Abstract OT3-02-10: Nordic trip, a randomized phase 3 study in early triple negative breast cancer

Background: Adjuvant treatment among the heterogeneous group of triple negative breast cancers (TNBC) is still a challenge. Recently published data indicate that platinum salts may have a role in the treatment of TNBC (v Minckwitz 2014), especially in BRCA-associated cases (Tutt 2014). Subgroup analyses from two large adjuvant studies indicate that also oral capecitabine may add a significant value in this subset of BC (Lindman 2010, O'Shaughnessy, 2010).

As a planned collaboration between the nordic countries, we are currently preparing a three-armed randomized phase 3 study of the addition of carboplatin and capecitabine respectively to a chemo backbone consisting of a taxane-antracycline based treatment in both the adjuvant and the neoadjuvant setting.

Objectives: The primary endpoint will be invasive disease-free survival (IDFS). Secondary endpoints will include IDFS in subsets of TNBC, eg according to gene-expression-based subtypes of TNBC(Lehmann 2011), and BRCA-mutation status. In the cohort treated neoadjuvant, biomarkers predicting pathological response will be identified with the purpose to validate them in the adjuvant cohort.

Method: 1800 patients (pts) with early TNBC stage 1 (>10 mm) - 3 will be randomized 1:1:1 to three treatment arms.

A: nab-paclitaxel (nP) followed by epirubicine-cyclophosphamide (EC)

B: nP-capecitabine followed by EC-capecitabine.

C: nP-carboplatin followed by EC

Treatment will be given either in the adjuvant or in the neoadjuvant setting, the primary endpoint will include all randomized pts from both cohorts.

Statistical considerations: We assume a 75% five-year IDFS with standard treatment (A), and that a relative reduction of the event incidence of 30% for each of the two experimental treatments (B and C) would be a clinically relevant finding (HR=0.7). In order to achieve 80% power at a 0.05 significance level for each of the two comparisons A vs. B and A vs. C, 600 patients need to be evaluated in each of the three treatment arms. Stratification factors: pre- vs postoperative treatment, nodal status and treatment site.

Citation Format: Loman N, Linderholm B, Joensuu H, Ejlertsen B, Johannsson OT, Geisler J, Bendahl P-O, Ahlgren J, Lindman H. Nordic trip, a randomized phase 3 study in early triple negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT3-02-10.

Evaluation of the XRCC1 gene as a phenotypic modifier in BRCA1/2 mutation carriers. Results from the consortium of investigators of modifiers of BRCA1/BRCA2

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in genes involved in DNA repair are good candidates to be tested as phenotypic modifiers for carriers of mutations in the high-risk susceptibility genes BRCA1 and BRCA2. The base excision repair (BER) pathway could be particularly interesting given the relation of synthetic lethality that exists between one of the components of the pathway, PARP1, and both BRCA1 and BRCA2. In this study, we have evaluated the XRCC1 gene that participates in the BER pathway, as phenotypic modifier of BRCA1 and BRCA2.

METHODS

Three common SNPs in the gene, c.-77C>T (rs3213245) p.Arg280His (rs25489) and p.Gln399Arg (rs25487) were analysed in a series of 701 BRCA1 and 576 BRCA2 mutation carriers.

RESULTS

An association was observed between p.Arg280His-rs25489 and breast cancer risk for BRCA2 mutation carriers, with rare homozygotes at increased risk relative to common homozygotes (hazard ratio: 22.3, 95% confidence interval: 14.3-34, P<0.001). This association was further tested in a second series of 4480 BRCA1 and 3016 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1 and BRCA2.

CONCLUSIONS AND INTERPRETATION

No evidence of association was found when the larger series was analysed which lead us to conclude that none of the three SNPs are significant modifiers of breast cancer risk for mutation carriers.

Evaluation of a candidate breast cancer associated SNP in ERCC4 as a risk modifier in BRCA1 and BRCA2 mutation carriers. Results from the Consortium of Investigators of Modifiers of BRCA1/BRCA2 (CIMBA)

Background:

In this study we aimed to evaluate the role of a SNP in intron 1 of the ERCC4 gene (rs744154), previously reported to be associated with a reduced risk of breast cancer in the general population, as a breast cancer risk modifier in BRCA1 and BRCA2 mutation carriers.

Methods:

We have genotyped rs744154 in 9408 BRCA1 and 5632 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and assessed its association with breast cancer risk using a retrospective weighted cohort approach.

Results:

We found no evidence of association with breast cancer risk for BRCA1 (per-allele HR: 0.98, 95% CI: 0.93–1.04, P=0.5) or BRCA2 (per-allele HR: 0.97, 95% CI: 0.89–1.06, P=0.5) mutation carriers.

Conclusion:

This SNP is not a significant modifier of breast cancer risk for mutation carriers, though weak associations cannot be ruled out.

Reproductive factors in hereditary breast cancer

BACKGROUND

An early age at menarche, a short menstrual cycle length, and a high age at first full term pregnancy or nulliparity are known risk factors for breast cancer. These risk factors have previously been reported to differ between breast cancer patients with and without a family history of breast cancer and also between breast cancer patients and controls.

METHODS

Self-administered questionnaires were filled out by 95 women belonging to 24 families with known BRCA1 mutations, 16 women belonging to nine families with known BRCA2 mutations, and 95 women belonging to 65 families with hereditary breast cancer where no BRCA1 or BRCA2 mutations could be detected. Thirty-nine women were BRCA1 mutation carriers and 56 women were BRCA1 negative, 11 women were BRCA2 carriers and five BRCA2 negative. All women were born between 1905 and 1979.

RESULTS

Age at menarche, physiological menstrual cycle length at age 30 or at current age in younger women (when not using oral contraceptives), age at first full term pregnancy, and nulliparity did not significantly differ between BRCA1 mutation carriers and BRCA1 negative women. Too few women were BRCA2 negative to serve as a control group. BRCA2 mutation carriers were therefore compared with BRCA1 negative and BRCA2 negative women. None of the above reproductive factors did significantly differ between BRCA2 mutation carriers and from BRCA1 and BRCA2 families. Women from non-BRCA1/BRCA2 hereditary breast cancer families had a higher age at menarche, but this was no longer significant after adjustment for other factors in a multivariate model.

CONCLUSION

Our results suggest that reproductive risk factors of breast cancer are not related to BRCA1 or BRCA2 carrier status. There was also no indication that these factors differ in carriers of unknown susceptibility genes compared with non-carriers from BRCA1 and BRCA2 families.

High prevalence of the 999del5 mutation in icelandic breast and ovarian cancer patients

Studies on Icelandic breast cancer families have shown that most of them segregate a 999del5 BRCA2 mutation. Here, we report the frequency of the 999del5 BRCA2 mutation in an Icelandic control population and four different groups of cancer patients diagnosed with (a) breast cancer; (b) ovarian cancer; (c) prostate cancer (patients younger than 65 years); and (d) other cancer types. The proportions of individuals carrying the mutation were 0.4% in the control population and in the patient groups 8.5%, 7.9%, 2.7%, and 1.0%, respectively. Our results indicate that BRCA2 confers a very high risk of breast cancer and is responsible for a substantial fraction of breast and ovarian cancer in Iceland, but only a small proportion of other cancers.