Genetic variants of kinase suppressors of Ras (KSR1) to predict survival in patients with ERα-positive advanced breast cancer

In patients with breast cancer (BC), deregulation of estrogen receptor (ERα) activity may account for most resistance to endocrine therapies. Our previous study used a whole-human kinome siRNA screen to identify functional actors in ERα modulation and showed the implication of proteins kinase suppressors of ras (KSR1). From those findings we evaluated the clinical impact of KSR1 variants in patients with ERα+ BC treated with TAM. DNA was obtained from 222 patients with advanced ERα+ BC treated with TAM who had undergone surgery from 1981 to 2003. We selected three potentially functional relevant KSR1 polymorphisms; two within the 3'UTR (rs224190, rs1075952) and one in the coding exon 7 (rs2293180). The primary end points were overall survival (OS) and disease-free survival (DFS). After a 6.4-year median follow-up, patients carrying the rs2241906 TT genotype showed shorter DFS (2.1 vs 7.1 years, P=0.005) and OS (2.6 vs 8.4 years P=0.002) than those with the TC or TT genotypes. Those associations remained significant in the multivariable analysis adjusting age, lymph node status, LMTK3 and IGFR variants and HER2 status. The polymorphisms rs2241906 and rs1075952 were in linkage disequilibrium. No association was shown between rs2293180 and survival. Among the actors of ERα signaling, KSR1 rs2241906 variants may predict survival in patients with advanced ERα+ BC treated with adjuvant TAM.

The Cyclin D1 (CCND1) A870G polymorphism predicts clinical outcome to lapatinib and capecitabine in HER2-positive metastatic breast cancer

BACKGROUND: Lapatinib plus capecitabine emerged as an efficacious therapy in metastatic breast cancer (mBC). We aimed to identify germline single-nucleotide polymorphisms (SNPs) in genes involved in capecitabine catabolism and human epidermal receptor signaling that were associated with clinical outcome to assist in selecting patients likely to benefit from this combination.

PATIENTS AND METHODS: DNA was extracted from 240 of 399 patients enrolled in EGF100151 clinical trial (NCT00078572; clinicaltrials.gov) and SNPs were successfully evaluated in 234 patients. The associations between SNPs and clinical outcome were analyzed using Fisher's exact test, Kaplan-Meier curves, log-rank tests, likelihood ratio test within logistic or Cox regression model, as appropriate.

RESULTS: There were significant interactions between CCND1 A870G and clinical outcome. Patients carrying the A-allele were more likely to benefit from lapatinib plus capecitabine versus capecitabine when compared with patients harboring G/G (P = 0.022, 0.024 and 0.04, respectively). In patients with the A-allele, the response rate (RR) was significantly higher with lapatinib plus capecitabine (35%) compared with capecitabine (11%; P = 0.001) but not between treatments in patients with G/G (RR = 24% and 32%, respectively; P = 0.85). Time to tumor progression (TTP) was longer in patients with the A-allele treated with lapatinib plus capecitabine compared with capecitabine (median TTP = 7.9 and 3.4 months; P < 0.001), but not in patients with G/G (median TTP = 6.1 and 6.6 months; P = 0.92).

CONCLUSION: Our findings suggest that CCND1A870G may be useful in predicting clinical outcome in HER2-positive mBC patients treated with lapatinib plus capecitabine.