A phase II single-arm trial of niraparib in platinum-sensitive metastatic castration-resistant prostate cancer with DNA repair defects (PLATPARP)

TPS291

Background: Platinum-based chemotherapy, either as monotherapy or in combination with taxanes, is increasingly used for patients with metastatic castration-resistant prostate cancer (mCRPC) harboring germline and/or somatic homologous recombination repair gene mutations (HRRm). However, clinical responses with platinum-based therapy are often of limited duration and limited by cumulative toxicities. The PARP inhibitor (PARPi) olaparib is approved for the treatment of mCRPC patients with pathogenic HRRm after progression on enzalutamide or abiraterone. Importantly, sensitivity to platinum-based chemotherapy may predict improved clinical outcomes with PARPi, and ‘maintenance’ PARPi strategies are routinely used in patients with advanced ovarian and pancreatic malignancies with HRRm with initial clinical response to platinum chemotherapy. We hypothesize that maintenance niraparib, a PARPi with demonstrated activity in mCRPC with HRRm, will prolong clinical responses to platinum-based chemotherapy with acceptable toxicity in mCRPC patients harboring germline and/or somatic HRRm. Methods: We are conducting an open-label, single-arm, phase II study to evaluate the clinical benefit of maintenance niraparib in biomarker-defined, platinum-sensitive mCRPC patients. Eligible subjects harbor a pathogenic germline and/or somatic mutation in BRCA1/2, ATM, FANCA, CDK12, RAD51B, RAD54L, PALB2, CHEK2, HDAC2, or BRIP1 and have received at least 3 cycles (or minimum 9 weeks) of platinum-based chemotherapy for the treatment of mCRPC per investigator discretion. Following ³4 weeks since completion of chemotherapy, subjects without evidence of clinical or radiographic disease progression receive investigational treatment with maintenance niraparib (starting dose 200 mg daily). The primary objective is an improvement in 6 month PFS rate (PFS6) (H0: PFS6 rate 25%; H1: PFS6 rate 50%; power 0.77 with one-sided α = 0.05). Serial plasma samples are obtained for correlative analyses of markers of response and/or resistance to maintenance niraparib. Eight of a planned total of 18 subjects have enrolled (N=3 germline BRCA2; N=2 somatic BRCA2; N=1 germline PALB2; N=1 germline ATM; N=1 germline CHEK2). This study incorporates a novel, combined genetic and clinical patient-selection approach for PARPi therapy to optimize clinical outcomes. Clinical trial information: NCT04288687 .

Association between up-front surgery and risk of stroke in U.S. veterans with oropharyngeal squamous cell carcinoma

6057

Background: Cardiovascular disease and stroke are important causes of long-term morbidity and mortality in patients with oropharyngeal squamous cell carcinoma (OPSCC). Cancer treatments including radiotherapy to the neck and chemotherapy have been associated with increased risk of stroke. In the era of treatment de-intensification for OPSCC, up-front surgical treatment has been proposed as one strategy that allows for de-escalation or avoidance of (chemo)radiotherapy. We sought to quantify the cumulative incidence of stroke in patients treated for non-metastatic OPSCC, and then evaluate whether patients receiving up-front surgery for OPSCC have decreased risk of stroke compared to those undergoing non-surgical treatment. Methods: We identified a cohort of 10,436 United States veterans diagnosed with non-metastatic OPSCC from 2000-2020, of whom 2,717 received up-front surgery (with or without perioperative radiotherapy or chemoradiotherapy) and 7,719 received non-surgical therapy (definitive radiotherapy or chemoradiotherapy). We estimated the cumulative incidence of stroke in this population, accounting for death as a competing risk. To assess the association between up-front surgery and risk of stroke, we generated a propensity score for the probability of receiving surgical treatment and used inverse probability weighting to construct pseudo-populations balanced on all potential confounders. Cox regression models of the inverse probability weighted population were used to estimate the cause-specific hazard ratio of stroke associated with surgical vs non-surgical treatment. Results: The 10-year cumulative incidence of stroke was 12.5% (95% CI 11.8-13.23) and death was 57.3% (95% CI 56.2-58.4). Up-front surgical patients who underwent perioperative (chemo)radiotherapy had shorter radiation and chemotherapy courses compared to non-surgical patients, suggestive of lower treatment intensity. Propensity score generation and inverse probability weighting yielded good overlap and covariate balance between surgical and non-surgical treatment groups. The inverse probability weighted cause-specific hazard ratio of stroke associated with up-front surgical treatment was 0.77 (95% CI 0.66-0.91, p = 0.002). This association was consistent across subgroups defined by age ( > /≤65 years) and baseline cardiovascular risk factors (hypertension, hyperlipidemia, diabetes). Conclusions: In over 10,000 US veterans with OPSCC, cumulative incidence of stroke was 12.5% at 10 years. Up-front surgical treatment was associated with a 23% reduced risk of stroke compared to definitive (chemo)radiotherapy. These findings present an important additional risk-benefit consideration to factor into treatment decisions and patient counseling, and should motivate future studies to examine cardiovascular events in this high-risk population.

Frequencies of actionable alterations found by somatic tumor sequencing in veterans with metastatic prostate cancer

178

Background: Prostate cancer comprises one third of male Veteran cancers and is their second leading cause of cancer death. Metastatic prostate cancer is lethal. Next Generation Sequencing (NGS) of somatic tumors is recommended for metastatic prostate to identify actionable alterations targeted with approved therapies. Veterans with prostate cancers harboring alterations in genes involved in the DNA damage response (e.g. BRCA1/2) or high microsatellite instability (MSI-High) may be eligible for PARP inhibitors or checkpoint blockade immunotherapy, respectively. Potential candidates may be identified for ongoing clinical trials of novel precision oncology approaches. Methods: This is a retrospective analysis of clinical, genomic, demographic data from Veterans with metastatic prostate cancer who underwent somatic NGS using the Foundation Medicine NGS platform from 2019-February 2021. To be included, prostate cancer was submitted diagnosis for the NGS testing and metastatic disease determined by the VINCI natural language processing tool. Variables included demographic, clinical, and pathological characteristics (self-identified race/ethnicity, age, rurality of residence, Gleason score, specimen site, other cancer diagnosis, mutation frequency). Primary outcome was mutation rates in homologous recombination (HR) genes under current FDA approval for olaparib (ATM, BARD1, BRCA1, BRCA2, BRIP1, CDK12, CHEK1, CHEK2, FANCL, PALB2, RAD51B, RAD51C, RAD51D, RAD54L) or MSI-High. Raw variant data, submitted diagnosis, and clinical data were extracted from the NGS reports and harmonized for further variant annotation. Variant data included chromosome, position, reference and alternate allele, total depth, variant allele depth, and quality scores. Variants were annotated using ANNOVAR. Likely oncogenic and oncogenic mutations were identified using OncoKB. Results: 1,597 Veterans with metastatic prostate cancer underwent FMI NGS testing (63% White, 33% African American, 4% other). Median age was 66 years, 78.6% of cases from >60 years. Of the 1,597 who underwent blood or tumor testing, at least one likely oncogenic mutation in an HR gene under FDA approval for olaparib was found in 369 (23.1%) of Veterans (19% of tissue-based tests, 32.9% of blood-based tests). Of 651 liquid biopsy tests with at least one HR gene mutation, 125 of 214 (52%) had mutations at a variant allele frequency (VAF) <0.5% or were found in an MSI-High sample that could indicate a spurious mutation due to clonal hematopoiesis. 33 patients (2.1%) were MSI-High, (21 tissue-based and 12 blood-based). Frequencies of alterations in ATM (3.6%), CDK12 (5.6%), and BRCA2 (4%) in tissue-based tests were not significantly different from those reported in other series. Conclusions: NGS of somatic tumors from Veterans with metastatic prostate cancer identifies alterations that impact management and clinical outcomes.

Putative germline findings in tumor-only and liquid biopsy sequencing in veterans with aggressive prostate cancer

179

Background: Tumor-only and/or liquid-biopsy based Next Generation Sequencing (NGS)-based tests, which are routinely performed in metastatic prostate cancer patients, may identify putative germline mutations. The European Society of Medical Oncology (ESMO) made recommendations on findings which should be referred for germline genetic testing; however, it is unknown the burden of genetic testing referrals that may result from implementation of these recommendations. We therefore determined the frequency of putative germline findings in Veterans with metastatic prostate cancer who have undergone NGS-based sequencing of tumor and/or cell-free DNA (cfDNA) on the Foundation Medicine (FMI) platform. Methods: This is a retrospective analysis of Veterans with FMI NGS testing results reported from January 2019-February 2021 who had prostate cancer as the submitted diagnosis and metastatic diagnosis according to a VINCI natural language processing tool. Raw variant data were extracted from FMI reports and harmonized for variant annotation. Variants were annotated using ANNOVAR. Putative germline mutations were defined as 1) likely pathogenic or pathogenic (LP/P) by Clinvar annotation and VAF> 30%. Mutation rates are reported in genes recommended by ESMO to trigger referral for germline testing in all tumor types and all ages of diagnosis and proposed prostate cancer susceptibility genes ( ATM, BARD1, CHEK2). Results: 1,597 Veterans with metastatic prostate cancer underwent FMI NGS testing (63% White, 33% African American, 4% other). Median age was 66 years, with 78.6% of cases from men >60 years. Of 1,597 prostate cancer patients who underwent blood or tumor testing, n=85 (5.3%) had an LP/P mutation in an ESMO-guideline gene. When mutations in ATM, BARD1 and CHEK2 were added, n=133 (8.3%) of patients had an LP/P mutation. The most commonly identified putative germline findings were in BRCA2 (n=49 patients, 3.1%). 18 patients (1.1%) had mutations in other prostate cancer risk genes on the ESMO list ( BRCA1, MLH1, MSH2, MSH6, PMS2). 18 (1.1%) of patients had putative incidental germline findings, which included mutations in PALB2, BRIP1, RAD51C, RAD51D, SDHC. No putative incidental germline mutations were identified in RET, SDHA, SDHB, SDHD, TSC2, VHL. Comparing self-identified White versus self-identified Black patients, putative germline mutation rates were nearly the same in all ESMO-referral genes combined (8.2% vs 8.5%), BRCA2 (2.9% vs 3.0%), and ATM (2.4% vs 2.1%). Conclusions: While guidelines recommend that all veterans with metastatic prostate cancer undergo germline genetic testing, significant patient and system-level barriers continue to limit access to germline genetic testing for many Veterans. Tumor-only NGS testing, with a low rate of putative incidental findings, can help to prioritize which Veterans should be referred for germline genetic testing.

Outcomes of an advanced practice nurse (APN)-led cancer genetics service

71

Background: In oncology practice, there are increasing numbers of patients for whom genetic testing is recommended by the National Cancer Care Network (NCCN), including all metastatic and high-risk localized prostate cancer patients. However, there is a critical shortage of genetics services providers. Acuity for these consults can be high, particularly in the context of a treatment related decision. We hypothesized that nurses, particularly advanced practice nurses (APNs), can provide a workforce within VA that can address genetic testing and genetic care needs of prostate cancer patients. Methods: We initiated a cancer genetics service staffed with an advanced practice nurse (APN) geneticist and evaluated the success of the program at a large urban, academic-affiliated Veteran’s Affairs Medical Center (VAMC). Results: In the one year prior to the initiation of the APN geneticist-run program (10/1/2019-9/30/2020), 61 unaffected patients with a family history of cancer and 85 patients with cancer (36 with prostate cancer) were referred to a VA centralized telegenetics service. An average of seven cancer patients (average three with prostate cancer) were referred to VA telegenetics per month. Genetic testing was completed in eleven (18%) of unaffected patients and 21 (25%) of cancer patients. Five (13%) of tested patients were found to have a pathogenic or likely pathogenic mutation or variant of uncertain significance (VUS). In the eight months after initiation of the APN geneticist-run consult service (10/1/2020 - 5/30/2021), 39 unaffected patients with a family history of cancer and 90 patients with cancer (38 with prostate cancer) were referred. An average of 11 cancer patients (average five with prostate cancer) per month were referred. This represents a 57% increase in all cancer patient and a 67% increase in prostate cancer patient referrals. For those patients referred to the APN geneticist-run consult service, genetic testing was completed in three (7%) of unaffected patients and 30 (33%) of cancer patients (including 15 prostate cancer patients). The genetic testing rate therefore improved from 1.7 oncology patients per month to 3.9 oncology patients per month, an 130% increase in genetic testing. For prostate cancer patients, the genetic testing rate improved from 0.8 to 1.9 patients tested per month, representing a 137% increase. Comparison of genetic testing outcomes at one year will be included in the final presentation. Conclusions: Inclusion of an APN geneticist-run consult service embedded in oncology clinics will likely improve access to genetics services and genetic testing rates in cancer patients.

Burden of genetic testing in an academic biobank by pathological and family history-based criteria in prostate cancer (PCa)

1576

Background: Approximately 5% of localized PCa and 12% of metastatic PCa are associated with germline mutations in DNA repair genes. The National Comprehensive Cancer Network (NCCN) issued genetic testing guidelines to identify PCa patients (pts) likely to harbor a germline DNA repair mutation. The overall burden of this guideline-based, resource-intensive genetic testing is unknown. Using supervised phenotype-genotype information extraction algorithms, we determined the projected genetic testing burden at a single institution adhering to NCCN PCa genetic testing guidelines. Methods: A PCa cohort of 2127 pts was identified from the Penn Medicine BioBank via ICD 9/10 codes. Phenotypic data were extracted from the Penn Medicine Cancer Registry and electronic health record systems via natural language processing and manual chart review. Pts were classified based on 9 germline genetic testing criteria outlined in the NCCN PCa guidelines (Version 4.2019). Results: 895/2127 pts met at least 1 of the 9 NCCN genetic testing criteria, corresponding to a 42.1% overall genetic testing burden. 35.2% qualified for testing via high-risk localized PCa and 6.4% qualified via metastatic disease. Of the pts with localized PCa (n=2014), 15.1% qualified for genetic testing via high Gleason score, 5.1% via high-risk family history, 3.7% via PSA>20ng/mL, 8.7% via Ashkenazi Jewish descent, and 0.8% via intraductal/ductal histology. Conclusions: In this single-center PCa cohort, germline genetic testing was NCCN-guideline recommended for a larger proportion of pts than would otherwise be expected based on previously published reports. Future studies are needed to validate the sensitivity and specificity of these criteria for identifying germline mutations. Our study also highlights a need for novel methods to improve the efficiency of genetic testing for a large cohort. [Table: see text]

Randomized trial of web-based genetic education versus usual care in advanced cancer patients undergoing tumor genetic testing: Results from the ECOG-ACRIN NCI Community Oncology Research Program (NCORP; EAQ152) COMET trial

2008

Background: Enthusiasm for precision oncology may obscure the complex psychosocial and ethical considerations for tumor genetic testing. Low patient genetic knowledge has been documented and heightens the risk for adverse experiences. We developed a web-based intervention to increase genetic knowledge and decrease distress among advanced cancer patients undergoing tumor genetic testing. Methods: 594 patients (80% from NCORP Community Sites) were recruited and randomized to web-intervention (n = 293) or usual care (n = 301), prior to receipt of tumor genetic test results. Primary outcomes were genetic knowledge, anxiety, depression, and cancer-specific distress measured at T0 (prior to intervention), T1 (post-intervention), T2 (after receipt of tumor results) and T3 (3 months post receipt of tumor results). Secondary outcomes included satisfaction, regret and disappointment. The effect of web-intervention was evaluated using t-test, multiple linear regression and logistic regression, with an intent-to-treat approach. Results: Patients randomized to web-intervention had better knowledge improvement than those randomized to usual care (T1-T0, p < 0.0001; T2-T0, p = 0.003). No difference was observed in change scores for anxiety, depression or cancer-specific distress. To find the moderators of intervention effect (including sex, age, education, and literacy) two 2-way interactions were noted with statistical significance: higher depression among those in the intervention arm versus the control arm for patients with lower literacy (p = 0.03); and lower cancer-specific distress among women in the intervention arm than with usual care but no such effect noted in men (p = 0.01). 71% of patients reported receiving tumor test results and this did not differ by arm. Only 20% of patients reported regret and disappointment at T2, which was more likely for those without a mutation of interest (MOI) detected vs those with a MOI detected (OR = 2.08, 95% CI, 1.13 to 3.83, p = 0.02). Conclusions: Web-based education prior to receipt of tumor genetic test results increases patient understanding of tumor genetic testing. While the intervention did not significantly reduce distress, results suggest that women who received the intervention had lower cancer-specific distress than those with usual care. Future refinements to the web-intervention are needed to address low literacy groups, men and patients with no actionable results. Clinical trial information: NCT02823652.

Performance of polygenic risk scores for cancer prediction in an academic biobank

1528

Background: The discovery of rare genetic variants associated with cancer have a tremendous impact on reducing cancer morbidity and mortality when identified; however, rare variants are found in less than 5% of cancer patients. Genome wide association studies (GWAS) have identified hundreds of common genetic variants significantly associated with a number of cancers, but the clinical utility of individual variants or a polygenic risk score (PRS) derived from multiple variants is still unclear. Methods: We tested the ability of polygenic risk score (PRS) models developed from genome-wide significant variants to differentiate cases versus controls in the Penn Medicine Biobank. Cases for 15 different cancers and cancer-free controls were identified using electronic health record billing codes for 11,524 European American and 5,994 African American individuals from the Penn Medicine Biobank. Results: The discriminatory ability of the 15 PRS models to distinguish their respective cancer cases versus controls ranged from 0.68-0.79 in European Americans and 0.74-0.93 in African Americans. Seven of the 15 cancer PRS trended towards an association with their cancer at a p<0.05 (Table), and PRS for prostate, thyroid and melanoma were significantly associated with their cancers at a bonferroni corrected p<0.003 with OR 1.3-1.6 in European Americans. Conclusions: Our data demonstrate that common variants with significant associations from GWAS studies can distinguish cancer cases versus controls for some cancers in an unselected biobank population. Given the small effects, future studies are needed to determine how best to incorporate PRS with other risk factors in the precision prediction of cancer risk. [Table: see text]

Gliomas in the context of Li-Fraumeni syndrome: An international cohort

1517

Background: Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome associated with germline mutation in the TP53 tumor suppressor gene. As a result of increased awareness and surveillance imaging, more asymptomatic low-grade brain lesions are being identified, raising important questions regarding the management of those patients. Sporadic low-grade gliomas (LGG) in the pediatric age rarely transform to malignant lesions, whereas the prognosis of high-grade gliomas (HGG) is grim in all age groups. Although HGG is a hallmark of LFS, little is known of the natural history of these lesions in this syndrome. Methods: For this multi-institutional retrospective study, anonymized clinicopathologic data from TP53 mutation carriers with gliomas were collected and analysed. Results: Our cohort included 61 patients, of whom 71% (n = 45) were children or young adults (age < 25 years). 39% of patients with known family history of cancer had a close relative with a brain tumor. Of 31 patients with low grade lesions at presentation, 83% (n = 26) were identified through surveillance. Five-year progression free survival (PFS) for these patients was 48%, though two patients progressed later. Furthermore, at 5 years 25% of these patients had biopsy proven malignant transformation to HGG. This “transformation free survival” rate did not plateau, as at 7 years 56% of patients transformed. When considering death from a brain tumor, the 5- and 10- year overall survival (OS) for the LGG group was 100% and 83%, respectively. Additional 3 patients succumbed to other LFS related malignancies. For the HGG group, consisting of 30 patients, the 5 year OS was 35% (median follow-up 19.5 months), comparing favorably with the sporadic HGG population as reported in the literature. Almost all of these patients presented with clinical symptoms. Notably, 12 (40%) of them had a prior malignancy. Conclusions: Our analysis suggests that the risk of transformation of LGG in the setting of LFS is high and warrants ongoing surveillance. Interestingly, there are a considerable number of long- term survivors in our HGG group, although the median follow up is still short. Further study to examine potential genotype- phenotype correlations in germline TP53 mutation carriers will inform strategies to identify those patients at highest risk of glioma progression.

A randomized phase II trial of niraparib plus either nivolumab or ipilimumab in patients with advanced pancreatic cancer whose cancer has not progressed on platinum-based therapy

TPS4161

Background: The treatment paradigm for advanced pancreatic ductal adenocarcinoma (PDAC) typically involves ongoing chemotherapy until either disease progression or clinical deterioration. A subset of patients with advanced PDAC have exceptional responses to platinum-based chemotherapy. We hypothesized that durable platinum sensitivity in patients with advanced PDAC might be indicative of a DNA repair deficiency, and that these patients may respond to a combination of niraparib, a PARP inhibitor, plus immune checkpoint blockade. Methods: We have enrolled 25 of 84 planned patients on study NCT 03404960. Eligibility criteria include inoperable PDAC and stability on platinum-based chemotherapy for ≥16 weeks without evidence of progressive disease. Patients who have progressed on platinum-based treatment or who have received prior therapy with PARP inhibitors are excluded. Patients are randomized to receive oral niraparib 200mg PO daily plus nivolumab 240mg IV every two weeks in continuous 28 day cycles or oral niraparib 200mg PO daily plus ipilimumab 3mg/kg IV every three weeks for four doses in continuous 21 day cycles. The primary endpoint is progression-free survival at 6 months. Secondary endpoints include response rate, duration of response and overall survival. Paired biopsies are obtained, as well as serial blood collections for circulating tumor cells (CTCs), circulating tumor DNA (ctDNA) and peripheral blood mononuclear cells (PBMCs). Correlative assays will include germline whole exome sequencing and analyses of serially collected PBMCs, CTCs and ctDNA to identify genomic and immunologic innate and adaptive resistance mechanisms. Clinical trial information: NCT 03404960.

Abstract PD4-07: PET imaging of PARP-1 expression in breast cancer

18F-FluorThanatrace ([18F]-FTT) is a novel radiotracer shown to quantify Poly [ADP-ribose] polymerase 1 (PARP-1) expression in vitro and in vivo through a receptor-ligand interaction. A recent study at the University of Pennsylvania in women with ovarian cancer demonstrated in vivo visualization of PARP-1 expression in tumors using this radiotracer that closely correlated with an in vitro assay of PARP-1 in tumor tissue (Makvandi, M. J. Clin. Invest. 128:2116, 2018). A radioligand with PARP-1 specificity, [125I]-KX1, was also developed as a companion tool for ex vivo evaluation of PARP-1 expression and PARP inhibitor (PARPi) drug occupancy by radioligand binding assay (Makvandi, M. Cancer Res. 76:4516, 2016). As the first step in validating this biomarker in breast cancer, we performed a prospective clinical trial comparing in vivo [18F]-FTTuptake and ex vivo PARP-1 expression in women with primary breast cancer.

Methods: 24 patients with Stage I-IV primary breast cancer were imaged with [18F]-FTT prior to any therapy including surgery. We correlated in vivo uptake with ex vivo immunohistochemistry (IHC) for PARP-1 and [125I]-KX1 autoradiography in untreated surgical specimens. Tumors were analyzed for alterations in DNA repair genes, copy number-based as well as mutational signatures indicative of homologous recombination deficiency (HRD) and mutational burden, using our established protocol (Maxwell, KN, Nature Commun. 8:319, 2017).

Results: [18F]-FTT uptake was visualized above background in all primary breast tumors and known metastases. Two areas of unexpected uptake revealed an unknown contralateral breast cancer and an ovarian carcinoid, respectively. We expected that uptake might be highest in triple negative breast cancer (TNBC), where PARPi have been most heavily studied. However, a range of tracer uptake was observed in tumors independent of breast cancer subtype (hormone receptor positive/HER2 negative, TNBC, HER2+) and BRCA status. Uptake ratios (SUVmax tumor/SUV max opposite breast) ranged from 1.2-10.5 with a median 4.0. Ex vivo[125I]-KX1 autoradiography was performed on a subset of untreated primary tumors (n=5) and compared with IHC staining for PARP-1 on sequential sections. This revealed a close spatial correspondence between elevated PARP-1 expression by IHC and regions of elevated [125I]-KX1 binding radiographically. There was also a strong positive correlation between in vivo [18F]-FTT uptake and ex vivo quantitative [125I]-KX1 autoradiography (r=0.78). Genomic analysis of HRD in all tumors is pending and will be reported.

Conclusion: Initial analyses support the ability of [18F]-FTT to visualize and measure PARP-1 expression in breast cancer. This is the first step toward developing an imaging companion diagnostic to help guide PARP inhibitor treatment in breast cancer. Ongoing studies are expanding upon these results, testing the extent to which expression of PARP-1 by [18F]-FTT can predict response to PARP inhibitors and measure target engagement during therapy.

Citation Format: McDonald ES, Carlin S, Maxwell KN, Nayak A, Doot RK, Pantel AR, Farwell MD, Pryma DA, Clark AS, Shah P, DeMichele AM, Ziober A, Schubert EK, Palmer K, Lee HS, Matro J, de la Cruz L, Tchou J, Anderson DN, Feldman MD, Sheffer RE, Knollman H, Schnall MD, Makvandi M, Domchek S, Hubbard RA, Mach RH, Mankoff DA. PET imaging of PARP-1 expression in breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD4-07.

Abstract OT2-06-03: METAMORPH: METAstatic markers of recurrent tumor PHenotype for breast cancer

Up to 30% of patients diagnosed with breast cancer will develop recurrent disease within their lifetime, and currently this form of the disease is incurable. There are unmet needs to better understand underlying metastatic biology, identify new therapeutic targets and develop better methods for monitoring changes in disease, both to monitor response and elucidate resistance mechanisms. To address these needs, the METAMORPH Study encompasses a comprehensive approach that combines serial molecular tissue profiling at the RNA and DNA level with circulating markers (DTCs, CTCs, plasma tumor DNA), and ongoing assessment of therapeutic response.

METAMORPH is a prospective cohort study of women with suspected or confirmed recurrent breast cancer and accessible tumor by standard clinical biopsy, who are enrolled at the University of Pennsylvania prior to starting a new therapy for recurrent metastatic disease. The aims of this trial are to (1) evaluate the mechanisms through which recurrent breast cancer are genetically distinct from the primary tumor, (2) evaluate the circulating tumor biomarker trajectory of recurrent disease, (3) elucidate “escape pathways” of progressing tumors that emerge during the selective pressure of therapy, and (4) explore clinical utility of tumor and blood testing. The study protocol integrates research aims into clinical care, including a standardized approach to disease assessment and biopsy, pathologic confirmation of histology and receptor subtype, panel-based CLIA-approved genomic profiling, collection of research specimens, and standardized reporting of results, which are returned to patients and physicians. Patients are followed for treatment and outcome, and serial samples are collected at progression. A companion protocol, COMET, provides education about genomic testing and assesses patient understanding and impact of results. To date, 155 patients have enrolled, 142 (92%) have been biopsied, 120 (77%) have had sufficient DNA for molecular profiling and 109 (70%) have had genomic panel testing. Accrual is ongoing, with an initial target of 300 patients. Multiple sites within the UPHS Health System are enrolling. Contact information: angela.demichele@uphs.upenn.edu.

Key words: Metastatic disease, tumor profiling.

Citation Format: DeMichele A, Soucier-Ernst DJ, Clark C, Shih N, Stavropoulos W, Maxwell KN, Feldman M, Lierbamen D, Morrissette JJD, Paul MR, Pan T-C, Wang J, Belka GK, Chen Y, Yee S, Carpenter E, Fox K, Matro J, Clark A, Shah P, Domchek S, Bradbury A, Chodosh L. METAMORPH: METAstatic markers of recurrent tumor PHenotype for 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 OT2-06-03.

A single arm phase II study of rucaparib maintenance in patients with advanced pancreatic adenocarcinoma and a known deleterious BRCA1, BRCA2 or PALB2 mutation who have achieved stability on platinum therapy

TPS531

Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with a median overall survival of < 1 year. A subset of PDAC is characterized by a homologous recombination deficiency (HRD). The most well-defined patients within this group are those with deleterious mutations in BRCA1, BRCA2 and PALB2. This subset of tumors respond exceptionally well to treatment with platinum agents, leading to durable responses. However, cumulative toxicity can complicate or even prevent continued therapy, and there is an unmet need to establish maintenance strategies for such patients.Prior studies have shown that BRCA1 and BRCA2 associated PDACs respond to PARP inhibitors. Cross-resistance to platinum and PARP inhibitors exists, so initiating PARP inhibitor therapy after the development of platinum-resistance is an inferior approach. In this setting, we have designed a phase II trial of rucaparib as maintenance therapy for patients with deleterious BRCA1, BRCA2 or PALB2 who have sustained stability on platinum-based treatment. Methods: We have enrolled 2 of 42 planned patients on study NCT03140670. Eligibility criteria include inoperable PDAC, a known somatic or germline deleterious mutation in BRCA1, BRCA2 or PALB2 and stability on platinum-based chemotherapy for ≥16 weeks. Patients who have progressed on platinum-based treatment or who have received prior therapy with PARP inhibitors are excluded. Patients will receive oral rucaparib twice daily continuously in 28-day cycles. The primary endpoint is progression-free survival at 6 months. Secondary endpoints include response rate, duration of response and overall survival. A pre-treatment tumor biopsy and biopsy at progression will be obtained, as well as serial blood collections for circulating tumor material. Correlative assays will include tumor and circulating tumor DNA sequencing to identify genomic predictors of outcome and study resistance mechanisms. Clinical trial information: NCT03140670.

Abstract P5-10-04: Spectrum of hereditary breast and ovarian cancer gene variants in an African American cohort

Background: Few reports describe the spectrum of mutations in breast and ovarian cancer predisposition genes found specifically in African Americans. Methods: 560 women who self-identified as African American (AA) from the University of Pennsylvania and Wayne State University were included in this IRB-approved, case-control study. Cases (n=218 with a personal history of breast and/or ovarian cancer) and controls (n=342 without breast or ovarian cancer) underwent germline genetic testing using the Color Genomics 19-gene breast and ovarian cancer risk panel. The subset of AA patients diagnosed with breast cancer ≤40 (n=185) was compared to an institutional cohort of white patients with breast cancer diagnosed ≤40 (n=189). Results: Of 218 AA cases, 70 had pathogenic or likely pathogenic (P/LP) mutations (BRCA1: n=36; BRCA2: n=24; TP53: n=3; RAD51D: n=2; ATM: n=2; CHEK2: n=2 and MSH6: n=1). Forty-two of 218 patients (19%) had at least one variant of uncertain significance (VUS). Of 342 AA controls, 5 women had P mutations in 5 distinct genes: BRCA2, ATM, BRIP1, PALB2 and PMS2. 55 control patients (16%) had at least one VUS. Many of the 75 P/LP mutations (cases, 70 mutations; controls, 5 mutations) in the full AA cohort were unique variants. In the 135 patients who had BRCA1/BRCA2 sequencing prior to testing under this protocol, the Color Genomics platform identified all 56 pathogenic mutations. Among AA patients diagnosed with breast cancer ≤40 (n=185), the incidence of TP53 and ATM pathogenic mutations was similar to the white, early-onset breast cancer cohort (n=189): TP53, 1% in both cohorts; ATM = 1% in AA patients and 2% in whites. However, no patients in the AA, early-onset cohort had germline CHEK2 mutations, compared to 4% of white, early-onset breast cancer patients (p=0.007). Conclusions: Taken together, the results of this study demonstrate the importance of considering germline mutation testing in the AA population. Examination of mutations and disease phenotypes within the AA population may facilitate understanding of the clinical risk associated with variants of uncertain significance. Further comparative data between the AA and white cohorts will be presented.

Citation Format: Shah PD, Digiovanni L, Maxwell KN, Bradbury AR, Van Den Akker J, Kim S, Gil E, Simon MS, Nathanson KL, Domchek SM. Spectrum of hereditary breast and ovarian cancer gene variants in an African American cohort [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-10-04.

Abstract P6-07-05: Mutational spectrum and tumor response in metastatic breast cancer

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 (&gt;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.

Abstract P2-09-01: Patient reported outcomes of multiplex breast cancer susceptibility testing utilizing a tiered-binned counseling and informed consent model in BRCA1/2 negative patients

Background:The risks, benefits and utilities of multiplex panels for breast cancer susceptibility are unknown and new counseling and informed consent models are needed. We sought to obtain patient reported outcomes of multiplex testing in BRCA1/2 negative patients utilizing a novel, previously piloted tiered-binned counseling model for multiplex testing. Methods:BRCA1/2 negative participants completed pre(V1) and post-test counseling(V2) and surveys evaluating cognitive, affective and behavioral responses to a 25-gene multiplex testing panel. We used linear regressions with estimation by GEE where appropriate. Results:376 patients have been approached. To date, 124 participants(33%) have consented to the study, 21(6%) declined and 231(61%) are considering. Of 95 who have completed pre-test counseling(V1), 88(93%) elected to proceed with 25-gene panel testing and (81%) were classified as making an informed choice after tiered-binned counseling. 6/53(11%) participants received a positive result, including 1 mutation in MSH2 and 5 in moderate penetrance genes (2 ATM, 1 BARD1, 1 CHEK2, 1 PALB2). 22/53(42%) participants received a variant of unknown significance(VUS). General anxiety and perceived utility decreased significantly with pre-test counseling and after results (Table 1). Knowledge increased with pre-test counseling; cancer worry increased after receipt of multiplex results. Higher cancer worry was associated only with lower income (2.6 points/income category, p&lt;0.01). Those with a VUS had greater decreases in perceived utility compared to negative (p=0.01) or positive (p=0.003) results. To date, there are no other significant differences in knowledge, distress or uncertainty by test result. Medical management recommendations for the proband changed in 3/6 with a positive result. Cascade testing in the family was discussed as an option in 3/6 with a positive result. Conclusions:Many BRCA1/2-negative patients proceed with 25-gene cancer susceptibility testing if offered and most make informed choices utilizing a tiered-binned genetic counseling model. The tiered-binned counseling model is associated with increased knowledge, decreases in general anxiety and uncertainty after pre-test counseling and disclosure of results, but an increase in cancer worry after result disclosure. The clinical utility, long-term outcomes and differences in patient reported outcomes by test result remain unknown.

Table 1 Baseline, Mean(SD)After V1, Mean(SD)After V2, Mean(SD) N=75ˆ;N=49ˆˆN=75ˆ;N=49ˆˆN=49ˆˆGeneral Anxiety (range 0-21)6.4(3.9)*;6.9(3.9)**6.0(4.3)*;6.6(4.2)**5.8(4.5)**General Depression (range 0-212.8(2.9);3.1(3.2)3.0(3.5);3.1(3.6)3.0(3.7)State Anxiety (range 20-80)35.5(11.2);36.6(11.9)35.5(11.8);36.8(11.9)36.1(12.2)Cancer Worry (range 0-75)18.2(13.5);20.1(13.8)**16.7(12.5);17.2(11.9)**21.0(13.9)**Knowledge (range 17-82)65.7(5.0)**;66.5(5.0)**68.0(5.7)**;68.4(5.6)**67.3(4.9)**Uncertainty (range 0-15)5.8(3.9);6.2(4.3)5.6(3.7);5.4(3.2)5.6(3.5)Perceived Utility (range 24-120)75.2(14.0)*;75.9(14.0)**73.0(14.1)*;74.1(13.4)**68.4(16.9)***p≤0.05 **p≤0.01. ˆcompleted V1. ˆˆcompleted V1 & V2. To date, 53 have received results and 49 have completed post-disclosure surveys.

Citation Format: Bradbury AR, Patrick-Miller L, Egleston BE, Maxwell KN, Brandt A, Brower J, DiGiovanni L, Long JM, Powers J, Stopfer J, Nathanson KL, Domchek SM. Patient reported outcomes of multiplex breast cancer susceptibility testing utilizing a tiered-binned counseling and informed consent model in BRCA1/2 negative patients. [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 P2-09-01.

The mutational spectrum of breast and ovarian tumors from BRCA1 and BRCA2 mutation carriers

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Background: Individuals who carry one mutated copy of the BRCA1 or BRCA2 genes have elevated lifetime risks of breast and ovarian cancer. A number of studies have investigated the somatic mutational spectra of breast and ovarian tumors; however, BRCA1/2mutated tumors are underrepresented. Methods: Sixty-eight formalin-fixed paraffin embedded samples from BRCA1/2patients have been identified. Massively parallel sequencing using 48 gene capture is in process, whole exome sequencing of tumor and matched germline DNA is planned. Data are analyzed using a custom bioinformatics pipeline. Results: In analysis of data from the first 26 breast (4 BRCA1, 6 BRCA2) and ovarian (8 BRCA1, 8 BRCA2) tumors, the majority (23/26, 88%) had 0-2 variants in 48 cancer genes. Known deleterious TP53 mutations were the only variants identified in 2/4 BRCA1 and 2/6 BRCA2 breast tumors. Of those remaining, 2 BRCA1 and 1 BRCA2 breast tumors had no identified deleterious mutations. Two BRCA2 breast tumors with no TP53 mutations had known deleterious mutations in a single gene each - FGFR2 and PI3KCA. One BRCA2 breast tumor with no TP53 mutation had a variant of uncertain significance in FLT3. Finally, one BRCA2 breast tumor had a very high mutational rate, with one deleterious TP53 mutation and 7 other small deletion and single nucleotide variants. For the ovarian tumors, 15/16 BRCA1 and BRCA2 tumors had known deleterious TP53 mutations; the ovarian tumor with no TP53 mutation had no other variants. TP53 mutations were the sole identified mutations in 8 ovarian tumors. One ovarian tumor carried a known JAK3 activating mutation and 4 ovarian tumors carried one variant of uncertain significance in a single gene - SMO, PDGFRA, GNA11 and NRAS. Finally, two ovarian tumors were found to have high mutational rates. Conclusions: Using a targeted resequencing panel, we confirmed the high rate of TP53 mutations in BRCA1/2 breast tumors and observed a higher than expected rate in BRCA1/2 ovarian tumors. Importantly, we have identified mutations in other known driver genes using FFPE samples, allowing generalizability to other sites. These analyses may uncover novel mutations that could be exploited in the development of targeted therapeutic agents for BRCA1/2 carriers.

The spd-2 gene is required for polarization of the anteroposterior axis and formation of the sperm asters in the Caenorhabditis elegans zygote

In the Caenorhabditis elegans zygote, polarization of the anteroposterior (AP) axis occurs during a brief period of reorganization that follows fertilization and results in the establishment of discrete cytoplasmic and cortical domains. In the cytoplasm, germ-line or P granules are circulated by an actomyosin-driven fountain flow of cytoplasm and localize to the posterior, while in the cortex, two proteins required for AP polarity, PAR-2 and PAR-3, localize to the posterior and the anterior, respectively. The identity of the positional cue that determines AP axis orientation is not known, although it has been postulated to be a component of the sperm pronucleus/centrosome complex (SPCC) as the position of the SPCC correlates with the orientation of the AP axis and the direction of the fountain flows. Here, we show that mutations in the spd-2 gene disrupt polarization of the AP axis. In mutant zygotes, the fountain flow of cytoplasm and associated asymmetric cortical contractions are absent, P granules do not localize, and cortical PAR-3 does not become asymmetrically distributed. Interestingly, cortical PAR-2 localizes randomly to either or both poles. The random positioning of PAR-2 requires PAR-3 and indicates that a spd-2-dependent mechanism normally modulates PAR-2/PAR-3 interactions to correctly position PAR-2 at the posterior. spd-2 mutations also disrupt formation of the SPCC by delaying and attenuating the formation of sperm asters until after the period of reorganization, suggesting that spd-2 mutations disrupt formation of the positional cue. Our results also indicate that sperm asters are not essential for pronuclear migration but are required for rapid female pronuclear movement and premitotic positioning of the pronuclei.