Research Spotlight

Posted June 15th 2016

Human leukocyte antigen supertype matching after myeloablative hematopoietic cell transplantation with 7/8 matched unrelated donor allografts: A report from the Center for International Blood and Marrow Transplant Research.

Medhat Z. Askar M.D.

Medhat Z. Askar M.D.

Lazaryan, A., T. Wang, S. R. Spellman, H. L. Wang, J. Pidala, T. Nishihori, M. Askar, R. Olsson, M. Oudshoorn, H. Abdel-Azim, A. Yong, M. Gandhi, C. Dandoy, B. Savani, G. Hale, K. Page, M. Bitan, R. Reshef, W. Drobyski, S. G. Marsh, K. Schultz, C. R. Muller, M. A. Fernandez-Vina, M. R. Verneris, M. M. Horowitz, M. Arora, D. J. Weisdorf and S. J. Lee (2016). “Human leukocyte antigen supertype matching after myeloablative hematopoietic cell transplantation with 7/8 matched unrelated donor allografts: A report from the center for international blood and marrow transplant research.” Haematologica: May 2016 [Epub ahead of print].

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The diversity of the human leukocyte antigen (HLA) class I and II alleles can be simplified by consolidating them into fewer supertypes based on functional or predicted structural similarities in epitope binding grooves of HLA molecules. We studied the impact of matched and mismatched HLA-A (265 vs. 429), -B (230 vs. 92), -C (365 vs. 349), and -DRB1 (153 vs. 51) supertypes on clinical outcomes of 1934 patients with acute leukemias or myelodysplasia/myeloproliferative disorders. All patients were reported to the Center for International Blood and Marrow Transplant Research following single-allele mismatched unrelated donor myeloablative conditioning hematopoietic cell transplantation. Single mismatched alleles were categorized into 6 HLA-A (A01, A01A03, A01A24, A02, A03, A24), 6 HLA-B (B07, B08, B27, B44, B58, B62), 2 HLA-C (C1, C2), and 5 HLA-DRB1 (DR1, DR3, DR4, DR5, DR9) supertypes. Supertype B mismatch was associated with increased risk of grade II-IV acute graft-versus-host disease (hazard ratio =1.78, p=0.0025) compared to supertype B match. Supertype B07-B44 mismatch was associated with a higher incidence of both grade II-IV (hazard ratio=3.11, p=0.002) and III-IV (hazard ratio=3.15, p=0.01) acute graft-versus-host- disease. No significant associations were detected between supertype-matched versus -mismatched groups at other HLA loci. These data suggest that avoiding HLA-B supertype mismatches can mitigate the risk of grade II-IV acute graft-versus-host disease in 7/8-mismatched unrelated donor hematopoietic cell transplantation when multiple HLA-B supertype-matched donors are available, and call for future studies to define the mechanisms by which supertype mismatching affects outcomes after alternative donor hematopoietic cell transplantation.


Posted May 15th 2016

Egfr fusions as novel therapeutic targets in lung cancer.

Kartik Konduri M.D.

Kartik Konduri, M.D.

Konduri, K., J. N. Gallant, Y. K. Chae, F. J. Giles, B. J. Gitlitz, K. Gowen, E. Ichihara, T. K. Owonikoko, V. Peddareddigari, S. S. Ramalingam, S. K. Reddy, B. Eaby-Sandy, T. Vavala, A. Whiteley, H. Chen, Y. Yan, J. H. Sheehan, J. Meiler, D. Morosini, J. S. Ross, P. J. Stephens, V. A. Miller, S. M. Ali and C. M. Lovly (2016). “Egfr fusions as novel therapeutic targets in lung cancer.” Cancer Discov Apr 21 [Epub ahead of print].

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Here, we report that novel epidermal growth factor receptor (EGFR) gene fusions comprising the N-terminal of EGFR linked to various fusion partners, most commonly RAD51, are recurrent in lung cancer. We describe five patients with metastatic lung cancer whose tumors harbored EGFR fusions, four of whom were treated with EGFR tyrosine kinase inhibitors (TKIs) with documented anti-tumor responses. In vitro, EGFR-RAD51 fusions are oncogenic and can be therapeutically targeted with available EGFR TKIs and therapeutic antibodies. These results support the dependence of EGFR-rearranged tumors on EGFR-mediated signaling and suggest several therapeutic strategies for patients whose tumors harbor this novel alteration.


Posted May 15th 2016

A founder mutation in vps11 causes an autosomal recessive leukoencephalopathy linked to autophagic defects.

Raphael Schiffmann M.D.

Raphael Schiffmann M.D.

Zhang, J., V. Lachance, A. Schaffner, X. Li, A. Fedick, L. E. Kaye, J. Liao, J. Rosenfeld, N. Yachelevich, M. L. Chu, W. G. Mitchell, R. G. Boles, E. Moran, M. Tokita, E. Gorman, K. Bagley, W. Zhang, F. Xia, M. Leduc, Y. Yang, C. Eng, L. J. Wong, R. Schiffmann, G. A. Diaz, R. Kornreich, R. Thummel, M. Wasserstein, Z. Yue and L. Edelmann (2016). “A founder mutation in vps11 causes an autosomal recessive leukoencephalopathy linked to autophagic defects.” PLoS Genet 12(4): e1005848.

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Genetic leukoencephalopathies (gLEs) are a group of heterogeneous disorders with white matter abnormalities affecting the central nervous system (CNS). The causative mutation in ~50% of gLEs is unknown. Using whole exome sequencing (WES), we identified homozygosity for a missense variant, VPS11: c.2536T>G (p.C846G), as the genetic cause of a leukoencephalopathy syndrome in five individuals from three unrelated Ashkenazi Jewish (AJ) families. All five patients exhibited highly concordant disease progression characterized by infantile onset leukoencephalopathy with brain white matter abnormalities, severe motor impairment, cortical blindness, intellectual disability, and seizures. The carrier frequency of the VPS11: c.2536T>G variant is 1:250 in the AJ population (n = 2,026). VPS11 protein is a core component of HOPS (homotypic fusion and protein sorting) and CORVET (class C core vacuole/endosome tethering) protein complexes involved in membrane trafficking and fusion of the lysosomes and endosomes. The cysteine 846 resides in an evolutionarily conserved cysteine-rich RING-H2 domain in carboxyl terminal regions of VPS11 proteins. Our data shows that the C846G mutation causes aberrant ubiquitination and accelerated turnover of VPS11 protein as well as compromised VPS11-VPS18 complex assembly, suggesting a loss of function in the mutant protein. Reduced VPS11 expression leads to an impaired autophagic activity in human cells. Importantly, zebrafish harboring a vps11 mutation with truncated RING-H2 domain demonstrated a significant reduction in CNS myelination following extensive neuronal death in the hindbrain and midbrain. Thus, our study reveals a defect in VPS11 as the underlying etiology for an autosomal recessive leukoencephalopathy disorder associated with a dysfunctional autophagy-lysosome trafficking pathway.


Posted May 15th 2016

Long-term follow-up and sudden unexpected death in gaucher disease type 3 in egypt.

Raphael Schiffmann M.D.

Raphael Schiffmann, M.D.

Abdelwahab, M., D. Blankenship and R. Schiffmann (2016). “Long-term follow-up and sudden unexpected death in gaucher disease type 3 in egypt.” Neurol Genet 2(2): e55.

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OBJECTIVE: To describe the long-term follow-up and distinct phenotype of a large cohort of patients with Gaucher disease type 3 on enzyme replacement therapy (ERT) in Egypt. METHODS: A prospective cohort study of 78 patients on ERT who were followed for up to 9 years with yearly evaluations that included EEG and cognitive testing. RESULTS: Of the patients, 73% were homozygous for the L444P GBA1 mutation; all but 7 were neurologically symptomatic. Supranuclear gaze palsy with variable but stable cognitive function was present in 91% of patients. Convergent strabismus and bulbar dysfunction were noted in 22% and 37%, respectively. Features of oppositional defiant disorder were present in 54% of patients. Twenty-three patients (30%) developed seizures while on ERT for 1-9 years. Of those, 12 patients (15%) died suddenly and unexpectedly at a mean age of 6.7 +/- 5.0 years (range 1.5-18). Sudden death was usually associated with a seizure disorder or a terminal seizure, but 7 of 12 patients had a preceding normal EEG. An additional 11% had background slowing or epileptogenic activity on EEG without clinical seizures. There were 3 familial cases of sudden unexpected death. CONCLUSIONS: Despite having the most common GBA1 genotype known to be associated with neuronopathic Gaucher disease, patients with Gaucher disease type 3 in Egypt have a phenotype and a clinical outcome on ERT that are very different from those observed in other populations. Identifying putative modifying genes of this ethnic group is likely to lead to better therapy for neuronopathic Gaucher disease generally.


Posted May 15th 2016

Pustular psoriasis eruption with dabrafenib, a braf inhibitor.

Alan M. Menter M.D.

Alan M. Menter M.D.

Fawaz, B., L. Dickson and A. Menter (2016). “Pustular psoriasis eruption with dabrafenib, a braf inhibitor.” J Dermatolog Treat Apr 14 [Epub ahead of print]

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Targeted BRAF inhibition with vemurafenib and dabrafenib has dramatically improved the survival rate in metastatic melanoma. These agents are now being tested for their efficacy against other tumors with BRAF mutations, including lung adenocarcinoma. While cutaneous adverse events are prevalent with BRAF inhibition, our patient, to our knowledge, is the first to develop a psoriatic eruption with BRAF inhibitors. We postulate that the elevation of tumor necrosis factor-alpha (TNF-alpha) and the paradoxical activation of the mitogen-activated protein kinase (MAPK) pathway due to BRAF inhibition may be responsible for the eruption. More studies are needed to further elucidate the immunopathogenic mechanisms behind this adverse event. The response to MEK inhibitors and/or increased TNF-alpha inhibition may help support or debunk our hypothesis.