Sandra Krüger

PD-L1 is an independent prognostic predictor in gastric cancer of Western patients

Targeting the PD-1/PD-L1 immune checkpoint signaling is a novel promising treatment strategy in several tumor entities, and it is suggested that PD-L1/PD-1 expression is predictive for a PD-1/PD-L1 checkpoint inhibitor treatment response. We investigated the expression of PD-L1 and PD-1 by immunohistochemistry in a large and well characterized gastric cancer (GC) cohort of Caucasian patients, consisting of 465 GC samples and 15 corresponding liver metastases. Staining results were correlated with clinico-pathological characteristics and survival. PD-L1 expression was found in tumor cells of 140 GCs (30.1%) and 9 liver metastases (60%) respectively in immune cells of 411 GCs (88.4%) and 11 liver metastases (73.3%). PD-1 was expressed in tumor infiltrating lymphocytes in 250 GCs (53.8%) and in 11 liver metastases (73.3%). PD-L1 expression was significantly more prevalent in men, GCs of the proximal stomach, unclassified, papillary, Her2/neu-positive, Epstein-Barr-virus-positive, microsatellite instable, and PIK3CA-mutated GCs. A high PD-L1/PD-1 expression was associated with a significantly better patient outcome, and PD-L1 turned out to be an independent survival prognosticator. The correlation of PD-L1/PD-1 expression with distinct clinico-pathological patient characteristics may serve as a surrogate marker of PD-L1-positive GCs and may direct the use of immune checkpoint treatment strategies.

HER2/neu testing in primary colorectal carcinoma.

Background:Anti-HER2/neu therapy is well-established in breast and gastric carcinoma. The increased understanding of this pathway led to the identification of new promising drugs in addition to trastuzumab, offering further perspectives. The role of HER2/neu in colorectal carcinoma is controversially discussed, as discrepant data has been reported.Methods:Here, we retrospectively assessed the prevalence of HER2/neu positivity in a large series of colorectal carcinoma, testing HER2/neu status according to current recommendations. We correlated the results to clinico-pathological data and patient survival.Results:Overall, in 1645 primary colorectal carcinoma cases, 1.6% of the cases were HER2/neu positive. HER2/neu positivity significantly correlated with higher UICC stages (P=0.017) and lymph node metastases (P=0.029). In the subgroup of sigmoideal and rectal carcinomas, positive HER2/neu status was associated with T-category (P=0.041) and higher UICC stages (P=0.022). Although statistically not significant, HER2/neu-positive colorectal carcinomas displayed a tendency to poorer overall survival.Conclusions:These results illustrate the importance of testing HER2/neu by approved diagnostic techniques and scoring systems. We assume that although the prevalence of HER2/neu positivity in colorectal carcinoma is low, HER2/neu testing in advanced, nodal-positive colorectal carcinoma is reasonable, offering a potential target in high risk colorectal carcinoma.

Melanomas of unknown primary frequently harbor TERT-promoter mutations.

Commonly, in patients with melanoma metastases of an unknown primary tumor (MUP), an extensive search for the primary tumor is carried out. Recently, highly recurrent telomerase reverse transcriptase (TERT)-promoter mutations were found in malignant melanomas, which may function as driver mutations of skin cancer. The aim of this study was to test the hypothesis that MUP and mucosal melanomas harbor different prevalences of TERT-promoter mutations. Thirty-nine patients with MUP and 53 patients with mucosal melanomas were retrieved. In total, 152 paraffin samples of 92 patients were analyzed, and in 38 patients, multiple samples were tested. Mutational analysis of the TERT-promoter, BRAF, NRAS, and KIT genes was carried out. In total, 92 patients were eligible for mutational analysis. TERT-promoter mutations were found in 33 patients (35.9%): chr5, 1,295,228 C>T (18 patients); chr5, 1,295,250 C>T (11 patients); chr5, 1,295,228–229 CC>TT (three patients); chr5, 1,295,242–243 CC>TT (one patient). The mutations were significantly more prevalent in MUP [26 (66.7%)] than in mucosal melanomas [seven patients (13.2%); P<0.001]. In MUP, BRAF mutations were found in 46.2% of patients (18 patients) and NRAS mutations in 28.2% of patients (11 patients). In mucosal melanoma, NRAS mutations were found in 18.9% of patients (10), and BRAF and KIT mutations in 7.5% of patients (four patients), respectively. The prevalence of TERT-promoter mutations was associated with the patients sex [23 (51.1%) men, 10 (21.3%) women; P=0.004]. No significant correlation was found between TERT-mutation and patient survival. The TERT-promoter genotype of MUP points toward a cutaneous and not mucosal origin. The significant sex differences merit further attention in having putative therapeutic implications.

Metastatic melanoma of unknown primary resembles the genotype of cutaneous melanomas

BACKGROUND Although 90% of all melanomas are of cutaneous origin, some patients present with melanoma metastases of unknown origin (MUP). Commonly, in these patients an extensive search for the primary tumor is carried out. In the past, genetic analyses have shown substantial differences in pathogenetic mutations among cutaneous, acral and mucosal melanomas. The aim of this study was to assess the mutational status of MUP in order to better characterize the putative origin of the primary tumor and to evaluate potential prognostic factors. PATIENTS AND METHODS The medical records of 44 patients with MUP were analyzed and a survival analysis was conducted. In total, 66 paraffin samples of 44 patients were analyzed, and in 15 patients multiple metastases were tested. Mutational analysis of the BRAF, NRAS and KIT genes was carried out. RESULTS Twenty-three patients (52.3%) had a mutation in the BRAF gene and 12 patients (23.8%) had a mutation in the NRAS gene. There were neither mutations in the KIT gene. In patients with multiple samples, there was 100% consistency regarding mutational status among the different metastases. The median overall survival (OS) was 86.4 months (39-134). The American Joint Committee on Cancer stage at first diagnosis of metastatic melanoma (stage III versus IV) was significantly associated with OS (P < 0.001), BRAF or NRAS mutation status had no significant prognostic impact on clinical outcomes. CONCLUSIONS MUP resembles the genotype of cutaneous melanoma and not that of mucosal melanomas.

MET in gastric cancer – discarding a 10% cutoff rule

We aimed to develop a putative predictive biomarker score for future hepatocyte growth factor receptor (MET)‐targeted therapy of gastric cancer (GC).

The novel negative checkpoint regulator VISTA is expressed in gastric carcinoma and associated with PD-L1/PD-1: A future perspective for a combined gastric cancer therapy?

ABSTRACT A combined blockade of V-domain Ig suppressor of T-cell activation (VISTA) and PD-1 is a promising new cancer treatment option, which was efficient in murine tumor models and is currently tested in first phase I studies. Here, we analyzed the VISTA expression in a large and well-characterized gastric cancer (GC) cohort on 464 therapy-naive GC samples and 14 corresponding liver metastases using immunohistochemistry. Staining results were correlated with clinico-pathological characteristics, genetic alterations and survival. VISTA expression in tumor cells was detected in 41 GCs (8.8%) and 2 corresponding liver metastases (14.3%). Moreover, VISTA expression in immune cells was observed in 388 GCs (83.6%) and 6 liver metastases (42.9%). VISTA expression was associated with the Laurén phenotype, tumor localization, Epstein–Barr virus infection, KRAS- and PIK3CA-mutational status and PD-L1 expression. There was no significant correlation with patient outcome. Moreover, a change of VISTA expression in immune cells during tumor progression was observed. The co-incidence of VISTA and PD-L1 expression indicates a dual immune evasion mechanism of GC tumor cells and makes GC an interesting target for novel combined immune checkpoint inhibitor treatments.

Clinicopathologic Characteristics of Microsatellite Instable Gastric Carcinomas Revisited: Urgent Need for Standardization

Microsatellite instable gastric cancer (MSI-GC) is a specific molecular subtype of GC. We studied the phenotypes, genotypes, and clinicopathologic characteristics of MSI-GC in a white GC cohort and compared our findings with an extended literature review. The study cohort consisted of 482 patients. Specimens were available from 452 cases and were used for immunostaining (MLH1, PMS2, MSH2, MSH6) and molecular biological analyses (BAT-25, BAT-26, NR-21, NR-24, NR-27; Epstein-Barr virus in situ hybridization). Thirty-four (7.5%) GCs were MSI. Loss of MLH1 and/or PMS2 was found in 30 (88%) MSI-GC, 3 (9%) showed loss of MSH2 and/or MSH6. One (3%) MSI-GC was identified only by molecular biological testing. A single case was heterogeneous and contained microsatellite-stable and instable tumor areas. Twenty-one (62%) MSI-GCs showed unusual histologic features. MSI-GC was not found in diffuse-type or Epstein-Barr virus-positive GC. MSI-GC was significantly more prevalent in elderly patients, distal stomach, and was associated with a significantly lower number of lymph node metastases and a significantly better overall and tumor-specific survival. MSI-GC constitutes a small but relevant subgroup of GC with distinct clinicopathologic characteristics. Our literature review illustrates the shortcomings of missing standardized testing algorithms with prevalences of MSI-GC ranging from 0% to 44.5%. Future studies should test the hypothesis that patients with MSI-GCs may not need adjuvant/perioperative chemotherapy. However, this will require a standardized, quality-controlled diagnostic algorithm of MSI for GC.

Clinicopathological characteristics of RHOA mutations in a Central European gastric cancer cohort

Genomically stable gastric cancers (GCs) are enriched for the diffuse phenotype and hotspot mutations of RHOA. Here we aimed to validate the occurrence, phenotype and clinicopathological characteristics of RHOA mutant GCs in an independent Central European GC cohort consisting of 415 patients. The RHOA genotype (exon 2 and 3) was correlated with various genotypic, phenotypic and clinicopathological patient characteristics. Sixteen (3.9%) tumours had a RHOA mutation including four hitherto unreported mutations, that is, p.G17Efs*24, p.V24F, p.T37A and p.L69R. RHOA mutation was more prevalent in women (5.4% vs 2.8%), distal GCs (4.5% vs 2.4%), in poorly differentiated GCs (G3/G4; 4.8% vs 1.1%), T1/T2 tumours (6.2% vs 3.1%) and lacked distant metastases. Nine RHOA mutant GCs had a diffuse, four an intestinal, two an unclassified and one a mixed Laurén phenotype. KRAS and RHOA mutations were mutually exclusive. A single case showed both a RHOA and a PIK3CA mutation. No significant difference was found in the overall survival between RHOA mutant and wildtype GCs. Our study confirms the occurrence and clinicopathological characteristics of RHOA hotspot mutations in an independent patient cohort. However, we found no evidence for a prognostic or growth advantageous effect of RHOA mutations in GC.

MALDI-mass spectrometry imaging identifies vitronectin as a common constituent of amyloid deposits.

Amyloids are pathological intra- and extracellular fibrillar aggregates of polypeptides with a cross-β-sheet structure and characteristic tinctorial properties. The amyloid deposits commonly enclose several non-fibrillar components of the extracellular matrix. Their potential to regulate the formation and aggregation process of amyloid fibrils is still poorly understood. For a better understanding of the role of the extracellular matrix in amyloidosis, it is essential to gain deeper insights into the composition of amyloid deposits. Here, we utilized matrix-assisted laser desorption and ionization mass spectrometry imaging to identify extracellular matrix compounds in amyloid deposits. Using this technique, we identified and determined the spatial distribution of vitronectin within AApoAI-, ALλ-, ATTR- and AIns amyloid deposits and, using immunohistochemistry, validated the spatial overlap of vitronectin with amyloids in 175 cases with diverse types of amyloid in several different tissues.

PTAA and B10: new approaches to amyloid detection in tissue-evaluation of amyloid detection in tissue with a conjugated polyelectrolyte and a fibril-specific antibody fragment.

Aims: We analysed the suitability of two little known substances for the detection of amyloid in surgical pathology specimens, that is the conjugated polyelectrolyte polythiophene acetic acid (PTAA) and the camelid antibody domain B10. Methods: We compared the amyloid detection of PTAA and B10 to Congo red in 106 amyloid-containing tissue biopsies of diverse anatomical and precursor origin by evaluating the accordance in four grades (grade 0: no staining, grade 1: staining of <33% of the amyloid deposits, grade 2: 33–66% and grade 3: >66%). Results: PTAA showed grade 2–3 staining in 57 (54%) cases, while B10 presented this accordance in only 25 (24%) tissue biopsies. Grade 1 staining was found in 11 (10%) samples with PTAA and in 62 (58%) cases with B10. No staining at all (grade 0) occurred in 38 (36%) biopsies when using PTAA and in 19 (18%) cases when using B10. Conclusion: Although conformation-sensitive detection seemed promising, PTAA and B10 stain only a fraction of the examined amyloid samples when using routine surgical pathology settings. This study emphasises the necessity of having optimised pre-analytical protocols for recovery, storage and handling of samples if these novel amyloid ligands are to be used in routine diagnosis of amyloid.