BRAF inhibition in hairy cell leukemia with low-dose vemurafenib.

The activating mutation of the BRAF serine/threonine protein kinase (BRAF V600E) is the key driver mutation in hairy cell leukemia (HCL), suggesting opportunities for therapeutic targeting. We analyzed the course of 21 HCL patients treated with vemurafenib outside of trials with individual dosing regimens (240-1920 mg/d; median treatment duration, 90 days). Vemurafenib treatment improved blood counts in all patients, with platelets, neutrophils, and hemoglobin recovering within 28, 43, and 55 days (median), respectively. Complete remission was achieved in 40% (6/15 of evaluable patients) and median event-free survival was 17 months. Response rate and kinetics of response were independent of vemurafenib dosing. Retreatment with vemurafenib led to similar response patterns (n = 6). Pharmacodynamic analysis of BRAF V600E downstream targets showed that vemurafenib (480 mg/d) completely abrogated extracellular signal-regulated kinase phosphorylation of hairy cells in vivo. Typical side effects also occurred at low dosing regimens. We observed the development of acute myeloid lymphoma (AML) subtype M6 in 1 patient, and the course suggested disease acceleration triggered by vemurafenib. The phosphatidylinositol 3-kinase hotspot mutation (E545K) was identified in the AML clone, providing a potential novel mechanism for paradoxical BRAF activation. These data provide proof of dependence of HCL on active BRAF signaling. We provide evidence that antitumor and side effects are observed with 480 mg vemurafenib, suggesting that dosing regimens in BRAF-driven cancers could warrant reassessment in trials with implications for cost of cancer care.

Expression of Mucin-1 in multiple myeloma and its precursors: correlation with glycosylation and subcellular localization.

AIMS: Recent reports suggest a possible role for extracellular (MUC1N) and transmembrane (MUC1C) subunits of Mucin 1 (MUC1) in the pathogenesis of multiple myeloma (MM). Nuclear translocation of MUC1C is involved in activation of various oncogenic signalling pathways and both MUC1 subunits are potential therapeutic targets. We aimed at performing a comprehensive expression analysis of the MUC1 subunits in plasma cell dyscrasias. METHODS AND RESULTS: Immunohistochemistry with monoclonal antibodies against the MUC1N subunit (EMA and 5E10) tumour-associated glycoforms of MUC1N (5E5) and the MUC1C subunit were applied to a series of biopsies from normal controls (n = 10) and plasma cell dyscrasias (n = 121). Clonal plasma cells showed reduced MUC1N expression, and the 5E5 MUC1N epitope was expressed only in neoplastic plasma cells. Nuclear localization of MUC1C was equally frequent in all disease stages and did not differ from the control cases. Loss of both MUC1 subunits in MM (n = 12) was associated with significantly shorter overall survival and was more frequent in pretreated MM samples. CONCLUSIONS: Our findings indicate that aberrant glycosylation of MUC1 is an early event in the pathogenesis of MM. In contrast, MUC1C nuclear localization is not likely to be a driver of tumour progression.

Oncogene-induced senescence: a potential breakpoint mechanism against malignant transformation in plasma cell disorders.

Oncogene-induced senescence (OIS) is a cellular tumor-suppressive mechanism present in several premalignant conditions. Here, we analyze the possible impact of OIS on malignant transformation in plasma cell disorders. Tumor samples from 125 patients with different disease stages were analyzed immunohistochemically for expression of senescence markers. Protein expression of cyclin-dependent kinase inhibitor p21Cip1/Waf1 was significantly higher in smoldering multiple myeloma (SMM) compared to monoclonal gammopathy of undetermined significance (MGUS) (p = .02) or symptomatic multiple myeloma (MM) (p = .005). SMM plasma cells expressing p21Cip1/Waf1 were negative for Ki67, consistent with senescence. While p27Kip1 was highly expressed in healthy controls, MGUS and SMM, expression decreased significantly in MM (p = .02). SMM plasma cells displayed a mutually exclusive expression of p21Cip1/Waf1/p27Kip1 suggesting compensatory mechanisms of senescence. In conclusion, we found markers of cellular senescence differentially expressed in SMM compared to MGUS and MM supporting the hypothesis of OIS as a breakpoint mechanism against malignant transformation in plasma cell disorders.

Intraindividual Comparison of 18F-PSMA-1007 PET/CT, Multiparametric MRI, and Radical Prostatectomy Specimens in Patients with Primary Prostate Cancer: A Retrospective, Proof-of-Concept Study.

68Ga-prostate-specific membrane antigen (PSMA)-11 PET/CT represents an advanced method for the staging of primary prostate cancer (PCa) and diagnosis of recurrent or metastatic PCa. However, because of the narrow availability of 68Ga the development of alternative tracers is of high interest. The objective of this study was to examine the value of the new PET tracer 18F-PSMA-1007 for the staging of local disease by comparing it with multiparametric MRI (mpMRI) and radical prostatectomy (RP) histopathology. Methods: In 2016, 18F-PSMA-1007 PET/CT was performed in 10 men with biopsy-confirmed high-risk PCa. Nine patients underwent mpMRI in the process of primary diagnosis. Consecutively, RP was performed in all 10 men. Agreement analysis was performed retrospectively. PSMA staining was added for representative sections in RP specimen slices. Localization and agreement analysis of 18F-PSMA-1007 PET/CT, mpMRI, and RP specimens was performed by dividing the prostate into 38 sections as described in the prostate imaging reporting and data system (PI-RADS) (version 2). Sensitivity, specificity, positive predictive values, negative predictive values (NPVs), and accuracy were calculated for total and near-total agreement. Results:18F-PSMA-1007 PET/CT had an NPV of 68% and an accuracy of 75%, and mpMRI had an NPV of 88% and an accuracy of 73% for total agreement. Near-total agreement analysis resulted in an NPV of 91% and an accuracy of 93% for 18F-PSMA-1007 PET/CT and 91% and 87% for mpMRI, respectively. Retrospective combination of mpMRI and PET/CT had an accuracy of 81% for total and 93% for near-total agreement. Conclusion: Comparison with RP histopathology demonstrates that 18F-PSMA-1007 PET/CT is promising for accurate local staging of PCa.

Klippel-Trénaunay-Weber syndrome associated with abdominal aortic aneurysm in childhood.

Klippel-Trénaunay-Weber syndrome (KTWS), also known as angioosteohypertrophy syndrome, is a rare congenital malformation with unknown etiology characterized by the combination of capillary malformations (port-wine strain), venous varicosities, and a soft tissue or bony hypertrophy of the affected limb. It is known to be rarely associated with abdominal aortic aneurysm (AAA) in adults. We report the first published case of KTWS and a rapidly progressing symptomatic AAA undergoing open repair in a child. This underlines the importance of AAA screening and treatment rather than surveillance in patients with KTWS.