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Anatomic Pathology Abstracts, 2/18

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Editors: Rouzan Karabakhtsian, MD, PhD, associate professor of pathology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY; Rachel Stewart, DO, PhD, molecular genetic pathology fellow, University of Utah/ARUP Laboratories, Salt Lake City; Nicole Panarelli, MD, associate professor of pathology, Albert Einstein College of Medicine, Montefiore Medical Center; and Shaomin Hu, MD, PhD, pathology resident, Albert Einstein College of Medicine, Montefiore Medical Center.

ARTEMIS trial: quantifying pathological response to neoadjuvant chemotherapy

Prognostic value of histologic grade 1 in lower gastrointestinal graft versus host disease

DCIS mutational driver events representative of invasive breast cancer

Cutaneous eruptions in patients who received immune checkpoint blockade

Correlation of immune phenotype with IDH mutation in diffuse glioma

P16 immunohistochemistry in high-risk HPV-related oropharyngeal SCC

CTNNB1 mutation to identify endometrial cancer patients at risk of recurrence

ARTEMIS trial: quantifying pathological response to neoadjuvant chemotherapy

The Affordability and Real-World Antiplatelet Treatment Effectiveness after Myocardial Infarction Study, also known as the ARTEMIS trial, tested standard neoadjuvant chemotherapy with or without bevacizumab in the treatment of HER2-negative early breast cancer. The ARTEMIS investigators compared data from central pathology review with report review and the reporting behavior of the two central pathologists. Eight hundred women with HER2-negative early invasive breast cancer were recruited for the study. Response to chemotherapy was assessed from local pathology reports for pathological complete response in breast and axillary lymph nodes. Sections from the original core biopsy and surgical excision were centrally reviewed by one of the two trial pathologists, who was blinded to the local pathology reports. The pathologists recorded response to chemotherapy descriptively and calculated residual cancer burden. Ten percent of the cases were double reported to compare the central pathologists’ reporting behavior. Full sample retrieval was obtained for 681 of the 781 (87 percent) patients who underwent surgery within the trial and were evaluable for pathological complete response. A total of 483 (71 percent) were assessed by one of the pathologists and 198 (29 percent) by the other. Residual cancer burden calculations were possible in 587 of 681 (86 percent) of the centrally reviewed patients, as 94 of the 681 (14 percent) had positive sentinel nodes removed before neoadjuvant chemotherapy, invalidating residual cancer burden scoring. Good concordance between the two pathologists was noted for residual cancer burden classes within the 65-patient quality assurance exercise (kappa, 0.63; 95 percent confidence interval, 0.57–0.69). The investigators obtained similar results for the between-treatment arm comparison, both from the report review and the central pathology review. For pathological complete response, the report review was as good as central pathology review. For minimal residual disease, the report review overestimated the extent of residual disease. In the ARTEMIS trial, central pathology review added little to the determination of pathological complete response, but it played a role in evaluating low levels of residual disease. Calculation of residual cancer burden was a simple and reproducible method of quantifying response to neoadjuvant chemotherapy, as demonstrated by comparing the performance of the two pathologists.

Thomas JSJ, Provenzano E, Hiller L, et al, for the ARTEMIS Investigators Group. Central pathology review with two-stage quality assurance for pathological response after neoadjuvant chemotherapy in the ARTEMIS trial. Mod Pathol. 2017;30:1069–1077.

Correspondence: Dr. J. S. J. Thomas at jeremy.thomas@nhslothian.scot.nhs.uk or jstjthomas@gmail.com

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Prognostic value of histologic grade 1 in lower gastrointestinal graft versus host disease

Histologic confirmation is a standard practice to diagnose gastrointestinal graft versus host disease and is often used in making treatment decisions. A histologic grade is often determined in patients diagnosed with the disease. Although extensive crypt loss (histologic grade 4) is associated with high nonrelapse mortality, the prognostic value of the more common grade 1 is poorly understood. Because clinical decisions are made based on the degree of histologic evidence, it is important to establish the prognostic significance of grade 1. Therefore, the authors evaluated 309 patients, between 2009 and 2012, who underwent endoscopic biopsy for suspected gastrointestinal graft versus host disease (GI GVHD) within six months post-transplant. The presence of histologic grade 1 in patients with lower GI GVHD, but not isolated upper GI GVHD, was associated with increased nonrelapse mortality (hazard ratio, 2.7; P = .02) when compared with the nonrelapse mortality for patients with negative biopsies. Multivariate competing-risk regression analysis confirmed the independent impact of histologic grade 1 in patients with early clinical stages of lower GI GVHD (stages 0 to 2; hazard ratio, 2.7; P = .044). When compared with advanced histologic grades, histologic grade 1 did not lessen the adverse outcome for patients with advanced lower GI GVHD (stages 3 to 4; cumulative incidence nonrelapse mortality, 84 percent). The authors concluded that the presence of histologic grade 1 is associated with increased nonrelapse mortality in patients presenting with lower GI GVHD (stages 0 to 2) and is sufficient support for the decision to initiate therapy. At the same time, histologic grade 1 does not lessen the markedly adverse impact of advanced lower GI GVHD (stages 3 to 4) and is not synonymous with mild GVHD.

Im JS, Abraham SC, Saliba RM, et al. Histologic grade 1 is associated with increased nonrelapsed mortality in lower gastrointestinal graft versus host disease. Am J Surg Pathol. 2017;41:1483–1490.

Correspondence: Dr. Amin M. Alousi at aalousi@mdanderson.org

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DCIS mutational driver events representative of invasive breast cancer

The spectrum of genomic alterations in ductal carcinoma in situ is relatively unexplored, yet it is likely to provide insights into DCIS’ biology, progression to invasive carcinoma, and risk of recurrence. The authors conducted a study in which they assessed DCIS (N=20) with a range of phenotypes by massively parallel sequencing for mutations and copy number alterations and variants validated by Sanger sequencing. They identified PIK3CA mutations in 11 of 20 (55 percent), TP53 mutations in six of 20 (30 percent), and GATA3 mutations in nine of 20 (45 percent). Screening an additional 91 cases for GATA3 mutations identified a final frequency of 27 percent (30 of 111), with a high proportion of missense variants (eight of 30). TP53 mutations were exclusive to high-grade DCIS and more frequent in progesterone receptor-negative tumors than in progesterone receptor-positive tumors (P = .037). TP53 mutant tumors also had a significantly higher fraction of the genome altered by copy number than did wild-type tumors (P = .005), including a significant positive association with amplification or gain of ERBB2 (P<.05). The association between TP53 mutation and ERBB2 amplification was confirmed in a wider DCIS cohort using p53 immunohistochemistry as a surrogate marker for TP53 mutations (P = .03). RUNX1 mutations and MAP2K4 copy number loss were novel findings in DCIS. Frequent copy number alterations included gains on 1q, 8q, 17q, and 20q, and losses on 8p, 11q, 16q, and 17p. Patterns of genomic alterations observed in DCIS were similar to those previously reported for invasive breast cancers, with all DCIS having at least one bona fide breast cancer driver event. However, the authors noted an increase in GATA3 mutations and fewer copy number changes in DCIS than in invasive carcinomas. The role of such alterations as prognostic and predictive biomarkers of DCIS is an avenue for further investigation.

Pang JB, Savas P, Fellowes AP, et al. Breast ductal carcinoma in situ carry mutational driver events representative of invasive breast cancer. Mod Pathol. 2017;30:952–963.

Correspondence: Dr. K. L. Gorringe at kylie.gorringe@petermac.org

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Cutaneous eruptions in patients who received immune checkpoint blockade

Cutaneous eruptions are among the most common immune-related adverse events associated with antiprogrammed cell death protein 1/programmed cell death ligand 1 therapy. They are often characterized, clinically and histologically, as lichenoid. Nonlichenoid patterns may also occur and are likely to be encountered by surgical pathologists given the increasing clinical use of the aforementioned agents. The authors conducted a study to describe the histopathologic features of nonlichenoid cutaneous immune-related adverse events (IRAEs) in patients receiving antiprogrammed cell death protein 1/programmed cell death ligand 1 therapies for a variety of underlying advanced malignancies. The study included 16 patients, with 17 biopsied eruptions, from two academic institutions that had extensive experience administering and monitoring responses to immune checkpoint blockade and treating the potential side effects. Eruptions occurred a median of 10 days (range, one day to 11.4 months) after treatment was initiated. Nearly half of the specimens demonstrated a psoriasiform/spongiotic or an urticarial-type reaction pattern on histologic review. Patterns consistent with Grover disease, bullous pemphigoid, and granulomatous dermatitis were also observed. Nearly two-thirds of patients required systemic corticosteroids for treatment of the cutaneous IRAE, and 19 percent of patients discontinued immunotherapy due to skin eruptions. Seventy-five percent of patients showed an objective antitumor response. The authors concluded that the diverse array of nonlichenoid cutaneous IRAEs presented in their study should reflect and inform the scope of histologic patterns encountered by the practicing surgical pathologist. Such eruptions are seen in patients with a variety of underlying tumor types, many of whom ultimately demonstrate a favorable response to immune checkpoint blockade.

Kaunitz GJ, Loss M, Rizvi H, et al. Cutaneous eruptions in patients receiving immune checkpoint blockade: clinicopathologic analysis of the nonlichenoid histologic pattern. Am J Surg Pathol. 2017;41:1381–1389.

Correspondence: Dr. Janis M. Taube at jtaube1@jhmi.edu

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Correlation of immune phenotype with IDH mutation in diffuse glioma

Tumor-infiltrating lymphocytes and programmed death ligand 1 are targets of immune checkpoint inhibitors. Forty-three World Health Organization grade II/III gliomas (39 IDH-mutant [mut] and four IDH-wild-type [wt]) and 14 IDH-mut glioblastomas were analyzed for tumor-infiltrating lymphocyte (CD3+; PD1+) infiltration and programmed death ligand 1 (PD-L1) expression in a study. The results were compared with the data from a previously published series of 117 IDH-wt glioblastomas. PD-L1 gene-expression levels were evaluated in 677 diffuse gliomas (grades II–IV) from The Cancer Genome Atlas database. Tumor-infiltrating lymphocyte and PD-L1 expression were observed in approximately half of the World Health Organization grade II/III gliomas. IDH-wt status was associated with significantly higher tumor-infiltrating lymphocyte infiltration and PD-L1 expression among all (grades II–IV) cases (n = 174; P<.001) and within the cohort of glioblastomas (n = 131; P<.001). In the low-grade glioma and glioblastoma cohorts of The Cancer Genome Atlas, significantly higher PD-L1 gene-expression levels were evident in IDH-wt compared with IDH-mut samples (low-grade glioma: N = 516, P =1.933e-11; glioblastoma: N = 161, P<.009). Lower PD-L1 gene expression was associated with increased promoter methylation (Spearman correlation coefficient, –0.36; P<.01) in the low-grade glioma cohort of The Cancer Genome Atlas. IDH-mut gliomas had higher PD-L1 gene promoter methylation levels than IDH-wt gliomas (P<.01). The authors concluded that the immunological tumor microenvironment of diffuse gliomas differs in association with IDH mutation status. IDH-wt gliomas display a more prominent tumor-infiltrating lymphocyte infiltration and higher PD-L1 expression than IDH-mut cases. This may be, at least in part, due to differential PD-L1 gene promoter methylation levels. The authors’ findings may be relevant for immune modulatory treatment strategies in glioma patients.

Berghoff AS, Kiesel B, Widhalm G, et al. Correlation of immune phenotype with IDH mutation in diffuse glioma. Neuro Oncol. 2017;19:1460–1468.

Correspondence: Dr. Matthias Preusser at matthias.preusser@meduniwien.ac.at

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P16 immunohistochemistry in high-risk HPV-related oropharyngeal SCC

High-risk human papillomavirus-related oropharyngeal squamous cell carcinomas have a more favorable prognosis than HPV-negative ones. P16 immunohistochemistry has been recommended as a prognostic test in clinical practice. Several p16 antibodies are available, and their performance has not been directly compared. The authors evaluated three commercially available p16 antibody clones—E6H4, JC8, and G175-405—using 199 cases of oropharyngeal squamous cell carcinoma from a tissue microarray, read by three pathologists using three different cutoffs for positivity—any staining, more than 50 percent, and more than 75 percent. The positive predictive values for high-risk HPV status by RNA in situ hybridization for the E6H4, JC8, and G175-405 clones were 98 percent, 100 percent, and 99 percent at the 75 percent cutoff, but the negative predictive values were much more variable, at 86 percent, 69 percent, and 56 percent, respectively. These improved using the 50 percent cutoff, becoming similar for all three antibodies. Intensity varied substantially, with 85 percent of E6H4, 72 percent of JC8, and 67 percent of G175-405 showing strong (3+) intensity. With Kaplan-Meier survival plots at the 75 percent cutoff, the E6H4 clone showed the largest differential in disease-specific and overall survival between p16-positive and p16-negative results. Reducing the cutoff to 50 percent increased correlation with HPV in situ hybridization and improved the survival differential for the JC8 and G175-405 clones without decreasing performance for the E6H4 clone. Interobserver agreement was also assessed by kappa scores and was highest for the E6H4 clone. Overall, these study results show modest but important performance differences between the three p16 antibody clones, suggesting that the E6H4 clone performs best because it has the strongest staining intensity, greatest differential in outcomes between positive and negative results, lowest interobserver variability, and lowest background, nonspecific staining. The results also suggest that a 75 percent cutoff is very functional but that, in this patient population with high HPV incidence, cutoffs of 50 percent and any staining may be more effective, particularly for the non-E6H4 clones.

Shelton J, Purgina BM, Cipriani NA, et al. P16 immunohistochemistry in oropharyngeal squamous cell carcinoma: a comparison of antibody clones using patient outcomes and high-risk human papillomavirus RNA status. Mod Pathol. 2017;30:1194–1203.

Correspondence: Dr. J. S. Lewis Jr. at james.lewis@vanderbilt.edu

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CTNNB1 mutation to identify endometrial cancer patients at risk of recurrence

Although the majority of patients with low-grade, early stage endometrial cancer will have good survival outcomes with surgery alone, those patients who recur tend to do poorly. Identifying the subset of patients who are at high risk of recurrence and would benefit from adjuvant treatment has been difficult. The authors conducted a study to evaluate the impact of somatic tumor mutation on survival outcomes in this patient population. For the study, low grade was defined as endometrioid FIGO grade 1 or 2, and early stage was defined as endometrioid stage I or II (disease confined to the uterus). Next-generation sequencing was performed using panels comprising 46 to 200 genes. Recurrence-free and overall survival were compared across gene mutational status in univariate and multivariate analyses. In all, 342 patients were identified, 245 of whom had endometrioid histology. For grades 1–2 and stages I–II endometrioid endometrial cancer patients, age (hazard ratio [HR], 1.07; 95 percent confidence interval [CI], 1.03–1.10), CTNNB1 mutation (HR, 5.97; 95 percent CI, 2.69–13.21), and TP53 mutation (HR, 4.07; 95 percent CI, 1.57–10.54) were associated with worse recurrence-free survival on multivariate analysis. When considering endometrioid tumors of all grades and stages, CTNNB1 mutant tumors were associated with significantly higher rates of grades 1–2 disease, lower rates of deep myometrial invasion, and lower rates of lymphatic/vascular space invasion. When both TP53 and CTNNB1 mutations were considered, the presence of either a TP53 mutation or CTNNB1 mutation remained a statistically significant predictor of recurrence-free survival on multivariate analysis and was associated with a more precise confidence interval (HR, 4.69; 95 percent CI, 2.38–9.24). Therefore, mutational analysis of a two‑gene panel of CTNNB1 and TP53 can help identify a subset of low-grade, early stage endometrial cancer patients who are at high risk of recurrence.

Kurnit KC, Kim GN, Fellman BM, et al. ­CTNNB1 (beta-catenin) mutation identifies low grade, early stage endometrial cancer patients at increased risk of recurrence. Mod Pathol. 2017;30:1032–1041.

Correspondence: Dr. R. R. Broaddus at rbroaddus@mdanderson.org

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