New aspects into pathophysiology and molecular diagnostics of myeloproliferative neoplasms

The Philadelphia chromosome negative myeloproliferative neoplasms (MPN) comprise diverse entities of hematopoetic stem cell disorders with hematopoetic stem cell transplantation as the only curative therapeutic option. A collective finding of some subgroups is the activating point mutation of JAK2 p.V617F, important for diagnosis and detection of minimal residual disease (MRD) but a rather late event in the course of MPN. In this study, we first focused on characteristics of the neoplastic peripheral blood CD34- positive stem cell fraction. Thus, we could reveal a characteristic aberrant morphology and phenotype, and performing cDNA- array analysis most notably an imbalance of DNA- dependent protein kinase subunits which may contribute to the accumulation of chromosomal aberrations, accumulation of hematopoetic cell, and prolongation of CD34- positive peripheral blood stem cells life span (Wickenhauser, Perez, et al. 2003; Siebolts, Breuhahn, et al. 2009). Moreover, there is evidence of a distinct, non-neoplastic, CD34- positive peripheral blood stem cell population which may offer perspectives in treatment of the diseases (Siebolts, Ates, et al. 2005). The CD34- positive stem cell fraction, as the underlying source of the malignancy, is of course of particular importance, not only for understanding of the pathophysiological process but also for understanding of relapse and regenerative incidents. Performing fluorescence in situ hybridization on bone marrow biopsies, we found an almost complete chimerism following stem cell transplantation concerning the differentiated hematopoesis, whereas CD34- positive cells remained of recipient origin to a higher proportion (Thiele, Varus, et al. 2007; Siebolts, Thiele, et al. 2008). Since hematopoetic stem cell transplantation, especially after invention of reduced intensity conditioning (RIC) is a feasible curative option for an increasing number of MPN patients, reliable detection of the specific JAK2 p.V617F mutation as a sign of minimal residual disease (MRD) becomes more and more important. Therefore, we created in combination of a robust QPCR with a wild- type blocking PCR, a powerful tool for reliable detection of MRD in these patients (Siebolts, Lange, et al. 2010). Future prospects of MPN research will also focus on the newly-discovered field of non-coding RNA. Therefore, we tested the possibility to perform further retrospective analysis on easily accessible paraffin embedded formalin fixed tissue, and could show for the first time that extraction of sufficient amount of miRNA, with subsequent expression analysis is possible even after decalcification and also after decades (Siebolts, Varnholt, et al. 2009)

The Potential Use of Electrochemotherapy in the Treatment of Uveal Melanoma: In Vitro Results in 3D Tumor Cultures and In Vivo Results in a Chick Embryo Model

Uveal melanoma (UM) is the most common primary intraocular tumor that arises from neoplastic melanocytes in the choroid, iris, and ciliary body. Electrochemotherapy (ECT) has been successfully established for the treatment of skin and soft tissue metastatic lesions, deep-seated tumors of the liver, bone metastases, and unresectable pancreas lesions. The aim of this study was to evaluate the effect of ECT in vitro in 3D spheroid culture systems in primary and metastatic UM cell lines. We also investigated the chick embryo chorioallantoic membrane (CAM) as an in vivo model system for the growth and treatment of UM tumors using ECT. The cytotoxic effect of ECT in 3D spheroids was analyzed seven days following treatment by assessment of the size and MTT [(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction] assay. The cytotoxicity of ECT after intratumoral or intraarterial administration was evaluated histologically. In vitro and in vivo ECT caused a significant reduction in tumor size and viability compared to electroporation or chemotherapy in both sections of our study. The current results underline the effectiveness of ECT in the treatment of UM and prepare the way for further investigation of its potential application in UM

Targeted ultra-deep sequencing reveals recurrent and mutually exclusive mutations of cancer genes in blastic plasmacytoid dendritic cell neoplasm

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare haematopoietic malignancy characterized by dismal prognosis and overall poor therapeutic response. Since the biology of BPDCN is barely understood, our study aims to shed light on the genetic make-up of these highly malignant tumors. Using targeted high-coverage massive parallel sequencing, we investigated 50 common cancer genes in 33 BPDCN samples. We detected point mutations in NRAS (27.3% of cases), ATM (21.2%), MET, KRAS, IDH2, KIT (9.1% each), APC and RB1 (6.1% each), as well as in VHL, BRAF, MLH1, TP53 and RET (3% each). Moreover, NRAS, KRAS and ATM mutations were found to be mutually exclusive and we observed recurrent mutations in NRAS, IDH2, APC and ATM. CDKN2A deletions were detected in 27.3% of the cases followed by deletions of RB1 (9.1%), PTEN and TP53 (3% each). The mutual exclusive distribution of some mutations may point to different subgroups of BPDCN whose biological significance remains to be explored

Treatment of RET-Positive Advanced Medullary Thyroid Cancer with Multi-Tyrosine Kinase Inhibitors — A Retrospective Multi-Center Registry Analysis

SIMPLE SUMMARY: Lately, a more personalized approach in the management of advanced thyroid cancer patients has improved the outcomes, and several novel molecularly guided therapies, including selective RET inhibitors (sRETis), have demonstrated promising efficacy in clinical trials. RET (rearranged during transfection) variants are the most prevalent oncogenic event in medullary thyroid cancer (MTC). We here found RET oncogene variants in 44/48 prospectively collected MTC tumor samples from patients treated with more unselective kinase inhibitors vandetanib and/or cabozantinib. Our study shows that RET variants were highly prevalent in patients with advanced MTC, and the treatment results in RET-positive cases were similar to those reported in unselected cohorts. ABSTRACT: Background: RET (rearranged during transfection) variants are the most prevalent oncogenic events in medullary thyroid cancer (MTC). In advanced disease, multi-tyrosine kinase inhibitors (MKIs) cabozantinib and vandetanib are the approved standard treatment irrespective of RET status. The actual outcome of patients with RET-positive MTC treated with MKIs is ill described. Methods: We here retrospectively determined the RET oncogene variant status with a targeted DNA Custom Panel in a prospectively collected cohort of 48 patients with advanced MTC treated with vandetanib and/or cabozantinib at four German referral centers. Progression-free survival (PFS) and overall survival (OS) probabilities were estimated using the Kaplan-Meier method. Results: In total, 44/48 (92%) patients had germline or somatic RET variants. The M918T variant was found in 29/44 (66%) cases. In total, 2/32 (6%) patients with a somatic RET variant had further somatic variants, while in 1/32 (3%) patient with a germline RET variant, additional variants were found. Only 1/48 (2%) patient had a pathogenic HRAS variant, and no variants were found in 3 cases. In first-line treatment, the median OS was 53 (95% CI (95% confidence interval), 32–NR (not reached); n = 36), and the median PFS was 21 months (12–39; n = 33) in RET-positive MTC patients. In second-line treatment, the median OS was 18 (13–79; n = 22), and the median PFS was 3.5 months (2–14; n = 22) in RET-positive cases. Conclusions: RET variants were highly prevalent in patients with advanced MTC. The treatment results in RET-positive cases were similar to those reported in unselected cohorts

Late recurrence of a single gland primary hyperparathyroidism—Atypical parathyroid adenoma or misdiagnosed parathyroid carcinoma

Key Clinical Message This case report aims to raise awareness of differential diagnoses of hypercalcemia and primary hyperparathyroidism, including parathyroid carcinoma and atypical adenoma, and to highlight the diagnostic challenges. Abstract Parathyroid carcinoma is a rare and often fatal cause of primary hyperparathyroidism and hypercalcemia. To date, there is still no clear‐cut diagnostic pathway for parathyroid carcinoma established, which results in major diagnostic ambiguity and complexity. Clinical differentiation between benign parathyroid adenoma and carcinoma is challenging and ultimately the diagnosis remains histopathological. We present a case of a 58‐year‐old female patient with parathyroid tumor recurrence after parathyroidectomy because of primary hyperparathyroidism. The first tumor was histologically classified as an atypical parathyroid adenoma by a specialized endocrine pathologist. Eleven years after the primary tumor resection a new tumor recurred. Retrospectively, after the tumor recurrence, the primary diagnosis of the atypical adenoma was questioned, and the tumor was temporarily classified to rather be a parathyroid carcinoma. This case aims to raise awareness for the diagnostic challenge of parathyroid carcinomas as a rare cause of primary hyperparathyroidism and therewith to improve treatment and prognosis