ΔKi67 proliferation index as independent predictive and prognostic factor of outcome in luminal breast cancer: data from neoadjuvant letrozole-based treatment

A key tool for monitoring breast cancer patients under neoadjuvant treatment is the identification of reliable predictive markers. Ki67 has been identified as a prognostic and predictive marker in ER-positive breast cancer. Ninety ER-positive, HER2 negative locally advanced breast cancer patients received letrozole (2.5 mg daily) and cyclophosphamide (50 mg daily) with/without Sorafenib (400 mg/bid daily) for 6 months before undergoing surgery. Ki67 expression and tumor size measured with caliber were determined at baseline, after 30 days of treatment and at the end of treatment. Patients were assigned to a clinical response category according to Response Evaluation Criteria in Solid Tumors, both at 30 days and before surgery and further classified as high-responder and low-responder according to the median variation of Ki67 values between biopsy and 30 days and between biopsy and surgery time. The predictive role of Ki67 and its changes with regard to clinical response and survival was analyzed. No differences in terms of survival outcomes emerged between the arms of treatment, while we observed a higher percentage of women with progression or stable disease in arm with the combination containing Sorafenib (20.5% vs 7.1%, p = 0.06). Clinical complete responders experienced a greater overall variation in Ki67 when compared with partial responders and patients with progressive/stable disease (66.7% vs 30.7%, p = 0.009). High responders showed a better outcome than low responders in terms of both disease-free survival (p = 0.009) and overall survival (p = 0.002). ΔKi67 score evaluated between basal and residual tumor at definitive surgery showed to be highly predictive of clinical complete response, and a potential parameter to be used for predicting disease-free survival and overall survival in luminal breast cancer treated with neoadjuvant endocrine-based therapy.

Efficacy of extended aromatase inhibitors for hormone-receptor-positive breast cancer: A literature-based meta-analysis of randomized trials

BACKGROUND

Endocrine treatment with Tamoxifen and aromatase inhibitors (AIs) is a staple in the management of hormone receptor positive breast cancer (HR + BC). It has become clear that HR + BC carries a consistent risk of relapse up to 15 years post-diagnosis. While increasing evidence supports the use of extended adjuvant Tamoxifen over 5 years, controversial data are available on the optimal duration of extended AIs adjuvant treatment. We performed a meta-analysis to assess the real impact of extended adjuvant therapy with AIs on disease-free survival (DFS).

METHODS

A literature-based meta-analysis of randomized controlled trials (RCTs) was undertaken. Relevant publications from PubMed, the Cochrane Library, and abstracts from American Society of Clinical Oncology (ASCO) and San Antonio Breast Cancer (SABCS) symposia were searched. Primary and secondary endpoints were Disease Free Survival (DFS) and overall survival (OS) respectively. A subgroup analysis was also performed to elucidate the impact of nodal involvement.

RESULTS

The pooled analysis revealed a significant increase in DFS in the extended AIs group (hazard ratio (HR): 0.78, 95% CI: 0.68-0.90; P = 0.0006). The subgroup analysis according to nodal status showed a greater DFS benefit with extended AIs in patients with positive nodes (HR = 0.67 versus 0.80). Our analysis also demonstrated no improvement in OS with extended AIs (HR = 0.99, 95%CI: 0.87-1.12; P = 0.84).

CONCLUSION

This work confirmed the efficacy of extended adjuvant treatment with AIs for HR + early breast cancer, with a 22% increase in DFS, but no impact on OS. Greater efficacy was observed in women with positive nodal status.

Sentinel lymph node surgery after neoadjuvant chemotherapy in patients with T2 to T4, N0 and N1 breast cancer

BACKGROUND

Histological status of axillary lymph nodes is an important prognostic factor in patients receiving surgery for breast cancer (BC). Sentinel lymph node (SLN) biopsy (B) has rapidly replaced axillary lymph node dissection (ALND), and is now the standard of care for axillary staging in patients with clinically node-negative (N0) operable BC. The aim of this study is to compare pretreatment lymphoscintigraphy with a post primary systemic treatment (PST) scan in order to reduce the false-negative rates for SLNB.

METHODS

In this single-institution study we considered 170 consecutive T2-4 N0-1 M0 BC patients treated with anthracycline-based PST. At the time of incisional biopsy, we performed sentinel lymphatic mapping. After PST, all patients repeated lymphoscintigraphy with the same methodology. During definitive surgery we performed further sentinel lymphatic mapping, SLNB and ALND.

RESULTS

The SLN was removed in 158/170 patients giving an identification rate of 92.9% (95% confidence interval (CI) = 88.0-96.3%) and a false-negative rate of 14.0% (95% CI = 6.3-25.8%). SLNB revealed a sensitivity of 86.0% (95% CI = 74.2-93.7%), an accuracy of 94.9% (95% CI = 90.3-97.8%) and a negative predictive value of 92.7% (95% CI = 86.1-96.8%).

CONCLUSION

Identification rate, sensitivity and accuracy are in accordance with other studies on SLNB after PST, even after clinically negative node conversion following PST. This study confirms that diagnostic biopsy and neoadjuvant chemotherapy maintain breast lymphatic drainage unaltered.

Combination of letrozole, metronomic cyclophosphamide and sorafenib is well-tolerated and shows activity in patients with primary breast cancer

PURPOSE

To assess whether the combination of letrozole, metronomic cyclophosphamide and sorafenib (LCS) is well tolerated and shows activity in primary breast cancer (BC).

METHODS

Thirteen oestrogen receptor-positive, postmenopausal, T2-4, N0-1 BC patients received the LCS combination for 6 months. In these patients we examined the pharmacokinetics of sorafenib and cyclophosphamide, toxicity of the regimen, the clinical response to therapy and changes in the levels of biologically relevant biomarkers.

RESULTS

Adequate plasma concentrations of sorafenib were achieved in patients when it was dosed in combination with L+C. The mean plasma concentrations of C were consistently lower following administration of LCS, compared with administration of L+C only. The most common drug-related grade 3/4 adverse events were skin rash (69.3%), hand-foot skin reaction (69.3%) and diarrhoea (46.1%). According to RECIST Criteria, a clinical complete response was observed in 6 of 13 patients. A significant reduction in tumour size, evaluated with MRI, was also observed between baseline and 14 days of treatment in all 13 patients (P=0.005). A significant reduction in SUV uptake, measured by (18)FDG-PET/CT, was observed in all patients between baseline and 30 days of treatment (P=0.015) and between baseline and definitive surgery (P=0.0002). Using modified CT Criteria, a response was demonstrated in 8 out of 10 evaluable patients at 30 days and in 11 out of 13 evaluable patients at the definitive surgery. A significant reduction in Ki67 expression was observed in all patients at day 14 compared with baseline (P<0.00001) and in 9 out of 13 patients at the definitive surgery compared with baseline (P<0.03). There was also a significant suppression of CD31 and VEGF-A expression in response to treatment (P=0.01 and P=0.007, respectively).

CONCLUSIONS

The LCS combination is feasible and tolerable. The tumour response and target biomarker modulation indicate that the combination is clinically and biologically active.

Prospective neoadjuvant analysis of PET imaging and mechanisms of resistance to Trastuzumab shows role of HIF1 and autophagy

Background:

Although Trastuzumab has improved survival of HER2+ breast cancer patients, resistance to the agent pre-exists or develops through the course of therapy. Here we show that a specific metabolism and autophagy-related cancer cell phenotype relates to resistance of HER2+ breast cancer to Trastuzumab and chemotherapy.

Methods:

Twenty-eight patients with locally advanced primary breast cancer were prospectively scheduled to received one cycle of Trastuzumab followed by a new biopsy on day 21, followed by taxol/Trastuzumab chemotherapy for four cycles before surgery. FDG PET/CT scan was used to monitor tumour response. Tissue samples were immunohistochemically analysed for metabolism and autophagy markers.

Results:

In pre-Trastuzumab biopsies, the LC3A+/HER2+ cell population was correlated with HIF1α expression (P=0.01), while GLUT1 and LC3B expression were correlated with Ki67 proliferation index (P=0.01 and P=0.01, respectively). FDG PET tumour dimensions before therapy were correlated with LC3B expression (P=0.005). Administration of Trastuzumab significantly reduced clinical and PET-detected tumour dimensions (P<0.01). An inverse association of tumour response with the percentage of cells expressing HIF1α at baseline was documented (P=0.01). Administration of Trastuzumab resulted in a decrease of the proliferation index (P=0.004), GLUT1 (P=0.04) and HER2 (P=0.01) expression. In contrast, the percentage of LC3A+/HER2+ cells was increased (P=0.01). High baseline HIF1α expression was the only parameter associated with poorer pathological response to preoperative chemotherapy (P=0.001).

Conclusions:

As the HER2+/LC3A+ phenotype, which often overexpresses HIF1α, is a major subpopulation increasing after therapy with Trastuzumab, LC3A- and HIF1α-targeting therapies should be investigated for the augmentation of anti-HER2 therapy efficacy.

Abstract P6-05-08: Nuclear HER3 localisation plays a role in trastuzumab resistance in HER2-positive breast cancer

Background: HER3 is known to locate in the nucleus. Unlike HER4, nuclear HER3 translocation has not been reported to be due to a proteolytic cleavage process by ADAM17 and gamma-secretase. The mechanisms of nuclear HER3 induction and its role in relation to trastuzumab treatment and resistance for HER2-positive breast cancer is unclear.

Methods: Using nuclear fractionation and confocal microscopy, nuclear HER3 localisation was investigated in response to trastuzumab with or without ADAM17 inhibitor and gamma-secretase inhibitor in a panel of HER2 expressing cell lines. We also correlated nuclear HER3 expression by immunohistochemistry with treatment response in patients who underwent window trastuzumab study as well as the survival outcome in a cohort of HER2-positive breast cancer patients using Kaplan–Meier survival curves with Log-rank test.

Results: HER3 ligand heregulin and trastuzumab was found to induce nuclear HER3 translocation in HER2-positive breast cancer cell lines, including SKBR3. Nuclear HER3 was also enriched in acquired trastuzumab resistant SKBR3 cells (SKBr3-TR). Trastuzumab treatment induced several HER3 fragments and HER3100kD was found to be responsible for nuclear HER3 enrichment by fractionation. This fragment was confirmed to be a specific band of HER3 as shown by HER3 knockdown. Nuclear HER3 was reduced by inhibiting either gamma-secretase or ADAM17 inhibitor. Gamma-secretase or ADAM17 inhibitor reduced HER3100kD in both SKBr3 and SKBr3-TR cells.

In HER2-positive breast cancer patients who underwent window trastuzumab study, baseline nuclear HER3 status was not a predictor of response for trastuzumab monotherapy at day 21. However, nuclear HER3 was enriched after trastuzumab treatment in a poor-responder patient. Total HER3 expression level in cytoplasm positively was correlated with poor response to trastuzumab monotherapy in HER2-positive patients (r = 0.67, p = 0.05). There was no statistically significant difference in disease-free survival between positive and negative nuclear HER3 expression but the number of patients was small (n = 87). Further validation to assess nuclear HER3 expression as a prognostic and predictive biomarker in HER2-positive breast cancer patients undergoing trastuzumab treatment will be assessed in randomized tumour samples from FinHER study.

Conclusion: Heregulin and trastuzumab treatment seems to induce nuclear HER3 translocation in some of the HER2 positive breast cancer cells. This may be due to proteolytic cleavage of HER3 as it is reduced by ADAM17 or gamma-secretase inhibitor. Enriched nuclear localisation of HER3 seems to be one possible mechanism of acquired resistance to trastuzumab in HER2-positive breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-05-08.

Increased pathological complete response rate after a long-term neoadjuvant letrozole treatment in postmenopausal oestrogen and/or progesterone receptor-positive breast cancer

Background:

The objective of this study was to determine the optimal scheduling of 2.5 mg daily letrozole in neoadjuvant breast cancer patients to obtain pathological complete response (pathCR) and assess Ki-67 expression as an early predictor of response.

Patients and methods:

This single institution study comprised 120 oestrogen receptor (ER)-positive postmenopausal women with primary breast cancer (clinical stage ⩾T2, N0–1), from three sequential cohorts (cohort A of 40, cohort B of 40 and cohort C of 40 patients, respectively) based on different duration of the neoadjuvant letrozole. Biological markers such as ER, progesterone receptor, HER2 and Ki-67 expression were tested at diagnosis and at definitive surgery.

Results:

A total of 89 patients (75.4%) achieved an objective response with 44 (37.3%) clinical CRs and 45 (38.1%) partial responses. The clinical CRs were significantly observed in cohort C (23 out of 40 patients, 57.5%) and B (16 out of 38 patients, 42.1%) compared with cohort A (5 out of 40 patients, 12.5%) (P-value for trend <0.001). Letrozole induced a similar significant reduction in Ki-67 index after treatment in all cohorts. The pathCR rate was significantly more frequent in cohort C (7 out of 40 patients, 17.5%) than in cohort A (1 out of 40 patients, 2.5%) and B (2 out of 40 patients, 5.0%) (P-value for trend <0.04).

Conclusion:

One-year neoadjuvant letrozole therapy leads to a higher pathCR rate and may be the optimal length of drug exposure.

Abstract PD07-03: INCREASED PATHOLOGIC COMPLETE RESPONSE RATE AFTER A LONG TERM NEOADJUVANT LETROZOLE TREATMENT IN POSTMENOPAUSAL ESTROGEN AND/OR PROGESTERONE RECEPTOR-POSITIVE BREAST CANCER

Background: Neoadjuvant endocrine therapy has been increasingly employed in clinical practice to improve surgical options for postmenopausal women with bulky hormone receptor-positive breast cancer. Recent studies indicate that tumor response and in particular the pathologic complete response (CR) in this setting may predict long-term outcome. The letrozole approval in neoadjuvant setting is based on a study that included 4 months of letrozole treatment only. Prospective studies have not investigated treatment duration beyond 6 months, and retrospective studies suggest that useful responses can occur after this period. The purpose of this study was to determine the clinical and pathologic response of 2.5 mg daily letrozole used with different schedule in breast cancer patients (pts) unfit for chemotherapy.

Patients and Methods: This single Institution retrospective study comprised 102 postmenopausal women with primary breast cancer (clinical stage ≥T2, N0-1), who were divided into 3 subgroups (34 each in single subgroup) according to the different duration of neoadjuvant letrozole treatment: 4 months (subgroup A), 8 months (subgroup B) or 12 months (subgroup C) of treatment. The subgroups were comparable in terms of baseline characteristics.

Results: Pts and tumor characteristics included: median age 77.3 years (range 53.9–95.4); 100% estrogen receptor-positive, 81.4% progesterone receptor-positive; median Ki67 13.5% (range 2–90%). All pts were evaluable for clinical and pathologic response. A total of 77 pts (75.5%) achieved an objective response at individual end: 40 (39.2%) clinical CR and 37 (36.3%) partial responses (PR). The clinical CR were significantly confined to subgroups C (20/34 pts, 58.8%) and B (16/34 pts, 47.1%) than to subgroup A (4/34 pts, 11.8%) (p for trend = 0.00001). Objective response rate was 46.1% (47/102 pts) at month 4, 83.8% (57/68 pts) at month 8, and 94.1% (32/34 pts) at month 12 compared with baseline. As expected, letrozole induced a significant reduction of Ki67 expression after treatment in any single subgroup, without significant differences between them. With very interest, the pathologic CR rate was significantly higher in subgroup C (7/34 pts, 20.6%) than in subgroups A (1/34 pt, 2.9%) and B (1/34 pt, 2.9%) (p for trend &lt;0.02).

Conclusions: One-year neoadjuvant letrozole therapy can lead to a high pathologic CR rate. This observation suggests that pathologic CR may be a reliable endpoint after endocrine therapy, but a long-term drug exposure is needed. The optimal letrozole treatment duration in neoadjuvant setting is a matter of future research.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD07-03.