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| © 2009 Elsevier Ltd. All rights reserved. |
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Joint ECCO 15 - 34TH ESMO
Multidisciplinary Congress
BERLIN, 20 - 24 SEPTEMBER 2009
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Abstract P-6073:
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| Interim analysis of epidermal-growth factor receptor (EGFR) expression in a single-arm, phase II, first-line study (20060314) of panitumumab with FOLFIRI in the management of metastatic colorectal cancer (mCRC) |
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Citation: European Journal of Cancer Supplements, Vol 7 No 2, September 2009, Page 343
C. Koehne1, R. Hofheinz2, L. Mineur3, H. Letocha4, R. Greil5, J. Thaler6, E. Gamelin7, E. Fernebro8, L. Wright9, M. Karthaus10
1Onkologie Klinikum Oldenburg, Klinik für Onkologie und Hämatologie, Oldenburg, Germany
2Klinikum Mannheim, III. Medizinische Klinik, Mannheim, Germany
3Institut Sainte-Catherine, Oncologie Radiothérapie, Avignon, France
4Central Hospital Västerås, Department of Oncology, Västerås, Sweden
5Universitaetsklinik f. Innere Medizin III, Onkologie, Salzburg, Austria
6Klinikum Wels-Grieskirchen, Hämatologie und internistische Onkologie, Wels, Austria
7Centre Paul Papin, Service d'Oncologie Médicale, Angers, France
8Lund University, Department of Oncology, Lund, Sweden
9Amgen Limited, Biostatistics, Uxbridge, United Kingdom
10Klinikum Neuperlach, Department Hämatologie und Onkologie, München, Germany
Background: The fully human anti-EGFR monoclonal antibody panitumumab (Vectibix®) is an important monotherapy treatment option for chemotherapy-refractory patients (pts) with EGFR-expressing, KRAS wild-type mCRC. Preclinical data show sensitivity of EGFR inhibitors to be linked to EGFR expression as determined by immunohistochemistry (IHC). Thus, EGFR expression has historically been a defining criterion for treatment with an EGFR inhibitor. However, growing clinical evidence suggest that this marker correlates poorly with response, with objective responses observed in pts with no or all levels of EGFR expression.
Material and Methods: Pts with histologically confirmed mCRC receive panitumumab (6 mg/kg) and FOLFIRI every 2 weeks. This Amgen-sponsored study (20060314) is ongoing to evaluate the primary endpoint objective response rate and secondary endpoints, including disease control rate, time to response and progression-free survival. This abstract will review the correlation between EGFR expression and response rate (≥17 weeks evaluation) in pts with KRAS wild-type or mutant tumours.
Results: Recruitment completed 18 June 08 with 154 pts enrolled. At interim analysis (15 Oct 08), KRAS evaluable samples for 92% of pts and EGFR evaluable samples for 84% of pts are available. Of the 85 pts with KRAS wild-type (wt) tumours, and the 57 pts with KRAS mutant (mt) tumours 78%/54% are male; median age is 64 years (range 21–84)/66 years (range 37–80) and 95%/93% of pts had ECOG PS 0–1, respectively. A higher proportion of responders in the wt subset have no EGFR staining versus non-responders (28% vs 5%; Table) with no notable difference seen for pts in the mt subset (13% vs 12%). In the wt subset incidence of moderate and strong maximum staining intensity is lower for responders than non-responders.
| | KRAS wt (n = 84) | KRAS mt (n = 56) | All pts (n = 152) |
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| | Responder (N = 40) | Non-responder (n = 44) | Responder (n = 16) | Non-responder (n = 40) | Responder (n = 63) | Non-responder (n = 89) |
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| Pts with EGFR data | 36 (90) | 43 (98) | 15 (94) | 33 (83) | 52 (83) | 77 (87) |
| 3+ (strong) | 3 (8) | 11 (26) | 2 (13) | 1 (3) | 5 (10) | 12 (16) |
| 2+ (moderate) | 6 (17) | 14 (33) | 7 (47) | 11 (33) | 13 (25) | 26 (34) |
| 1+ (weak) | 17 (47) | 16 (37) | 4 (27) | 17 (52) | 22 (42) | 33 (43) |
| 0 | 10 (28) | 2 (5) | 2 (13) | 4 (12) | 12 (23) | 6 (8) |
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Conclusions: Within the parameters of this small data set, this analysis suggests that EGFR expression unlike KRAS status may not be essential for determining response to treatment.
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