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Leadership & Members

Wistar Faculty

Meenhard Herlyn, D.V.M., D.Sc., Director

Meenhard Herlyn has been a cancer researcher since his arrival at Wistar in 1976 and has participated in the Wistar Institute Cancer Center’s leadership as a program leader since 1985. He is currently the leader of the Cancer Center’s Molecular and Cellular Oncogenesis Program. His current research focuses on the biological significance of stem cells in skin morphogenesis and in transformation, invasion and metastasis, using a variety of in vivo and in vitro models. He has over 400 peer-reviewed publications, 80 percent of which are in melanoma. He is the principal investigator of two P0-1 National Institutes of Health grants on melanoma, one of which has been fully funded since 1980. Herlyn is an active member of two graduate groups at the University of Pennsylvania: Cellular and Molecular Biology and Bioengineering. He has been an independently funded investigator for 25 years.

Dr. Herlyn has received several awards including: the Wings of Hope, Melanoma Research Award and the Diana Ashby Award for Excellence in Melanoma Research in 2004; the American Skin Association Annual Skin Cancer/Melanoma Achievement Award in 2005; the Scientific Research Award for Outstanding Contributions in Melanoma Research; American Cancer Society, Southeast Region, Pennsylvania Division in 2006; the Pan-American Pigment Cell Society Achievement Award and the Lifetime Achievement Award in Melanoma Research from the Society of Melanoma Research in 2007; and the Josef-von-Plenk Award by the Austrian Society for Dermatology and Venerology in 2008. 

David Speicher, Ph.D.

David Speicher received his Ph.D. training in biochemistry at the Pennsylvania State University, followed by postdoctoral training in the pathology department of the Yale Medical School. He is currently professor and director of the Systems and Computational Biology Center at The Wistar Institute.

One major focus of Dr. Speicher's research program is development of novel multi-dimensional proteome profiling methods and application of these methods to identify novel serological diagnostic markers of cancer and other human diseases. His laboratory was an active participant in the Human Proteome Organization's Plasma Proteome Pilot Project and a multi-institutional EDRN-WHI pilot project to discover plasma biomarkers of colon cancer. In addition, his research group uses protein biochemical and biophysical techniques to study protein structure-function relationships of membrane-associated proteins. He serves on a number of scientific advisory boards and National Institutes of Health study sections, and has presented more than 80 invited lectures and seminars. He has published more than 135 peer-reviewed research manuscripts and 45 book chapters or reviews. He edited a book entitled Proteome Research – Interpreting the Genome, serves on a number of editorial boards, including the journals Proteomics, Analytical Biochemistry, Biomarker Insights and PharmaGenomics, and is a senior editor for Cancer Research.  

Ashani Weeraratna, Ph.D.

Ashani Weeraratna received a Ph.D. in Molecular and Cellular Oncology from George Washington University Medical Center’s Department of Pharmacology. From 1998 to 2000, she was post-doctoral fellow at The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins Oncology Center, before joining the National Human Genome Research Institute as a staff scientist. Currently, Dr. Weeraratna is an associate professor in the Molecular and Cellular Oncogenesis Program of The Wistar Institute Cancer Center.

Dr. Weeraratna's research focuses on unraveling the molecular mechanisms involved in melanoma metastasis with a particular emphasis on the Wnt signaling pathway, which comprises a family of proteins that have been shown to have great implications in fetal development as well as cancer. Another major interest of her laboratory lies in examining the link between changes in the tumor microenvironment, such as hypoxia, and aging associated senescence, and melanoma progression.

Jessie Villanueva, Ph.D.

Jessie Villanueva earned a Ph.D. in Molecular Cell and Developmental Biology from University of Miami School of Medicine. She then pursued postdoctoral training at the University of Pennsylvania School of Medicine, where she began to further investigate the role of a mutation in the BRAF gene that has been discovered to be mutated in half of all cases of melanoma, an aggressive form of skin cancer whose rates have climbed steadily in recent years. The mutant BRAF turns on a signaling pathway that drives cell division and, tumor formation.

At Wistar, Dr. Villanueva’s work has demonstrated that recently developed RAF inhibitors are, at best, transient in their tumor-killing effectiveness. In a 2010 article published in the journal Cancer Cell, she presented findings that show how tumor cells are able to adapt to RAF inhibitors and find a way to bypass the effects of the drug. As melanoma is a highly heterogeneous disease, multiple mechanisms of resistance are likely to arise in patients. The Villanueva laboratory is using an array of biochemical and genetic approaches to identify additional mechanisms of intrinsic and acquired resistance and test combinations of different inhibitors targeting pathways including MEK and PI3K. Their goal is to identify the best combination therapies that can overcome drug resistance and could move forward into clinical trials.


Adjunct Members

David Elder, M.B., Ch.B., FRCPA

David E. Elder is professor of pathology and laboratory medicine at the Hospital of the University of Pennsylvania, and vice chair for anatomic pathology. He is also an adjunct professor at Wistar. He has studied the pathology, biology, and epidemiology of melanoma in a career spanning 25 years of association with the Pigmented Lesion Group, of which he is a founding member and co-director at Penn. He has collaborated continuously with Meenherd Herlyn since 1980. With his mentor, Wallace H. Clark, Jr., he was instrumental in the initial characterization of dysplastic nevi, and in the identification and characterization of the distinctive phases of melanoma tumor progression, including especially the defining features and significance of progression from the nontumorigenic radial to the tumorigenic vertical growth phase. His laboratory is engaged in the identification and evaluation of diagnostic and prognostic markers for melanoma. Dr. Elder is actively involved in diagnostic general surgical pathology and is expert in pigmented lesion and skin cancer pathology, serving as a reference consultant at Penn, and also for the national and international community.  Dr. Elder is editor-in-chief of the comprehensive text "Lever's Histopathology of the Skin", which has been published continuously since 1948, and is now going into its tenth edition. 

Phyllis Gimotty, Ph.D.

Phyllis Gimotty is professor of biostatistics, senior scholar in the Center for Clinical Epidemiology and Biostatistics (CCEB) at the University of Pennsylvania and member of the Abramson Cancer Center of the University of Pennsylvania (ACCUP). Dr. Gimotty’s work has focused on the development and evaluation of biomarkers and statistical models for risk, diagnosis and prediction in melanoma and ovarian cancer. In addition, she currently directs biostatistics cores for three translational cores, and is co-director of the Biostatistics and Bioinformations Core of the Fox Chase Cancer Center/Penn SPORE on Ovarian Cancer. She has served as a member of the Statistical Task Force and the Melanoma Committee of the American Joint Commission on Cancer (2006-2008) and currently is a member of the American Joint Committee on Cancer Modelers Working Group. Dr. Gimotty is a member of the American Society of Clinical Oncology’s (ASCO) panel to develop clinical guidelines in cooperation with the Surgical Oncology Society for the use of sentinel node biopsy in patients with malignant melanoma. Dr. Gimotty is also the principal investigator of the Cancer Biostatistics Training Grant at the University of Pennsylvania. 

Katherine Nathanson, M.D.

Katherine Nathanson is an assistant professor in the Division of Medical Genetics within the department of medicine in the School of Medicine. She is a cancer geneticist and has extensive experience with molecular genotyping and analysis of genetic variants in relationship to cancer susceptibility and somatic genetics of cancer. The main body of her work has focused on characterizing inherited genetic changes in relationship to breast cancer susceptibility, but she has more recently branched out to study melanoma, renal and testicular cancers. In studying the former two, she focuses on somatic genetic changes and therapeutic response. Nathanson is the principal investigator on two R01grants; the first is on genetic susceptibility to testicular germ cell tumors and the second on somatic genetic predictors of response to therapy in melanoma. She also holds a grant from the Breast Cancer Research Foundation (BCRF), which supports her work in hereditary breast cancer. Finally, she is clinically active and sees patients with high-risk cancer susceptibility syndromes. 

Lynn Schuchter, M.D.

Lynn Schuchter is professor of Medicine (Hematology/Oncology) and is a recognized expert in the field of melanoma. She is an experienced investigator in the development and conduct of melanoma clinical trials. She has more than 20 years of experience caring for patient with both early and advanced melanoma. She is an expert in translational research, and thus serves as important link between basic scientists and clinical investigators. Schuchter has been a member of the Melanoma Program at the Abramson Cancer Center of the University of Pennsylvania (ACCUP) since 1989, and was appointed leader of the program in July 2007. She is co-principle investigator of the Wistar/Penn Skin Cancer SPORE, leader of the Career Development Program, and co-leader of the Administrative Core. 

Robert Vonderheide, M.D., D.Phil.

Robert Vonderheide is an associate professor of Medicine in the division of hematology oncology and department of medicine at the University of Pennsylvania School of Medicine. He is co-leader of the Immunology Program of the Abramson Cancer Center and an investigator of the Abramson Family Cancer Research Institute. Dr. Vonderheide received a D.Phil. in 1989 in immunology from Oxford University, where he studied as a Rhodes Scholar, and he received his M.D. from Harvard Medical School in 1993. He completed his training at the Massachusetts General Hospital and the Dana-Farber Cancer Institute before being recruited to the University of Pennsylvania School of Medicine in 2001. His laboratory combines efforts in both basic research and clinical investigation to advance the understanding of tumor immunology and to develop novel immunotherapies for cancer. He is principal investigator of an R01 grant to investigate a novel vaccine targeting telomerase and is principal investigator on a P01grant investigating cytokine gene therapy. Vonderheide led the first-in-human study of a novel agonist CD40 mAb which has shown promise in patients with advanced melanoma. 

Xiaowei Xu, M.D., Ph.D.

Xiaowei Xu is an assistant professor of Pathology and Dermatology at the University of Pennsylvania. He completed his Pathology residency at the University of Pennsylvania and dermatopathology fellowship at Harvard. He is a dermatopathologist with extensive experience on pigmented lesions. He has over 60 peer-reviewed publications and is the associate editor of dermatopathology textbook “Lever’s Histopathology of the Skin." The main body of his work has focused on skin neural crest stem cells and melanoma progression. He is the principal investigator of a R01and R21 grants; the R01 grant is on neural crest stem cells in the hair follicles and their role during melanocyte development and the R21 grant seeks to develop ultrasensitive assays to detect serum circulating antigens in melanoma patients. He is clinically active and is responsible for reading cases for the Pigmented Lesion Clinic and Melanoma Clinics at Penn.