Using integrated approaches to identify and implement novel therapies for the treatment of rare pediatric cancers such as melanoma, gastrointestinal stromal tumors and soft tissue sarcomas.
My research is centered on increasing our understanding of rare pediatric cancers. By combining clinicopathologic features with genomics, we are discovering the molecular nuances of pediatric cancers such as melanoma, gastrointestinal stromal tumors (GISTs) and soft tissue sarcomas. Our findings can then be used to stratify patients, tailor current treatments and pursue novel treatment strategies.
While pediatric cancer in itself is uncommon, there are some forms which are considered rare. These rare cancers make up between 10% to 11% of all pediatric cancer cases. I aim to understand why these rare cancers affect children and define how the pediatric forms of these cancers differ from the adult forms. Collectively, this information informs treatment strategies and can lead to novel treatment options.
Our integrated clinicopathological and genomic-based approach to study pediatric melanoma has resulted in the reclassification of this rare cancer into three distinct subsets: conventional or adult-type melanoma, melanoma arising in a giant melanocytic nevus and atypical Spitz tumor/spitz melanoma. We have identified that conventional melanoma presents similarly to adult melanoma while spitz melanoma, the most common pediatric melanoma, differs from adult melanoma and is characterized by gene fusions instead of mutations. These findings have drastically impacted the way these cancers are treated in children. Melanoma arising in a giant melanocytic nevus is resistant to therapy, and our continuing work aims to increase our understanding of this aggressive cancer so new treatment strategies can be developed and implemented.
Currently, St. Jude has a registry for pediatric melanoma, participates in clinical trials for melanoma and provides treatment and second opinions for patients with pediatric melanoma through the St. Jude Pediatric and Adolescent Melanoma Referral Clinic.
Gastrointestinal stromal tumors
Gastrointestinal stromal tumors (GISTs) are uncommon tumors which are typically genetically different in children as compared to adults. Unique molecular characteristics of these tumors in younger patients–such as succinate dehydrogenase (SDH) deficiency–has led to incorporation of genetic predisposition screening guidelines and alternate therapies.
Soft Tissue Sarcomas
Soft tissue sarcomas are cancerous tumors originating in the tissues. Of all childhood tumors diagnosed each year, less than five percent are classified as soft tissue sarcomas. Of these, rhabdomyosarcoma–tumors in the skeletal muscle–are the most common. Much of my research with soft tissue sarcomas is focused on limiting the amount of treatment while maintaining survival in low-risk patients and identifying new strategies to improve survival of high-risk patients. We are also using genomics to stratify patients and exploring the use of a liposomal-encapsulated irinotecan chemotherapy.
Aside from rhabdomyosarcoma, dozens of other non-rhabdomyosarcoma soft tissue sarcomas exist. We are investigating potential clinical treatments for several of these tumors, which is medically complex due to the heterogenous nature of these tumors.
Dr. Pappo is a pediatric oncologist who received his MD from the Medical School at the Universidad Anahuac in Mexico City. He then completed a residency at the University of Texas Health Science Center, a fellowship at the Children’s Medical Center of Dallas and the University of Texas Southwestern Medical Center and a clinical fellowship with the American Cancer Society. Dr. Pappo is a Member of the St. Jude Faculty, the Director of the Solid Tumor Division in the Department of Oncology and Co-Leader of the Developmental Biology and Solid Tumor Program. He is also the Alvin Mauer Endowed Chair. His clinical and research interests lie in the development of novel therapies for pediatric solid tumors, specifically rare pediatric cancers such as melanoma, GISTs and soft tissue sarcomas.