title: Clinical Translation and Validation of a Predictive Biomarker for Patritumab, an Anti-human Epidermal Growth Factor Receptor 3 (HER3) Monoclonal Antibody, in Patients With Advanced Non-small Cell Lung Cancer.
abstract: BACKGROUND
  During early clinical development, prospective identification of a predictive biomarker and validation of an assay method may not always be feasible. Dichotomizing a continuous biomarker measure to classify responders also leads to challenges. We present a case study of a prospective-retrospective approach for a continuous biomarker identified after patient enrollment but defined prospectively before the unblinding of data. An analysis of the strengths and weaknesses of this approach and the challenges encountered in its practical application are also provided.
  
  
  METHODS
  HERALD (NCT02134015) was a double-blind, phase 2 study in patients with non-small cell lung cancer (NSCLC) randomized to erlotinib with placebo or with high or low doses of patritumab, a monoclonal antibody targeted against human epidermal growth factor receptor 3 (HER3). While the primary objective was to assess safety and progression-free survival (PFS), a secondary objective was to determine a single predictive biomarker hypothesis to identify subjects most likely to benefit from the addition of patritumab. Although not identified as the primary biomarker in the study protocol, on the basis of preclinical results from 2 independent laboratories, expression levels of the HER3 ligand heregulin (HRG) were prospectively declared the predictive biomarker before data unblinding but after subject enrollment. An assay to measure HRG mRNA was developed and validated. Other biomarkers, such as epidermal growth factor receptor (EGFR) mutation status, were also evaluated in an exploratory fashion. The cutoff value for high vs. low HRG mRNA levels was set at the median delta threshold cycle. A maximum likelihood analysis was performed to evaluate the provisional cutoff. The relationship of HRG values to PFS hazard ratios (HRs) was assessed as a measure of internal validation. Additional NSCLC samples were analyzed to characterize HRG mRNA distribution.
  
  
  RESULTS
  The subgroup of patients with high HRG mRNA levels ("HRG-high") demonstrated clinical benefit from patritumab treatment with HRs of 0.37 (P = 0.0283) and 0.29 (P = 0.0027) in the high- and low-dose patritumab arms, respectively. However, only 102 of the 215 randomized patients (47.4%) had sufficient tumor samples for HRG mRNA measurement. Maximum likelihood analysis showed that the provisional cutoff was within the optimal range. In the placebo arm, the HRG-high subgroup demonstrated worse prognosis compared with HRG-low. A continuous relationship was observed between increased HRG mRNA levels and lower HR. Additional NSCLC samples (N = 300) demonstrated a similar unimodal distribution to that observed in this study, suggesting that the defined cutoff may be applicable to future NSCLC studies.
  
  
  CONCLUSIONS
  The prospective-retrospective approach was successful in clinically validating a probable predictive biomarker. Post hoc in vitro studies and statistical analyses permitted further testing of the underlying assumptions. However, limitations of this analysis include the incomplete collection of adequate tumor tissue and a lack of stratification. In a phase 3 study, findings are being confirmed, and the HRG cutoff value is being further refined.
  NCT02134015.
authors.affiliation: Daiichi Sankyo Pharma Development, 399 Thornall St, Edison, NJ 08837, USA.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Mendell
authors.affiliation: Daiichi Sankyo Pharma Development, 399 Thornall St, Edison, NJ 08837, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Freeman
authors.affiliation: Daiichi Sankyo Pharma Development, 399 Thornall St, Edison, NJ 08837, USA.
authors.forename: Wenqin
authors.initials: W
authors.lastname: Feng
authors.affiliation: U3 Pharma GmbH, Fraunhoferstraße 22, 82152 Martinsried, Germany.
authors.forename: Thore
authors.initials: T
authors.lastname: Hettmann
authors.affiliation: U3 Pharma GmbH, Fraunhoferstraße 22, 82152 Martinsried, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schneider
authors.affiliation: U3 Pharma GmbH, Fraunhoferstraße 22, 82152 Martinsried, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Blum
authors.affiliation: U3 Pharma GmbH, Fraunhoferstraße 22, 82152 Martinsried, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Ruhe
authors.affiliation: U3 Pharma GmbH, Fraunhoferstraße 22, 82152 Martinsried, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Bange
authors.affiliation: Daiichi Sankyo Co., Ltd., 1-2-58, Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Nakamaru
authors.affiliation: Daiichi Sankyo Pharma Development, 399 Thornall St, Edison, NJ 08837, USA.
authors.forename: Shuquan
authors.initials: S
authors.lastname: Chen
authors.affiliation: Daiichi Sankyo, Inc., Two Hilton Court, Parsippany, NJ 07054, USA.
authors.forename: Zenta
authors.initials: Z
authors.lastname: Tsuchihashi
authors.affiliation: Asklepios Fachkliniken, München Gauting, Robert-Koch-Allee 2, 82131 Gauting, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: von Pawel
authors.affiliation: Daiichi Sankyo Pharma Development, 399 Thornall St, Edison, NJ 08837, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Copigneaux
authors.affiliation: Daiichi Sankyo Pharma Development, 399 Thornall St, Edison, NJ 08837, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Beckman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D057134:Antibodies, Neutralizing / Q000008:administration & dosage / Q000627:therapeutic use*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics; D000080908:Broadly Neutralizing Antibodies; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000401:mortality; D018572:Disease-Free Survival; D004311:Double-Blind Method; D066246:ErbB Receptors / Q000235:genetics; D000069347:Erlotinib Hydrochloride / Q000008:administration & dosage / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D020890:Neuregulin-1 / Q000097:blood / Q000235:genetics*; D011446:Prospective Studies; D020893:Receptor, ErbB-3 / Q000097:blood / Q000276:immunology; D012189:Retrospective Studies; D057170:Translational Research, Biomedical; D016896:Treatment Outcome
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D057134:Antibodies, Neutralizing; D014408:Biomarkers, Tumor; D000080908:Broadly Neutralizing Antibodies; C094131:NRG1 protein, human; D020890:Neuregulin-1; C585471:patritumab; D000069347:Erlotinib Hydrochloride; C512478:EGFR protein, human; C581292:ERBB3 protein, human; D066246:ErbB Receptors; D020893:Receptor, ErbB-3
keywords: Biomarker; Erlotinib; HER3; Heregulin; Non-small cell lung cancer; Patritumab