Efficacy of front-line treatment for hormone receptor-positive HER2-negative metastatic breast cancer with germline BRCA1/2 mutation

BACKGROUND

Efficacy of endocrine therapy in HR+/HER2- metastatic breast cancer could differ depending on the presence of BRCA1/2 germline mutation.

METHODS

The ESME metastatic breast cancer platform (NCT03275311) is a French real world database. Multivariable models including a time-varying approach and landmark analyses assessed the association between time-dependent gBRCA status (categorised as gBRCAm, gBRCAwt (wild type), and untested), overall survival (OS), and first-line progression-free survival (PFS1).

RESULTS

A total of 170 patients were gBRCAm carriers, 676 gBRCAwt, and 12,930 were untested at baseline. In the multivariable analysis, gBRCAm carriers overall had a lower OS compared to gBRCAwt (adjusted HR [95% CI] 1.26 [1.03-1.55]). gBRCAm patients treated with front-line endocrine therapy had lower adjusted OS (adjusted HR [95% CI] = 1.54 [1.03-2.32]) and PFS1 (adjusted HR [95% CI] 1.58 [1.17-2.12]) compared to gBRCAwt patients. However, for patients who received frontline chemotherapy, neither OS nor PFS1 differed between gBRCAm carriers and the other groups (HR versus gBRCAwt for OS: 1.12 [0.88-1.41], p = 0.350; PFS1: 1.09 [0.90-1.31], p = 0.379).

CONCLUSION

In this large cohort of HR+/HER2- MBC patients treated in a pre-CDK4/6 inhibitors era, gBRCAm status was associated with a lower OS and lower PFS following first-line endocrine therapy, but not following first-line chemotherapy.

HPV ctDNA detection of high-risk HPV types during chemoradiotherapy for locally advanced cervical cancer

BACKGROUND

Chemoradiotherapy (CRT) is the standard of care for patients diagnosed with locally advanced cervical cancer (LACC), a human papillomavirus (HPV)-related cancer that relapses in 30%-60% of patients. This study aimed to (i) design HPV droplet digital PCR (ddPCR) assays for blood detection (including rare genotypes) and (ii) monitor blood HPV circulating tumor DNA (HPV ctDNA) levels during CRT in patients with LACC.

METHODS

We analyzed blood and tumor samples from 55 patients with HPV-positive LACC treated by CRT in a retrospective cohort (n = 41) and a prospective cohort (n = 14). HPV-ctDNA detection was carried out by genotype-specific ddPCR.

RESULTS

HPV ctDNA was successfully detected in 69% of patients (n = 38/55) before CRT for LACC, including nine patients with a rare genotype. HPV-ctDNA level was correlated with HPV copy number in the tumor (r = 0.41, P < 0.001). HPV-ctDNA positivity for HPV18 (20%, n = 2/10) was significantly lower than for HPV16 (77%, n = 27/35) or other types (90%, n = 9/10, P = 0.002). HPV-ctDNA detection (positive versus negative) before CRT was associated with tumor stage (P = 0.037) and lymph node status (P = 0.02). Taking into account all samples from the end of CRT and during follow-up in the prospective cohort, positive HPV-ctDNA detection was associated with lower disease-free survival (DFS) (P = 0.048) and overall survival (OS) (P = 0.0013).

CONCLUSION

This is one of the largest studies to report HPV-ctDNA detection before CRT and showed clearance of HPV ctDNA at the end of treatment in most patients. Residual HPV ctDNA at the end of CRT or during follow-up could help to identify patients more likely to experience subsequent relapse.

Abstract P1-09-07: Breast cancer characteristics and outcomes in patients with TP53 germline mutation

Introduction

Li-Fraumeni syndrome (LFS) resulting from monoallelic germline TP53 gene mutation is a rare hereditary cancer predisposition. Breast cancer (BC) is the most common cancer among women with TP53 germline mutation with a risk ranging from 49% to 85% by the age of 60 years old. Most of these cancers are early onset. Few patients' cases have been reported so far in the literature. Our aim was to describe the medical history of a cohort of LFS women diagnosed with BC recruited from a single institution. The characteristics combined were genetic alteration diagnosis, tumor characteristics, treatment, outcome, and LFS associated cancers.

Methods

We retrospectively identified breast cancer patients with TP53 germline mutation from the Institut Curie (Paris, France) database and described their cancer characteristics and medical history.

Results

From 1989 to 2015, 25 patients affected with BC (31 tumors) and TP53 germline mutation carrier were identified, with a median follow up of 6.5 years. Median age at BC diagnosis was 30.5 years. All patients were women. 33% had a previously identified TP53 mutation in their family. 70% of them had BC as their first cancer event. 60% of the patients presented with another LFS associated cancer or non-related cancers: osteosarcoma (22%), glioblastoma (18%), pulmonary carcinoma (13%), gastric linitis plastica (9%), malignant hemopathy (9%), soft tissue sarcoma (9%), adrenocortical carcinoma (4%), ovarian cystadenocarcinoma (4%), renal tumor (4%), choroid plexus carcinoma (4%).

92% of the breast tumors were ductal carcinoma (28% DCIS and 64% IDC), 7% were sarcoma (1 phyllodesarcoma, 1 pleiomorphic liposarcoma); there were no lobular carcinoma. Among the IDC, 50% were HER2 positive, 72% were hormone-receptor positive.

Most patients had a mastectomy (64%), and most of them received radiation (55%). However, when TP53 mutation had been identified prior to the treatment, none of the patients received radiotherapy (5 patients). Most patients received chemotherapy (70%) (37% in neoadjuvant setting, 33% in adjuvant setting, 25% for metastatic setting). 40% of the patients received hormone therapy (37% as adjuvant treatment, 7% for metastatic disease)

Most of the patients did not relapse from BC (75%). Overall, only 17% of the patients had metastatic BC. To date, 12 patients of our series have died (48%), 6 patients (24%) from other LFS-associated cancers and 4 patients from BC (16%).

Conclusion

To the best of our knowledge, this descriptive series is the largest study of tumor characteristics and medical history of LFS-women with BC, the most frequent cancer among women with TP53 germline mutation. It confirms the higher HER2 overexpression rate observed in LFS-patients BC, as suggested in the literature and showed a high rate of DCIS at initial presentation. Most of the patients developed other LFS-associated cancers. In depth molecular analysis of these BC will be performed in order to gain insight into their biological specificities and to adapt the therapeutic management of this poor prognosis syndrome.

Citation Format: Tran M, Loirat D, Colas C, Bozec L, Laurence V, Lerebours F, Cabel L, Bidard F-C, Stoppa-Lyonnet D, Vincent-Salomon A, Gauthier-Villars M, Lavigne M, De Pauw A. Breast cancer characteristics and outcomes in patients with TP53 germline mutation [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-09-07.

Circulating tumor cell count and thrombosis in metastatic breast cancer

Essentials Tumor cells circulating in blood (CTC) may favor thrombotic events in cancer patients. We assessed the impact of CTC on the risk of thrombosis in metastatic breast cancer. Baseline CTC detection was the only independent factor associated with the risk of thrombosis. CTC detection under therapy may be the hidden link between tumor progression & thrombosis.

SUMMARY

Background Circulating tumor cell (CTC) count is a major prognostic factor in metastatic breast cancer (MBC) and has been reported to be associated with thrombosis in short-term studies on MBC patients. Objective To assess whether CTC detection (CellSearch® ) before first-line chemotherapy impacts the risk of thrombosis throughout the course of MBC. Patients/Methods Among patients included before first-line chemotherapy for MBC in the prospective IC2006-04 CTC detection study (NCT00898014), the electronic medical files of those patients treated at Institut Curie (Paris, France) were searched in silico and manually checked for incident venous or arterial thrombotic events (TE) in the course of MBC. Univariate and multivariate analyses were performed using Cox and Fine-Gray models, adjusted for age and Khorana score. Results/Conclusions With a median follow-up of 64 months (25-81 months), among the 142 patients included, 34 (24%) experienced a TE (incidence rate, 8 TE/100 patient-years). The TE incidence rate was 13 TE/100 patient-years for the 80 patients with ≥ 1 CTC/7.5 mL of blood before initiating first-line chemotherapy, vs. only 4 TE/100 patient-years for the 62 CTC-negative patients. Fine-Gray multivariate analysis (with death as competing event) included age, Khorana score and baseline lactate dehydrogenase and CTC levels: detectable CTC was the only factor significantly associated with an increased risk of TE (sub-distribution hazard ratio [SHR] for patients with [1-4] CTC = 3.1, 95% CI [1.1; 8.6], SHR for patients with ≥ 5 CTC = 1.4, 95% CI [0.5; 4.6]). This study shows that CTC detection before starting first-line chemotherapy is an independent risk factor for TE in MBC patients.