 malignancies in 16 patients from 13 FNA (10 lymph nodes, 1 lung, and 2 bone lesions) and 4 effusion (3 pleural and 1 pericardial) specimens. Malignancies included carcinomas (lung, breast, ovarian, and unknown primary), melanoma, and myeloma. Paired NGS testing was performed in 7 patients who had surgical biopsy or cell block specimens available. Routinely processed residual FNA rinse material and body fluids were used for DNA extraction and NGS (targeted gene panel). RESULTS NGS was successfully performed on all 17 specimens. A significant amount of DNA was obtained from the residual FNA rinse (176.3 ng/μL) compared with the paired cell block slides (10.6 ng/μL). Two of the 10 lung adenocarcinomas (20%) demonstrated epidermal growth factor receptor (EGFR) mutations, including 1 leucine-to-arginine substitution at codon 858 (L858R) in exon 21 and 1 codon 2235_2249 deletion (resulting in an in-frame deletion of 5 amino acids from position 746 to 750 [glutamic acid, leucine, arginine, glutamic acid, and alanine]; E746_A750del) in exon 19. Three KRAS [Kirsten rat sarcoma viral oncogene homolog] mutations, 1 BRAF (v-Raf murine sarcoma viral oncogene homolog B1) mutation, and 1 NRAS (neuroblastoma RAS viral oncogene homolog) mutation were identified in the remaining lung adenocarcinomas. Patients who underwent paired testing demonstrated 100% concordant mutations. CONCLUSIONS Targeted NGS can be performed on residual FNA rinse and body fluid specimens. This approach is particularly important when a paucicellular cell block or biopsy specimen is encountered. Cancer (Cancer Cytopathol) 2015. © 2015 American Cancer Society.

Leukemia cutis (LC), the infiltration of the epidermis, dermis, or subcutis with leukemia cells, complicates 5–10% of cases of acute myeloid leukemia (AML) in adults and is considered a marker of poor prognosis.1–3 While the association between AML with monocytic features and LC has been described, little is known about the association of other AML characteristics and LC.2,4,5 Recently, a number of recurrent gene mutations have been described in AML; however, the association of these mutations and LC has not been systematically investigated.6,7 Using amplicon-based next-generation sequencing (NGS) of a panel of recurrent, hematologic malignancy-associated mutations, we sought to determine the association between molecular markers and LC. We identified 284 patients diagnosed with AML at the University of Pennsylvania (2001–2014) who had undergone targeted NGS analysis of 33 genes associated with hematologic malignancy;8 of these, 23 are recurrently mutated in AML and were studied (listed in Table 2). These 284 cases were identified either from the Hematologic Malignancies Tissue Bank at the University of Pennsylvania (2001–2013), or from a pathology database of patients tested in a clinical context (after February 2013). Using a clinical database of acute leukemia patients (February 2011 – August 2014) who were evaluated for NPM1 mutations by a targeted method, an additional 276 patients with known NPM1 status were identified. Redundant cases were excluded. Table 2. AML-Associated Somatic Mutations and Leukemia Cutis (n=284). All cases of AML were confirmed by a hematopathologists review of the diagnostic material. The presence of monocytic features was determined by a combination of morphology and immunophenotypic analysis, as well as cytochemistry, as appropriate. For each AML patient, a dermatopathology database was reviewed to identify cases of skin biopsy-proven LC at any time during the disease course. Independent dermatopathology review was obtained for indeterminate cases of LC; cases still classified as indeterminate after re-review were excluded from the analysis. Information regarding clinical and disease characteristics was determined by review of the medical records. Targeted NGS testing of 33 genes associated with hematologic malignancies (including NPM1) was conducted by the Center for Personalized Diagnostics at the University of Pennsylvania. Average read depth was 3000X, minimal depth was 250x, and reporting frequency cutoff for variants was 5%.8 Mutations were classified into four categories: pathogenic, likely disease-associated, variant of uncertain significance (VUS), or likely benign based on review of publically available data; only pathogenic or likely disease-associated mutations were included in this analysis. Targeted NPM1 analysis was performed in the Department of Pathology at the University of Pennsylvania. The targeted NPM1 test consists of multiplex RT-PCR followed by detection on a liquid bead array. This assay allows for the simultaneous detection of the most common NPM1 mutations in exon 12 (type A, B, and D). The analytical sensitivity of the assay is approximately 0.01%. The Institutional Review Board of the University of Pennsylvania approved this research. Patient and clinical characteristics were summarized by descriptive statistics. Association between the presence of mutation and LC was assessed by the chi-square test or logistic regression, stratified by monocytic subtype when appropriate. Only genes with a mutation frequency ≥ 5% (n=24) were assessed for association with LC. All statistical tests were two-sided, with P values 90%) of NPM1 status at diagnosis and relapse.9 A further limitation of our study is the lack of response and survival data in this cohort. NPM1-mutant AML in the absence of FLT3-ITD mutation is reported to have a favorable association in both younger and older patients, while the presence of LC has been associated with unfavorable outcome.2,10–12 The implication of having both of these prognostic features is unknown and should be the subject of further investigation. The cellular mechanisms through which NPM1 mutations might alter leukemic myeloblasts homing to the skin require further study. Regardless of mechanism, our data support the World Health Organization’s provisional classification of NPM1-mutated AML as a distinct biological entity. We note that an association between NPM1 mutation and myeloid sarcoma has formerly been described, supporting the unique biology of NPM1-mutated AML.13 In summary, our data suggests that the previously described association between AML with monocytic features and LC may largely be explained by an association between NPM1 and LC.

Background Next-generation sequencing (NGS) of surgically resected solid tumor samples has become integral to personalized medicine approaches for cancer treatment and monitoring. Liquid biopsies, or the enrichment and characterization of circulating tumor cells (CTCs) from blood, can provide noninvasive detection of evolving tumor mutations to improve cancer patient care. However, the application of solid tumor NGS approaches to circulating tumor samples has been hampered by the low-input DNA available from rare CTCs. Moreover, whole genome amplification (WGA) approaches used to generate sufficient input DNA are often incompatible with blood collection tube preservatives used to facilitate clinical sample batching. Methods To address this, we have developed a novel approach combining tumor cell isolation from preserved blood with Repli-G WGA and Illumina TruSeq Amplicon Cancer Panel-based NGS. We purified cell pools ranging from 10 to 1000 cells from three different cell lines, and quantitatively demonstrate comparable quality of DNA extracted from preserved versus unpreserved samples. Results Preservation and WGA were compatible with the generation of high-quality libraries. Known point mutations and gene amplification were detected for libraries that had been prepared from amplified DNA from preserved blood. Conclusion These spiking experiments provide proof of concept of a clinically applicable workflow for real-time monitoring of patient tumor using noninvasive liquid biopsies.

Breast cancer metastases differ biologically from primary disease; therefore, metastatic biopsies may assist in treatment decision making. Commercial genomic testing of both tumor and circulating tumor DNA have become available clinically, but utility of these tests in breast cancer management remains unclear. Patients undergoing a clinically indicated metastatic tumor biopsy were consented to the ongoing METAMORPH registry. Tumor and blood were collected at the time of disease progression before subsequent therapy, and patients were followed for response on subsequent treatment. Tumor testing (n = 53) and concurrent cell-free DNA (n = 32) in a subset of patients was performed using CLIA-approved assays. The proportion of patients with a genomic alteration was lower in tumor than in blood (69 vs. 91%; p = 0.06). After restricting analysis to alterations covered on both platforms, 83% of tumor alterations were detected in blood, while 90% of blood alterations were detected in tumor. Mutational load specific for the panel genes was calculated for both tumor and blood. Time to progression on subsequent treatment was significantly shorter for patients whose tumors had high panel-specific mutational load (HR 0.31, 95% CI 0.12–0.78) or a TP53 mutation (HR 0.35, 95% CI 0.20–0.79), after adjusting for stage at presentation, hormone receptor status, prior treatment type, and number of lines of metastatic treatment. Treating oncologists must distinguish platform differences from true biological heterogeneity when comparing tumor and cfDNA genomic testing results. Tumor and concurrent cfDNA contribute unique genomic information in metastatic breast cancer patients, providing potentially useful biomarkers for aggressive metastatic disease.

Background: The majority of deaths from breast cancer are due to distant metastatic disease. Despite this, few systematic genomic analyses have been performed on metastatic tumors. This results from the relative difficulty of performing biopsies on metastatic tumors, as well as the uncertainty regarding genomic determinism, according to which the majority of actionable mutations present in metastases can be discovered in the primary tumor. Methods: “METAMORPH” is an ongoing prospective cohort study of women with suspected or confirmed recurrent breast cancer enrolled prior to starting a new therapy for recurrent metastatic disease. Biopsies of metastatic lesions were performed under radiologic guidance, and archival primary tumors were subsequently obtained. WES and sWGS were performed to determine coding mutations and aberrant copy-number in metastatic tumors from 67 patients, 33 of which were assayed with corresponding matched primary tumors. Results: Using Bayesian approaches, we find that cancers fit one of two patterns: canonical linear evolution (whereby the metastatic tumor arises from one or more advanced primary tumor subclones) vs. branched evolution (whereby both primary and metastatic tumors develop mutations that go on to become clonal within their respective tumors after the time of dissemination). In cases where tumors show evidence of branched evolution or small subclone dissemination, we expect that a large proportion of mutations may not be represented in both the primary and corresponding metastatic tumors. Indeed, primary-metastatic tumor pairs show substantial discordance at the genomic level, sharing only ˜30% of mutations and ˜28% of copy-number alterations on average. Furthermore, we find that metastatic tumors have decreased clonal heterogeneity, suggesting a history of selection. Indeed, we find clinically relevant mutations that are present exclusively in the primary or the corresponding recurrent metastatic tumor, as well as genes that are recurrently altered in metastatic tumors, such as amplification of SRC-1, loss of genes encoding CDK inhibitors, and alterations in JAK1/2/3.Finally, compared to the primary tumors from which they arose, metastatic tumors exhibit increased frequencies of alterations in several discrete pathways, including those involving the extracellular matrix as well as PI3K/AKT/mTOR, estrogen, and HER2 signaling. Conclusions: The low degree of genomic concordance between primary and metastatic tumors due to evolutionary distance, as well as the presence of activating and targetable mutations specifically in metastatic tumors, suggests that there is value in comprehensively characterizing metastatic tumors to inform patient treatment and identify novel targets underlying breast cancer progression. Citation Format: Paul MR, Pan T-C, Pant D, Belka GK, Chen Y, Shih N, Lieberman D, Morrissette JJD, Soucier-Ernst D, Clark C, Stavropoulos W, Maxwell K, Feldman M, DeMichele A, Chodosh LA. Evolutionary history and genomic landscape of metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD8-04.

Background: While several comprehensive genomic sequencing tests are clinically available for breast cancer(BC), little is known about the spectrum of findings reported in the general population and clinical utility of findings for patients(pts). Here we report tumor sequencing from the METAMORPH study, a comprehensive genomic testing approach in pts with metastatic(met) BC. Methods: Pts with either known or suspected BC mets consented to and clinically underwent concurrent diagnostic and research tumor biopsies(bx). FFPE specimens were profiled via Illumina TruSeq Cancer Panel next generation sequencing platform covering 212 amplicons in 47 cancer genes. Pathology, treatment and outcome data were prospectively collected and tracked. Aside from Her2-directed treatment, therapy was not mutation (mut)-matched. Results: 64 pts enrolled between 11/2013 – 05/2015. Of these, 48 had bx successfully sequenced (75%). Of those without sequencing, 5 had negative/insufficient tissue, 2 had insufficient DNA, remainder no bx/pending. Median age of those sequenced was 56 (range 31-78); 81% Caucasian, 17% African American. 25% (12 pts) presented with de novo stage IV disease. Of those with recurrence (n=36), 83% had prior adjuvant chemotherapy; 81% hormone receptor positive(HR+) had prior endocrine therapy. Median # prior lines of therapy for met disease was 2 (IQR 0 – 8). Tumor characteristics, including mut analyses, are shown in Table 1. # muts did not differ significantly by subtype(p=0.22). Frequency of TP53 and PIK3CA hotspot muts was nearly identical to TCGA. Median # muts was 1 for pts with both de novo mets and recurrence(p=0.79). # of muts was not associated with time to recurrence(p=0.80). Excluding pts found to have TP53 mut only or ERBB2 alterations in known Her2+ disease, 42% of pts were identified as having at least one potentially actionable alteration (PIK3CA mut, AKT1 mut or EGFR amplification). Median time to treatment failure(TTF) on subsequent therapy was 4.1 months for overall group, and 4.1, 6.2, and 1.6 months for HR+/Her2-, any Her2+ and TN, respectively, adjusted for line of therapy(p=0.03). After adjustment for # lines of prior met therapy, TTF was 4.7 vs. 4.1 months for pts with any mut vs. none(p=0.89); 5.7 vs 4.1 months for PIK3CA+ vs. not (p=0.94); 3.3 vs. 6.5 months for TP53+ vs. not (p=0.03). Conclusion: Pts with met BC have frequent and potentially actionable muts.While overall # of muts did not affect response, tumors with TP53 muts had shorter response to subsequent therapy in this cohort. Additional data are needed to determine the clinical utility of mut testing in met BC, for both standard and mut-matched therapy. Total (n=48)HR+/Her2- (n=28)Any HER2+ (n=7)TN (n=13)Receptor concordant with primary 100%78%77%# Mutations Median (Range)1 (0-4)1 (0-3)1 (1-2)1 (0-4)014 (29%)10 (36 %)04 (31%)118 (38%)11 (39%)4 (57%)3 (23%)213 (27%)5 (18%)3 (43%)5 (38%)3+3 (6%)2 (7%)01 (8%)Prevalent Mutations (>20%)TP53 (38%), PIK3CA (35%)PIK3CA (50%), TP53 (25%)TP53 (60%), ERBB2amp (86%)TP53 (62%),PIK3CA (23%)Other Alterations (#)ATM (1), KIT (1), PDGFRA (1), PTEN(1), RB1 (1), SMAD4 (1), SMO (1), STK11 (1)AKT1 (1), ATM VUS (1), ERBB2 (1), PTEN (1), SMAD4 VUS (1), SMO VUS (1)ERBB2 (1), STK11(1)EGFR amp (2), KIT amp (1),PDGFRA amp (1), RB1 VUS (1) Citation Format: Soucier-Ernst D, Colameco C, Troxel AB, Clark C, Shih N, Maxwell KN, Morrissette J, Lieberman D, Feldman M, Goodman N, Bradbury A, Clark A, Domchek S, Fox K, Glick J, Matro J, Nathanson K, Chodosh L, DeMichele A. Mutational spectrum and tumor response in metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-07-05.

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA While massively parallel sequencing technology has greatly expanded the number of molecular genetic tests available in oncology, little is known about the spectrum and clinical utility of findings obtained from testing tumors and circulating tumor material in specific patient populations. Here we report findings from the METAMORPH study, in which stage IV breast cancer patients had metastatic tumor biopsies (metDNA) and concurrently collected cell-free circulating tumor DNA (cfDNA). Illumina TruSeq Cancer Panel (for metDNA) and Guardant360 (for cfDNA) were performed. 28 patients had both tests; results are shown in the Table. 68% of patients had at least one alteration in metDNA and 86% in cfDNA. PIK3CA mutations were most common, occurring in 43% and 36% of patients’ metDNA and cfDNA, respectively. Overall, 16 of 28 (57%) of patients had the same alterations identified in both metDNA and cfDNA. Excluding ERBB2 amplifications in HER2+ patients, 43% of patients’ metDNA and 57% of patients’ cfDNA contained pathogenic mutations or variants of uncertain significance (VUS) for which there are approved targeted therapies or clinical trials. Overall, 80 alterations were identified, 23 of which were detected by both assays. Multiple reasons for discordance in calls between metDNA and cfDNA assays were identified. While biological phenomena (e.g. tumor heterogeneity) may contribute to discordance, technical issues played an important role. Additional studies using whole exome sequencing and other platforms to further assess biological evolution of metastatic disease and clinical utility of molecular profiling of metastatic tumors and cell-free DNA are needed. Table 1 | | Tumor DNA (metDNA) | Cell-free DNA (cfDNA) | |:----------------------------------------------------------------------------------------- | ---------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------- | | # pts with alteration (%) | 19/28 (68%) | 24/28 (86%) | | ER+/Her2- (n = 17) | 10/17 | 15/17 | | Her2+ (n = 4) | 4/4 | 2/4 | | TNBC (n = 7) | 5/7 | 7/7 | | Total # alterations in # genes | 31 in 7 genes | 72 in 19 genes | | Genes w/alterations (total); Bold: genes for which exists a possible targeted therapeutic | PIK3CA (13), TP53 (10), ERBB2 (4), EGFR, RB1, SMAD4, STK11 | PIK3CA (14), TP53 (14), EGFR (9), ERBB2 (6), BRAF (6), MET (6), JAK2 (3), NOTCH1 (2), FBXW7 (2), ARAD, FGFR2, JAK3, KRAS, MYC, NPM1, PROC, RET, SMAD4, SMARCB1 | | Variants only covered by one assay | | 33 | | Variants detected in both but only reported by one assay | 3 (2 indels, 1 VUS) | 1 (1 synonymous) | | Variants detected by only one assay | 1 amplification at 7-fold; 4 SNVs (AF range 19-75%) | 2 amplifications at