Cyclin-Dependent Kinase 4/6 Inhibitor Outcomes in Patients With Advanced Breast Cancer Carrying Germline Pathogenic Variants in DNA Repair-Related Genes

PURPOSE

In recent years, unprecedented benefits have been observed with the development of cyclin-dependent kinase (CDK) 4 and 6 inhibitors for the treatment of hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer. However, there is scarce evidence of their value in specific populations, such as patients carrying germline pathogenic variants in DNA repair-related genes.

PATIENTS AND METHODS

We retrospectively studied the efficacy of CDK 4/6 inhibitors plus endocrine therapy in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer. Three cohorts were compared, including patients harboring germline pathogenic variants in DNA repair-related genes (gBRCA1/2-ATM-CHEK2 mutated), those tested without these mutations (wild type [WT]), and the nontested subgroup. Relevant prognostic factors including age, metastatic site (visceral v nonvisceral), Eastern Cooperative Oncology Group, and prior treatment with CDK 4/6 inhibitors were stratified by univariate and multivariate Cox regression models.

RESULTS

Among the total population (n = 217), 15 (6.9%) patients carried gBRCA1/2 (n = 10)-ATM (n = 4)-CHEK2 (n = 1) pathogenic variants, 45 (20.7%) were WT, and 157 (72.4%) were nontested. Gene pathogenic variant carriers were younger (P < .001). Most patients (164, 75.6%) had not received prior endocrine therapy in the advanced setting. Median progression-free survival was shorter in patients with evaluated germline pathogenic variants (10.2 months [95% CI, 5.7 to 14.7]), compared with WT and nontested patients (15.6 months [95% CI, 7.8 to 23.4], and (17.6 months [95% CI, 12.9 to 22.2]; P = .002). Consistently, a worse median overall survival was observed in the subgroup with germline pathogenic variants than in the WT group (P = .006). Multivariable analysis showed that mutation status was an independent prognostic factor of progression-free survival (P = .020) and overall survival (P = .012).

CONCLUSION

In this retrospective real-world study, gBRCA1/2-ATM-CHEK2 pathogenic variants were independently associated with poor outcomes in patients with advanced breast cancer treated with CDK4/6 inhibitors.

Breast Cancer in Young Women Presents With More Aggressive Pathologic Characteristics: Retrospective Analysis From an Argentine National Database

PURPOSE

Multiple studies have reported that breast cancer in young patients is associated with aggressive characteristics, and it is suggested that prognosis is worse independently of pathologic variables.

PATIENTS AND METHODS

We performed a retrospective analysis of the Breast Cancer Registry of the Argentinian Society of Mastology, including public and private centers. Patients ≤ 40 years of age at diagnosis were classified as "young," and patients ≤ 35 years of age at diagnosis were classified as "very young." Univariate and multivariate analyses were performed to detect differences between groups.

RESULTS

Patients ≤ 40 years of age comprised 10.40% (739/7,105) of the participants, with an average age of 35.61 ± 4.04 years. Multivariate analysis showed that human epidermal growth factor receptor 2 (HER2)-positive tumor phenotype (odds ratio [OR], 1.82), nodal involvement (OR, 1.69), histologic grade (grade 3 OR, 1.41), and tumor size (T2 OR, 1.37; T3-T4, 1.47) were independently associated with younger age at diagnosis. Patients ≤ 35 years of age (n = 286), compared with patients 36 to 40 years of age, had a higher proportion of HER2 tumors (24.58% v 16.94%; P = .021), absence of progesterone receptor expression (29.85% v 22.95%; P = .043), and stage 3 cancer (29.34% v 18.52%; P < .001). Fewer breast-conserving surgeries (75.37% v 62.89%; P < .001) and more adjuvant chemotherapy (59.04% v 36.66%; P < 0.001) were reported in patients ≤ 40 years of age.

CONCLUSION

In the population studied, breast cancer in young women was associated with aggressive pathologic features and locally advanced disease at the time of diagnosis. Moreover, tumor characteristics in very young patients with breast cancer nested in the population ≤ 40 years of age showed differences in important prognostic factors. More high-quality evidence is needed to improve treatment strategies in these patients.

Abstract P3-01-07: Second axillary sentinel lymph node biopsy for breast tumor recurrence: Instituto Alexander Fleming experience in Buenos Aires, Argentina

Sentinel Lymph Node Biopsy (SLNB) is the standard technique for axillary staging of patients with operable breast cancer and a clinically negative axilla because it avoids unwarranted axillary dissection and consequently reduces postoperative morbidity.

Purpose: The aim of this study is to determinate the feasibility and accuracy of the second SLNB for patients with ipsilateral breast cancer recurrences with clinically negative axilla, who were treated previously with breast surgery and study of the axilla.

Methods: Retrospective review of the database of the Instituto Alexander Fleming. Between October 2009 and October 2014, 1029 patients with diagnosis of breast cancer required surgery. The study included 26 patients with the diagnosis of operable local breast cancer recurrence, who had previously undergone axillary surgery either as SLNB, sampling or axillary lymph node dissection (ALND). They subsequently underwent additional breast surgery and a second SLNB.

Results: The mean age of the ipsilateral breast cancer recurrences was 59.23 years (range: 32-87) and the most common histologic subtype was invasive ductal carcinoma in 22 patients (84.6%) and 4 patients (15.4%) with invasive lobular carcinoma. 4 patients (15.4%) had previously ALND or sampling and 22 patients (84.6%) SLNB. The identification rate of the second SLNB was 92.31%. Only 2 patients were not identify, one patient with a previous axillary sampling and another one with previous SLNB. In those patients the ALND was performed and the axilla was negative. Lymphoscintigraphy failed to identify any SLN in 6 patients (23%), 2 patients which were not identify and 4 patients only detected with patent blue. The average number of nodes removed at second SLNB was 1.8 (range: 1-5). Second SLNBs were negative in 21 patients (80.8%), and macrometastasis disease was identified in 2 patients and complete ALND was performed.

In 1 patients additional extra-axillary aberrant drainages was observed in the contralateral axilla and interpectoral, and other 3 patients had aberrant drainage in the contralateral axilla (1 patient), internal mammary regions (1 patient), and interpectoral (1 patient). Aberrant drainage pathways were not routinely dissected. Only those accessible during surgery were removed.

The median time between first surgery and ipsilateral breast tumor recurrence was 7.19 years (range: 1-22). The disease free survival (DFS) was 9.16 years (range: 2.25-24).

Conclusion: In the present serie we show a high identification rate of 92.31% in the second SLNB, comparable with other international series published in the literature (range: 51-97%). A second SLNB should be considered for patients with ipsilateral breast tumor recurrence who underwent conservative surgery and have clinically negative axilla. The procedure is technically feasible and accurate for selected patients, and avoids unnecessary ALND. Extra-axillary sentinel lymph node localization rates are higher than for primary SLNB but the clinical significance and management of extra-axillary nodes needs to be clarified.

Citation Format: Maino M, Fabiano V, Ponce C, Loza M, Costanzo V, Nervo A, Nadal J, Mysler D, Amat M, Coló F, Loza J, Chacón R. Second axillary sentinel lymph node biopsy for breast tumor recurrence: Instituto Alexander Fleming experience in Buenos Aires, Argentina. [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 P3-01-07.

Termination of pregnancy in dogs by oral administration of dexamethasone

Dexamethasone was administered orally for 7.5 or 10 d to each of 20 pregnant bitches beginning at an estimated 28 to 51 d of gestation, using 1 of 2 dose regimens. Five bitches were given dexamethasone 3 times a day for 10 d, with the highest dose of 0.2 mg/kg for 5 d and then at progressively decreasing doses of 0.16-0.02 mg/kg for 5 d. The 15 remaining bitches were given dexamethasone 2 times a day for 7.5 d, increasing from 0.1 to 0.2 mg/kg over the first 3 administrations, then remaining at 0.2 mg/kg on Days 2 to 5, and decreasing from 0.16 to 0.02 mg/kg over the last 5 administrations. The side effects, including mild polydipsia and polyuria, disappeared when treatment was discontinued. Depending on the stage of pregnancy, uterine contents were either resorbed or aborted, or both. Pregnancy was terminated within 2 to 16 d after the start of treatment in all treated bitches, at 2 to 5 d of treatment in 2 of 3 bitches treated at 40 to 51 d of pregnancy, and at 0 to 4 d after the end of treatment in most of the 17 bitches treated at 28 to 35 days of pregnancy. Oral administration of dexamethasone appears to be a potentially useful pharmacologic treatment for the termination of unwanted pregnancy in the bitch.