University of Costa Rica, San José, Costa Rica—Enrique Freer (director, HPV diagnostics laboratory), José Bonilla (head, HPV immunology laboratory). United States National Cancer Institute, Bethesda, MD, USA—Allan Hildesheim (co-principal investigator & NCI co-project officer), Aimée R. Kreimer (co-investigator), Douglas R. Lowy (DRL; HPV virologist), Nora Macklin (trial coordinator),

Mark Schiffman (medical monitor & NCI RAD001 co-project officer), John T. Schiller (JTS; HPV virologist), Mark Sherman (QC pathologist), Diane Solomon (medical monitor & QC pathologist), Sholom Wacholder (statistician). SAIC, NCI-Frederick, Frederick, MD, UDA—Ligia Pinto (head, HPV immunology laboratory), Troy Kemp (immunologist). Georgetown University, this website Washington, DC, USA—Mary Sidawy (histopathologist). DDL Diagnostic Laboratory, Netherlands—Wim Quint (virologist, HPV DNA testing), Leen-Jan van Doorn (HPV DNA testing). F.S., G.C. and G.D. are employees of the GlaxoSmithKline group of companies. G.D. and F.S. receive stock options/restricted shares from the GlaxoSmithKline group of companies, and G.D. has previously received patent royalties

from Wyeth Vaccines. The other authors declare that they have no conflicts of interest. The NCI receives licensing fees for HPV vaccines. A.H. (NCI principal investigator), S.W. (NCI statistician) and R.H. (Costa Rica principal investigator) were responsible for the design and conduct of the study. From GlaxoSmithKline Vaccines, G.D. contributed to discussions regarding trial mafosfamide design and conduct. G.C. contributed toward data analyses and interpretation, and prepared the statistical analysis report submitted to the FDA. F.S. and G.D. critically reviewed the study report in close collaboration with NCI and Costa Rica co-principal investigators. A.H. wrote the manuscript, and all other

authors reviewed and commented on the initial and subsequent drafts. All authors had full access to the data and gave final approval before submission. The Costa Rica HPV vaccine trial is a long-standing collaboration between investigators in Costa Rica and the National Cancer Institute (NCI). The trial is sponsored and funded by the NCI (contract N01-CP-11005), with funding support from the National Institutes of Health Office of Research on Women’s Health, and done with the support from the Ministry of Health of Costa Rica. Vaccine was provided for our trial by GlaxoSmithKline Biologicals, under a Clinical Trials Agreement with the NCI. GlaxoSmithKline Biologicals also provided support for aspects of the trial associated with regulatory submission needs of the company under US Food and Drug Administration BB-IND 7920. JTS and DRL report that they are named inventors on US Government-owned HPV vaccine patents that are licensed to GlaxoSmithKline and Merck. They are entitled to limited royalties as specified by federal law.