The value of early depth of response in predicting long-term outcome in EGFR-mutant lung cancer.

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The value of early depth of response in predicting long-term outcome in EGFR-mutant lung cancer.

J Thorac Oncol. 2018 Mar 23;:

Authors: Lee CK, Lord S, Marschner I, Wu YL, Sequist L, Rosell R, Fukuoka M, Mitsudomi T, Asher R, Davies L, Gebski V, Gralla R, Mok T, Chih-Hsin Yang J

Abstract
INTRODUCTION: Traditionally, marked tumor shrinkage has been assumed to portend better outcome. We investigated whether depth of tumor response was associated with improved survival outcomes in advanced EGFR-mutant non-small cell lung cancer (NSCLC).
METHODS: Individual patient data from randomized trials (EURTAC, IPASS, ENSURE, LUX-Lung 3, and LUX-Lung 6) were used. The association of depth of response with progression-free survival (PFS) and overall survival (OS) was examined using landmark analyses. Depth of response, based on radiologic assessments at 6-week and 12-week, was calculated as the relative changes in the sum of the longest diameters of the target lesions from baseline.
RESULTS: Of 1081 evaluable patients at 6-week with no disease progression, 71.2% achieved RECIST response. Using a landmark analysis, EGFR-TKI was more effective than chemotherapy (PFS hazard ratio [HR] 0.36, P<.0001); and was associated with greater mean tumor shrinkage than chemotherapy (35.1% versus 18.5%, P<.0001). However, there was no significant difference in the relative PFS benefit between treatment groups across the entire spectrum of tumor shrinkage (P=.18 for test of interaction between treatment and continuously measured depth of response). Depth of response at 6 weeks was not associated with PFS when adjusted for treatment effect (HR 0.96, P=.78). Similar results were obtained for 12-week landmark analysis and for OS outcome.
CONCLUSIONS: The PFS advantage of EGFR-TKI over chemotherapy in advanced EGFR mutant NSCLC is not explained by depth of response at 6 or 12 weeks. It should not be used as a surrogate of benefit in future trials or routine clinical decision making.

PMID: 29580950 [PubMed - as supplied by publisher]

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