Significance of folate receptor alpha and thymidylate synthase protein expression in patients with non-small-cell lung cancer treated with pemetrexed

Daniel C. Christoph, Bernadette Reyna Asuncion, Biftu Hassan, Cindy Tran, Julia D. Maltzman, Daniel J. O'Shannessy, Murry W. Wynes, Thomas C. Gauler, Jeremias Wohlschlaeger, Mathias Hoiczyk, Martin Schuler, Wilfried E. Eberhardt, Fred R. Hirsch

Research output: Contribution to journalArticlepeer-review

74 Scopus citations

Abstract

INTRODUCTION: Folate receptor alpha (FRA) regulates cellular uptake of folates and antifolates. Information about FRA protein expression in metastatic non-small-cell lung cancer (NSCLC) is limited. We investigated FRA as a biomarker for pemetrexed-based chemotherapy and compared it with thymidylate synthase (TS), the main target of pemetrexed. METHODS: Pretreatment tumor specimens from 207 patients with advanced NSCLC were assessed for FRA and TS protein expression by immunohistochemistry using the H-score (range, 0-300) and correlated to patients' clinicopathological data, radiographic response, progression-free survival (PFS), and overall survival (OS). RESULTS: Low total (cytoplasmic and nuclear) TS protein expression (H-score < 210) was associated with improved PFS (median: 5.6 versus 3.5 months; hazard ratio [HR] = 0.6379, p = 0.0131) and prolonged OS (median: 22.5 versus 11.5 months; HR = 0.5680,p = 0.0107). An association between lower TS levels and response to pemetrexed-based therapy was found-mean H-score 187 ± 5, median 180 for responders versus mean H-score 201 ± 4, median 210, for non-responders, p = 0.0244. High intracellular FRA expression (H-score ≥110) was associated with prolonged OS (28.9 versus 11.7 months, HR = 0.5316, p = 0.0040) and a trend for association with PFS (5.6 versus 4.1 months, HR = 0.7395, p = 0.0801) was noted. Membranous FRA expression was seen in 83% of patients, moreover, high membranous expression (H-score ≥20) was associated with improved PFS (5.6 versus 3.7 months, HR = 0.6445, p = 0.0306) and OS (22.1 versus 11.5 months, HR = 0.5378, p = 0.0131). CONCLUSIONS: A large number of NSCLC patients have high expression of FRA and/or a low level of TS expression. Expression levels of FRA and TS were associated with clinical benefit from pemetrexed therapy.

Original languageEnglish
Pages (from-to)19-30
Number of pages12
JournalJournal of Thoracic Oncology
Volume8
Issue number1
DOIs
StatePublished - Jan 2013
Externally publishedYes

Keywords

  • Biomarker
  • Folate receptor alpha
  • Non-small-cell lung cancer
  • Pemetrexed
  • Thymidylate synthase

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