HER2 Testing Research Articles

1635PD - Accessibility and affordability to trastuzumab for breast cancer patients: Voices of the global oncology community from ONCOLLEGE 001 survey, part 2

BackgroundONCOLLEGE-001 project surveyed the global accessibility (ACC)/ affordability (AFF) to HER2-testing (H2T) & medicines for breast cancer (BC). The 1st analysis showed critical issues of ACC & AFF of H2T in lower- middle income countries. Part 2 of the survey focuses on ACC, AFF and prioritization of anti-HER2 medicines; here, we present the data for trastuzumab (T). MethodsAn internet-based survey was developed by the international ONCOLLEGE working group. Data were analyzed per country-income (World Bank groupings) and World Health Organization Regions. Responders authorized for the use of the data. ResultsResponses were received from 210 providers (78% medical or clinical oncologists) across 45 countries (all income groups, all regions). 8% of providers reported no T available in their setting, of which 60% are from low and low-middle income countries (LMICs) and the remaining from upper- middle (UMIC). Where T was available, 15% of the responders reported ACC only as out of pocket expenditure (OOP) for patients, of which almost 70% from LMICs. More than 2/3 of the responders described to order the H2T regardless ACC to affordable trastuzumab for patients, retaining the prognostic information of HER2- overexpression to inform treatment decision- making (e.g. risk grouping for early breast cancer). The patterns of reimbursement for T influenced the percentage of eligible HER2 patients receiving the anti-HER2 drug: T is received in more than 50% of the eligible population in 8%, 41% and 74% in LMIC, UMIC and HIC (high- income) settings, respectively. In 71% of settings where trastuzumab is provided only as OOP, <1/4 of the eligible patients could access affordable T. ConclusionsThe heterogeneous pattern of ACC and AFF of H2T & anti-HER2 medicines influenced the chance of breast cancer patients to receive T. Data on the use of trastuzumab biosimilars and other HER2 blockers is under analysis. International systematized cross-cutting and comprehensive efforts across the cancer continuum are warranted to inform and shape the areas of research implementation for cancer - aiming to optimize the cure and care for all cancer patients and prevent catastrophic OOP. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

813P - Increased assessment of HER2 in metastatic gastroesophageal cancer patients: A nationwide population-based cohort study

BackgroundAddition of trastuzumab to first-line palliative chemotherapy in esophagogastric cancer patients with HER2 overexpression has shown to improve survival and is therefore considered standard of care. The aim of this study was to assess HER2 testing, trastuzumab administration and overall survival (OS) in a nationwide cohort of metastatic esophagogastric cancer patients. MethodsPatients with synchronous metastatic esophagogastric adenocarcinoma diagnosed between 2010-2016 that received palliative systemic treatment (N=2846) were identified from the Netherlands Cancer Registry. Details on HER2 assessment were extracted from pathology reports from the Dutch Pathology Registry. For determination of HER2 positivity or negativity, the criteria on HER2 assessment of the ToGA trial were used. Proportions of HER2 tested patients were analyzed between hospital volume categories using Chi-square tests, and over time using trend analysis. OS was tested using the Kaplan Meier method and log rank test. ResultsHER2 assessment was performed in 54% of all 2846 patients that received palliative chemotherapy, and increased from 18% to 88% between 2010 and 2016 (P<0.01). Median OS of all patients increased from 6.9 (IQR 3.5-12.0) months in 2010-2013 to 7.9 (IQR 3.6-13.6) months in 2014-2016 (P<0.001). Between the hospitals, the proportion of tested patients varied between 29-100%, and was the highest in high-volume hospitals (P<0.01). HER2 status was positive in 19%, negative in 67% and unknown in 14% of the 1524 tested patients. Overall, 77% of the HER2 positive patients received trastuzumab. Median OS was significantly higher in patients with both positive (8.8 months) and negative (7.4 months) HER2 status that were diagnosed in 2015-2016, compared with non-tested patients (5.6 months; P<0.05). ConclusionsDaily practice management of metastatic esophagogastric cancer patients has changed due to increased determination of HER2 status and administration of trastuzumab, which might have contributed to the improved survival in these patients. Advances in clinical practice could include a further increase in awareness of HER2 testing among pathologists and clinicians, especially in low-volume hospitals, and in the administration of trastuzumab in case of HER2 overexpression. Legal entity responsible for the studyThe authors. FundingRoche. DisclosureR.H.A. Verhoeven: Research grant / Funding (institution): BMS; Research grant / Funding (institution): Roche. N. Haj Mohammad: Advisory / Consultancy: BMS; Advisory / Consultancy: MSD. J. de Vos-Geelen: Non-remunerated activity/ies: BTG; Research grant / Funding (institution), Non-remunerated activity/ies: Servier; Advisory / Consultancy: Shire. T. Van Voorthuizen: Non-remunerated activity/ies: Astellas; Non-remunerated activity/ies: Ipsen; Non-remunerated activity/ies: Roche; Non-remunerated activity/ies: Bayer. M. van Oijen: Research grant / Funding (institution): Roche; Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Merck Serono; Research grant / Funding (institution): Nordic; Research grant / Funding (institution): Servier; Research grant / Funding (institution): Amgen. H.W.M. van Laarhoven: Research grant / Funding (institution): Bayer; Advisory / Consultancy, Research grant / Funding (institution): BMS; Advisory / Consultancy, Research grant / Funding (institution): Celgene; Advisory / Consultancy, Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Merck Serono; Research grant / Funding (institution): MSD; Advisory / Consultancy, Research grant / Funding (institution): Nordic; Research grant / Funding (institution): Philips; Research grant / Funding (institution): Roche. All other authors have declared no conflicts of interest.

HER2 testing of gynecologic carcinosarcomas: tumor stratification for potential targeted therapy.

A recent phase II clinical trial showed increased progression-free survival in patients with HER2-positive endometrial serous carcinoma receiving trastuzumab in addition to carboplatin-paclitaxel chemotherapy. Similar to endometrial serous carcinomas, carcinosarcomas of the female genital tract have a dismal prognosis and could potentially benefit from new targeted therapeutic approaches. We aimed to systematically evaluate the characteristics of HER2 expression/amplification in gynecologic carcinosarcomas using standardized staining methods and scoring criteria. Tumors from 80 patients (65 uterine, 15 tubo-ovarian) were included, containing a serous (60%), endometrioid (10%), clear cell (3%), undifferentiated (3%), neuroendocrine (1%), or mixed (24%) carcinoma, and either a homologous (46%), or a heterologous (54%) sarcoma component. HER2 scores were assigned to both components per the 2007 and 2013 ASCO/CAP breast scoring criteria. A total of 13 cases (12 uterine, 1 ovarian, 16%) were HER2 positive (either by immunohistochemistry or FISH) using the 2013 criteria, while only 10 cases (9 uterine, 1 ovarian, 13%) were HER2 positive per the 2007 criteria. Nine cases showed a change in their HER2 immunohistochemical score between the two scoring systems, including two cases with a change in the overall HER2 status from negative (2007) to positive (2013). Heterogeneity of HER2 protein expression was observed in 38% of HER2-positive tumors, and a lateral/basolateral membranous staining pattern was common. The sarcoma component showed 2+, equivocal HER2 expression in five cases, one of which also demonstrated HER2 amplification by FISH. All HER2-positive carcinosarcomas had either a serous or a mixed carcinoma component, and all but one HER2-positive tumors were of uterine primaries. Our study demonstrates that gynecologic carcinosarcomas share similarities in their HER2 expression/amplification profiles to endometrial serous carcinomas, which should be taken into account when assessing their HER2 status to ensure appropriate patient selection for potential targeted HER2-based therapies in the future.

Treatment Algorithm for Patients With Gastric Adenocarcinoma: An Austrian Consensus on Systemic Therapy.

Despite recent advances in the treatment of gastric cancer, mortality related to this disease is still substantial. Surgery and chemotherapy represent the cornerstones of patient management. Targeted treatments that include anti-angiogenic agents and the advent of immunotherapies can contribute to improved patient prognosis. Herein, we present an Austrian consensus on the systemic treatment of patients with gastric adenocarcinoma and lower gastroesophageal junction, including those with human epidermal growth factor receptor 2 (HER2)-positive disease. The consensus considers the curative setting, as well as first-line to late-line systemic treatment options in the palliative setting. For HER2-positive disease, first-line and second-line therapies are discussed, as well as HER2 testing. Potential future therapies are also listed, with a focus on anti-angiogenic treatments and checkpoint inhibition, that might provide a further step forward in the management of patients with gastric cancer.

Interlaboratory Comparison of Immunohistochemical Testing for Equivocal Her2: Results of the 2014-2017 Center-Southern Italy HER2 Survey

In recent years many efforts have been made aiming to ensure the efficiency of each pathology lab in HER2 IHC determination in breast and in gastric cancer [1-6].

HER2 double-equivocal breast cancer in Chinese patients: a high concordance of HER2 status between different blocks from the same tumor

PurposeHuman epidermal growth factor receptor 2 (HER2) status is both an independent prognostic factor and a predictive factor for the efficacy of targeted therapy for breast cancer, so it is critical to accurately detect HER2 protein expression and/or gene amplification. According to the recommendations of the 2013 American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP) guidelines for HER2 breast cancer testing, an additional test should be pursued on a different block from the same tumor as one of the options for patients with immunohistochemistry (IHC) 2+ and a HER2/CEP17 ratio of < 2.0 with an average HER2 signals per tumor cell of ≥ 4.0 and < 6.0 by reflex test using dual-probe fluorescence in situ hybridization (FISH) (double-equivocal HER2). Our aim in this study is to explore the consistency of HER2 status between the two blocks.MethodsWe retrospectively analyzed 5685 primary invasive breast cancers between April 2015 and January 2019 from Peking Union Medical College Hospital. For cases with double-equivocal HER2 revealed in initial blocks, HER2 gene status was evaluated by FISH in a different block from the same tumor. The FISH score was interpreted according to the 2013 ASCO/CAP guidelines for HER2 testing.ResultsIn our cohort of 5685 specimens, the overall HER2 IHC3+, 2+, 1+ and 0 cases were 20.5%, 31.8%, 28.3%, and 19.5%, respectively. Then, 13.7%, 66.3%, and 20.0% of HER2 amplification, non-amplification, and equivocation rates were found, respectively, in IHC2+ patients (n = 1777) by reflex FISH assay. For specimens with double-equivocal HER2 (n = 333), HER2 status was assessed in another block from the same tumor by FISH and then the frequency of HER2 positive, negative, and equivocation was estimated at 5.7%, 22.5%, and 71.8%, respectively. Because double-equivocal HER2 cases are classified in the HER2 negative category by the 2018 ASCO/CAP HER2 testing guidelines, only 1.3% (19/1511) of HER2 positive patients were determined through additional HER2 testing in another block from the HER2 negative population.ConclusionsHER2 status in different blocks from the same tumor in primary invasive breast cancer was highly concordant. Our data supported the recommendation of the 2018 ASCO/CAP HER2 testing guidelines in breast cancer to remove the suggestion for additional HER2 testing using another block contained in the previous version.

The impact of molecular status on survival outcomes for invasive micropapillary carcinoma of the breast.

Invasive micropapillary carcinoma (IMPC) is an uncommon variant of breast cancer. Previous studies demonstrated this subtype is often hormone receptor (HR)-positive, resulting in survival outcomes similar to invasive ductal carcinoma. However, many of these studies were conducted prior to HER2 testing availability. We aim to determine the impact of molecular marker status (including HER2 status) on IMPC survival outcomes. The National Cancer Data Base (NCDB) was used to retrieve patients with biopsy-proven IMPC from 2007 to 2012. Only patients with known HR and HER2 status were included. Cox multivariate regression was used to determine prognostic factors. In total, 865 patients were included; median follow-up was 2.5years. Overall, 651 patients (75.3%) had HR+HER2- disease, 128 (14.8%) had HR+HER2+ disease, 41 (4.7%) had HR-HER2+disease, and 45 (5.2%) had triple negative disease. Patients with triple negative disease were more likely to have poorly differentiated histology (66.7%), lymphovascular invasion (73.3%), stage 3 disease (37.8%), undergone mastectomy (68.9%), and positive surgical margins (15.6%). On Cox multivariate regression, those with triple negative disease had worse overall survival (hazard ratio [HR] 7.28, P<0.001). Other adverse prognostic factors included African-American descent (HR 2.24, P=0.018), comorbidity score of 1 (HR 2.50, P=0.011), comorbidity score ≥2 (HR 3.27, P=0.06), and ≥3 positive lymph nodes (HR 3.23, P=0.007). Similar to invasive ductal carcinoma, triple negative disease in IMPC results in worse survival outcomes. This is the largest and first study to characterize molecular status (including HER2 status) in patients with IMPC and its impact on survival outcomes.

Genomic comparison of paired primary breast carcinomas and lymph node macrometastases using the Oncotype DX Breast Recurrence Score® test

Adjuvant therapy decisions may in part be based on results of Oncotype DX Breast Recurrence Score® (RS) testing of primary tumors. When necessary, lymph node metastases may be considered as a surrogate. Here we evaluate the concordance in gene expression between primary breast cancers and synchronous lymph node metastases, based on results from quantitative RT-PCR-based RS testing between matched primary tumors and synchronous nodal metastases. This retrospective, exploratory study included patients (≥ 18years old) treated at our center (2005-2009) who had ER+ , HER2-negative invasive breast cancer and synchronous nodal metastases with available tumor blocks from both sites. Paired tissue blocks underwent RS testing, and RS and single-gene results for ER, PR, and HER2 were explored between paired samples. A wide distribution of RS results in tumors and in synchronous nodal metastases were modestly correlated between 84 paired samples analyzed (Pearson correlation 0.69 [95% CI 0.55-0.78]). Overall concordance in RS group classification between samples was 63%. ER, PR, and HER2 by RT-PCR between the primary tumor and lymph node were also modestly correlated (Pearson correlation [95% CI] 0.64 [0.50-0.75], 0.64 [0.49-0.75], and 0.51 [0.33-0.65], respectively). Categorical concordance (positive or negative) was 100% for ER, 77% for PR, and 100% for HER2. There is modest correlation in continuous gene expression, as measured by the RS and single-gene results for ER, PR, and HER2 between paired primary tumors and synchronous nodal metastases. RS testing for ER+ breast cancer should continue to be based on analysis of primary tumors.

Systematic literature review of clinical trials of endocrine therapies for premenopausal women with metastatic HR+ HER2- breast cancer.

Several endocrine-based therapies have recently been evaluated as treatments for premenopausal women with hormone-receptor-positive/human-epidermal-growth-factor-receptor 2 negative (HR+/HER2-) metastatic breast cancer (mBC). We conducted a systematic review and assessed the feasibility of an indirect treatment comparison (ITC) to characterize the comparative efficacy of endocrine-based therapies in this setting. A systematic literature review (SLR) of Medline, EMBASE, Cochrane Library and key conferences was performed to identify randomized clinical trials (RCTs) satisfying the following criteria: (a) included pre/perimenopausal women with HR+/HER2- mBC, (b) included endocrine-based therapies, (c) reported efficacy, safety, or quality of life outcomes, and (d) was published in 2007 or later (when HER2 testing was standardized). The clinical and methodological similarities across trials were assessed to evaluate the feasibility of an ITC. Four RCTs (PALOMA-3, MONARCH-2, KCSG BR10-04 and MONALEESA-7) and eight regimens (palbociclib+fulvestrant+goserelin, fulvestrant+goserelin, abemaciclib+fulvestrant+gonadotropin-releasing hormone agonist [GnRHa], fulvestrant+GnRHa, anastrozole+goserelin, goserelin, ribociclib+NSAI/tamoxifen+goserelin and NSAI/tamoxifen+goserelin) were selected. MONALEESA-7 was the only phase 3 trial investigating endocrine-based therapies as first-line in only pre/perimenopausal women with HR+/HER2- mBC; the other three trials focused on the ET-failure setting and their pre/perimenopausal populations were relatively small. ITCs were methodologically unfeasible due to critical differences in treatment settings and lack of common comparators across trials. Therefore, we were not able to characterize the relative efficacy of the different endocrine-based therapies available in the premenopausal HR+/HER2- mBC setting. This systematic review provides a comprehensive assessment of the available trial evidence on the efficacy and safety of endocrine-based therapies for premenopausal women with HR+/HER2- mBC. Only four trials have reported relevant data in this setting, and MONALEESA-7 is currently the only trial focused on premenopausal HR+ HER2- mBC in the first-line setting.

HER2 Testing in Gastric and Gastroesophageal Adenocarcinoma—Review and Update

Abstract Adenocarcinomas of the stomach and gastroesophageal junction are commonly encountered by practicing pathologists. In cases of advanced unresectable or metastatic disease, a patient may be a candidate for anti–human epidermal growth factor receptor 2 (HER2) targeted therapy. Eligibility for anti-HER2 therapy is determined by the pathologist, following an algorithm utilizing HER2 immunohistochemistry alone or in combination with chromogenic or fluorescence in situ hybridization. HER2 immunohistochemistry is interpreted using 4-tier scoring criteria that were devised and validated specifically for gastric adenocarcinomas. Here, current guidelines for utilization and interpretation of HER2 immunohistochemistry and in situ hybridization are reviewed. Also included is a discussion of some of the interpretation difficulties and pitfalls that may be encountered in routine pathology practice.

Human epidermal growth factor receptor 2-positive digestive tumors.

This manuscript aims at providing an update and overview on the role of Human epidermal growth factor receptor 2 (HER2) testing and HER2-directed therapies in digestive tumors. Phase 3 trial data demonstrating a survival benefit of HER2-targeting treatments are limited to gastric cancer. However, HER2 positivity is also found in 5-6% of colorectal, 7% of pancreatic, and 16% of extrahepatic biliary cancers. Although phase 2 trial data support the use of the combination of trastuzumab and lapatinib with chemotherapy in HER2-positive colorectal cancer, the patient's benefit from targeted treatment of HER2-positive biliary or pancreatic neoplasms is currently unclear, and further clinical trials are necessary. With the exception of gastric cancer, there are currently no defined guidelines for HER2 testing in other digestive tumors. Various HER2-targeting therapies, which are standard of care in HER2-positive breast cancer, failed in HER2-positive gastric cancers. Thus, the predictive value of HER2 overexpression depends on the tumor type, and results of breast cancer trials cannot a priori be extrapolated to digestive cancers. Next-generation sequencing panel diagnostics may furthermore identify targetable activating mutations in gastric, extrahepatic biliary, and colorectal cancer, particularly if traditional testing (immunohistochemistry/in-situ hybridization) is negative. However, their clinical relevance needs to be determined.

Safety and Efficacy of the Addition of Lapatinib to Perioperative Chemotherapy for Resectable HER2-Positive Gastroesophageal Adenocarcinoma

Perioperative chemotherapy and surgery are a standard of care for operable gastroesophageal adenocarcinoma. Anti-HER2 therapy improves survival in patients with advanced HER2-positive disease. The safety and feasibility of adding lapatinib to perioperative chemotherapy should be assessed. To assess the safety of adding lapatinib to epirubicin, cisplatin, and capecitabine (ECX) chemotherapy and to establish a recommended dose regimen for a phase 3 trial. Phase 2 randomized, open-label trial comparing standard ECX (sECX: 3 preoperative and 3 postoperative cycles of ECX with modified ECX plus lapatinib (mECX+L). This multicenter national trial was conducted in 29 centers in the United Kingdom in patients with histologically proven, HER2-positive, operable gastroesophageal adenocarcinoma. Registration for ERBB/HER2 testing took place from February 25, 2013, to April 19, 2016, and randomization took place between May 24, 2013, and April 21, 2016. Data were analyzed May 10, 2017, to May 25, 2017. Patients were randomized 1:1 open-label to sECX (3 preoperative and 3 postoperative cycles of 50 mg/m2 of intravenous epirubicin on day 1, 60 mg/m2 intravenous cisplatin on day 1, 1250 mg/m2 of oral capecitabine on days 1 through 21) or mECX+L (ECX plus lapatinib days 1 through 21 in each cycle and as 6 maintenance doses). The first 10 patients in the mECX+L arm were treated with 1000 mg/m2 of capecitabine and 1250 mg of lapatinib per day, after which preoperative toxic effects were reviewed according to predefined criteria to determine doses for subsequent patients. Proportion of patients experiencing grade 3 or 4 diarrhea with mECX+L. A rate of 20% or less was considered acceptable. No formal comparison between arms was planned. Between February 2013, and April 2016, 441 patients underwent central HER2 testing and 63 (14%) were classified as HER2 positive. Forty-six patients were randomized; 44 (24 sECX, 20 mECX+L) are included in this analysis. Two of the first 10 patients in the mECX+L arm reported preoperative grade 3 diarrhea; thus, no dose increase was made. The primary endpoint of preoperative grade 3 or 4 diarrhea rates were 0 of 24 in the sECX arm (0%) and 4 of 20 in the mECX+L arm (21%). One of 24 in the sECX arm and 3 of 20 in the mECX+L arm stopped preoperative treatment early, and for 4 of 19 in the mECX+L arm, lapatinib dose was reduced. Postoperative complication rates were similar in each arm. Administration of 1250 mg of lapatinib per day in combination with ECX chemotherapy was feasible with some increase in toxic effects, which did not compromise operative management. ISRCTN.org identifier: 46020948; clinicaltrialsregister.eu identifier: 2006-000811-12.

Pathologic complete response rate according to HER2 detection methods in HER2-positive breast cancer treated with neoadjuvant systemic therapy.

Human epidermal growth factor receptor 2 (HER2)-positive breast cancers are known to have significant clinical and pathological response to neoadjuvant systemic therapy (NST). The aim of this study was to identify factors associated with pathological complete response (pCR), defined as no residual invasive carcinoma in the breast and axillary lymph nodes (ypT0/is ypN0), among patients with HER2-positive breast cancer and to compare pCR rates between breast cancers with HER2 protein overexpression by immunohistochemistry (IHC) versus HER2 gene amplification by fluorescence in situ hybridization (FISH) in the absence of protein overexpression by IHC. We conducted a retrospective review of HER2-positive breast cancer patients treated with NST and surgery at Memorial Sloan Kettering Cancer Center between January 2013 and May 2018. Estrogen receptor (ER), progesterone receptor (PR), and HER2 status were assessed according to the 2018 ASCO/CAP guidelines. During the study period, 560 patients were identified. Of 531 patients with IHC results available, 455 patients had HER2 IHC 3+, and 76 had IHC < 3+ but HER2 amplification detected by FISH. The overall pCR rate was 59% (330/560). The pCR rate among patients with HER2 protein overexpression (IHC 3+) was 67%, compared to 17% among patients with HER2 amplification by FISH (IHC < 3+). On univariate and multivariate analyses, HER2 protein overexpression by IHC (IHC 3+) was a significant predictor of pCR, along with grade 3 histology, PR-negative status, and dual anti-HER2 therapy. Although both HER2 IHC and FISH are standard HER2 testing methods in breast cancer, achievement of pCR is associated with HER2 IHC expression level, among other factors.

HER2 testing: Insights from pathologists’ perspective on challenging HER2 cases.

e12512 Background: HER2 status dictates treatment decisions in breast cancer making the precision and accuracy of laboratory testing essential. While most HER2 testing is straightforward using ASCO-CAP interpretation guidelines, 5% of cases fall into the less common categories (groups 2-4) and can present unusual diagnostic dilemmas. 6 high volume HER2 FISH laboratories evaluated 10 challenging HER2 cases. The results highlight the challenges and potential for variability in interpreting rare cases with unusual results. Methods: Ten diagnostically challenging HER2 FISH cases were selected from our breast cancer archives (41 months/3863 cases). Unstained slides were evaluated by 6 high volume laboratories. Laboratories performed HER2 FISH testing (along with HER2 IHC as needed) and rendered an interpretation. Participants discussed results during a conference call. Cases included the following situations: low-level amplification (ratio ≥ 2.0, mean HER2 signals/cell between 4.0-5.9), HER2 mean copy number or ratio near a clinically actionable threshold, complex heterogeneity or clones, and a technical challenge (signal clustering). Results: All laboratories elected to perform HER2 IHC in conjunction with FISH in all cases. Only 3/10 cases resulted in 100% agreement between the 6 institutions, all of which were in the category addressing complex heterogeneity. During the study, we identified a problematic subset (low amplified FISH cases) which may have discordant (negative) IHC results. Another problematic scenario is the finding of a small, highly amplified HER2 clone. Lastly, we identified cases with high cell to cell variability, and we saw discordant values resulting in disparate overall HER2 interpretations. Conclusions: Oncologists and pathologists should be aware of these challenges and the potential for variability in interpretation of these rare case scenarios. Evaluation for concordance between IHC and FISH results, correlation with other clinico-pathologic features and additional steps to ensure the accuracy of test results can help resolve unusual results, but grey zones may still remain and should be discussed when making clinical decisions based on HER2 test results.

Matching insurance claims data with EMR molecular status data in non-small cell lung cancer (NSCLC) patients: Understanding real-world molecular testing and prevalence rates at the site and investigator level.

e20568 Background: Many targeted therapy clinical trials require a somatic gene mutation/alteration for eligibility. We assessed the feasibility of leveraging Real-World Data (RWD) to enrol NSCLC patients into clinical trials. Methods: US insurance claims data were extracted to identify lung cancer patients. These data were matched with EMR data also containing NSCLC patients’ details regarding the occurrence and results of molecular testing for EGFR, ALK, ROS1, JAK2, HER2 and RET somatic alterations, achieving a level of granular detail beyond that available in each individual dataset. A one-year extraction period was applied, with no gender or age restrictions. Results: Results for the matched dataset are summarised in the table below - the overall patient record match was 89.6%. Conclusions: The observed prevalence correlated reasonably well with literature reported prevalence for the molecular biomarkers associated commercially available targeted therapies in NSCLC (EGFR, ALK, ROS1). The sample size for the remaining biomarkers was too small to draw conclusions, though the presence of data correlating to these is of interest, considering that there are no currently approved targeted therapies in NSCLC tailored to these predictive biomarkers. This approach could be expanded upon to recruit patients into targeted therapy clinical trials as the dataset is fully linkable to sites and investigators. With the emergence of broad genomic profiling, the availability of molecular data to support clinical trial enrolment is also expected to grow.[Table: see text]

Reassignment of HER2 status for subgroups of breast cancer according to the 2018 updated American Society of Clinical Oncology and College of American Pathologists guidelines: The impact of combined immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) reflex testing in a large national reference laboratory.

3144 Background: Updated ASCO/CAP Guidelines for HER2 testing in breast cancer have been most impactful on the resolution of certain challenging groups of FISH results. We review the change in assignment of HER2 status in a large series of breast cancers referred to a large national reference laboratory for FISH testing since the introduction of the 2018 updated guidelines. Methods: Patient samples submitted to the Mayo Clinic Cytogenetics Laboratory (N = 2208) were analyzed by FISH. Samples with Group 2, Group 3, or Group 4 FISH results were reflexed to immunohistochemistry (IHC) in our central laboratory; FISH slides for those cases with equivocal 2+ IHC results were re-scored in the regions of invasive cancer showing more intense membranous staining. A subset of 202 samples with Group 4 FISH results were also reflexed to the previously employed reflex FISH assay (HER2/D17S122), and these were also re-analyzed according to the new reflex IHC/FISH process. Results: 382 of 2208 breast cancer samples tested (17.3%) had FISH results categorized as Group 2 (N = 17, 0.8%), Group 3 (N = 34, 1.5%), or Group 4 (N = 331, 15%) and required reflex IHC testing, and of those, 75% were 2+ equivocal and required targeted re-analysis of the FISH slide according to the 2018 updated guidelines. Re-analysis of the FISH slide resulted in switching between Groups 1-5 in 19.4% of cases, but HER2 status was changed by FISH re-scoring in only 7.7% of cases re-scored (1.0% of all samples), generally due to only minor shifts in HER2 copy number and HER2/control ratios between the initial and IHC-guided reflex FISH scores. In the subset of 202 cases tested by both reflex methods, the previously employed HER2/D17S122 reflex probe set was positive in 123 cases (60.9%), whereas reflex IHC/FISH was positive in only 10 cases (7.9%). Including positive reflex IHC (0.4%) and positive reflex FISH results (2.1%), the overall assignment of positive HER2 status on our series of 2208 cases was 11.5%. Conclusions: Overall rates of HER2 positive FISH results have declined under the most recent ASCO/CAP guideline update as a consequence of new recommendations for reflex testing for Groups 2-4. This change is largely due to reassignment of Group 2 and Group 4 results as negative in the absence of positive IHC.

Cyclin D1 differential activation and its prognostic impact in patients with advanced breast cancer treated with trastuzumab

IntroductionWe sought to determine the level of activation of the critical components of the cyclin D1-mediated pathway and to evaluate their prognostic significance across the different molecular subtypes of advanced breast cancer.Patients and methodsThe study population comprised 219 female patients with advanced breast cancer who had been found to have human epidermal growth factor receptor 2 (HER2)-positive disease by local testing and were all treated with trastuzumab-based regimens. For all tumours, central testing for HER2 was performed, and cyclin D1 gene (CCND1) amplification, mRNA and protein expression were assessed by FISH, quantitative real-time-PCR and immunohistochemistry, respectively. Prognostic impact on clinical endpoints was evaluated with Cox regression analyses.ResultsAfter central testing, only 134 (61.2%) of 219 patients were confirmed to have HER2 gene amplification by FISH and/or 3+ HER2 protein expression by immunohistochemistry. After a median follow-up time of 136.0 months (95% CI 123.3 to 148.9), 105 (78.4%) HER2-positive patients and 76 (89.4%) HER2-negative patients had died, while 80% of the former and 87.1% of the latter had experienced a disease relapse. Patients with positive oestrogen receptor/progesterone receptor status presented with higher cyclin D1 mRNA expression. In the HER2-negative subgroup, patients with negative cyclin D1 protein expression were at higher risk of progression (HR= 1.66, 95%CI 1.01 to 2.72, Wald’s p=0.045). Among de novo metastatic patients, the risk of progression was higher for patients with non-amplified CCND1 tumours (HR= 2.00, 95% CI 1.03 to 3.90, p=0.041).ConclusionAberrant activation of the cyclin D1-mediated pathway appears to reduce the risk of progression in HER2-negative tumours, but not in HER2-positive ones.

Impact of the 2018 ASCO/CAP HER2 Guideline Focused Update.

The 2018 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) human epidermal growth factor receptor 2 (HER2) guideline focused update revises the HER2 scoring criteria. We evaluated the impact on HER2 rates in breast carcinoma diagnosed at our center. In a retrospective series of breast core biopsies with invasive carcinoma diagnosed between 2014 and 2017 (n = 1,350), HER2 status was classified according to 2013 and 2018 ASCO/CAP guidelines and changes in HER2 status identified. The 2018 guidelines reclassified the HER2 status of 6% of patients. Most changed from HER2 equivocal status (equivocal by immunohistochemistry and fluorescence in situ hybridization under the 2013 guidelines) to HER2-negative status (2018 guidelines). The HER2-positive rate decreased by 0.4%. The 2018 guidelines decrease the rate of HER2 equivocal and positive breast cancer and reduce repeat HER2 testing on excision specimens. Approximately 0.4% of patients will become newly ineligible for anti-HER2 therapy.

HER2 Positivity Predicts Unresponsiveness to EGFR-Targeted Treatment in Metastatic Colorectal Cancer.

HER2 amplification is detected in 3% of patients with colorectal cancer (CRC), making tumors in the metastatic setting vulnerable to double pharmacological HER2 blockade. Preclinical findings show that it also might impair response to anti-epidermal growth factor receptor (EGFR) treatment. Patients with KRAS exon 2 wild-type metastatic CRC underwent molecular screening of HER2 positivity by HERACLES criteria (immunohistochemistry 3+ or 2+ in ≥50% of cells, confirmed by fluorescence in situ hybridization). A sample of consecutive HER2-negative patients was selected as control. A regression modeling strategy was applied to identify predictors explaining the bulk of HER2 positivity and the association with response to previous anti-EGFR treatment. From August 2012 to April 2018, a total of 100 HER2-positive metastatic CRC tumors were detected out of 1,485 KRAS exon 2 wild-type screened patients (6.7%). HER2-positive patients show more frequently lung metastases (odds ratio [OR], 2.04; 95% confidence interval [CI], 1.15-3.61; p = .014) and higher tumor burden (OR, 1.48; 95% CI, 1.10-2.01; p = .011), and tumors were more likely to be left sided (OR, 0.50; 95% CI, 0.22-1.11; p = .088). HER2-positive patients who received treatment with anti-EGFR agents (n = 79) showed poorer outcome (objective response rate, 31.2% vs. 46.9%, p = .031; progression-free survival, 5.7 months vs. 7 months, p = .087). Testing for HER2 should be offered to all patients with metastatic CRC because the occurrence of this biomarker is unlikely to be predicted based on main clinicopathological features. Patients with HER2-amplified metastatic CRC are less likely to respond to anti-EGFR therapy. Patients with HER2-amplified/overexpressed metastatic colorectal cancer (mCRC) harbor a driver actionable molecular alteration that has been shown in preclinical models to hamper efficacy of the anti-epidermal growth factor receptor (EGFR) targeted therapies. The present study confirmed that this molecular feature was associated with worse objective tumor response and shorter progression-free survival in response to previous anti-EGFR therapies. Moreover, it was found that the occurrence of this biomarker is unlikely to be predicted based on main clinicopathological features. Therefore, HER2 status assessment should be included in the molecular diagnostic workup of all mCRC for speedy referral to clinical trials encompassing HER2-targeted double blockade independently of previous anti-EGFR treatment.

43. Considerations for implementation of the new ASCO/CAP guidelines for HER2 testing in the clinical laboratory

Human Epidermal Growth Factor Receptor 2 (HER2) testing provides important prognostic and predictive information for women with breast cancer. Approximately 5% of cases evaluated by FISH have hybridization patterns that are not clearly positive or negative. In 2018, the American Society of Clinical Oncology (ASCO) and College of American Pathologists (CAP) issued updated testing guidelines, which integrate concomitant IHC review for FISH cases with an unclear result (groups 2, 3, and 4), to make a final HER2 result determination.