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• 11543

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  P2.06 - Poster Session 2 - Prognostic and Predictive Biomarkers (ID 165)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Biology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11564

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    P2.06-021 - Is RRM1 a predictive marker for vinorelbine efficacy - the results from a cohort of malignant pleural mesotheliomas treated with cisplatin and vinorelbine. (ID 3104)

    09:30 - 09:30  |  Author(s): C. Bech
    • Abstract

    Background
    In a recently published study our group proposes a possible predictive impact of immunohistochemically detected RRM1 on vinorelbine efficacy in advanced NSCLC. This thesis was based on results from a randomized phase III trial comparing triplet-chemotherapy (paclitaxel, cisplatin, gemcitabine) to standard doublet-therapy (cisplatin, vinorelbine). We found that increased expression of RRM1 was associated with significantly decreased progression-free survival (PFS) and overall survival (OS) only in the patients receiving cisplatin-vinorelbine therapy. These findings were suprising since the overexpression of RRM1 is conventionally associated with resistance towards the chemotherapeutic agent gemcitabine, which is a potent inhibitor of ribonucleotide reductase (RNR). RNR is an essential enzyme for DNA synthesis that converts ribonucleoside di-phosphates into deoxyribonucleoside di-phosphates. The enzyme consists of a large sub-unit (RRM1) and a small sub-unit (RRM2). Vinorelbine is a spindle-poison and resistance towards this agent has never been associated with RRM1 over-expression. It has however been shown that vinorelbine can reduce the repair of radiotherapy-induced DNA damage in small-cell lung-cancer cell-lines, pointing to a possible interaction between vinorelbine and the DNA repair system. This study aimed at further exploring the possible predictive value of immunohistochemically detected RRM1 in patients receiving vinorelbine therapy. For this purpose we chose a cohort of malignant pleural mesothelioma patients treated with cisplatin and vinorelbine in a phase II trial.

    Methods
    Fifty-four consecutive patients with MPM, were enrolled between February 2003 and September 2006 into a phase II trial with cisplatin and vinorelbine. The formalin-fixed paraffin-embedded bioptic tumor specimens from these MPM patients were retrospectively evaluated for RRM1 expression by immunohistochemistry (IHC) using an H-score. The cut-off point was chosen as the upper quartile value of the H-scores to separate positive (H-score ≥upper quartile) from negative (H-score

    Results
    Sixty-six patients had enough tumor tissue for IHC. The upper quartile H-score was 3 yielding 15 positive and 34 (69%) negative tumors in the cisplatin-vinorelbine treated group. In the carboplatin-pemetrexed treated group there were 6 positive and 11 (64%) negative tumors. There was a significant overall survival advantage only in the RRM1-negative patients treated with cisplatin and vinorelbine (log rank p= 0.002). This group had a two-year survival rate of 47% opposed to 13 % for the RRM1-positive tumors treated with this combination. In the carboplatin-pemetrexed-treated group there were no differences in overall survival according to marker status, with two-year survival rates of 0% and 9% in the RRM1-positive and –negative group respectively.

    Conclusion
    Patients with RRM1-negative tumors treated with cisplatin-vinorelbine combination therapy had a prolonged overall survival. There was no survival advantage in the RRM1-negative group when patients were treated with carboplatin and pemetrexed. Our study suggest a possible role of RRM1 in predicting efficacy of cisplatin-vinorelbine combination chemotherapy ,also in MPM, which supports the similar finding from our group in NSCLC patients. Thus, RRM1 may be a biomarker for vinorelbine though the results require further validation.