PURPOSE Colony-stimulating factor-3 receptor ( CSF3R)-T618I is a recurrent activating mutation in chronic neutrophilic leukemia (CNL) and to a lesser extent in atypical chronic myeloid leukemia (aCML) resulting in constitutive JAK-STAT signaling. We sought to evaluate safety and efficacy of the JAK1/2 inhibitor ruxolitinib in patients with CNL and aCML, irrespective of CSF3R mutation status. METHODS We conducted a phase II study of ruxolitinib in 44 patients (21 CNL and 23 aCML). The primary end point was overall hematologic response rate (ORR) by the end of 6 continuous 28-day cycles for the first 25 patients enrolled. We considered a response as either partial (PR) or complete response (CR). We expanded accrual to 44 patients to increase our ability to evaluate secondary end points, including grade ≥ 3 adverse events, spleen volume, symptom assessment, genetic correlates of response, and 2-year survival. RESULTS ORR was 32% for the first 25 enrolled patients (8 PR [7 CNL and 1 aCML]). In the larger cohort of 44 patients, 35% had a response (11 PR [9 CNL and 2 aCML] and 4 CR [CNL]), and 50% had oncogenic CSF3R mutations. The mean absolute allele burden reduction of CSF3R-T618I after 6 cycles was greatest in the CR group, compared with the PR and no response groups. The most common cause of death is due to disease progression. Grade ≥ 3 anemia and thrombocytopenia were observed in 34% and 14% of patients, respectively. No serious adverse events attributed to ruxolitinib were observed. CONCLUSION Ruxolitinib was well tolerated and demonstrated an estimated response rate of 32%. Patients with a diagnosis of CNL and/or harboring CSF3R-T618I were most likely to respond.

Inhaled anesthetics are believed to produce anesthesia by their actions on ion channels. Because inhaled anesthetics robustly enhance GABA A receptor (GABA A -R) responses to GABA, these receptors are considered prime targets of anesthetic action. However, the importance of GABA A -Rs and individual GABA A -R subunits to specific anesthetic-induced behavioral effects in the intact animal is unknown. We hypothesized that inhaled anesthetics produce amnesia, as assessed by loss of fear conditioning, by acting on the forebrain GABA A -Rs that harbor the ␣1 subunit. To test this, we used global knockout mice that completely lack the ␣1 subunit and forebrain-specific, conditional knockout mice that lack the ␣1 subunit only in the hippocampus, cortex, and amygdala. Both knockout mice were 75 to 145% less sensitive to the amnestic effects of the inhaled anesthetic isoflurane. These results indicate that ␣1-containing GABA A -Rs in the hippocampus, amygdala, and/or cortex influence the amnestic effects of inhaled anesthetics and may be an important molecular target of the drug isoflurane.

Mutations in the calreticulin gene (CALR) were recently identified in approximately 70–80% of patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis. All frameshift mutations generate a recurring novel C-terminus. Here we provide evidence that mutant calreticulin does not accumulate efficiently in cells and is abnormally enriched in the nucleus and extracellular space compared to wildtype calreticulin. The main determinant of these findings is the loss of the calcium-binding and KDEL domains. Expression of type I mutant CALR in Ba/F3 cells confers minimal IL-3-independent growth. Interestingly, expression of type I and type II mutant CALR in a non-hematopoietic cell line does not directly activate JAK/STAT signaling compared to JAK2-V617F expression. These results led us to investigate paracrine mechanisms of JAK/STAT activation. Here we show that conditioned media from cells expressing type I mutant CALR exaggerate cytokine production from normal monocytes with or without treatment with a toll-like receptor agonist. These effects are not dependent on the novel C-terminus. These studies offer novel insights into the mechanism of JAK/STAT activation in patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis.

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Epithelioid sarcoma is a rare, malignant, soft tissue neoplasm that can be classified into proximal, distal and fibroma-like subtypes. Regardless of subtype, epithelioid sarcoma often shows morphologic and immunophenotypic evidence of epithelial differentiation. Current therapeutic strategies include surgical resection, amputation, radiation or chemotherapy, although the overall prognosis remains poor. The epidermal growth factor receptor (EGFR) is a novel therapeutic target in carcinomas. In some carcinomas, EGFR kinase domain mutations or gene amplification may correlate with response to specific inhibitors. EGFR expression has been reported in some sarcoma types, but expression, amplification and mutations have not been studied in epithelioid sarcoma. We evaluated 15 cases of epithelioid sarcoma from 14 patients for EGFR expression using immunohistochemistry, EGFR copy number aberration using fluorescence in situ hybridization and screened for mutations in the tyrosine kinase domain of the EGFR gene using direct sequencing. In all, 14 of the 15 epithelioid sarcomas (93%) showed expression of EGFR by immunohistochemistry. A majority of the cases (n ¼ 11, 73%) showed strong (2 þ to 3 þ ) and homogeneous (475% of cells) membrane staining. No amplification or polysomy of the EGFR gene or mutations of the tyrosine kinase domain of EGFR (exons 18-21) were detected. These results imply that although EGFR is expressed in most epithelioid sarcomas regardless of subtype, gene amplification and activating mutations in the tyrosine kinase domain appear to be rare or absent. Thus, the benefit of targeted therapy against EGFR in patients with epithelioid sarcoma remains to be determined.

Overall we identify elevated D-dimer concentrations ≥19 000 ng/mL FEU are a sensitive indicator of acute promyelocytic leukemia (APL), with a sensitivity of 96% and specificity of 92% in the subtyping of acute leukemias, and that the presence of schistocytes in peripheral blood smears is not a diagnostically sensitive screening test for DIC with a sensitivity of 36%.

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