Prognostic Factors across Poorly Differentiated Neuroendocrine Neoplasms: A Pooled Analysis

INTRODUCTION

Poorly differentiated neuroendocrine carcinomas (NECs) are characterized by aggressive clinical course and poor prognosis. No reliable prognostic markers have been validated to date; thus, the definition of a specific NEC prognostic algorithm represents a clinical need. This study aimed to analyze a large NEC case series to validate the specific prognostic factors identified in previous studies on gastro-entero-pancreatic and lung NECs and to assess if further prognostic parameters can be isolated.

METHODS

A pooled analysis of four NEC retrospective studies was performed to evaluate the prognostic role of Ki-67 cut-off, the overall survival (OS) according to primary cancer site, and further prognostic parameters using multivariable Cox proportional hazards model and machine learning random survival forest (RSF).

RESULTS

422 NECs were analyzed. The most represented tumor site was the colorectum (n = 156, 37%), followed by the lungs (n = 111, 26%), gastroesophageal site (n = 83, 20%; 66 gastric, 79%) and pancreas (n = 42, 10%). The Ki-67 index was the most relevant predictor, followed by morphology (pure or mixed/combined NECs), stage, and site. The predicted RSF response for survival at 1, 2, or 3 years showed decreasing survival with increasing Ki-67, pure NEC morphology, stage III-IV, and colorectal NEC disease. Patients with Ki-67 <55% and mixed/combined morphology had better survival than those with pure morphology. Morphology pure or mixed/combined became irrelevant in NEC survival when Ki-67 was ≥55%. The prognosis of metastatic patients who did not receive any treatment tended to be worse compared to that of the treated group. The prognostic impact of Rb1 immunolabeling appears to be limited when multiple risk factors are simultaneously assessed.

CONCLUSION

The most effective parameters to predict OS for NEC patients could be Ki-67, pure or mixed/combined morphology, stage, and site.

Ki-67 Index of 55% Distinguishes Two Groups of Bronchopulmonary Pure and Composite Large Cell Neuroendocrine Carcinomas with Distinct Prognosis

BACKGROUND

Little information is available concerning prognostic factors for bronchopulmonary large cell neuroendocrine carcinomas (BP-LCNECs) and even less is known about combined LCNECs (Co-LCNECs). We investigated whether an integrated morphological, immunohistochemical, and molecular approach could be used for their prognostic evaluation.

METHODS

Morphological (including combined features), proliferative (mitotic count/Ki-67 index), immunohistochemical (napsin A, p40, TTF-1, CD44, OTP, SSTR2A, SSTR5, mASH1, p53, RB1, and MDM2), and genomic (TP53, RB1, ATM, JAK2, KRAS, and STK11) findings were analyzed in BP-LCNECs from 5 Italian centers, and correlated with overall survival (OS). The Ki-67 index was expressed as the percentage of positive cells in hot spots as indicated in the WHO 2019 Digestive System Tumors and, for Co-LCNECs, the Ki-67 index was evaluated only in the LCNEC component.

RESULTS

A total of 111 LCNECs were distinguished into 70 pure LCNECs, 35 Co-LCNECs (27 with adenocarcinoma [ADC] and 8 with squamous cell carcinoma [SqCC]), and 6 LCNECs with only napsin A immunoreactivity. The Ki-67 index cutoff at 55% evaluated in the neuroendocrine component was the most powerful predictor of OS (log-rank p = 0.0001) in all LCNECs; 34 cases had a Ki-67 index <55% (LCNEC-A) and 77 had a Ki-67 index ≥55% (LCNEC-B). Statistically significant differences in OS (log-rank p = 0.0001) were also observed between pure and Co-LCNECs. A significant difference in OS was found between pure LCNECs-A and Co-LCNECs-A (p < 0.05) but not between pure LCNECs-B and Co-LCNECs-B. Co-LCNEC-ADC and LCNEC napsin A+ cases had longer OS than pure LCNEC and Co-LCNEC-SqCC cases (log-rank p = 0.0001). On multivariable analysis, tumor location, pure versus combined features, and napsin A, but no single gene mutation, were significantly associated with OS after adjustment for Ki-67 index and study center (p < 0.05).

CONCLUSIONS

The Ki-67 proliferation index and the morphological characterization of combined features in LCNECs seem to be important tools for predicting clinical outcome in BP-LCNECs.

Gastroenteropancreatic High-Grade Neuroendocrine Neoplasms: Histology and Molecular Analysis, Two Sides of the Same Coin

BACKGROUND

In gastroenteropancreatic (GEP) high-grade neuroendocrine neoplasms (H-NENs), Ki-67 threshold of 55% defines three prognosis subclasses: neuroendocrine tumor (NET) G3, neuroendocrine carcinoma (NEC) <55%, and NEC ≥55%. We investigated whether the molecular profiling of H-NENs differs among these subcategories and evaluated potential therapeutic targets, including PD-L1.

METHODS

In GEP-NEN patients, we evaluated: (i) 55% threshold for Ki-67 labeling index for further stratifying NEC and (ii) immunoreactivity and gene mutations by immunohistochemistry and targeted next-generation sequencing (T-NGS).

RESULTS

Fifteen NETs G3 and 39 NECs were identified. Ki-67 labeling index was <55% in 9 NECs and ≥55% in 30 NECs. Gene mutations by NGS (TP53, 32.9%; KRAS, 5.5%; BRAF, 4.1%) were detected in 46.6% NENs, significantly enriched in NEC ≥55% (76.7%) compared to NEC <55% (55.6%) or NET (20.0%). PD-L1 staining in tumor-infiltrating lymphocytes was observed in NEC ≥55% (36.7%; p = 0.03). Median OS was 4.3 years in NET G3, 1.8 years in NEC <55%, and 0.7 years in NEC ≥55% (p <0.0001); it was 2.3 years with NGS wild-type, 0.7 years with ≥1 mutation (p <0.0001), 0.8 years in PD-L1-positive patients, and 1.7 years in PD-L1-negative subjects (p = 0.0004). In multivariate analysis, only the proposed subclassification approach yielded statistically significant differences between groups (NEC <55% vs. NET G3, HR 14.1, 95% CI 2.2-89.8, p = 0.005; NEC ≥55% vs. NET G3, HR 25.8, 95% CI 3.9-169, p = 0.0007).

CONCLUSIONS

These findings identify NEC ≥55% as a biologically and prognostically distinct subtype and pave the way for more personalized treatment.

Microenvironment and tumor inflammatory features improve prognostic prediction in gastro-entero-pancreatic neuroendocrine neoplasms

Microenvironment‐related immune and inflammatory markers, when combined with established Ki‐67 and morphology parameters, can improve prognostic prediction in gastro‐entero‐pancreatic neuroendocrine neoplasms (GEP‐NENs). Therefore, we evaluated the prognostic value of microenvironment and tumor inflammatory features (MoTIFs) in GEP‐NENs. For this purpose, formalin‐fixed paraffin‐embedded tissue sections from 350 patients were profiled by immunohistochemistry for immune, inflammatory, angiogenesis, proliferation, NEN‐, and fibroblast‐related markers. A total of 314 patients were used to generate overall survival (OS) and disease‐free survival (DFS) MoTIFs prognostic indices (PIs). PIs and additional variables were assessed using Cox models to generate nomograms for predicting 5‐year OS and DFS. A total of 36 patients were used for external validation of PIs and nomograms' prognostic segregations. From our analysis, G1/G2 versus G3 GEP‐NENs showed phenotypic divergence with immune‐inflammatory markers. HLA, CD3, CD8, and PD‐1/PD‐L1 IHC expression separated G3 into two sub‐categories with high versus low adaptive immunity‐related features. MoTIFs PI for OS based on COX‐2^Tumor(T) > 4, PD‐1^Stromal(S) > 0, CD8^S < 1, and HLA‐I^S < 1 was associated with worst survival (hazard ratio [HR] 2.50; 95% confidence interval [CI], 2.12–2.96; p < 0.0001). MoTIFs PI for DFS was based on COX‐2^T > 4, PD‐1^S > 4, HLA‐I^S < 1, HLA‐I^T < 2, HLA‐DR^S < 6 (HR 1.77; 95% CI, 1.58–1.99; p < 0.0001). Two nomograms were developed including morphology (HR 4.83; 95% CI, 2.30–10.15; p < 0.001) and Ki‐67 (HR 11.32; 95% CI, 5.28–24.24; p < 0.001) for OS, and morphology (PI = 0: HR 10.23; 95% CI, 5.67–18.47; PI = 5: HR 2.87; 95% CI, 1.21–6.81; p < 0.001) and MoTIFs PI for DFS in well‐differentiated GEP‐NENs (HR 6.21; 95% CI, 2.52–13.31; p < 0.001). We conclude that G1/G2 to G3 transition is associated with immune‐inflammatory profile changes; in fact, MoTIFs combined with morphology and Ki‐67 improve 5‐year DFS prediction in GEP‐NENs. The immune context of a subset of G3 poorly differentiated tumors is consistent with activation of adaptive immunity, suggesting a potential for responsiveness to immunotherapy targeting immune checkpoints.

Integration of transcriptional and mutational data simplifies the stratification of peripheral T-cell lymphoma

The histological diagnosis of peripheral T-cell lymphoma (PTCL) can represent a challenge, particularly in the case of closely related entities such as angioimmunoblastic T-lymphoma (AITL), PTCL-not otherwise specified (PTCL-NOS), and ALK-negative anaplastic large-cell lymphoma (ALCL). Although gene expression profiling and next generations sequencing have been proven to define specific features recurrently associated with distinct entities, genomic-based stratifications have not yet led to definitive diagnostic criteria and/or entered into the routine clinical practice. Herein, to improve the current molecular classification between AITL and PTCL-NOS, we analyzed the transcriptional profiles from 503 PTCLs stratified according to their molecular configuration and integrated them with genomic data of recurrently mutated genes (RHOA ^G17V , TET2, IDH2 ^R172 , and DNMT3A) in 53 cases (39 AITLs and 14 PTCL-NOSs) included in the series. Our analysis unraveled that the mutational status of RHOA ^G17V , TET2, and DNMT3A poorly correlated, individually, with peculiar transcriptional fingerprints. Conversely, in IDH2 ^R172 samples a strong transcriptional signature was identified that could act as a surrogate for mutational status. The integrated analysis of clinical, mutational, and molecular data led to a simplified 19-gene signature that retains high accuracy in differentiating the main nodal PTCL entities. The expression levels of those genes were confirmed in an independent cohort profiled by RNA-sequencing.

PD-L1, LAG3, and HLA-DR are increasingly expressed during smoldering myeloma progression

Symptomatic multiple myeloma (MM) is a plasma cell neoplasm that represents the final stage of a continuum of clinical conditions that start from monoclonal gammopathy of unknown significance (MGUS), then transits in the more advance, but still asymptomatic, smoldering MM (SMM), with a final evolution in symptomatic MM. To investigate SMM microenvironment modifications, we studied 16 patients diagnosed at our hospital. Eight of them (group A) developed MM within 2 years from diagnosis while the others (group B) had stable SMM. Samples were bone marrow biopsies at diagnosis and after 2 years (± 4 months) and were analyzed by immunohistochemical analysis. Firstly, we found a significant increase in both CD4+ cells (11 vs 17%, p < 0.01) and CD8+ cells (15 vs 18%, p < 0.01) between diagnosis and at follow-up samples (whole cohort). This was associated to an increase in the CD4+/CD8+ ratio (0.74 vs 0.93, p < 0.01). Secondly, we discovered an increased expression of T cell inhibitory molecules during SMM evolution. In fact, plasma cell PD-L1 and microenvironment cell LAG3 expression increased from 1 to 12% (p = 0.03) and 4 to 10% (p = 0.04), respectively, from diagnosis to follow-up. Also, plasma cells and microenvironment cells HLA-DR expression augmented during SMM evolution from 7 to 10% (p = 0.04) and 29 to 39% (p = 0.01), respectively. When comparing group A vs group B, we found an increased CD68-KP1+ cell infiltration in favor of group B at diagnosis (23 vs 28%, p = 0.01) and a greater plasma cell infiltration at follow-up (50 vs 26%, p < 0.01). Our findings suggest how immune escape mechanisms appear earlier during multiple myeloma evolution, and that LAG3 could be a possible immunologic target in this setting.

Abstract 3123: Peripheral T cell lymphoma-associated fibroblasts promote tumor growth in an in vivo model

Peripheral T-cell lymphomas (PTCLs) represent a rare and heterogeneous group of aggressive non-Hodgkin's lymphomas comprising different entities. Anthracycline-based regimens (usually CHOP, cyclophosphamide/doxorubicin/vincristine/prednisone) followed by stem cell transplantation are considered the standard of care in the front-line setting. However, long-term disease control can be achieved only in 30-40% of young patients. Increasing evidences highlight the role of tumor microenvironment in sustaining tumor progression and aggressiveness. Among microenvironment components, a central role is played by cancer associated fibroblast (CAFs). Recent studies demonstrated that this is applicable not only to solid tumors but also to haematological malignancies. Here, we report for the first time the isolation and characterization of PTCL-CAFs and their role in promoting cell proliferation.

We kept in culture a skin biopsy of a cutaneous localization of a peripheral T cell lymphoma. Fibroblast-like cells grown out from the biopsy were isolated, cultivated for few passages and then characterized. Flow cytometric analyses revealed that the cell population entirely expressed cell-surface antigens specific for fibroblasts, such as CD140b and CD90, while they did not express CD45 and CD31, thus excluding hematopoietic or endothelial origin. Biochemical analyses confirmed that all cells were positive for vimentin, while αSMA expression highlighted the activated status of the cells isolated. We then assessed the in vitro effect of CAFs on PTCL cell growth by co-colture experiments. For this purpose, we coltured for 8 days the PTCL cell line OCI-Ly12 in fresh medium or in medium previously conditioned by CAFs or normal skin fibroblasts (NFs). PTCL cell growth was not affected by co-colture either with CAFs or with NFs. Moreover, the presence of conditioned medium did not alter the response of OCI-Ly12 cells to CHOP treatments. We then assessed the in vivo effect of PTCL-CAFs. We subcutaneously injected CAFs alone, OCI-Ly12 cells alone and OCI-Ly12 together with CAFs (ratio 1:1) in NOD/SCID mice and monitored tumor growth for 20 days. In contrast to the effect observed in vitro, co-injection of CAFs with cancer cells substantially promoted tumor growth (tumor volume OCI-Ly12 0,87±0,47 cm3; OCI-Ly12+CAFs 2,30±0,26 cm3). As expected, CAFs alone did not develop a measurable mass. Subsequent immunohistochemical staining with CD31 revealed the presence of more vascular structures in tumors originated by OCI-Ly12+CAFs co-injection than by OCI-Ly12 alone, suggesting that CAFs presence sustains tumor growth by promoting angiogenesis.

In summary, we show that PTCL-derived CAFs promote cancer cell growth in vivo, while leaving unaffected cell growth in vitro and the response to chemotherapy. This is the first evidence of the role played by the microenvironment in promoting malignant cell proliferation in PTCLs.

Citation Format: Martina Magni, Sara Rizzitano, Alessio Pellegrinelli, Paolo Corradini, Cristiana Carniti. Peripheral T cell lymphoma-associated fibroblasts promote tumor growth in an in vivo model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3123.

Ki67 proliferative index of the neuroendocrine component drives MANEC prognosis

Mixed adenoneuroendocrine carcinomas (MANECs) are composed of a poorly differentiated neuroendocrine carcinoma (NEC) and a non-neuroendocrine (non-NEC) neoplastic epithelial component, each representing at least 30% of the tumor. At present, prognostic factors for MANECs remain largely unexplored. We investigated the clinical-pathologic features of a large multicenter series of digestive system MANECs. Surgical specimens of 200 MANEC candidates were centrally reviewed; diagnosis was confirmed in 160 cases. While morphology, proliferation (mitotic count (MC), Ki67 index) and immunophenotype (p53, SSTR2a, beta-Catenin, Bcl-2, p16, Rb1, ALDH, mismatch repair proteins and CD117) were investigated separately in both components, genomic (TP53, KRAS, BRAF) alterations were searched for on the entire tumor. Data were correlated with overall survival (OS). MANEC sites were: 92 colorectal, 44 gastroesophageal and 24 pancreatobiliary. Median OS was 13.2 months. After adjustment for primary site, Ki67 index of the NEC component (but not of the non-NEC component) was the most powerful prognostic marker. At multivariable analysis, patients with Ki67 ≥ 55% had an 8-fold risk of death (hazard ratio (HR) 7.83; 95% confidence interval (CI) 4.17-14.7; P < 0.0001) and a median OS of 12.2 months compared to those with Ki67 < 55% (median OS 40.5 months). MC (HR 1.51; 95% CI 1.03-2.20, P = 0.04) was a weaker prognostic index. Colorectal primary site (HR 1.60; 95% CI 1.11-2.32; P = 0.01) was significantly associated with poorer survival. No single immunomarker, in either component, was statistically significant. This retrospective analysis of a large series of digestive system MANECs, showed that the NEC component, particularly its Ki67 index, was the main prognostic driver.

Histopathologic response and growth patterns of colorectal cancer liver metastases (CRCLM) in patients treated with triplets plus bevacizumab (bev) or anti-EGFRs

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Background: The histopathological response to pre-operative chemotherapy is associated with clinical outcome in patients (pts) undergoing secondary resection of CRCLM. Three different histopathological growth patterns (HGPs) of CRCLM have been described: desmoplastic (i.e. with a capsule of stroma separating tumor and normal cells), pushing (i.e. with limited infiltration of normal hepatic plates by tumor cells) and replacement (i.e. with abundant infiltration of normal hepatic plates by tumor cells and vessel cooption). Methods: Histopathological parameters of response were evaluated in specimens from 159 pts who underwent secondary resection of CRCLM, after receiving triplet (FOLFOXIRI or COI) plus bev (N = 103) or anti-EGFR (N = 56) in 5 first-line clinical studies (TRIBE, MOMA, MACBETH, COI-B and COI-E). The aims of this analysis were to evaluate the prognostic role of histopathologic response and to investigate the prognostic role of HGPs and their potential different sensitivity to targeted agents. Results: When compared with partial (TRG 3) and no (TRG 4-5) pathologic response (N = 118), major response (TRG 1-2, N = 41) was associated with longer RFS (mRFS: 28.0 versus 11.0 mos, HR = 0.57, 95%CI = 0.39–0.86; p = 0.007) and OS (mOS: unreached versus 42.1 mos, HR = 0.54, 95%CI = 0.31-0.93; p = 0.027). No association of baseline clinical characteristics and RAS and BRAF status with major response was found. Major response was more frequent among pts treated with bev than with anti-EGFRs (OR = 2.83, 95%CI = 1.20–6.65; p = 0.015) and was associated with deepness of response as a continuous variable (HR = 1.02, 95% CI = 1.00–1.04; p = 0.011). In the desmoplastic HGP (N = 28) a higher percentage of major response was reported (57% vs 17% in pushing and 22% in replacement HGP, p < 0.001) and a numerical advantage from anti-EGFR vs bev was evident in terms of both major response and RFS. Conversely, in the pushing HGP (N = 66) a significant benefit from bev vs anti-EGFR in major response and RFS was observed. No difference was described in the replacement HGP (N = 65). Conclusions: The assessment of HGPs may be useful to predict benefit from available targeted agents.

IMP3 expression in small-intestine neuroendocrine neoplasms: a new predictor of recurrence

PURPOSE

Small-intestine neuroendocrine neoplasms are heterogeneous neoplasms arising from endocrine cells of the intestinal mucosa. Ki-67 is the main determinant of prognosis in neuroendocrine neoplasms. However, the search for new prognostic makers represents a key point with regard to small-intestine neuroendocrine neoplasms. The oncofetal protein IMP3 plays a role in cell growth and its expression has a prognostic value in lung neoplasms.

METHODS

From January 1998 to August 2015, all the consecutive small-intestine neuroendocrine neoplasms patients suitable for surgery were included: 51 patients (32 males, median age 68 years) had small-intestine neuroendocrine neoplasms classified according to the WHO 2010 classification. In all the cases IMP3 expression was evaluated on primary tumors and, when available, on nodal and distant metastases. The medical records and pathological slides of these patients were used to determine the clinical characteristics, pathological diagnoses, and outcome information.

RESULTS

The overall 5-year and 10-year survival rate were 53.9 and 42% respectively. At Cox proportional hazards regression grading was the major factor influencing both OS and progression-free survival at univariate (p = 0.0002 and 0.0051, respectively) and multivariate analysis (p = 0.0004 and 0.0043, respectively). Also IMP3 expression at the nodal metastases resulted a factor significantly associated with progression-free survival at both univariate (p = 0.0066) and multivariate analysis (p = 0.0059, HR 3.58). IMP3 expression did not correlate with the Ki-67 (p = n.s.).

CONCLUSIONS

In this study, IMP3 at the nodal site resulted to be associated with low progression-free survival in small-intestine neuroendocrine neoplasms, independently of the Ki-67 index. We suggest that the integration of IMP3 and Ki-67 would help better stratify the risk of progression in small-intestine neuroendocrine neoplasms.

Dose-Dense Temozolomide in Patients with MGMT-Silenced Chemorefractory Colorectal Cancer

BACKGROUND

In a phase II study, we showed that temozolomide (TMZ) was tolerable and active in heavily pre-treated patients with advanced colorectal cancer (CRC) and MGMT methylation. A schedule of dose-dense TMZ may have enhanced activity due to the higher cumulative dose and induction of MGMT depletion, even in resistant tumors.

METHODS

Thirty-two patients with chemorefractory MGMT-methylated CRC were treated with TMZ at a daily dose of 75 mg/m(2) for 21 consecutive days every 4 weeks, for up to six cycles or until the occurrence of progressive disease/unacceptable toxicity. The primary endpoint was treatment activity in terms of objective response rate (ORR). MGMT protein expression was tested by immunohistochemistry (IHC) on two pooled cohorts: patients from the previous study of standard-dose TMZ and those from the current investigation.

RESULTS

From November 2013 to December 2014, 32 patients were treated at Fondazione IRCCS Istituto Nazionale dei Tumori. We observed only three episodes of grade 3 asthenia and no significant myelotoxicity. The ORR was 16 % (all partial responses occurring in RAS-BRAF-mutated tumors). Median progression-free survival (PFS) and overall survival (OS) were 2.3 and 6.7 months, respectively. Patients with MGMT-low expression by IHC had a significantly higher ORR (p < 0.0001) and PFS (p = 0.001) compared to those with MGMT-high expression, while no difference was observed in OS.

CONCLUSIONS

Our data confirm the encouraging activity of TMZ in chemorefractory CRC patients selected for MGMT silencing, even in the RAS-BRAF-mutated population. The role of MGMT IHC as a biomarker for improving patient selection warrants further prospective confirmation.

Loss of succinate dehydrogenase subunit B (SDHB) as a prognostic factor in advanced ileal well-differentiated neuroendocrine tumors

PURPOSE

Abnormal expression of succinate dehydrogenase, (SDH), in particular of the B subunit (SDHB), is implicated in the pathogenesis of neuroendocrine tumors. This study evaluates the distribution of SDHB in WHO grading G1 and G2 intestinal, well-differentiated neuroendocrine tumors and corresponding lymph node or liver metastases.

METHODS

We collected ileal well-differentiated neuroendocrine tumors specimens from consecutive patients with prior primary resection and distant synchronous or metachronous liver metastases. We obtained 195 specimens from primary tumors (n = 106) and metastases (n = 89). The expression (E) of SDHB and the immunostaining intensity (I) were evaluated semiquantitatively and combined into a single score. SDHB score was evaluated in primitive tumor and metastatic specimens.

RESULTS

SDHB was found in all tumor cells. Mean SDHB expression was 72.7 % ± 17.1 % in primitive specimens and 27.9 % ± 24.6 % in metastatic specimens (p < 0.0001). SDH intensity was higher in primitive specimens (p < 0.0001). SDHB score was 9-12 in 96 specimens of the primitive group and 2 metastatic specimens (p < 0.0001). None of the analyzed parameters was predictive of overall survival in the primitive subset. In the metastatic subset, loss of SDHB expression, intensity, and score were prognostic factors for survival. Lower expression and intensity of SDHB in metastatic lesions were associated with longer overall survival. When combining SDHB score and Ki-67 % in the metastatic subset, a lower SDHB score was associated with prolonged overall survival, independently from Ki-67 %.

CONCLUSIONS

SDHB score was different in primitive and metastatic specimens. The combination of SDHB score and Ki-67 % was a stronger predictor of overall survival than Ki-67 % alone. This stratification might help predict survival.

The Clinicopathologic Heterogeneity of Grade 3 Gastroenteropancreatic Neuroendocrine Neoplasms: Morphological Differentiation and Proliferation Identify Different Prognostic Categories

BACKGROUND/AIMS

Gastroenteropancreatic (GEP) neuroendocrine carcinomas (NECs) are defined as neuroendocrine neoplasms (NENs) with a Ki-67 index >20% according to the 2010 WHO classification. Some reports suggest that this category is heterogeneous. We retrospectively studied a series of 136 patients affected by grade 3 GEP-NECs with the aim to clarify the prognostic role of tumor morphological differentiation, proliferation, defect in mismatch repair proteins (MMRd), CD117 expression, and site of origin. The primary endpoint was the correlation between these parameters and the overall survival (OS).

METHODS

Univariate and multivariable Cox proportional hazards regression analyses were used to assess the prognostic significance of various clinical and histopathologic features.

RESULTS

With a median follow-up of 81 months, the median OS was 12.9 months. At multivariate analysis, morphological differentiation, Ki-67 index, MMRd, stage, and CD117 expression were independent prognostic markers in NECs. Three different prognostic categories of NECs were identified according to the degree of morphologic differentiation (well vs. poorly differentiated) and Ki-67 index (<55% vs. ≥55%). On this basis, median OS was 43.6 months in well-differentiated neoplasms with a Ki-67 index 20-55% (named type A), 24.5 months in poorly differentiated neoplasms with a Ki-67 index 20-55% (type B), and 5.3 months (p < 0.0001) in poorly differentiated neoplasms with a Ki-67 index ≥55% (type C).

CONCLUSIONS

The present study suggests that GEP-NECs represent a heterogeneous group of neoplasms which can be better classified in different prognostic categories using both tumor morphology and Ki-67 index.

Digital PCR assessment of MGMT promoter methylation coupled with reduced protein expression optimises prediction of response to alkylating agents in metastatic colorectal cancer patients

BACKGROUND

O(6)-methylguanine-DNA-methyltransferase (MGMT) is a repair protein, and its deficiency makes tumours more susceptible to the cytotoxic effect of alkylating agents. Five clinical trials with temozolomide or dacarbazine have been performed in metastatic colorectal cancer (mCRC) with selection based on methyl-specific PCR (MSP) testing with modest results. We hypothesised that mitigated results are consequences of unspecific patient selection and that alternative methodologies for MGMT testing such as immunohistochemistry (IHC) and digital polymerase chain reaction (PCR) could enhance patient enrolment.

PATIENTS AND METHODS

Formalin-fixed paraffin embedded archival tumour tissue samples from four phase II studies of temozolomide or dacarbazine in MGMT MSP-positive mCRCs were analysed by IHC for MGMT protein expression and by methyl-BEAMing (MB) for percentage of promoter methylation. Pooled data were then retrospectively analysed according to objective response rate, progression-free survival (PFS) and overall survival (OS).

RESULTS

One hundred and five patients were included in the study. Twelve had achieved partial response (PR) (11.4%), 24 stable disease (SD; 22.9%) and 69 progressive disease (PD; 65.7%). Patients with PR/SD had lower IHC scores and higher MB levels than those with PD. MGMT expression by IHC was negatively and MB levels positively associated with PFS (p < 0.001 and 0.004, respectively), but not with OS. By combining both assays, IHC low/MB high patients displayed an 87% reduction in the hazard of progression (p < 0.001) and a 77% in the hazard for death (p = 0.001).

CONCLUSION

In mCRC selected for MGMT deficiency by MSP, IHC and MB testing improve clinical outcome to alkylating agents. Their combination could enhance patient selection in this setting.

Heterogeneity of Acquired Resistance to Anti-EGFR Monoclonal Antibodies in Patients with Metastatic Colorectal Cancer

Purpose: Even if RAS-BRAF wild-type and HER2/MET-negative metastatic colorectal cancer (mCRC) patients frequently respond to anti-EGFR mAbs, acquired resistance almost invariably occurs. Mechanisms of resistance to EGFR blockade include the emergence of KRAS, NRAS, and EGFR extracellular domain mutations as well as HER2/MET alterations. However, these findings derive from retrospective studies that analyzed one single resistance mechanism at a time; moreover, it is still unclear how molecular heterogeneity affects clonal evolution in patients. In this work, we aimed at extensively characterizing and correlating the molecular characteristics of tissue- and blood-based data in a prospective cohort of patients with mCRC who received anti-EGFR antibodies.Experimental design: Twenty-two RAS-BRAF wild-type, HER2/MET-negative mCRC patients progressing on anti-EGFR therapy after initial response underwent rebiopsy. Next-generation sequencing and silver in situ hybridization (SISH)/IHC analyses were performed both on archival tumors and postprogression samples. Circulating tumor (ctDNA) molecular profiles were obtained in matched tissue-plasma samples.Results:RAS mutations and HER2/MET amplification were the most frequently detected resistance mechanisms in both tissue and blood sample analysis. On the other hand, BRAF and EGFR ectodomain mutations were much rarer. Patients with acquired MET amplification showed worse PFS on anti-EGFRs. We detected both intralesion heterogeneity, as suggested by co-occurrence of different resistance mechanisms in the same sample, and interlesion heterogeneity. The combined analysis of tissue and blood (ctDNA) results highlights the complexity of clonal evolution triggered by EGFR blockade.Conclusions: Our results indicate that it may be extremely challenging to target the complex landscape of molecular heterogeneity associated with emergence of resistance to targeted therapies in patients with mCRC. Clin Cancer Res; 23(10); 2414-22. ©2016 AACR.

Abstract B57: Comprehensive molecular characterization of acquired resistance to anti-EGFR monoclonal antibodies (MoAbs) in patients with metastatic colorectal cancer (mCRC)

Background: Acquired resistance to anti-EGFR MoAbs (cetuximab and panitumumab) represents a challenge in the treatment of mCRC, but its molecular mechanisms are not completely understood. Even in presence of RAS-BRAF-PI3KCA ”quadruple wt” and HER-2/MET negative status for protein expression and gene amplification, pts who primarily respond to anti-EGFR MoAbs will eventually develop secondary resistance. Prior retrospective and small series uniquely investigated a single biomarker, showing in some cases the emergence of KRAS mutations,HER-2 or MET amplifications. Our study aimed at comprehensively describing all known molecular alterations possibly associated with acquired resistance.

Methods: Pts with mCRC were prospectively treated with cetuximab- or panitumumab-based therapy until progressive disease. All archival tumors were defined as RAS-BRAF-PI3KCA”quadruple wt” by Sanger sequencing, as well as HER-2/MET negative by both immunohistochemistry (IHC) and in-situ hybridization (ISH). At the time of disease progression, tumor re-biopsy was performed on the most accessible site of metastasis, as institutional procedure for a wide phase 1 screening program. On both archival tissue and re-biopsy, next generation sequencing of 50 genes' hotspot regions included in the Hotspot Cancer Panel v2 (Life Technologies) was performed by using the Ion Torrent Personal Genome Machine platform (Life Technologies). Moreover,HER-2/MET status were repeated on tumor re-biopsy by IHC and ISH.

Results: Seventeen pts were recruited. All had prior objective response to anti-EGFRs. Next-generation sequencing confirmed RAS-BRAF-PI3KCA wt status on archival tumors. The results of our analyses on tumor re-biopsies are shown in the table:

IDNGS: Acquired mutations (% mutant alleles)cellularity% mutant alleles normalized for cellularityHER2 ISHMET ISH#1KRAS Q61H (37%)80%46%--#2-Amplified-#3BRAF V600E (13%)90%14%--#4NRAS Q61R (13%)40%32%--#5--Amplified#6KRAS Q61K (4%)70%6%&lt;10% cells Amplified-#7---#8---#9KRAS G12R (17%)50%34%--#10-Amplified-#11-Amplified-#12---#13---#14---#15--Amplified#16-Amplified-#17---

Acquired RAS or BRAF mutations were found in 4 (23%) and 1 (6%) cases, respectively. Acquired HER-2 or MET amplification were found in 4 (23%) and 2 (12%) cases, respectively. As shown for patient #6, some degree of intra-tumor heterogeneity may exist due to concomitant presence of low represented RAS-mutated and HER-2 amplified sub-clones. In some cases (35%), a detectable acquired mechanism of resistance remains unknown.

Conclusions: Based on our results, currently known molecular alterations associated with acquired resistance were mainly mutually exclusive. In a relevant subset of cases additional molecular profiling is warranted.

Citation Format: Filippo Pietrantonio, Rosa Berenato, Federica Perrone, Annunziata Gloghini, Elena Tamborini, Benedetta Picciani, Adele Busico, Giulio Settanni, Chiara Costanza Volpi, Ambra Vittoria Gualeni, Alessio Pellegrinelli, Massimo Milione, Marta Caporale, Monica Niger, Maria Di Bartolomeo, Filippo de Braud. Comprehensive molecular characterization of acquired resistance to anti-EGFR monoclonal antibodies (MoAbs) in patients with metastatic colorectal cancer (mCRC). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B57.

Analysis of NSCLC tumour heterogeneity, proliferative and 18F-FDG PET indices reveals Ki67 prognostic role in adenocarcinomas

AIMS

The role of tumour metabolic and proliferative indices in predicting non-small-cell lung cancer (NSCLC) patients' prognosis is unclear. We correlated fluorine 18 ((18) F)-fluorodeoxyglucose (FDG)-positron emission tomography (PET) value and Ki67 index to patients' survival, taking into account tumour heterogeneity, disease characteristics and genetic aberrations.

METHODS AND RESULTS

A series of 383 NSCLCs was arranged into tissue microarrays and Ki67 staining was analysed by immunohistochemistry. The maximum standardized uptake (SUV(MAX) ) value detected by (18) F-FDG-PET analysis was calculated over a region of interest. Large-cell and squamous cell carcinomas had higher proliferative and metabolic activities than adenocarcinomas, and the two measures were correlated significantly. The hot-spot Ki67 value was correlated with patients' survival and the cut-off to discriminate patients in the survival risk groups was 20%. Ki67 hot-spot values were greater in anaplastic lymphoma kinase (ALK) rearranged tumours. Adenocarcinomas showed the highest intratumour heterogeneity in proliferative activity and the hot-spot Ki67 value predicted only the prognosis of patients in this group. Although tumour metabolic activity was not associated with patients' prognosis, a SUV(MAX) > 2 was related to nodal metastases, tumour size and grade.

CONCLUSIONS

Our results highlight how tumour heterogeneity influences evaluation of prognostic biomarkers. Our data support Ki67 evaluation to estimate NSCLC patients' prognosis, particularly for adenocarcinoma.

Abstract LB-119: MGMT immunohistochemistry (IHC) improves patients’ selection for temozolomide (TMZ) treatment in advanced chemorefractory MGMT-methylated colorectal cancer

Background: We showed that standard dose TMZ (150 mg/mq/day day1-5q28) is tolerable and active in 32 heavily pre-treated patients with advanced CRC and MGMT promoter methylation (Pietrantonio et al., Ann Oncol 2014). In a subsequent study, we included 32 pts treated with dose-dense TMZ (75 mg/mq/day day 1-21q28, for up to 6 cycles or until progression/unacceptable toxicity). Additional predictive markers are needed for improved selection of patients for TMZ therapy in metastatic CRC. Retained MGMT expression by IHC was proposed as marker for negative selection of pts with brain tumors. We conducted a retrospective analysis to assess MGMT expression in our 2 studies and to correlate this with the outcomes.

Methods: All 64 patients included in the 2 studies were defined as MGMT methylation-positive according to methylation-specific PCR. A total of 40 patients had tissue available for IHC. Expression of nuclear MGMT protein was defined scored semiquantitatively according to extension and intensity. Using ROC analysis, IHC score &lt;4 was considered as MGMT-low expression vs. IHC score 4-12 as MGMT-high. Extended RAS-BRAF mutations were assessed by Sanger sequencing.

Results: Herein, we report for the first time the results of the dose-dense TMZ study. We obtained 4 confirmed partial responses and 2 stable disease, accounting for a response rate of 12% and a clinical benefit of 18%. Median PFS was 1.8 months. OS data are not mature. Thus, the results are comparable to those obtained in the previous study.

MGMT-low expression was found in 15 (38%) samples and MGMT-high in 25 (62%). RAS-BRAF mutations were found in 28 (70%) pts and were not correlated with MGMT expression (p = 1). Response rate was significantly higher in patients with MGMT-low (53%) vs. those with MGMT-high (p&lt;0.0001). Progression-free survival was significantly longer in MGMT-low vs. MGMT-high(5 vs. 2.3 months; p = 0.001). Further analyses are ongoing to validate MGMT IHC as a biomarker and to correlate it with quantitative gene methylation analysis.

Conclusions: In this translational study on MGMT methylated CRC, absence of MGMT expression was significantly correlated with tumor response and benefit from TMZ treatment.

Citation Format: Filippo De Braud, Filippo Pietrantonio, Maria Di Bartolomeo, Katia Fiorella Dotti, Claudia Maggi, Roberto Iacovelli, Marta Caporale, Rosa Berenato, Federica Perrone, Elena Tamborini, Alessio Pellegrinelli, Stefano Federici, Fabrizio Festinese, Giuseppe Pelosi, Ilaria Bossi, Paola Valentina Consonni, Susanna Maggi, Massimo Milione. MGMT immunohistochemistry (IHC) improves patients’ selection for temozolomide (TMZ) treatment in advanced chemorefractory MGMT-methylated colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-119. doi:10.1158/1538-7445.AM2015-LB-119

Ewing sarcoma of the small bowel: a study of seven cases, including one with the uncommonly reported EWSR1-FEV translocation

AIMS

Primary Ewing sarcoma of the ileum has rarely been documented. Little is known about its pathogenesis and clinical implications, and it would be helpful to identify novel molecular markers. EWSR1-FEV translocation is exceedingly rare in Ewing sarcoma, as FEV expression is restricted to prostate, brain and serotonin neuroendocrine cells (NE) and related tumours.

METHODS AND RESULTS

Paraffin sections or snap-frozen material were used in this investigation. Tumours were investigated by means of immunohistochemistry, RT-PCR (EWSR1-FLI1, EWSR1-ERG and EWSR1-FEV transcripts), FISH analysis (EWSR1 break-apart and specific EWSR1-FEV translocation) and spectral karyotyping (SKY). Ten ileal neuroendocrine tumours (INET) made up the control group for EWSR1-FEV translocation. Among 445 Ewing sarcomas cases spanning a period of 20 years, seven (1.6%) arose in the ileum. All tumours were immunoreactive for synaptophysin, CD99, FLI1 and vimentin. FISH identified EWSR1 rearrangement in all cases, with EWSR1-FLI1 transcripts being detected in all but one tumour showing the uncommon EWSR1-FEV rearrangement, with SKY, RT-PCR and FISH confirmation. The mean survival of EWSR1-FLI1 patients was 14 months, whereas the EWSR1-FEV patient was alive after 15 years despite several recurrences controlled by surgery alone. No INET showed EWSR1 translocation.

CONCLUSIONS

Most primary Ewing sarcomas of the ileum show the common EWSR1-FLI1 translocation, but EWSR1-FEV could be specific for tumours arising in the ileum and showing better prognosis.

High pathologic response rate of hepatic colorectal cancer metastases (HCRM) following neoadjuvant bevacizumab (Bev)-based treatment (tx)

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Background: Pathologic response of HCRM to neoadjuvant tx is associated to better outcome. In retrospective analyses Bev-based tx improved tumor regression grade (TRG), while cetuximab (Cmab) increased RECIST response and R0 resections in prospective studies. The aim of this analysis was to assess the effect of Bev vs Cmab-based tx in terms of HCRM pathological response and outcome. Methods: Fifty-eight pts with HCRM were resected at National cancer Institute of Milan from 2007 to 2012 following Bev (n=30) or Cmab (n=28) based neoadjuvant tx. Pathological response was classified from TRG 1 for pathological complete response (pCR), to TRG5 for no response; TRG 1-3, for histological response; TRG 4-5 for scarce/no response (Rubbia-Brandt L, Ann Oncol 2007). Results: KRAS missing in 9 pts (3 Bev/6 Cmab), mutated in 18 pts (60%) in Bev vs 4 (14%) in Cmab group.Median number of resected metastases: 4.6 vs 3.9; mean TRG: 2.9 (2.2-4) in Bev vs 3.8 (3-5) in Cmab group (p=0.04 at Kruskal-Wallis test). Pathological response rate was higher for Bev vs Cmab (70% vs 39%; p=0.037 at Chi-square test). Bev also increased pCRs (20% vs 0%, p=0.024 at Fisher’s test). With generalized estimating equation for all resected nodules, mean TRG was lower in Bev vs Cmab group: 2.6 (2-4) vs 3.7 (3-4), p<0.001. At univariate analysis, no PFS and OS difference was observed according to tx. Multivariable Cox models shown below: Conclusions: Bev-based tx obtained an excellent pathological response rate, despite the high proportion of KRAS mutated tumors, and further prospective confirmation of these data is planned. [Table: see text]

Rantes distribution and cellular localization in the brain of HIV-infected patients

OBJECTIVE

To study the immunochemical distribution ofRantes chemokine and its correlation with HIV-p24 expression, in brains with HIV-related lesions.

MATERIAL AND METHODS

17 HIV-positive cases of HIV-related brain lesions, 7 HIV-positive cases without cerebral HIV-related lesions (5 with opportunistic brain diseases), and 7 HIV-negative cases as controls (4 with brain lesion) were selected.

RESULTS

High expression of Rantes was observed in the cases with inflammatory brain lesions (22/24 HIV-positive and 2/7 HIV-negative patients). Positivity was observed in the diffuse and nodular microglial cells and lymphocytes. In the patients with HIV-related lesions, the presence of Rantes-stained microglia did not correlate with that of HIV-p24-positive cells. Positive astrocytes were only found in the HIV-positive patients. Multinucleated giant cells were always Rantes-negative.

CONCLUSIONS

Our results seem to demonstrate the role of Rantes chemokine in inducing inflammatory brain perivascular and microglial reactions both in HIV-positive and -negative patients.

Beta amyloid precursor protein and patterns of HIV p24 immunohistochemistry in different brain areas of AIDS patients

OBJECTIVES

To evaluate the correlation between immunohistochemical positive patterns (globular and filamentous structures) of beta-amyloid precursor protein (beta-APP), used as a marker of axonal damage, and the different distribution of HIV p24 antigens, in three different brain areas of AIDS patients.

METHODS

Eighteen AIDS patients with HIV-related brain lesions were included in the study. Forty-nine sections from basal ganglia, frontal cortex and hippocampus were selected. After microwave oven pre-treatment, the sections were incubated with anti-HIV p24 and anti-beta-APP monoclonal antibodies; the reactions were developed with peroxidase/3,3'diaminobenzidine. The positivity was graded by semi-quantitative scores. Double immunohistochemical staining was used to evaluate the co-localization of the antigens.

RESULTS

HIV p24 immunohistochemistry was positive in 44 of 49 sections (89%), with a prevalence of interstitial positive cells and positive microglial nodules in 27 and 13 sections respectively. beta-APP-positive structures were demonstrated in 23 of 44 sections (52%) with HIV-related lesions, and were absent from the five sections without viral expression. Globular and filamentous lesions were observed in 21 of 23 sections and 10 of 23 lesions respectively. Moreover, a high grade of globular type lesion was related to an elevated presence of diffuse interstitial HIV p24-positive cells in basal ganglia; double immunohistochemical reactions demonstrated the co-localization of beta-APP globules and HIV p24 antigens.

CONCLUSIONS

The data obtained confirm the coexpression of beta-APP and viral antigens in particular areas of the brain with HIV-related lesions; there is a strict correlation between beta-APP globules (indicating chronic cerebral damage) and the interstitial pattern of HIV p24 immunohistochemistry.

Etiology of microglial nodules in brains of patients with acquired immunodeficiency syndrome

Microglial nodules associated with opportunistic and HIV-related lesions are frequently found in the brains of AIDS patients. However, in many cases, the causative agent is only presumptively suspected. We reviewed 199 brains of AIDS patients with micronodular lesions to clarify their etiology by immunohistochemistry (to Toxoplasma gondii, cytomegalovirus, herpes simplex virus I/II, varicella zoster virus and HIV-p24 core protein), PCR (for herpetic viruses and Mycobacterium tuberculosis) and electron microscopy. Productive HIV infection was observed in 110 cases (55.1%): 30 cases with Toxoplasma gondii encephalitis, 30 with cytomegalovirus encephalitis, eight with multiple cerebral diseases, while in the remaining 42 cases HIV was the only pathogenetic agent. Multinucleated giant cells (hallmark of HIV infection) were found in the MGNs of 85/110 cases with HIV-related lesions; the remaining 25 cases had only p24 positive cells but no multinucleated giant cells. In these latter cases the micronodular lesions had been initially attributed to the main opportunistic agent found in the brain, or defined as subacute encephalitis. Individual microglial nodules positive for an opportunistic pathogen were generally negative for HIV antigens. In 13 cases no opportunistic agent or HIV productive infection was found. In these cases, PCR and electron microscopy examination for HIV and other viral infections were negative. Our data suggest that HIV-immunohistochemistry should be used for the etiological diagnosis of micronodular lesions in AIDS brains, even in the presence of other pathogens. After extensive search, the etiology of the microglial nodules remains unknown in only a small percentage of cases.

Eradication of helminthic infections

The eradication of helminthic infections described by models of the Nåsell-Hirsch type is investigated. Simple criteria are proposed for comparing the efficiency of different modes of eradication.