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Weidhaas JB, Harris J, Gillison M, Blakaj DM, Krempl GA, Higgins KA, Phan J, Dunlap NE, Mahmood S, Dorth JA, Caudell JJ, Desai AB, Galloway TJ, Pennington JDD, Zhou Z, Lathrop J, Torres-Saavedra P, Hayes DN, Yom SS, Le QT. The KRAS-Variant and Cetuximab in HPV-Positive Oropharyngeal Cancer in NRG/RTOG 1016. Int J Radiat Oncol Biol Phys 2023; 117:S151. [PMID: 37784383 DOI: 10.1016/j.ijrobp.2023.06.571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) NRG/RTOG 1016 was a non-inferiority phase III trial comparing radiation with cisplatin versus cetuximab monotherapy for patients with HPV-positive oropharyngeal squamous cell carcinoma (SCC). The trial did not meet the non-inferiority criteria for overall survival (OS) and had significantly worse progression-free survival (PFS) and locoregional failure (LRF) in patients treated with cetuximab. Based on prior evidence that HNSCC patients with a germ-line mutation in KRAS (the KRAS-variant) had a positive response to radiation with cisplatin plus cetuximab without increased toxicity, samples from RTOG 1016 were used to test the protocol-specified hypothesis that KRAS-variant patients will have better outcomes when receiving IMRT + cetuximab monotherapy compared to IMRT + cisplatin. MATERIALS/METHODS The KRAS-variant was tested in 562 samples at MiraDx, a CLIA-certified laboratory. OS, PFS, LRF, and distant metastases (DM) were as defined per the RTOG 1016 protocol, and hazard ratios (HRs) were estimated by (cause-specific) Cox models. Negative binomial regression was used to model the number of treatment-related acute and late (≤ and > 180 days from end of treatment, respectively) grade 3-5 adverse events. To assess the predictive role of the KRAS-variant, all models included KRAS, assigned treatment, and their interaction, with the interaction tested at two-sided 0.05. HRs and toxicity ratios are expressed as IMRT + cetuximab / IMRT + cisplatin. RESULTS The prevalence of the KRAS-variant was 16% with similar patient and tumor characteristics and well-balanced treatment arms for variant and non-variant patients. Median follow-up was 8.6 years. There was no significant interaction between KRAS and treatment for OS (p = 0.99), PFS (p = 0.56), LRF (p = 0.09), or DM (p = 0.19) (Table 1). In KRAS-variant patients the mean acute and late toxicity ratios were 0.53 (95% CI 0.36, 0.80) and 1.62 (95% CI 0.57, 4.62). In non-variant patients, the mean acute and late toxicity ratios were 0.80 (95% CI 0.67, 0.95) and 0.55 (95% CI 0.35, 0.87), respectively. The interaction of KRAS and treatment was not significant for acute (p = 0.07) or late toxicity (p = 0.07). CONCLUSION While this study does not directly refute prior evidence that KRAS-variant patients benefit from radiation + cisplatin and cetuximab, this study does not support the hypothesis that the KRAS-variant is a predictive biomarker of improved outcome in HPV+ oropharyngeal SCC patients treated with IMRT + cetuximab alone, and suggests that for KRAS-variant patients, potential benefits in LRF and acute toxicity with cetuximab may be offset by worse DM and worse late toxicity.
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Affiliation(s)
- J B Weidhaas
- Department of Radiation Oncology, UCLA, Los Angeles, CA
| | - J Harris
- NRG Oncology Statistics and Data Management Center, Philadelphia, PA
| | | | - D M Blakaj
- James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, OH
| | - G A Krempl
- University of Oklahoma Health Sciences Center, OKLAHOMA CITY, OK
| | - K A Higgins
- Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA
| | - J Phan
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - N E Dunlap
- Department of Radiation Oncology, Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY
| | - S Mahmood
- Allan Blair Cancer Centre, Saskatchewan, SK, Canada
| | - J A Dorth
- Department of Radiation Oncology, University Hospitals Case Medical Center, Cleveland, OH
| | | | | | - T J Galloway
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA
| | | | | | | | - P Torres-Saavedra
- NRG Oncology Statistics and Data Management Center, Philadelphia, PA
| | | | - S S Yom
- University of California, San Francisco, Department of Radiation Oncology, San Francisco, CA
| | - Q T Le
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA
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