Distinct Acute Lymphoblastic Leukemia (ALL)-associated Janus Kinase 3 (JAK3) Mutants Exhibit Different Cytokine-Receptor Requirements and JAK Inhibitor Specificities.

JAK1 and JAK3 are recurrently mutated in acute lymphoblastic leukemia. These tyrosine kinases associate with heterodimeric cytokine receptors such as IL-7 receptor or IL-9 receptor, in which JAK1 is appended to the specific chain, and JAK3 is appended to the common gamma chain. Here, we studied the role of these receptor complexes in mediating the oncogenic activity of JAK3 mutants. Although JAK3(V674A) and the majority of other JAK3 mutants needed to bind to a functional cytokine receptor complex to constitutively activate STAT5, JAK3(L857P) was unexpectedly found to not depend on such receptor complexes for its activity, which was induced without receptor or JAK1 co-expression. Introducing a mutation in the FERM domain that abolished JAK-receptor interaction did not affect JAK3(L857P) activity, whereas it inhibited the other receptor-dependent mutants. The same cytokine receptor independence as for JAK3(L857P) was observed for homologous Leu(857) mutations of JAK1 and JAK2 and for JAK3(L875H). This different cytokine receptor requirement correlated with different functional properties in vivo and with distinct sensitivity to JAK inhibitors. Transduction of murine hematopoietic cells with JAK3(V674A) led homogenously to lymphoblastic leukemias in BALB/c mice. In contrast, transduction with JAK3(L857P) induced various types of lymphoid and myeloid leukemias. Moreover, ruxolitinib, which preferentially blocks JAK1 and JAK2, abolished the proliferation of cells transformed by the receptor-dependent JAK3(V674A), yet proved much less potent on cells expressing JAK3(L857P). These particular cells were, in contrast, more sensitive to JAK3-specific inhibitors. Altogether, our results showed that different JAK3 mutations induce constitutive activation through distinct mechanisms, pointing to specific therapeutic perspectives.
© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

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Low-molecular-weight carbohydrate Pentaisomaltose may replace dimethyl sulfoxide as a safer cryoprotectant for cryopreservation of peripheral blood stem cells.

Cryopreserved hematopoietic stem cell products are widely used for certain hematologic malignancies. Dimethyl sulfoxide (DMSO) is the most widely used cryoprotective agent (CPA) today, but due to indications of cellular toxicity, changes of the cellular epigenetic state, and patient-related side effects, there is an increasing demand for DMSO-free alternatives. We therefore investigated whether Pentaisomaltose (PIM), a low-molecular-weight carbohydrate (1 kDa), can be used for cryopreservation of peripheral blood stem cells, more specifically hematopoietic progenitor cell apheresis (HPC(A)) product.
We cryopreserved patient or donor HPC(A) products using 10% DMSO or 16% PIM and quantified the recovery of CD34+ cells and CD34+ subpopulations by multicolor flow cytometry. In addition, we compared the frequency of HPCs after DMSO and PIM cryopreservation using the colony-forming cells (CFCs) assay.
The mean CD34+ cell recovery was 56.3 ± 23.7% (11.4%-97.3%) and 58.2 ± 10.0% (45.7%-76.9%) for 10% DMSO and 16% PIM, respectively. The distribution of CD34+ cell subpopulations was similar when comparing DMSO or PIM as CPA. CFC assay showed mean colony numbers of 70.7 ± 25.4 (range, 37.8-115.5) and 67.7 ± 15.7 (range, 48-86) for 10% DMSO and 16% PIM, respectively.
Our findings demonstrate that PIM cryopreservation of HPC(A) products provides recovery of CD34+ cells, CD34+ subpopulations, and CFCs similar to that of DMSO cryopreservation and therefore may have the potential to be used for cryopreservation of peripheral blood stem cells.
© 2016 The Authors Transfusion published by Wiley Periodicals, Inc. on behalf of AABB.

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Haem-dependent dimerization of PGRMC1/Sigma-2 receptor facilitates cancer proliferation and chemoresistance.

Progesterone-receptor membrane component 1 (PGRMC1/Sigma-2 receptor) is a haem-containing protein that interacts with epidermal growth factor receptor (EGFR) and cytochromes P450 to regulate cancer proliferation and chemoresistance; its structural basis remains unknown. Here crystallographic analyses of the PGRMC1 cytosolic domain at 1.95 Å resolution reveal that it forms a stable dimer through stacking interactions of two protruding haem molecules. The haem iron is five-coordinated by Tyr113, and the open surface of the haem mediates dimerization. Carbon monoxide (CO) interferes with PGRMC1 dimerization by binding to the sixth coordination site of the haem. Haem-mediated PGRMC1 dimerization is required for interactions with EGFR and cytochromes P450, cancer proliferation and chemoresistance against anti-cancer drugs; these events are attenuated by either CO or haem deprivation in cancer cells. This study demonstrates protein dimerization via haem-haem stacking, which has not been seen in eukaryotes, and provides insights into its functional significance in cancer.

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A Placebo-Controlled Trial of AQW051 in Patients With Moderate to Severe Levodopa-Induced Dyskinesia.

This phase 2 randomized, double-blind, placebo-controlled study evaluated the efficacy and safety of the nicotinic acetylcholine receptor α7 agonist AQW051 in patients with Parkinson’s disease and levodopa-induced dyskinesia.
Patients with idiopathic Parkinson’s disease and moderate to severe levodopa-induced dyskinesia were randomized to AQW051 10 mg (n = 24), AQW051 50 mg (n = 24), or placebo (n = 23) once daily for 28 days. Coprimary end points were change in Modified Abnormal Involuntary Movement Scale and Unified Parkinson’s Disease Rating Scale part III scores. Secondary outcomes included pharmacokinetics.
In total, 67 patients completed the study. AQW051-treated patients experienced no significant improvements in Modified Abnormal Involuntary Movement Scale or Unified Parkinson’s Disease Rating Scale part III scores by day 28. AQW051 was well tolerated; the most common adverse events were dyskinesia, fatigue, nausea, and falls.
AQW051 did not significantly reduce dyskinesia or parkinsonian severity. © 2016 International Parkinson and Movement Disorder Society.
© 2016 Movement Disorder Society.

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The Myriad myRisk® Hereditary Cancer Test Identifies 60 Percent More Deleterious Mutations in Patients with Endometrial Cancer

On March 18, 2016 Myriad Genetics, Inc. (NASDAQ:MYGN), a leader in molecular diagnostics and personalized medicine, reported it will present two important new studies at the 2016 Society for Gynecologic Oncology annual meeting in San Diego, Calif (Press release, Myriad Genetics, MAR 18, 2016, View Source [SID:1234509630]).

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The data demonstrate the ability of the myRisk Hereditary Cancer test to identify deleterious mutations in patients with endometrial cancer. Additionally, a different study showed the superior ability of the combined three biomarker myChoice HRD test to predict survival in patients with platinum treated ovarian cancer.

"Endometrial cancer is the most frequent gynecologic cancer and a significant number of these cases are due to mutations in hereditary cancer genes," said Johnathan Lancaster, M.D., Ph.D., chief medical officer, Myriad Genetic Laboratories. "Our new data show that gene panel testing can identify many more patients with harmful mutations than testing Lynch Syndrome genes alone. The additional information provided by the myRisk Hereditary Cancer test will help physicians optimize care for their patients."

Details about the featured Myriad presentations at SGO are below. Follow Myriad on Twitter via @MyriadGenetics and stay up-to-date with the meeting by using the hashtag #SGOMtg.

myRisk Hereditary Cancer Presentation — Endometrial Cancer

Title: Hereditary cancer panel testing in an unselected endometrial carcinoma cohort.
Date: Saturday, March 19, 2016: 7:50 to 9:55 a.m. PT.
Location: Podium — Abstract 6261.
Presenter: Kari Ring, MD Anderson Cancer Center.

This study evaluated the prevalence of cancer predisposition gene mutations in 381 endometrial cancer patients who had previously undergone tumor testing to screen for Lynch Syndrome. Patients were tested for mutations in 25 cancer genes using the myRisk Hereditary Cancer test. The results showed that 9.2 percent of endometrial cancer patients had a deleterious mutation, including 5.8 percent with a mutation in a Lynch Syndrome gene and 3.4 percent in 10 non-Lynch genes. Multi-gene panel testing with myRisk demonstrated the ability to identify 60 percent more mutations, several of which are associated with ovarian and uterine cancers. These findings support gene panel testing to identify patients who may be missed by current Lynch Syndrome testing alone.

myChoice HRD Presentation

Title: Homologous recombination deficiency (HRD) score shows superior association with outcome compared to its individual score components (LOH, TAI and LST) in platinum treated serous ovarian cancer.
Date: Saturday, March 19, 2016: 7:50 to 9:55 a.m. PT.
Location: Podium — Abstract 6286.
Presenter: Gordon B. Mills, M.D., Ph.D., MD Anderson Cancer Center.

This study compared the predictive ability of the combined three biomarker myChoice HRD score to the three independent measures of homologous recombination deficiency that comprise the assay including: loss of heterozygosity (LOH) score, telomeric-allelic imbalance (TAI) score, and large-scale state transitions (LST) score. The results showed that the combined myChoice HRD score predicted progression-free survival (p=2.2×10-6) and overall survival (p=1.0×10-8) in patients with platinum-treated ovarian cancer. In a bivariate analysis none of the individual biomarkers (LOH, TAI and LST) reached statistical significance for either progression free survival or overall survival. In this study, myChoice HRD was shown to be a superior predictor of clinical outcomes to any of the individual score components including LOH, TAI and LST.

About Myriad myRisk Hereditary Cancer Testing
The Myriad myRisk Hereditary Cancer test uses next-generation sequencing technology to evaluate 25 clinically significant genes associated with eight hereditary cancer sites including: breast, colon, ovarian, endometrial, pancreatic, prostate and gastric cancers and melanoma. For more information visit: myriad.com.

About myChoice HRD
Myriad’s myChoice HRD is the first homologous recombination deficiency test that can detect when a tumor has lost the ability to repair double-stranded DNA breaks, resulting in increased susceptibility to DNA-damaging drugs such as platinum drugs or PARP inhibitors. High myChoice HRD scores reflective of DNA repair deficiencies are prevalent in all breast cancer subtypes, ovarian and most other major cancers. In previously published data, Myriad showed that the myChoice HRD test predicted drug response to platinum therapy in certain patients with triple-negative breast and ovarian cancers. It is estimated that 1.8 million people in the United States and Europe who are diagnosed with cancers annually may be candidates for treatment with DNA-damaging agents. For more information visit: myriad.com.