title: Identification and Validation of Protein Biomarkers of Response to Neoadjuvant Platinum Chemotherapy in Muscle Invasive Urothelial Carcinoma.
abstract: BACKGROUND
  The 5-year cancer specific survival (CSS) for patients with muscle invasive urothelial carcinoma of the bladder (MIBC) treated with cystectomy alone is approximately 50%. Platinum based neoadjuvant chemotherapy (NAC) plus cystectomy results in a marginal 5-10% increase in 5-year CSS in MIBC. Interestingly, responders to NAC (<ypT2) have a 5-year CSS of 90% which is in stark contrast to the 30-40% CSS for those whose MIBC is resistance to NAC. While the implementation of NAC for MIBC is increasing, it is still not widely utilized due to concerns related to delay of cystectomy, potential side-effects, and inability to predict effectiveness. Recently suggested molecular signatures of chemoresponsiveness, which could prove useful in this setting, would be of considerable utility but are yet to be translated into clinical practice.
  
  
  METHODS
  mRNA expression data from a prior report on a NAC-treated MIBC cohort were re-analyzed in conjunction with the antibody database of the Human Protein Atlas (HPA) to identify candidate protein based biomarkers detectable by immunohistochemistry (IHC). These candidate biomarkers were subsequently tested in tissue microarrays derived from an independent cohort of NAC naive MIBC biopsy specimens from whom the patients were treated with neoadjuvant gemcitabine cisplatin NAC and subsequent cystectomy. The clinical parameters that have been previously associated with NAC response were also examined in our cohort.
  
  
  RESULTS
  Our analyses of the available mRNA gene expression data in a discovery cohort (n = 33) and the HPA resulted in 8 candidate protein biomarkers. The combination of GDPD3 and SPRED1 resulted in a multivariate classification tree that was significantly associated with NAC response status (Goodman-Kruskal γ = 0.85 p<0.0001) in our independent NAC treated MIBC cohort. This model was independent of the clinical factors of age and clinical tumor stage, which have been previously associated with NAC response by our group. The combination of both these protein biomarkers detected by IHC in biopsy specimens along with the relevant clinical parameters resulted in a prediction model able to significantly stratify the likelihood of NAC resistance in our cohort (n = 37) into two well separated halves: low-26% n = 19 and high-89% n = 18, Fisher's exact p = 0.0002).
  
  
  CONCLUSIONS
  We illustrate the feasibility of translating a gene expression signature of NAC response from a discovery cohort into immunohistochemical markers readily applicable to MIBC biopsy specimens in our independent cohort. The results from this study are being characterized in additional validation cohorts. Additionally, we anticipate that emerging somatic mutations in MIBC will also be important for NAC response prediction. The relationship of the findings in this study to the current understanding of variant histologic subtypes of MIBC along with the evolving molecular subtypes of MIBC as it relates to NAC response remains to be fully characterized.
authors.affiliation: Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America; Department of Urology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Baras
authors.affiliation: Department of Urology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Nilay
authors.initials: N
authors.lastname: Gandhi
authors.affiliation: Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Enrico
authors.initials: E
authors.lastname: Munari
authors.affiliation: Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Sheila
authors.initials: S
authors.lastname: Faraj
authors.affiliation: Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Luciana
authors.initials: L
authors.lastname: Shultz
authors.affiliation: Department of Oncology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Luigi
authors.initials: L
authors.lastname: Marchionni
authors.affiliation: Department of Urology, Albert Einstein College of Medicine, Bronx, New York, United States of America.
authors.forename: Mark
authors.initials: M
authors.lastname: Schoenberg
authors.affiliation: Department of Oncology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Noah
authors.initials: N
authors.lastname: Hahn
authors.forename: Mohammad Obaidul
authors.initials: MO
authors.lastname: Hoque
authors.affiliation: Department of Otolaryngology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Hoque
authors.affiliation: Department of Pathology, Queen's University, Kingston, Ontario, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Berman
authors.affiliation: Department of Urology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America; Department of Oncology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Trinity J
authors.initials: TJ
authors.lastname: Bivalacqua
authors.affiliation: Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America; Department of Urology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America; Department of Oncology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: George
authors.initials: G
authors.lastname: Netto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000235:genetics*; D002945:Cisplatin / Q000627:therapeutic use*; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D008875:Middle Aged; D019042:Muscle Neoplasms / Q000556:secondary*; D020360:Neoadjuvant Therapy; D012333:RNA, Messenger / Q000235:genetics; D016896:Treatment Outcome; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D019459:Urothelium / Q000473:pathology; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D003841:Deoxycytidine; D002945:Cisplatin; D000093542:Gemcitabine