Two biomarker-directed randomized trials in European and Chinese patients with nonsmall-cell lung cancer: the BRCA1-RAP80 Expression Customization (BREC) studies

BACKGROUND

In a Spanish Lung Cancer Group (SLCG) phase II trial, the combination of BRCA1 and receptor-associated protein 80 (RAP80) expression was significantly associated with outcome in Caucasian patients with nonsmall-cell lung cancer (NSCLC). The SLCG therefore undertook an industry-independent collaborative randomized phase III trial comparing nonselected cisplatin-based chemotherapy with therapy customized according to BRCA1/RAP80 expression. An analogous randomized phase II trial was carried out in China under the auspices of the SLCG to evaluate the effect of BRCA1/RAP80 expression in Asian patients.

PATIENTS AND METHODS

Eligibility criteria included stage IIIB-IV NSCLC and sufficient tumor specimen for molecular analysis. Randomization to the control or experimental arm was 1 : 1 in the SLCG trial and 1 : 3 in the Chinese trial. In both trials, patients in the control arm received docetaxel/cisplatin; in the experimental arm, patients with low RAP80 expression received gemcitabine/cisplatin, those with intermediate/high RAP80 expression and low/intermediate BRCA1 expression received docetaxel/cisplatin, and those with intermediate/high RAP80 expression and high BRCA1 expression received docetaxel alone. The primary end point was progression-free survival (PFS).

RESULTS

Two hundred and seventy-nine patients in the SLCG trial and 124 in the Chinese trial were assessable for PFS. PFS in the control and experimental arms in the SLCG trial was 5.49 and 4.38 months, respectively [log rank P = 0.07; hazard ratio (HR) 1.28; P = 0.03]. In the Chinese trial, PFS was 4.74 and 3.78 months, respectively (log rank P = 0.82; HR 0.95; P = 0.82).

CONCLUSION

Accrual was prematurely closed on the SLCG trial due to the absence of clinical benefit in the experimental over the control arm. However, the BREC studies provide proof of concept that an international, nonindustry, biomarker-directed trial is feasible. Thanks to the groundwork laid by these studies, we expect that ongoing further research on alternative biomarkers to elucidate DNA repair mechanisms will help define novel therapeutic approaches.

TRIAL REGISTRATION

NCT00617656/GECP-BREC and ChiCTR-TRC-12001860/BREC-CHINA.

Excision repair cross complementing 6 (ERCC6) single nucleotide polymorphism (SNP) and outcome to gemcitabine (gem)/cisplatin (cis) or docetaxel (doc)/cis in stage IV non-small cell lung cancer (NSCLC) patients (pts)

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Background: ERCC6 (alternate name CSB) is involved in both transcription coupled and base excision DNA repair, and the ERCC6 C-6530>G SNP is involved in gene regulation. Different levels of ERCC6 mRNA expression have been observed in cells according to ERCC6–6530 genotype. Methods: We investigated the ERCC6 C-6530>G SNP in 309 stage IV NSCLC pts treated with doc/cis (196 pts) and gem/cis (113 pts). DNA was extracted from peripheral lymphocytes and Taqman assay was used for SNP typing. Results: Distribution of ERCC6 genotypes was: CC 113 pts (36.6%); CG 157 pts (50.8%); GG 39 pts (12.6%). No differences in genotype were observed according to age, gender, performance status (PS), histology, chemotherapy regimen or second-line treatment. Overall time to progression (TTP) was 5.4 months (m) and median survival (MS) 9.9 m. No differences in TTP or MS were observed according to ERCC6 SNP types. However, when pts were broken down by chemotherapy regimen, TTP was 7 m for 31 CC pts treated with gem/cis and 5.4 m for 71 CC pts treated with doc/cis (P=0.04) ( Table ). MS was longer for CC pts treated with gem/cis (11 m) than for CC pts treated with doc/cis (8.9 m) (P=0.46). Differences were also observed in pts with PS 0 and in younger pts. Conclusions: ERCC6 C-6530>G SNP may confer differential sensitivity to gem or doc in combination with cis. We hypothesize that ERCC6 6350 CC is a surrogate of ERCC6 transcript, where lower ERCC6 expression levels may increase the activity of gem/cis in comparison to doc/cis.

No significant financial relationships to disclose.

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