In:
Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 37, No. 4_suppl ( 2019-02-01), p. 585-585
Abstract:
585 Background: Several previous reports indicated that cetuximab (Cmab) rechallenge may be efficacious in some patients for whom Cmab was previously effective. Liquid biopsy can detect the some emerging mutations for resistance with Cmab. Considering the plasticity and elasticity of sensitive clone, we assumed we could identify the patients with benefit from Cmab rechallenge by liquid biopsy. This current study investigates the predictability of efficacy for Cmab rechallenge by liquid biopsy in the E-Rechallenge Trial. Methods: The E-Rechallenge Trial is a multicenter phase II study in mCRC patients who have become refractory to fluoropyrimidines, L-OHP, CPT-11, Cmab, and bevacizumab, and in whom previous treatment with Cmab was effective in any earlier line (achieving CR, PR, or SD that persisted for ≥ 6 months). The other main eligibility criteria are; RAS wild type, measurable disease, aEFI ≥ 16 weeks between the last dose of Cmab during previous treatment and the start of Cmab rechallenge. Protocol treatment is the combination of weekly Cmab with biweekly CPT-11. Additional research of ctDNA was conducted optionally. Baseline plasma samples were analyzed for KRAS, NRAS, BRAF and EGFR S492R mutations using digital PCR (LBx probe, RIKEN GENESIS). A cut-off of the mutation allele frequency was 〉 0.1%. Results: Between Dec. 2014 and Oct. 2017, 33 patients were enrolled. The primary endpoint; the rates of PR/SD/PD were PR 15.6%/SD 40.6%/PD 43.8%. Twenty-four of 33 patients participated in the additional research. In the additional cohort, the rates of PR/SD/PD were PR 12.5%/SD 50.0%/PD 37.5%. The mutations were detected at the baseline of Cmab rechallenge as followings; KRAS exon 2 29.2%, exon 3,4 33.3%, BRAF V600E 12.5%, EGFR S492R 12.5%. In wild type of these genes the PR and SD rate increased to 25% and 50%, respectively. Conclusions: Cmab rechallenge showed some activity in the salvage setting, in patients for whom Cmab was previously effective. KRAS, BRAF, and EGFR S492R screening by liquid biopsy may contribute to identify patients with benefit from Cmab rechallenge. The additional data of ctDNA may be provided in the conference. Clinical trial information: UMIN 000016439.
Type of Medium:
Online Resource
ISSN:
0732-183X
,
1527-7755
DOI:
10.1200/JCO.2019.37.4_suppl.585
Language:
English
Publisher:
American Society of Clinical Oncology (ASCO)
Publication Date:
2019
detail.hit.zdb_id:
2005181-5
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