Leo Mascarenhas, MD

Associate Professor of Clinical Pediatrics

Section Head, Oncology

Director Solid Tumor Program

Director of Clinical Trials Office

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Leo Mascarenhas, MD is director of the Clinical Trials Office in the Children’s Center for Cancer and Blood Diseases and Principal Investigator for the National Cancer Institute funded Children’s Oncology Group grant at Children’s Hospital Los Angeles. He is an associate professor of Clinical Pediatrics at the Keck School of Medicine of the University of Southern California.

Childhood cancer is the leading cause of disease-related death in pediatrics in the United States. Dr. Mascarenhas and his team’s research focuses on developmental therapeutics for patients with bone and soft tissue sarcomas. Despite the remarkable progress made in the treatment of childhood cancer in the last four decades, improved therapies are still needed for our patients with a poor prognosis and less toxic therapies for those destined to survive. This can be accomplished only through basic, translational and clinical research.


  • An Exome Capture-Based RNA-Sequencing Assay for Genome-Wide Identification and Prioritization of Clinically Important Fusions in Pediatric Tumors J Mol Diagn. 2023 Nov 24. . View in PubMed
  • Comparative Clinicopathologic and Genomic Analysis of Hepatocellular Neoplasm, Not Otherwise Specified, and Hepatoblastoma Mod Pathol. 2023 Nov 20; 37(2):100385. . View in PubMed
  • Combined low-pass whole genome and targeted sequencing in liquid biopsies for pediatric solid tumors NPJ Precis Oncol. 2023 Feb 20; 7(1):21. . View in PubMed
  • Survival outcomes and surgical morbidity based on surgical approach to pulmonary metastasectomy in pediatric, adolescent and young adult patients with osteosarcoma Cancer Med. 2023 10; 12(20):20231-20241. . View in PubMed
  • Alveolar rhabdomyosarcoma has superior response rates to vinorelbine compared to embryonal rhabdomyosarcoma in patients with relapsed/refractory disease: A meta-analysis Cancer Med. 2023 05; 12(9):10222-10229. . View in PubMed
  • Phase I trial of Ganitumab plus Dasatinib to Cotarget the Insulin-Like Growth Factor 1 Receptor and Src Family Kinase YES in Rhabdomyosarcoma Clin Cancer Res. 2023 09 01; 29(17):3329-3339. . View in PubMed
  • Pediatric Metastatic Hepatoblastoma With an ARID1A Mutation and Rhabdoid Cells Int J Surg Pathol. 2022 May; 30(3):307-312. . View in PubMed
  • Mediastinal infantile hemangioma with spinal canal extension and extensive gastrointestinal involvement complicated by respiratory failure Pediatr Blood Cancer. 2022 11; 69(11):e29934. . View in PubMed
  • Clinical group and modified TNM stage for rhabdomyosarcoma: A review from the Children’s Oncology Group Pediatr Blood Cancer. 2022 06; 69(6):e29644. . View in PubMed
  • Kaposiform hemangioendothelioma of the bone in children and adolescents Pediatr Blood Cancer. 2022 01; 69(1):e29392. . View in PubMed
  • Diffuse Anaplastic Wilms Tumor in a Child With LAMA2 -related Muscular Dystrophy J Pediatr Hematol Oncol. 2022 11 01; 44(8):474-478. . View in PubMed
  • Reply to J-G. Wang et al. J Clin Oncol. 2022 05 01; 40(13):1507-1508. . View in PubMed
  • Independent Assessment of the Children’s Hepatic Tumors International Collaboration Risk Stratification for Hepatoblastoma and the Association of Tumor Histological Characteristics With Prognosis JAMA Netw Open. 2022 02 01; 5(2):e2148013. . View in PubMed
  • Potential methylation-regulated genes and pathways in hepatocellular neoplasm, not otherwise specified Front Oncol. 2022; 12:952325. . View in PubMed
  • Prioritization of Novel Agents for Patients with Rhabdomyosarcoma: A Report from the Children’s Oncology Group (COG) New Agents for Rhabdomyosarcoma Task Force J Clin Med. 2021 Apr 01; 10(7). . View in PubMed
  • Quality of Life in Adult and Pediatric Patients with Tropomyosin Receptor Kinase Fusion Cancer Receiving Larotrectinib Curr Probl Cancer. 2021 12; 45(6):100734. . View in PubMed
  • Alveolar rhabdomyosarcoma with regional nodal involvement: Results of a combined analysis from two cooperative groups Pediatr Blood Cancer. 2021 03; 68(3):e28832. . View in PubMed
  • Metabolic response as assessed by 18 F-fluorodeoxyglucose positron emission tomography-computed tomography does not predict outcome in patients with intermediate- or high-risk rhabdomyosarcoma: A report from the Children’s Oncology Group Soft Tissue Sarcoma Committee Cancer Med. 2021 02; 10(3):857-866. . View in PubMed
  • Phase 1 trial of olaratumab monotherapy and in combination with chemotherapy in pediatric patients with relapsed/refractory solid and central nervous system tumors Cancer Med. 2021 02; 10(3):843-856. . View in PubMed
  • Phase III Trial Adding Vincristine-Topotecan-Cyclophosphamide to the Initial Treatment of Patients With Nonmetastatic Ewing Sarcoma: A Children’s Oncology Group Report J Clin Oncol. 2021 12 20; 39(36):4029-4038. . View in PubMed
  • Survival outcomes of patients with localized FOXO1 fusion-positive rhabdomyosarcoma treated on recent clinical trials: A report from the Soft Tissue Sarcoma Committee of the Children’s Oncology Group Cancer. 2021 03 15; 127(6):946-956. . View in PubMed
  • A Step Forward in Realizing the Promise of Genomic Medicine for Childhood Rhabdomyosarcoma J Clin Oncol. 2021 09 10; 39(26):2851-2854. . View in PubMed
  • SARC025 arms 1 and 2: A phase 1 study of the poly(ADP-ribose) polymerase inhibitor niraparib with temozolomide or irinotecan in patients with advanced Ewing sarcoma Cancer. 2021 04 15; 127(8):1301-1310. . View in PubMed
  • A Randomized, Double-Blind, Placebo-Controlled, Phase II Study of Regorafenib Versus Placebo in Advanced/Metastatic, Treatment-Refractory Liposarcoma: Results from the SARC024 Study Oncologist. 2020 11; 25(11):e1655-e1662. . View in PubMed
  • Abnormal Pulmonary Lymphatic Flow in Patients With Lymphatic Anomalies and Respiratory Compromise Chest. 2020 08; 158(2):681-691. . View in PubMed
  • Larotrectinib in patients with TRK fusion-positive solid tumours: a pooled analysis of three phase 1/2 clinical trials Lancet Oncol. 2020 04; 21(4):531-540. . View in PubMed
  • Expanding the spectrum of dicer1-associated sarcomas Mod Pathol. 2020 01; 33(1):164-174. . View in PubMed
  • Results of a Randomized, Double-Blinded, Placebo-Controlled, Phase 25 Study of Saracatinib (AZD0530), in Patients with Recurrent Osteosarcoma Localized to the Lung. Sarcoma. 2020; 2020:7935475. . View in PubMed
  • SWI/SNF complex heterogeneity is related to polyphenotypic differentiation, prognosis, and immune response in rhabdoid tumors Neuro Oncol. 2020 06 09; 22(6):785-796. . View in PubMed
  • Effect of a Daily Text Messaging and Directly Supervised Therapy Intervention on Oral Mercaptopurine Adherence in Children With Acute Lymphoblastic Leukemia: A Randomized Clinical Trial JAMA Netw Open. 2020 08 03; 3(8):e2014205. . View in PubMed
  • Correction: Detection of circulating tumour DNA is associated with inferior outcomes in Ewing sarcoma and osteosarcoma: a report from the Children’s Oncology Group Br J Cancer. 2019 Apr; 120(8):869. . View in PubMed
  • Sunitinib in pediatric patients with advanced gastrointestinal stromal tumor: results from a phase I/II trial Cancer Chemother Pharmacol. 2019 07; 84(1):41-50. . View in PubMed
  • Survival and prognosis with osteosarcoma: outcomes in more than 2000 patients in the EURAMOS-1 (European and American Osteosarcoma Study) cohort Eur J Cancer. 2019 03; 109:36-50. . View in PubMed
  • Randomized Phase II Trial of Bevacizumab or Temsirolimus in Combination With Chemotherapy for First Relapse Rhabdomyosarcoma: A Report From the Children’s Oncology Group J Clin Oncol. 2019 11 01; 37(31):2866-2874. . View in PubMed
  • Risk-based treatment for patients with first relapse or progression of rhabdomyosarcoma: A report from the Children’s Oncology Group Cancer. 2019 08 01; 125(15):2602-2609. . View in PubMed
  • Randomized Double-Blind Phase II Study of Regorafenib in Patients With Metastatic Osteosarcoma J Clin Oncol. 2019 06 01; 37(16):1424-1431. . View in PubMed
  • Bronchial Mucoepidermoid Carcinoma With the Classic MAML2 Gene Rearrangement in a 2-year-old Boy Pediatr Dev Pathol. 2018 Sep-Oct; 21(5):480-485. . View in PubMed
  • Detection of circulating tumour DNA is associated with inferior outcomes in Ewing sarcoma and osteosarcoma: a report from the Children’s Oncology Group Br J Cancer. 2018 08; 119(5):615-621. . View in PubMed
  • Larotrectinib for paediatric solid tumours harbouring NTRK gene fusions: phase 1 results from a multicentre, open-label, phase 1/2 study Lancet Oncol. 2018 05; 19(5):705-714. . View in PubMed
  • Three synchronous malignancies in a patient with DICER1 syndrome Eur J Cancer. 2018 04; 93:140-143. . View in PubMed
  • Efficacy of Larotrectinib in TRK Fusion-Positive Cancers in Adults and Children N Engl J Med. 2018 02 22; 378(8):731-739. . View in PubMed
  • Addition of Vincristine and Irinotecan to Vincristine, Dactinomycin, and Cyclophosphamide Does Not Improve Outcome for Intermediate-Risk Rhabdomyosarcoma: A Report From the Children’s Oncology Group J Clin Oncol. 2018 09 20; 36(27):2770-2777. . View in PubMed
  • The use of neoadjuvant larotrectinib in the management of children with locally advanced TRK fusion sarcomas Cancer. 2018 11 01; 124(21):4241-4247. . View in PubMed
  • VIncristine, irinotecan, and temozolomide in children and adolescents with relapsed rhabdomyosarcoma Pediatr Blood Cancer. 2018 Jan; 65(1). . View in PubMed
  • Clinical and Genetic Risk Prediction of Subsequent CNS Tumors in Survivors of Childhood Cancer: A Report From the COG ALTE03N1 Study J Clin Oncol. 2017 Nov 10; 35(32):3688-3696. . View in PubMed
  • Hepatocellular malignant neoplasm, NOS: a clinicopathological study of 11 cases from a single institution Histopathology. 2017 Nov; 71(5):813-822. . View in PubMed
  • Mercaptopurine Ingestion Habits, Red Cell Thioguanine Nucleotide Levels, and Relapse Risk in Children With Acute Lymphoblastic Leukemia: A Report From the Children’s Oncology Group Study AALL03N1 J Clin Oncol. 2017 May 20; 35(15):1730-1736. . View in PubMed
  • Inherited germline ATRX mutation in two brothers with ATR-X syndrome and osteosarcoma Am J Med Genet A. 2017 May; 173(5):1390-1395. . View in PubMed
  • De novo hepatocellular carcinoma post-multivisceral transplantation in a child Pediatr Transplant. 2017 11; 21(7). . View in PubMed
  • Comparison of self-report and electronic monitoring of 6MP intake in childhood ALL: a Children’s Oncology Group study Blood. 2017 04 06; 129(14):1919-1926. . View in PubMed
  • Comparison of MAPIE versus MAP in patients with a poor response to preoperative chemotherapy for newly diagnosed high-grade osteosarcoma (EURAMOS-1): an open-label, international, randomised controlled trial Lancet Oncol. 2016 Oct; 17(10):1396-1408. . View in PubMed
  • Pilot Study of Adding Vincristine, Topotecan, and Cyclophosphamide to Interval-Compressed Chemotherapy in Newly Diagnosed Patients With Localized Ewing Sarcoma: A Report From the Children’s Oncology Group Pediatr Blood Cancer. 2016 Mar; 63(3):493-8. . View in PubMed
  • Pediatric phase I trial of oral sorafenib and topotecan in refractory or recurrent pediatric solid malignancies Cancer Med. 2016 Feb; 5(2):294-303. . View in PubMed
  • Pilot Feasibility Study of Comprehensive Pulmonary Evaluation Following Lung Radiation Therapy J Pediatr Hematol Oncol. 2015 Oct; 37(7):e412-8. . View in PubMed
  • Insulin-like Growth Factor 2 Gene Expression Molecularly Differentiates Pleuropulmonary Blastoma and Embryonal Rhabdomyosarcoma J Pediatr Hematol Oncol. 2015 Aug; 37(6):e356-60. . View in PubMed
  • Zoledronic Acid for the Treatment of Children With Refractory Central Giant Cell Granuloma J Pediatr Hematol Oncol. 2015 Aug; 37(6):e399-401. . View in PubMed
  • Systemic Exposure to Thiopurines and Risk of Relapse in Children With Acute Lymphoblastic Leukemia: A Children’s Oncology Group Study JAMA Oncol. 2015 Jun; 1(3):287-95. . View in PubMed
  • Correlation of pulmonary function abnormalities with dose volume histograms in children treated with lung irradiation Pediatr Pulmonol. 2015 Jun; 50(6):596-603. . View in PubMed
  • Is INI1-retained small cell undifferentiated histology in hepatoblastoma unfavorable? Hum Pathol. 2015 Apr; 46(4):620-4.. View in PubMed
  • Hepatoblastoma in a patient with methylmalonic aciduria Am J Med Genet A. 2015 Mar; 167A(3):635-8. . View in PubMed
  • Sarcomas Pediatr Clin North Am. 2015 Feb; 62(1):179-200. . View in PubMed
  • Oxaliplatin and Doxorubicin for relapsed or refractory high-risk neuroblastoma Pediatr Hematol Oncol. 2015 Feb; 32(1):26-31. . View in PubMed
  • Effect of neoadjuvant chemotherapy on resectability of stage III and IV hepatoblastoma Br J Surg. 2015 Jan; 102(1):108-13. . View in PubMed
  • Screening for cardiac dysfunction in anthracycline-exposed childhood cancer survivors Clin Cancer Res. 2014 Dec 15; 20(24):6314-23. . View in PubMed
  • De novo congenital melanoma: analysis of 2 cases with array comparative genomic hybridization Am J Dermatopathol. 2014 Nov; 36(11):915-9. . View in PubMed
  • Pulmonary function abnormalities in childhood cancer survivors treated with bleomycin Pediatr Blood Cancer. 2014 Sep; 61(9):1679-84. . View in PubMed
  • High dose alkylator therapy for extracranial malignant rhabdoid tumors in children Pediatr Blood Cancer. 2014 Aug; 61(8):1357-61. . View in PubMed
  • Hepatoblastoma and hypoplastic kidneys: a new association Pediatr Blood Cancer. 2014 Aug; 61(8):1476-8. . View in PubMed
  • Pulmonary outcomes in patients with Hodgkin lymphoma treated with involved field radiation Pediatr Blood Cancer. 2014 Jul; 61(7):1277-81. . View in PubMed
  • Successful treatment of recurrent metastatic nasopharyngeal carcinoma with oxaliplatin and doxorubicin J Pediatr Hematol Oncol. 2014 Jul; 36(5):e307-9. . View in PubMed
  • Carnitine and cardiac dysfunction in childhood cancer survivors treated with anthracyclines Cancer Epidemiol Biomarkers Prev. 2014 Jun; 23(6):1109-14. . View in PubMed
  • Nuclear protein in testis midline carcinoma misdiagnosed as adamantinoma J Clin Oncol. 2014 May 20; 32(15):e57-60. . View in PubMed
  • Treatment of multiply relapsed wilms tumor with vincristine, irinotecan, temozolomide and bevacizumab Pediatr Blood Cancer. 2014 Apr; 61(4):756-9. . View in PubMed
  • Hepatoblastoma in a 15-month-old female with trisomy 13 Am J Med Genet A. 2014 Feb; 164A(2):472-5. . View in PubMed
  • Inflammatory myofibroblastic tumors in childhood Pediatr Hematol Oncol. 2013 Oct; 30(7):640-5. . View in PubMed
  • Correlation of clinical and dosimetric factors with adverse pulmonary outcomes in children after lung irradiation Int J Radiat Oncol Biol Phys. 2013 Aug 01; 86(5):942-8. . View in PubMed
  • A phase I study of oxaliplatin and doxorubicin in pediatric patients with relapsed or refractory extracranial non-hematopoietic solid tumors Pediatr Blood Cancer. 2013 Jul; 60(7):1103-7. . View in PubMed
  • Orthopaedic case of the month: A 14-year-old boy with a medial thigh soft tissue mass Clin Orthop Relat Res. 2013 May; 471(5):1433-8. . View in PubMed
  • Ewing sarcoma of the tibia mimicking fibrous dysplasia J Pediatr Orthop B. 2013 May; 22(3):222-7. . View in PubMed
  • A phase I study of vincristine, irinotecan, temozolomide and bevacizumab (vitb) in pediatric patients with relapsed solid tumors PLoS One. 2013; 8(7):e68416. . View in PubMed
  • Tumor necrosis predicts survival following neo-adjuvant chemotherapy for hepatoblastoma Pediatr Blood Cancer. 2012 Sep; 59(3):493-8. . View in PubMed
  • Pleuropulmonary blastoma: a single-institution experience J Pediatr Hematol Oncol. 2012 Jul; 34(5):e182-5. . View in PubMed
  • Correlation of long-term pulmonary injury with radiation dose distribution in childhood cancer survivors Pract Radiat Oncol. 2012 Jul-Sep; 2(3):237-240. . View in PubMed
  • Nonadherence to oral mercaptopurine and risk of relapse in Hispanic and non-Hispanic white children with acute lymphoblastic leukemia: a report from the children’s oncology group J Clin Oncol. 2012 Jun 10; 30(17):2094-101. . View in PubMed
  • Body mass index (BMI) at diagnosis is associated with surgical wound complications in patients with localized osteosarcoma: a report from the Children’s Oncology Group Pediatr Blood Cancer. 2011 Dec 01; 57(6):939-42. . View in PubMed
  • Gorham’s disease and diffuse lymphangiomatosis in children and adolescents Pediatr Blood Cancer. 2011 Apr; 56(4):667-70. . View in PubMed
  • Expanded Access Through Cancer Trials Support Unit to Children’s Oncology Group Sarcoma Trial AEWS1031 for Adolescents and Young Adults J Adolesc Young Adult Oncol. 2011 Mar; 1(1):61-3. . View in PubMed
  • Randomized phase II window trial of two schedules of irinotecan with vincristine in patients with first relapse or progression of rhabdomyosarcoma: a report from the Children’s Oncology Group J Clin Oncol. 2010 Oct 20; 28(30):4658-63. . View in PubMed
  • Recurrent and refractory giant cell tumor of the jaw J Craniofac Surg. 2009 Nov; 20(6):2245-8. . View in PubMed
  • Effect of time to resumption of chemotherapy after definitive surgery on prognosis for non-metastatic osteosarcoma J Bone Joint Surg Am. 2009 Mar 01; 91(3):604-12. . View in PubMed
  • Prognostic factors for patients with Ewing sarcoma (EWS) at first recurrence following multi-modality therapy: A report from the Children’s Oncology Group Pediatr Blood Cancer. 2008 Sep; 51(3):334-8. . View in PubMed
  • Invasive diagnostic procedures for pulmonary infiltrates in pediatric hematopoietic stem cell transplant recipients Pediatr Transplant. 2007 Nov; 11(7):736-42. . View in PubMed
  • Extracranial malignant rhabdoid tumors in childhood: the Childrens Hospital Los Angeles experience Cancer. 2007 Nov 01; 110(9):2061-6. . View in PubMed
  • Treatment of infantile choriocarcinoma of the liver Pediatr Blood Cancer. 2007 Jul; 49(1):99-102. . View in PubMed
  • Severe methotrexate toxicity precipitated by intravenous radiographic contrast J Pediatr Hematol Oncol. 2007 Jul; 29(7):496-9. . View in PubMed
  • Evaluation of persistent pulmonary infiltrates in pediatric oncology patients Pediatr Blood Cancer. 2007 Feb; 48(2):165-72. . View in PubMed
  • Transient myeloproliferative disorder in a phenotypically normal infant with i(21q) mosaicism Cancer Genet Cytogenet. 2002 Jul 15; 136(2):138-40. . View in PubMed
  • Lentiviral vectors for efficient delivery of CD80 and granulocyte-macrophage- colony-stimulating factor in human acute lymphoblastic leukemia and acute myeloid leukemia cells to induce antileukemic immune responses Blood. 2000 Aug 15; 96(4):1317-26. . View in PubMed
  • Gene delivery to human B-precursor acute lymphoblastic leukemia cells Blood. 1998 Nov 15; 92(10):3537-45. . View in PubMed