Tumour immune microenvironment in resected thymic carcinomas as a predictor of clinical outcome.

BACKGROUND: The spatial distribution of tumour-infiltrating lymphocytes (TILs) is a novel descriptor characterising the tumour immune microenvironment (TIME). The aim of our study was to assess whether a specific TIME of surgically resected thymic carcinoma (TC) can predict tumour invasiveness, recurrence or survival. METHODS: Digital microscopy was performed on 39 TCs immunohistochemically stained to investigate the activation of the immune checkpoint pathway (PD-L1/PD-1), along with density and spatial distribution of TILs phenotypes (CD3+, CD4+, CD8+, FOXP3+, CD56+). The impact of PD-L1 and TIL density considering the intratumoural (iTILs) and stromal (sTILs) distribution on pathological characteristics and clinical outcomes were analysed. RESULTS: In early TC stages, we observed a higher total density of CD3+ (p = 0.05) and CD8+ (p = 0.02) TILs. PD-L1 was expressed in 71.8% of TCs. In advanced TC stages, we observed a lower density of CD3+ (p = 0.04) and CD8+ (p = 0.01) iTILs compared to early stages. Serum concentrations of PD-L1 were significantly higher in TCs compared to healthy controls: 134.43 ± 18.51 vs. 82.01 ± 6.34 pg/ml (p = 0.001), respectively. High densities of stromal CD4+ TILs (54 vs. 32%, p = 0.043) and CD8+ TILs (65 vs. 17%, p = 0.048) were associated with improved freedom from recurrence (FFR) and cause-specific survival (CSS). High density of FoxP3+ TILs were associated with improved FFR (p = 0.03) and CSS (p = 0.003). DISCUSSION: Mapping TIL subpopulations complement the armamentarium for prognostication of TC outcomes. The improved outcome in patients with high density of TILs supports the use of immune checkpoint inhibitors in TC patients.

Short-term and sustained clinical response following thymectomy in patients with myasthenia gravis.

BACKGROUND AND PURPOSE: This study was undertaken to investigate short- and long-term outcome following thymectomy in patients with acetylcholine receptor antibody (AChR-Ab)-positive myasthenia gravis (MG). METHODS: Rates of clinical response (defined as minimal manifestation, pharmacological remission, or complete stable remission) lasting for at least 1 year were retrospectively analyzed using Cox proportional hazard models. The occurrence of relapses was recorded during follow-up. Clinical factors associated with achieving an initial or a sustained response were analyzed. RESULTS: Ninety-four patients with a median age of 33 years (interquartile range [IQR] = 22-51), 68% with nonthymomatous MG and 32% with thymoma-associated MG, were included. An initial clinical response was reached in 72% (68/94). Neither sex, age at onset, thymus histology, delay to surgery after disease onset, surgical approach, corticosteroid treatment, nor clinical severity before thymectomy was significantly associated with achieving this endpoint. During long-term follow-up (median = 89.5 months, IQR = 46-189.5), only half of the patients with an initial response (34/68) had a sustained response without relapses. No clinical factors predicted whether the response would become sustained. In patients without immunosuppressive treatment before thymectomy (n = 24), a high AChR-Ab reduction rate after thymectomy was associated with a higher likelihood of achieving an initial response (p = 0.03). CONCLUSIONS: Sustained long-term clinical response of MG patients after thymectomy is significantly lower than the initial response rates would suggest. The observation that none of the evaluated clinical factors was associated with a worse outcome supports the current clinical practice of patient selection for thymectomy. The relative decline of AChR-Abs after surgery appears to be a promising prognostic marker.

LAG-3 expression in the inflammatory microenvironment of glioma.

PURPOSE: Immune modulatory therapies including immune checkpoint inhibitors have so far failed to result in clinically meaningful efficacy in glioma. We aimed to investigate lymphocyte activation gene 3 (LAG-3), an inhibitory receptor on immune cells and target of second-generation immune checkpoint inhibitors, in glioma. METHODS: 97 patients with diffuse glioma (68 with glioblastoma, 29 with WHO grade II-III glioma) were identified from the Neuro-Biobank of the Medical University of Vienna. LAG-3 expression in the inflammatory microenvironment was assessed by immunohistochemistry (monoclonal anti-LAG-3 antibody, clone 17B4) and correlated to CD3+ , CD8+ , CD20+ and PD-1+ tumor-infiltrating lymphocytes (TILs) and PD-L1 expression on tumor cells. RESULTS: LAG-3+ TILs could be observed in 10/97 (10.3%) IDH-wildtype samples and in none of the included IDH-mutant glioma samples (p = 0.057). Further, LAG-3+ TILs were only observed in WHO grade IV glioblastoma, while none of the investigated WHO grade II-III glioma presented with LAG-3+ TILs (p = 0.03). No association of O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation and presence of LAG-3+ TILs was observed (p = 0.726). LAG-3 expression was associated with the presence of CD3+ (p = 0.029), CD8+ (p = 0.001), PD-1+ (p < 0.001) TILs and PD-L1+ tumor cells (p = 0.021), respectively. No association of overall survival with LAG-3+ TIL infiltration was evident (median OS 9.9 vs. 14.2 months, p = 0.95). CONCLUSIONS: LAG-3 is only rarely expressed on TILs in IDH-wildtype glioma and associated with active inflammatory milieu as defined by higher TIL density. Immune microenvironment diversity should be considered in the design of future immunotherapy trials in glioma.

Molecular Guided Treatments in Gynecologic Oncology: Analysis of a Real-World Precision Cancer Medicine Platform.

INTRODUCTION: Advanced gynecologic cancers have a poor prognosis and constitute a major challenge for adequate treatment strategies. By analyzing and targeting molecular alterations, molecular guided treatments may be a viable option for the treatment of advanced gynecologic cancers. PATIENTS AND METHODS: In this single-center, real-world retrospective analysis of our platform for precision cancer medicine (PCM), we describe the molecular profiling of 72 patients diagnosed with different types of advanced gynecologic malignancies. Tumor samples of the patients were examined by next-generation sequencing panel and immunohistochemistry (IHC). RESULTS: In total, we identified 209 genetic aberrations in 72 patients. The ten most frequent alterations were TP53 (n = 42, 20%), KRAS (n = 14, 6.6%), PIK3CA (n = 11, 5.2%), PIK3R1 (n = 9, 4.3%), ATR (n = 8, 3.8%), PTEN (n = 8, 3.8%), BRCA1 (n = 6, 2.8%), NF1 (n = 4, 1.9%), NOTCH1 (n = 4, 1.9%), and POLE (n = 4, 1.9%), which account for more than half of all molecular alterations (52.6%). In 21 (29.1%) patients only one mutation could be detected, and 44 (61.1%) patients had more than one mutation. No molecular alterations were detected in seven (9.7%) patients. IHC detected expression of phosphorylated mammalian target of rapamycin and epidermal growth factor receptor in 58 (80.6%) and 53 (73.6%) patients, respectively. In over two thirds (n = 49, 68.1%), a targeted therapy was suggested, based on the identified genetic aberrations. The most frequently recommended specific treatment was the combination of everolimus with exemestane (n = 18, 25 %). CONCLUSION: Based on our observations, it seems that PCM might be a feasible approach for advanced gynecologic cancers with limited treatment options. IMPLICATIONS FOR PRACTICE: Nowadays molecular profiling of advanced gynecologic malignancies is feasible in the clinical routine. A molecular portrait should be done for every patient with an advanced therapy-refractory gynecologic malignancy to offer molecular-based treatment concepts.

Molecular quantification of tissue disease burden is a new biomarker and independent predictor of survival in mastocytosis.

A high allele burden of the KIT D816V mutation in peripheral blood or bone marrow aspirates indicates multi-lineage hematopoietic involvement and has been associated with an aggressive clinical course of systemic mastocytosis. Since mast cells are substantially underrepresented in these liquid specimens, their mutation burden likely underestimates the tumor burden of the disease. We used a novel previously validated digital polymerase chain reaction (PCR) method for KIT D816V analysis to systematically analyze the mutation burden in formalin-fixed, paraffin-embedded bone marrow tissue sections of 116 mastocytosis patients (91 with indolent and 25 with advanced systemic mastocytosis), and to evaluate for the first time the clinical value of the tissue mutation burden as a novel biomarker. The KIT D816V mutation burden in the tissue was significantly higher and correlated better with bone marrow mast cell infiltration (r=0.68 vs 0.48) and serum tryptase levels (r=0.68 vs 0.58) compared to that in liquid specimens. Furthermore, the KIT D816V tissue mutation burden was: (i) significantly higher in advanced than in indolent systemic mastocytosis (P=0.001); (ii) predicted survival of patients in multivariate analyses independently; and (iii) was significantly reduced after response to cytoreductive therapy. Finally, digital PCR was more sensitive in detecting KIT D816V in bone marrow sections of indolent systemic mastocytosis patients than melting curve analysis after peptide nucleic acid-mediated PCR clamping (97% vs 89%; P<0.05). In summary, digital PCR-based measurement of KIT D816V mutation burden in the tissue represents a novel biomarker with independent prognostic significance that can also be employed for monitoring disease progression and treatment response in systemic mastocytosis.

CCL2 is a KIT D816V-dependent modulator of the bone marrow microenvironment in systemic mastocytosis.

Systemic mastocytosis (SM) is characterized by abnormal accumulation of neoplastic mast cells harboring the activating KIT mutation D816V in the bone marrow and other internal organs. As found in other myeloproliferative neoplasms, increased production of profibrogenic and angiogenic cytokines and related alterations of the bone marrow microenvironment are commonly found in SM. However, little is known about mechanisms and effector molecules triggering fibrosis and angiogenesis in SM. Here we show that KIT D816V promotes expression of the proangiogenic cytokine CCL2 in neoplastic mast cells. Correspondingly, the KIT-targeting drug midostaurin and RNA interference-mediated knockdown of KIT reduced expression of CCL2. We also found that nuclear factor κB contributes to KIT-dependent upregulation of CCL2 in mast cells. In addition, CCL2 secreted by KIT D816V+ mast cells was found to promote the migration of human endothelial cells in vitro. Furthermore, knockdown of CCL2 in neoplastic mast cells resulted in reduced microvessel density and reduced tumor growth in vivo compared with CCL2-expressing cells. Finally, we measured CCL2 serum concentrations in patients with SM and found that CCL2 levels were significantly increased in mastocytosis patients compared with controls. CCL2 serum levels were higher in patients with advanced SM and were found to correlate with poor survival. In summary, we have identified CCL2 as a novel KIT D816V-dependent key regulator of vascular cell migration and angiogenesis in SM. CCL2 expression correlates with disease severity and prognosis. Whether CCL2 may serve as a therapeutic target in advanced SM remains to be determined in forthcoming studies.

Molecular pathology of lung cancer: current status and perspectives.

PURPOSE OF REVIEW: In this article, we summarize the current knowledge on molecular alterations in lung cancer that are targets for therapy, and provide an outlook on the future development of molecular pathology in precision oncology. RECENT FINDINGS: Lung cancer has become a paradigm for the success of molecular targeted therapies in solid tumors. Tyrosine kinase inhibitors are effective treatment options in adenocarcinoma patients with an EGFR, ALK, ROS1 or B-Raf Proto-Oncogene, Serine/Threonine kinase mutation. Additional molecular targets that are addressed in clinical trials include ERBB2, MET, RET, NTRK1 and FGFR. Therapies with antibodies that block the interaction of PD-L1 with PD-1 and thereby liberate an antitumor immune response have introduced a new era in cancer therapy with impressive therapeutic benefits. The high financial burden, treatment failures and therapeutic side effects of immunotherapies have prompted a search for biomarkers beyond PD-L1 expression, for example, tumor mutation load or immune cell profiling, that might more reliably identify patients that are likely to respond. SUMMARY: The discoveries of cancer research have been translated into the clinical management of lung cancer patients. So far, the approach of targeted therapy that is directed towards certain molecular alterations in a given tumor has been successful for adenocarcinomas, but not yet for squamous or small cell carcinomas. Further clinical progress will require a better understanding of the molecular interactions within cancer cells that will subsequently enable innovative drug designs. Diagnostic molecular pathology will be a provider of information on a tumor's features and thus, navigate precision cancer therapy.

Digital PCR: A Sensitive and Precise Method for KIT D816V Quantification in Mastocytosis.

BACKGROUND: The analytically sensitive detection of KIT D816V in blood and bone marrow is important for diagnosing systemic mastocytosis (SM). Additionally, precise quantification of the KIT D816V variant allele fraction (VAF) is relevant clinically because it helps to predict multilineage involvement and prognosis in cases of advanced SM. Digital PCR (dPCR) is a promising new method for sensitive detection and accurate quantification of somatic mutations. METHODS: We performed a validation study of dPCR for KIT D816V on 302 peripheral blood and bone marrow samples from 156 patients with mastocytosis for comparison with melting curve analysis after peptide nucleic acid-mediated PCR clamping (clamp-PCR) and allele-specific quantitative real-time PCR (qPCR). RESULTS: dPCR showed a limit of detection of 0.01% VAF with a mean CV of 8.5% and identified the mutation in 90% of patients compared with 70% for clamp-PCR (P < 0.001). Moreover, dPCR for KIT D816V was highly concordant with qPCR without systematic deviation of results, and confirmed the clinical value of KIT D816V VAF measurements. Thus, patients with advanced SM showed a significantly higher KIT D816V VAF (median, 2.43%) compared with patients with indolent SM (median, 0.14%; P < 0.001). Moreover, dPCR confirmed the prognostic significance of a high KIT D816V VAF regarding survival (P < 0.001). CONCLUSIONS: dPCR for KIT D816V provides a high degree of precision and sensitivity combined with the potential for interlaboratory standardization, which is crucial for the implementation of KIT D816V allele burden measurement. Thus, dPCR is suitable as a new method for KIT D816V testing in patients with mastocytosis.

Analysis of 10 Adrenocortical Carcinoma Patients in the Cohort of the Precision Medicine Platform MONDTI.

OBJECTIVE: Adrenocortical carcinoma (ACC) is a rare disease with a dismal prognosis. We aimed to evaluate if a personalized medicine approach may be useful for matching patients with ACC to targeted therapies. METHODS: This is an analysis of 10 molecularly profiled ACCs that were progressing under standard of care treatment. The profile consisted of a 50-gene next-generation sequencing panel, immunohistochemistry (IHC), and fluorescence in situ hybridization for several proteins or chromosomal aberrations. RESULTS: In 6 (60%) tumor samples, no somatic mutation was detected, while in 3 (30%) tumors 1 mutation was detected and in 1 (10%) tumor 2 mutations were detected. These mutations were CTNNB1 (2 samples), TP53 (1 sample), RB1 (1 sample) and APC (1 sample). Expression of phospho-mTOR and of EGFR was commonly detected by IHC (87.5 and 62.5%). In 4 (50%) samples, IHC revealed a weak expression of progesterone receptor. Less frequent alterations were expression of PDGFR-α, c-KIT, and estrogen receptor, each in 1 case. CONCLUSIONS: Based on the molecular profile, no recommendation for targeted therapy was made by the multi-disciplinary team. Currently, ACC might not be suitable for a precision medicine approach according to our tests.

Activity of Pembrolizumab in Recurrent Cervical Cancer: Case Series and Review of Published Data.

OBJECTIVES: Recent data support the use of pembrolizumab in cervical cancer. The aim of this study was to investigate pembrolizumab in heavily pretreated patients with recurrent cervical cancer. METHODS: Data from consecutive patients treated with pembrolizumab at a single academic institution were assessed. Programmed cell death ligand 1 (PD-L1) status and microsatellite instability were assessed from tumor samples. Irrespective of PD-L1 expression status, pembrolizumab was administered at fixed dose of 200 mg intravenously every 3 weeks. Treatment response was evaluated by computed tomography, using iRECIST (2017) criteria. Descriptive statistics were performed. Results from previous publications were summarized. RESULTS: In total, 11 heavily pretreated patients with recurrent cervical cancer received pembrolizumab. Of these, 2 (18%) patients showed partial response and 2 (18%) patients showed disease stabilization on computed tomography, resulting in a clinical benefit rate of 36%. These 4 patients are still on treatment and durable antitumor activity of up to 52 weeks was observed. Treatment was generally well tolerated with 1 patient showing dose-limiting toxicity. Median overall survival was 26 (3-53) weeks, and a 6-month overall survival rate of 65% was observed. Of the 5 patients with high PD-L1 expression, 3 showed response to treatment. CONCLUSIONS: Pembrolizumab shows promising activity in heavily pretreated patients with recurrent cervical cancer in a real-life clinical setting. Treatment was generally well tolerated, and adverse effects were manageable. Growing evidence supports the use of pembrolizumab in this group of patients.

Feasibility of personalized treatment concepts in gastrointestinal malignancies: Sub-group results of prospective clinical phase II trial EXACT.

OBJECTIVE: Advances in high-throughput genomic profiling and the development of new targeted therapies improve patient's survival. In gastrointestinal (GI) malignancies, the concept of personalized medicine (PM) was not investigated so far. The aim of this prospective study was to evaluate the efficacy of a personalized treatment in GI patients who failed standard treatment. METHODS: Out of the original prospective clinical phase II EXACT trial, 21 (38%) GI cancer patients who had no further treatment options were identified. A molecular profile (MP) via a 50 gene next generation sequencing (NGS) panel in combination with immunohistochemistry (IHC) was conducted using real-time biopsy tumor material. Results were discussed by a multidisciplinary team (MDT) to translate the individual MP in an experimental treatment. RESULTS: Of the 55 patients originally included in the EXACT trial, 21 (38%) suffered from GI malignancies. The final analysis showed that 15 (71%) patients had experienced a longer progression-free survival (PFS) upon experimental targeted treatment (124 d, quartiles 70/193 d), when compared with the PFS achieved by the previous conventional therapy (62 d, quartiles 55/83 d) (P=0.014). Thirteen (62%) patients receiving targeted treatment experienced a disease control according to Response Evaluation Criteria in Solid Tumors (RECIST). Median overall survival (OS) from the start of experimental therapy to time of censoring or death was 193 d (quartiles 115/374 d). CONCLUSIONS: PM was not investigated in GI malignancies so far in a prospective trial. This study shows that treatment based on real-time molecular tumor profiling led to a superior clinical benefit, and survival as well as response was significantly improved when compared with previous standard medications.

SPAG6 and L1TD1 are transcriptionally regulated by DNA methylation in non-small cell lung cancers.

BACKGROUND: DNA methylation regulates together with other epigenetic mechanisms the transcriptional activity of genes and is involved in the pathogenesis of malignant diseases including lung cancer. In non-small cell lung cancer (NSCLC) various tumor suppressor genes are already known to be tumor-specifically methylated. However, from the vast majority of a large number of genes which were identified to be tumor-specifically methylated, tumor-specific methylation was unknown so far. Thus, the major aim of this study was to investigate in detail the mechanism(s) responsible for transcriptional regulation of the genes SPAG6 and L1TD1 in NSCLCs. METHODS: We analysed publically available RNA-sequencing data and performed gene expression analyses by RT-PCR. DNA methylation analyses were done by methylation-sensitive high-resolution melt analyses and bisulfite genomic sequencing. We additionally investigated protein expression using immunohistochemistry. Cell culture experiments included tumor cell growth, proliferation, viability as well as colony formation assays. Moreover, we performed xenograft experiments using immunodeficient mice. RESULTS: We observed frequent downregulation of SPAG6 and L1TD1 mRNA expression in primary tumor (TU) samples compared to corresponding non-malignant lung tissue (NL) samples of NSCLC patients. We furthermore observed re-expression of both genes after treatment with epigenetically active drugs in most NSCLC cell lines with downregulated SPAG6 and L1TD1 mRNA expression. Frequent tumor-specific DNA methylation of SPAG6 and L1TD1 was detected when we analysed TU and corresponding NL samples of NSCLC patients. ROC curve analyses demonstrated that methylation of both genes is able to distinguish between TU and NL samples of these patients. Immunohistochemistry revealed a close association between SPAG6/L1TD1 methylation and downregulated protein expression of these genes. Moreover, by performing functional assays we observed reduced cell growth, proliferation and viability of pCMV6-L1TD1 transfected NSCLC cells. In addition, reduced volumes of tumors derived from pCMV6-L1TD1 compared to pCMV6-ENTRY transfected NCI-H1975 cells were seen in a xenograft tumor model. CONCLUSIONS: Overall, our results demonstrate that SPAG6 and L1TD1 are tumor-specifically methylated in NSCLCs and that DNA methylation is involved in the transcriptional regulation of these genes. Moreover, in vitro as well as in vivo experiments revealed tumor-cell growth suppressing properties of L1TD1 in NSCLC cells.

Pre-fibrotic/early primary myelofibrosis vs. WHO-defined essential thrombocythemia: The impact of minor clinical diagnostic criteria on the outcome of the disease.

The 2016 revised WHO criteria for the diagnosis of pre-fibrotic/early primary myelofibrosis (pre-PMF) require at least one of the following four borderline expressed minor clinical criteria: anemia, leukocytosis, elevated lactate dehydrogenase and splenomegaly. In this study, we evaluated the relative frequency of these four criteria in a group of 170 pre-PMF patients and compared them to 225 ET cases. More than 91% of pre-PMF cases showed one or more of these features required for diagnosis, by contrast with only 48% of ET patients. According to clinical data the cumulative risk of progression to advanced/overt PMF in pre-PMF was 36.9% after 15 years. After fitting cox regression models to analyze the impact of the minor criteria on overall survival, only leukocytosis remained as a significant predictor of survival in both pre-PMF and ET. Molecular characterization showed differences in survival in pre-PMF but not ET, with CALR being a more favorable mutation than JAK2. The different outcome of pre-PMF versus ET and associated molecular genetic data supports the concept of two different entities, rather than a continuum of the same disease. Although slightly less than 50% of ET patients also show one or more minor clinical criteria, accurate distinction between ET and pre-PMF is possible by following an integrated approach including histomorphological diagnosis and presence of minor clinical criteria.

A pilot study of confocal laser endomicroscopy for diagnosing gastrointestinal mucosa-associated lymphoid tissue (MALT) lymphoma.

BACKGROUND: Patients with gastrointestinal mucosa-associated lymphoid tissue (MALT) lymphoma require lifelong endoscopic follow-up. This study aimed to establish and evaluate confocal laser endomicroscopy (CLE) criteria for gastrointestinal MALT lymphoma. METHODS: This prospective trial was conducted after IRB approval at the Medical University of Vienna. Twenty-four consecutive patients (14 males and 10 females, median age 65 years) referred for staging or follow-up of (former) gastrointestinal MALT lymphoma underwent endosonography (EUS) and CLE including white light endoscopy (WLE) and conventional biopsy sampling of the upper gastrointestinal tract. CLE criteria of the disease were based on the first five patients with histologically proven MALT lymphoma. All CLE datasets were reviewed separately by two CLE experts. The diagnostic modalities were compared using conventional histology as the gold standard. RESULTS: Sixty-two percentages had a positive diagnosis of MALT lymphoma based on histology. The sensitivity was 80 % for EUS (0.51-0.95), 100 % for WLE (0.75-1) and 93 % for CLE (0.66-1); the specificity was 67 % for EUS (0.31-0.91), 23 % for WLE (0.04-0.60) and 100 % for CLE (0.63-1). The agreement with histology was moderate for EUS (kappa 0.47, p = 0.02), fair for WLE (kappa 0.26, p = 0.06) and almost perfect for CLE (kappa 0.91, p < 0.01). Expert evaluation identified all but one case of MALT lymphoma with excellent interobserver agreement (kappa 0.89, p < 0.01). In the case missed by CLE, MALT lymphoma involvement was restricted to deep tissue structures. CONCLUSIONS: Despite minor technical limitations, CLE is a promising alternative to conventional biopsy sampling in patients with gastrointestinal MALT lymphoma. CLINICALTRIALS. GOV NUMBER: NCT01583699.

B-cell deficiency and severe autoimmunity caused by deficiency of protein kinase C δ.

Primary B-cell disorders comprise a heterogeneous group of inherited immunodeficiencies, often associated with autoimmunity causing significant morbidity. The underlying genetic etiology remains elusive in the majority of patients. In this study, we investigated a patient from a consanguineous family suffering from recurrent infections and severe lupuslike autoimmunity. Immunophenotyping revealed progressive decrease of CD19(+) B cells, a defective class switch indicated by low numbers of IgM- and IgG-memory B cells, as well as increased numbers of CD21(low) B cells. Combined homozygosity mapping and exome sequencing identified a biallelic splice-site mutation in protein C kinase δ (PRKCD), causing the absence of the corresponding protein product. Consequently, phosphorylation of myristoylated alanine-rich C kinase substrate was decreased, and mRNA levels of nuclear factor interleukin (IL)-6 and IL-6 were increased. Our study uncovers human PRKCD deficiency as a novel cause of common variable immunodeficiency-like B-cell deficiency with severe autoimmunity.

CD52 is a molecular target in advanced systemic mastocytosis.

Advanced systemic mastocytosis (SM) is an aggressive hematopoietic neoplasm with poor prognosis and short survival times. So far, no curative therapy is available for affected patients. We have identified the cell surface antigen CD52 (CAMPATH-1) as a molecular target expressed abundantly on the surface of primary neoplastic mast cells (MCs) in patients with advanced SM. In contrast, neoplastic MCs of patients with indolent SM and normal MCs expressed only low levels or did not express CD52. To study the mechanisms of CD52 expression and the value of this antigen as a potential therapeutic target, we generated a human MC cell line, designated MCPV-1, by lentiviral immortalization of cord blood-derived MC progenitor cells. Functional studies revealed that activated RAS profoundly promotes surface expression of CD52. The CD52-targeting antibody alemtuzumab induced cell death in CD52(+) primary neoplastic MCs obtained from patients with SM as well as in MCPV-1 cells. NSG mice xenotransplanted with MCPV-1 cells survived significantly longer after treatment with alemtuzumab (median survival: 31 d untreated vs. 46 d treated; P=0.0012). We conclude that CD52 is a novel marker and potential therapeutic target in neoplastic MCs in patients with advanced SM.

Chronic mast cell leukemia (MCL) with KIT S476I: a rare entity defined by leukemic expansion of mature mast cells and absence of organ damage.

Mast cell leukemia (MCL) is a rare, life-threatening malignancy defined by a substantial increase in neoplastic mast cells (MCs) in bone marrow (BM) smears, drug-resistance, and a poor prognosis. In most patients, the survival time is less than 1 year. However, exceptional cases may present with a less malignant course. We report on a 49-year-old female patient with MCL diagnosed in 2013. In February 2013, first symptoms, including flushing, headache, and diarrhea, were recorded. In addition, mild anemia was detected. The disease was characterized by a massive increase in well-granulated, mature, and often spindle-shaped MCs (80 %) in BM smears. The serum tryptase level amounted to 332 ng/mL. Like in most other MCL patients, no skin lesions were detected. However, unlike in other patients, tryptase levels remained stable, and no other signs or symptoms of MCL-induced organ damage were found. Sequencing studies revealed an isolated S476I point mutation in KIT but no mutation in codon 816. The patient received histamine receptor blockers but refused cytoreductive therapy. After 9 months, still no progression or organ damage was detected. However, progression with transformation to acute MCL occurred after 12 months. We propose that the chronic type of MCL with stable conditions, absence of organ damage, and a mature MC morphology is recognized as a distinct entity that should be distinguished from the acute variant of MCL.

BRAFV600E mutant protein is expressed in cells of variable maturation in Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is a clinically and histologically heterogeneous disorder. Its classification as either reactive inflammatory or neoplastic has been a matter of debate. However, the recent finding of frequent BRAFV600E mutations in LCH argues for the latter. The exact cell type that harbors the mutation and is responsible for proliferation remains to be identified. We here apply a BRAFV600E mutation-specific antibody to detect the BRAF mutant cells in lesions from 89 patients with LCH. We found BRAFV600E mutations in 34 of 89 (38%) lesions. In lesions with the BRAFV600E mutation, the majority of cells coexpressing S-100 and CD1a harbored mutant BRAFV600E protein. These cells also expressed CD14 and CD36, whereas various fractions exhibited CD207. On the other hand, CD80 and CD86 expression was also present on BRAFV600E-positive cells. Thus, cells of variable maturation, exhibiting an immunohistochemical profile compatible either with myeloid cell or with dedifferentiated Langerhans cell antigens, carry the BRAFV600E mutation. In conclusion, we identify and characterize the neoplastic cells in LCH with BRAFV600E mutations by applying a mutation-specific marker and demonstrate feasibility for routine screening.

Initial bone marrow reticulin fibrosis in polycythemia vera exerts an impact on clinical outcome.

We examined the prevalence and prognostic relevance of bone marrow reticulin fibrosis in 526 patients with World Health Organization-defined polycythemia vera evaluated at the time of initial diagnosis. Seventy-four patients (14%) displayed mostly grade 1 reticulin fibrosis, with only 2 cases showing higher-grade fibrosis. Presenting clinical and laboratory characteristics, including JAK2V617F allele burden, between patients with and without fibrosis were similar for the most part, with the exception of a higher prevalence of palpable splenomegaly in patients with fibrosis (P < .01). Patients with fibrosis were less prone to experience thrombosis during their clinical course (1.1 vs 2.7 per 100 patient-years; P = .03) and more prone to develop post-polycythemia vera myelofibrosis (2.2 vs 0.8 per 100 patient-years; P = .01). There was no significant difference between the 2 groups in terms of overall or leukemia-free survival. The present study clarifies the incidence, degree, and prognostic relevance of bone marrow fibrosis obtained at time of initial diagnosis of polycythemia vera.