PD-1 Blockade in Tumors with Mismatch-Repair Deficiency.

BACKGROUND: Somatic mutations have the potential to encode "non-self" immunogenic antigens. We hypothesized that tumors with a large number of somatic mutations due to mismatch-repair defects may be susceptible to immune checkpoint blockade. METHODS: We conducted a phase 2 study to evaluate the clinical activity of pembrolizumab, an anti-programmed death 1 immune checkpoint inhibitor, in 41 patients with progressive metastatic carcinoma with or without mismatch-repair deficiency. Pembrolizumab was administered intravenously at a dose of 10 mg per kilogram of body weight every 14 days in patients with mismatch repair-deficient colorectal cancers, patients with mismatch repair-proficient colorectal cancers, and patients with mismatch repair-deficient cancers that were not colorectal. The coprimary end points were the immune-related objective response rate and the 20-week immune-related progression-free survival rate. RESULTS: The immune-related objective response rate and immune-related progression-free survival rate were 40% (4 of 10 patients) and 78% (7 of 9 patients), respectively, for mismatch repair-deficient colorectal cancers and 0% (0 of 18 patients) and 11% (2 of 18 patients) for mismatch repair-proficient colorectal cancers. The median progression-free survival and overall survival were not reached in the cohort with mismatch repair-deficient colorectal cancer but were 2.2 and 5.0 months, respectively, in the cohort with mismatch repair-proficient colorectal cancer (hazard ratio for disease progression or death, 0.10 [P<0.001], and hazard ratio for death, 0.22 [P=0.05]). Patients with mismatch repair-deficient noncolorectal cancer had responses similar to those of patients with mismatch repair-deficient colorectal cancer (immune-related objective response rate, 71% [5 of 7 patients]; immune-related progression-free survival rate, 67% [4 of 6 patients]). Whole-exome sequencing revealed a mean of 1782 somatic mutations per tumor in mismatch repair-deficient tumors, as compared with 73 in mismatch repair-proficient tumors (P=0.007), and high somatic mutation loads were associated with prolonged progression-free survival (P=0.02). CONCLUSIONS: This study showed that mismatch-repair status predicted clinical benefit of immune checkpoint blockade with pembrolizumab. (Funded by Johns Hopkins University and others; ClinicalTrials.gov number, NCT01876511.).

Whole-exome sequencing of duodenal neuroendocrine tumors in patients with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is a hereditary cancer predisposition syndrome characterized by frequent cutaneous and nervous system abnormalities. Patients with NF1 also have an increased prevalence of multiple gastrointestinal and peripancreatic neoplasms-neuroendocrine tumors of the ampulla that express somatostatin are particularly characteristic of NF1. In this study, we characterize the genetic alterations of a clinically well-characterized cohort of six NF1-associated duodenal neuroendocrine tumors using whole-exome sequencing. We identified inactivating somatic mutations in the NF1 gene in three of six tumors; the only other gene altered in more than one tumor was IFNB1. Copy number analysis revealed deletion/loss of heterozygosity of chromosome 22 in three of six patients. Analysis of germline variants revealed germline deleterious NF1 variants in four of six patients, as well as deleterious variants in other tumor suppressor genes in two of four patients with deleterious NF1 variants. Taken together, these data confirm the importance of somatic inactivation of the wild-type NF1 allele in the formation of NF1-associated duodenal neuroendocrine tumors and suggest that loss of chromosome 22 is important in at least a subset of cases. However, we did not identify any genes altered in the majority of NF1-associated duodenal neuroendocrine tumors that uniquely characterize the genomic landscape of this tumor. Still, the genetic alterations in these tumors are distinct from sporadic neuroendocrine tumors occurring at these sites, highlighting that unique genetic alterations drive syndromic tumors.

The outlet patch: gastric heterotopia of the colorectum and anus.

AIMS: Gastric heterotopia (GH) has been described throughout the gastrointestinal tract. However, the colorectal region is an extremely rare location for it. We describe the clinicopathological features of GH of the colon, rectum and anus. METHODS AND RESULTS: We identified 33 cases in 20 males and 13 females (median age = 54 years; range = 4 months-73 years). Sites included the rectum (n = 26), anus (n = 4), ileocaecal junction (n = 1), ascending colon (n = 1) and descending colon (n = 1). Presenting symptoms (n = 27) included haematochezia (41%) and altered bowel habits (4%); 15 patients (55%) were asymptomatic. On colonoscopy (n = 31), all appeared as solitary lesions (median size = 6.5 mm, range = 2-55 mm), either as polyps (61%), raised erythematous patches (23%), an ulcer (10%), within a rectal diverticulum (3%) or a haemorrhoid (3%). Patients were managed by polypectomy. One with an associated carcinoma in the area of GH underwent resection. No morbidity related to GH itself was reported following excision. Histologically, heterotopic gastric mucosa was oxyntic (85%), mixed oxyntic and non-oxyntic (12%) and not specified (3%) types. In five patients a pyloric gland adenoma (PGA) arose from heterotopic gastric mucosa, two of which contained a focus of invasive adenocarcinoma. One case had associated surface foveolar-type low-grade dysplasia. Another had associated adenocarcinoma arising from the heterotopic mucosa. One example harboured Helicobacter pylori organisms. CONCLUSIONS: We highlight the features of GH in the distal GIT - the 'outlet patch'. Association with PGA, surface dysplasia and adenocarcinoma suggests that lower tract GH can undergo neoplastic transformation.

Patients with a resected pancreatic mucinous cystic neoplasm have a better prognosis than patients with an intraductal papillary mucinous neoplasm: A large single institution series.

BACKGROUND/OBJECTIVES: Mucinous cystic neoplasms (MCNs) are rare pancreas tumors distinguished from intraductal papillary mucinous neoplasms (IPMNs) by the presence of ovarian-type stroma. Historical outcomes for MCNs vary due to previously ambiguous diagnostic criteria resulting in confusion with IPMNs. This study seeks to characterize and clarify the clinical features and long-term outcomes of MCNs versus IPMNs in the largest single-institution series of pathology-confirmed MCNs to date. METHODS: We compared 142 MCNs and 746 IPMNs resected at a single institution. MCNs were reviewed for confirmation of ovarian-type stroma and reclassified according to current WHO guidelines. RESULTS: MCNs presented almost exclusively in middle-aged women (median 47.5 years, 96.5% female) as solitary (100%), macrocystic (94.2%) lesions in the distal pancreas (92.1%). IPMNs were distributed equally by sex in an older population (median 69.0 years, 49.6% female) and favored the proximal pancreas (67.6%). Compared with IPMNs, MCNs were larger (4.2 cm vs 2.5 cm) and more often low-grade (71.1% vs 13.8%). Associated invasive carcinoma was less common in MCNs than in IPMNs (9.9% vs 32.4%). Surgical resection was curative for 100% of noninvasive MCNs. Patients with an MCN-associated invasive carcinoma had a much better prognosis than did patients with an IPMN-associated invasive carcinoma with 10-year disease-specific survival of 79.6% versus 27.2%, respectively. CONCLUSION: MCNs have a stereotypical clinical profile that is readily distinguishable from IPMNs based on demographic features, imaging, and pathology. Most MCNs are noninvasive and curable with surgical resection. Prognosis remains excellent even for invasive disease with 10-year survival approaching 80% following resection.

Pathogenesis, diagnosis, and management of gastric ischemia.

BACKGROUND & AIMS: Gastric ischemia is infrequently reported in the medical literature and under-recognized clinically and histopathologically. Various medical terms are used to describe gastric ischemia. We define and review the pathogenesis, diagnosis, and management of gastric ischemia. METHODS: We describe 6 cases of gastric ischemia. We discuss features of the gastric vascular supply and review literature on this disorder. RESULTS: Gastric ischemia results from diffuse or localized vascular insufficiency caused by etiologies such as systemic hypotension, vasculitis, or disseminated thromboembolism. The disorder is managed by fluid resuscitation, nasogastric tube placement (for intermittent air and fluid aspiration, to prevent or reduce gastric distention), aggressive acid reduction (via intravenous administration of proton pump inhibitors), and selective use of broad-spectrum antibiotics for patients with sepsis or gastric pneumatosis. CONCLUSIONS: Gastric ischemia has a poor prognosis. Early diagnosis is required for appropriate patient management.

Squamous cell carcinoma of the renal pelvis.

Primary squamous cell carcinoma (SCC) of the renal pelvis is rare because SCC represents only 0.5% to 0.8% of malignant renal tumors. Chronic irritation, inflammation, and infection induce squamous metaplasia of the renal collecting system, which may progress to dysplasia and carcinoma in most of affected individuals. Nephrolithiasis, especially formation of staghorn calculi, is the most common risk factor for SCC, which usually occurs in older adults (age 50-70 years) with no sex predilection. Clinical features include flank or abdominal mass, weight loss, hematuria, or paraneoplastic syndromes, such as hypercalcemia. Radiologically, SCC of the renal pelvis may appear as a solid mass, hydronephrosis, or calcifications. The radiologic differential diagnosis includes primary and secondary renal neoplasms and xanthogranulomatous pyelonephritis. Squamous cell carcinomas of the renal pelvis are usually large, necrotic, and ulcerated, with gross invasion of the renal parenchyma and perinephric soft tissue. Most SCCs of the renal pelvis are moderately or poorly differentiated and typically present at an advanced stage. Surgical resection and adjuvant chemoradiotherapy are rarely curative. The prognosis is dismal with a 5-year survival rate of less than 10%.

Extracavitary/solid variant of primary effusion lymphoma.

Primary effusion lymphoma (PEL) is a distinct clinicopathologic entity associated with human herpesvirus 8 (HHV8) infection that mostly affects patients with immunodeficiency. Primary effusion lymphoma usually presents as a malignant effusion involving the pleural, peritoneal, and/or pericardial cavities without a tumor mass. Rare cases of HHV8-positive lymphoma with features similar to PEL can present as tumor masses in the absence of cavity effusions and are considered to represent an extracavitary or solid variant of PEL. Here, we report 3 cases of extracavitary PEL arising in human immunodeficiency virus-infected men. Two patients had lymphadenopathy and underwent lymph node biopsy. One patient had a mass involving the ileum and ascending colon. In lymph nodes, the tumor was predominantly sinusoidal. The tumor involving the ileum and ascending colon presented as 2 masses, 12.5 × 10.6 × 2.6 cm in the colon and 3.6 × 2.7 × 1.9 cm in the ileum. In each case, the neoplasms were composed of large anaplastic cells, and 2 cases had "hallmark cells." Immunohistochemistry showed that all cases were positive for HHV8 and CD138. One case also expressed CD4 and CD30, and 1 case was positive for Epstein-Barr virus-encoded RNA. Evidence of B-cell differentiation was poorly developed in all tumors. These cases highlight the importance of assessing HHV8 in an anaplastic tumor that arises in a human immunodeficiency virus-positive patient and further contributes to the limited literature currently available for extracavitary PEL.

Venous thrombosis with both heterozygous factor V Leiden (R507Q) and factor II (G20210A) mutations.

Both hereditary and acquired factors increase the risk of venous thromboembolism, thus the clinical management of affected patients involves evaluation of genetic factors that predispose to hypercoagulability. Factor V Leiden (R507Q) and factor II (prothrombin) mutation (G20210A) are the two most common inherited hypercoagulability disorders among populations of European origin. Both factor V Leiden and factor II mutation (G20210A) represent gain-of-function mutations: factor V Leiden causes resistance to activated protein C, and factor II mutation (G20210A) results in higher levels of plasma prothrombin. Herein, we present an uncommon case of combined factor V Leiden mutation (R507Q) and factor II mutation (G20210A), and discuss the prevalence and features of each entity, as well as their role in the clinical management of affected patients.

Low-grade nonintestinal sinonasal adenocarcinoma: a diagnosis of exclusion.

The World Health Organization classifies primary sinonasal adenocarcinomas (SNACs) into salivary and nonsalivary types. Salivary types are usually well-defined myoepithelial neoplasms, which closely resemble their salivary counterparts. Nonsalivary types are separated into intestinal-type SNAC (ITAC) and non-ITAC, and both have low- and high-grade categories. Intestinal-type SNACs are aggressive tumors that resemble intestinal epithelium and often arise in the ethmoid sinus. Non-ITACs are of presumed seromucous gland origin, have marked morphologic heterogeneity, and can arise anywhere in the sinonasal tract. Moreover, ITACs typically demonstrate an intestinal-type immunohistochemical profile (CK20+, CK7-, CDX2+, and villin+), whereas non-ITACs reveal a respiratory-type profile (CK20-, CK7+, CDX2-, and villin-). Here, we present a case of low-grade, nonintestinal SNAC in a 17-year-old African American man and a discussion of the classification and pathologic features of primary SNACs.

New developments in the molecular pathogenesis of head and neck tumors: a review of tumor-specific fusion oncogenes in mucoepidermoid carcinoma, adenoid cystic carcinoma, and NUT midline carcinoma.

Tumor-specific chromosomal rearrangements often produce potent fusion oncogenes, which induce tumorigenesis by 2 alternative mechanisms: deregulation of the cell cycle resulting in gene overexpression or gene fusion resulting in a hybrid, chimeric oncogene. Tumor-specific recurrent chromosomal translocations and novel fusion oncogenes in aggressive head and neck malignancies have diagnostic, therapeutic, and prognostic implications. Recently, pathognomonic fusion transcripts have been identified in various uncommon, aggressive head and neck malignancies, including mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (ACC), and NUT midline carcinoma (NMC). The t(11;19)(q12;p13) translocation in MEC results in fusion of the MECT1 gene at 19p13 and the MAML2 gene at 11q21. The MECT1-MAML2 fusion transcript, present in more than half of MECs, is associated with lower histologic grades and improved survival, suggesting both diagnostic and prognostic roles in clinical management. The t(6;9)(q22-23;p23-24) translocation in ACC results in fusion of the MYB gene at 6q22-23 and the NFIB gene at 9p23-24. The MYB-NFIB fusion transcript, present in at least one third of salivary ACCs, can be detected by new reverse transcription polymerase chain reaction screening methods, and has emerged as a potential therapeutic target. The t(15;19)(q14;p13.1) translocation in NMC results in fusion of the NUT gene at 15q14 and the BRD4 gene at 19p13.1. This occurs in two thirds of NMC. Because NMC lacks characteristic clinicopathologic features and established therapeutic options, the BRD4-NUT fusion transcript may represent both a diagnostic marker and an optimal target for disease-specific drug therapy. Moreover, immunohistochemical advances have yielded a promising new monoclonal antibody against the NUT antigen, which may improve NMC diagnosis. Next-generation sequencing methods, such as the use of massively parallel and paired-end sequencing in the study of cancer genomes, will likely disclose novel fusion transcripts in more human malignancies. Hopefully, as technological advances unravel the molecular pathogenesis of aggressive carcinomas, diagnostic and therapeutic options will evolve to improve clinical outcomes.

Prognostic Implications of the Immune Tumor Microenvironment in Patients With Pancreatic and Gastrointestinal Neuroendocrine Tumors.

OBJECTIVES: The aim of this study was to characterize the tumor microenvironment of patients with gastroenteropancreatic neuroendocrine tumors relative to progression-free survival (PFS). METHODS: Immune profiling for CD3, CD8, programmed death-1/programmed death-ligand 1, and indoleamine 2,3-dioxygenase expression in 2 cohorts of gastroenteropancreatic neuroendocrine tumors: patients with short PFS (<4 years, n = 12) versus long PFS (≥4 years, n = 14) after surgery. Immune infiltrates in the tumor and interface were quantified. Programmed death-ligand 1 expression was determined within the tumor, stroma, and interface. RESULTS: Patients with shorter PFS had larger tumors (P = 0.02), mostly in the pancreas (P = 0.04). We observed a higher mean expression of CD3+, CD8+, programmed death-1+ cells, and indoleamine 2,3-dioxygenase at the interface compared with the tumor: log 10 mean differences 0.56 (95% confidence interval [CI], 0.43-0.68; P < 0.0001), 0.45 (95% CI, 0.32-0.59; P = 0.0002), 0.50 (95% CI, 0.40-0.61; P < 0.0001), and 0.24 (95% CI, 0.03-0.46; P = 0.046), respectively. Patients with longer PFS had higher intratumoral CD3+ T cells, log 10 mean difference 0.38 (95% CI, 0.19-0.57; P = 0.004). Programmed death-ligand 1 expression tended to be higher among patients with shortened PFS (odds ratio, 2.00; 95% CI, 0.68-5.91). CONCLUSIONS: Higher intratumoral CD3+ T-cell infiltrate was associated with longer PFS after resection.

Clinical deterioration during antituberculosis treatment in Africa: incidence, causes and risk factors.

BACKGROUND: HIV-1 and Mycobacterium tuberculosis cause substantial morbidity and mortality. Despite the availability of antiretroviral and antituberculosis treatment in Africa, clinical deterioration during antituberculosis treatment remains a frequent reason for hospital admission. We therefore determined the incidence, causes and risk factors for clinical deterioration. METHODS: Prospective cohort study of 292 adults who initiated antituberculosis treatment during a 3-month period. We evaluated those with clinical deterioration over the following 24 weeks of treatment. RESULTS: Seventy-one percent (209/292) of patients were HIV-1 infected (median CD4+: 129 cells/microL [IQR:62-277]). At tuberculosis diagnosis, 23% (34/145) of HIV-1 infected patients qualifying for antiretroviral treatment (ART) were receiving ART; 6 months later, 75% (109/145) had received ART. Within 24 weeks of initiating antituberculosis treatment, 40% (117/292) of patients experienced clinical deterioration due to co-morbid illness (n = 70), tuberculosis related illness (n = 47), non AIDS-defining HIV-1 related infection (n = 25) and AIDS-defining illness (n = 21). Using HIV-1 uninfected patients as the referent group, HIV-1 infected patients had an increasing risk of clinical deterioration as CD4+ counts decreased [CD4+>350 cells/microL: RR = 1.4, 95% CI = 0.7-2.9; CD4+:200-350 cells/microL: RR = 2.0, 95% CI = 1.1-3.6; CD4+<200 cells/microL: RR = 3.0, 95% CI = 1.9-4.7]. During follow-up, 26% (30/117) of patients with clinical deterioration required hospital admission and 15% (17/117) died. Fifteen deaths were in HIV-1 infected patients with a CD4+<200 cells/microL. CONCLUSIONS: In multivariate analysis, HIV-1 infection and a low CD4+ count at tuberculosis diagnosis were significant risk factors for clinical deterioration and death. The initiation of ART at a CD4+ count of <350 cells/microL will likely reduce the high burden of clinical deterioration.

Fibrolamellar hepatocellular carcinoma at a tertiary centre in South Africa: a case series.

BACKGROUND: Fibrolamellar carcinoma (FLC) is an uncommon malignant tumour of hepatocyte origin that differs from hepatocellular carcinoma (HCC) in aetiology, demographics, condition of the affected liver, and tumour markers. Controversy exists whether FLC demonstrates a more favourable prognosis than typical HCC. A review of existing literature reveals a dearth of FLC data from the African continent. METHODS: We utilised the prospective liver resection database at Groote Schuur Hospital to identify all patients who underwent surgery for FLC between 1990 and 2008. RESULTS: Seven patients (median age 21 years, range 19 - 42, 5 men, 2 women) underwent surgery for FLC. No patient had underlying liver disease or an elevated alpha fetoprotein (AFP) at either initial presentation or recurrence. Six patients had a solitary tumour at diagnosis (mean largest diameter = 12cm), and underwent left hepatectomy (N=2), right hepatectomy (N=1), extended right hepatectomy (N=1), right hepatectomy (N=1), extended right hepatectomy (N=1), and segmentectomies (N=2). Three patients underwent a portal lymphadenectomy for regional lymphatic tumour involvement. One patient with advanced extrahepatic portal nodal metastasis was unresectable. No peri-operative deaths occurred. Recurrence occurred post resection in all 6 patients. Median overall survival was 60 months, and overall 5-year survival was 4 out of 7 (57%). Post-resection survival (N=6) was 61 months, with a 5-year survival rate of 4 out of 6 (67%). The patient with unresectable disease survived 38 months after tumour embolisation with Lipiodol. CONCLUSION: Our series suggests that despite (i) a high resection rate of solitary lesions with clear tumour resection margins, and (ii) absence of underlying liver disease, FLC has a high recurrence rate with an ultimately poor clinical outcome. These findings concur with recent international experience of FLC. experience of FLC.

Multiple Immune-Suppressive Mechanisms in Fibrolamellar Carcinoma.

Fibrolamellar carcinoma (FLC) is a rare type of liver cancer that affects adolescents and young adults. The most effective treatment for FLC is surgical resection, but no standardized systemic therapy exists for patients with recurrent or unresectable FLC. As a first step to understand the immune microenvironment of FLC, we investigated targetable immune-checkpoint pathways, PD-1, PD-L1, B7-H3, IDO-1, and LAG3, in relation to CD8+ cytotoxic T-lymphocyte density. Thirty-two FLC tumor specimens were analyzed using IHC staining for PD-L1, CD8, PD-1, IDO, LAG3, and B7-H3. Sixty-three percent of FLC cases demonstrated membranous PD-L1 expression on tumor cells, and almost 70% of cases demonstrated PD-L1+ tumor-infiltrating lymphocytes and tumor-associated macrophages (TIL/TAM). Myeloid-derived cells appeared to be a major component of PD-L1+ tumor-infiltrating immune cells. Forty percent of the cases showed B7-H3 expression in the tumor zone, with 91% cases showing B7-H3 expression in TILs and TAMs. IDO and PD-1 expression was highest in the tumor interface zone. B7-H3 or IDO expression on tumor cells significantly correlated with higher CD8+ T-cell density. In conclusion, a high proportion of FLC cases showed robust expression of PD-1, PD-L1, B7-H3, and IDO in an adaptive immune-resistance pattern. Our findings provide further basis for targeting these different immune-checkpoint axes in FLC.