UC Irvine

Background

Ibrutinib is active in patients with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). In patients treated with ibrutinib for R/R CLL, del(17p), identified by interphase fluorescence in situ hybridization (FISH), is associated with inferior progression-free survival despite equivalent initial response rates. Del(17p) is frequently associated with a complex metaphase karyotype (CKT); the prognostic significance of CKT in ibrutinib-treated patients has not been reported.

Methods

This study reviewed 88 patients treated for R/R CLL at The University of Texas MD Anderson Cancer Center with investigational ibrutinib-based regimens from 2010 to 2013. Pretreatment FISH and lipopolysaccharide-stimulated metaphase cytogenetic analysis were performed on bone marrow.

Results

An adequate pretreatment metaphase karyotype was available for 56 of the 88 patients. The karyotype was complex in 21 of the 56 cases; 17 of the 21 had del(17p) according to FISH. The overall response rate, including partial remission with persistent lymphocytosis, was 94%; 18% had complete responses. In a multivariate analysis (MVA), only CKT was significantly associated with event-free survival (EFS; hazard ratio [HR], 6.6 [95% CI 1.7-25.6]; P = .006). Fludarabine-refractory CLL (HR, 6.9 [95% CI 1.8-27.1], P = .005) and CKT (HR 5.9 [95% CI 1.6-22.2], P = .008) were independently associated with inferior overall survival (OS) in MVA. Del(17p) by FISH was not significantly associated with EFS or OS in MVA.

Conclusions

CKT is a powerful predictor of outcomes for ibrutinib-treated patients with R/R CLL and may be a stronger predictor of biological behavior than del(17p) by FISH. Because of their relatively poor outcomes, patients with CKT are ideal candidates for studies of consolidative treatment strategies or novel treatment combinations.