Abstract OT2-04-05: Phase II trial of pre-operative stereotactic ablative radiotherapy (SABR) in early-stage breast cancer

Background:

Post-operative accelerated partial breast irradiation (APBI) has demonstrated efficacy in preventing in-breast tumor recurrence. Pre-operative administration of APBI may be advantageous as an intact breast tumor is smaller than its corresponding lumpectomy cavity, is easier to distinguish on treatment-planning images, and results in smaller and more accurately delineated target volumes. Pre-operative APBI may reduce the incidence of positive margins following breast-conserving surgery (BCS). Investigation is needed in the correlation of MR imaging with pathologic response 6 weeks after SABR. Also, evidence suggests that SABR induces immune activation in the tumor microenvironment; evaluation of excised tumor tissue will give insight into these processes.

Trial Design:

Treatment Planning and Delivery: CT simulation and treatment are performed in the prone position. Diagnostic MRI is fused to planning CT. GTV is delineated on registered breast MRI and includes the intact breast tumor. CTV is 15mm expansion of GTV. PTV is 3 mm expansion of CTV. VMAT or IMRT are permitted. Daily image-guidance aligning to tumor and biopsy-fiducial is mandatory. All subjects undergo pre-operative SABR to 28.5 Gy in 3 fractions of 9.5 Gy on different days separated by ≤48 hours. CTCAE v4 is used to assess toxicity 4-5 weeks after SABR. Pre-operative diagnostic MRI is performed 5-6 weeks following SABR. Imaging parameters to be evaluated include changes in tumor size, enhancement, and tumor margin description. BCS will be 6-8 weeks following SABR.

Tissue pathology: Margin status and degree of pathologic response are recorded from breast-conserving excisions, specimens are archived for future analysis.

Eligibility Criteria:

Inclusion criteria are women age ≥50 with biopsy proven invasive breast adenocarcinoma with tumor size ≤2cm on MRI, cN0 M0, ER+/HER2-, without history of invasive malignancy or prior breast/thoracic radiotherapy.

Exclusion criteria are active scleroderma or lupus erythematosus with skin involvement, MRI defined tumor within 10 mm of skin, implanted hardware prohibiting appropriate treatment planning or delivery, neoadjuvant chemotherapy, carrier of BRCA1 or 2 gene mutation, pregnancy.

Specific Aims:

The primary endpoint is pathologic complete response (pCR) in the breast tumor, secondary endpoints are incidence of adequate surgical margins (defined as “no tumor on ink”) and MRI response following SABR. Analyses of tumor immune response and microenvironment on pathologic specimens following SABR will also be performed.

Statistical Methods:

Fisher's exact test will be performed to examine associations between patient/tumor characteristics and pCR and surgical margins; these associations will be explored with multivariable logistic and linear regressions.

Accrual:

Present accrual is 9 subjects.

Expected accrual is 22 subjects; if ≥3 pCR are noted in the initial cohort, accrual will be expanded to 40 subjects.

Citation Format: Liveringhouse CL, Diaz R, Ahmed KA, Lee MC, Czerniecki B, Laronga C, Khakpour N, Weinfurtner RJ, Rosa M, Montejo ME. Phase II trial of pre-operative stereotactic ablative radiotherapy (SABR) in early-stage breast cancer [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 OT2-04-05.

P5-11-14: Flat Epithelial Atypia of the Breast: A Single Institution Experience

Background: Flat epithelial atypia of the breast is a relatively new entity of unknown significance. Our objective is to evaluate our surgical experience with this diagnosis.

Methods: A single institution database of breast patients from 2005–2010 was used to identify women who were diagnosed with flat epithelial atypia on core biopsy and subsequently underwent surgical excision. Patient data regarding history, type and reason for biopsy, and associated pathology was collected. Individuals diagnosed with flat epithelia atypia and cancer on core biopsies in the same breast were excluded.

Results: There were 52 patients who underwent surgical excision for the primary diagnosis of flat epithelial atypia. There were 3 (6%) patients with a personal history of breast cancer, 14 (27%) patients with a family history of breast cancer, and 11 (21%) patients with a concurrent new diagnosis of breast cancer in the contralateral breast. Core biopsy was recommended in most (81%) cases because of suspicious calcifications on mammography. Twenty-eight (54%) patients were found to have flat epithelial atypia associated with other atypical breast hyperplasia and 24 (46%) had flat epithelial atypia as the most significant lesion on core biopsy. In 8 (15%) patients, there was a sonographic correlate that was biopsied; 5 had only flat epithelial atypia and 3 had flat epithelial atypia associated with other atypical hyperplasia. Of the 52 patients there were 4 (8%) patients who upstaged to ductal carcinoma in-situ on surgical excision. There were no cases of invasive carcinoma. All ductal carcinoma in-situ cases were associated with other atypical breast hyperplasia, not flat epithelial atypia alone.

Conclusion: Though flat epithelial atypia may be associated with an increased risk of breast cancer, surgical excision of pure flat epithelial atypia may not be necessary. Larger studies are needed to corroborate these findings.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-11-14.

Results of Oncotype DX in early-stage invasive lobular carcinoma

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Background: The Oncotype DX (ODX) genomic assay has been used since 2004 to estimate prognosis and guide adjuvant treatment in patients with estrogen receptor-positive, node-negative invasive breast tumors. However, the impact of ODX assay testing in patients with invasive lobular carcinoma (ILC) has not been specifically reported. We describe our experience in patients with ILC who underwent ODX assay testing and how this affected adjuvant treatment.

Methods: An IRB approved retrospective review was performed on all patients undergoing treatment for early stage, node-negative ILC from 2006-2011. All cases were reviewed by a single pathologist (GA) for verification of histology and subtype. The impact of ODX assay testing on treatment management was evaluated.

Results: Thirty-nine patients underwent ODX genomic assay testing of early stage, node-negative ILC with a median age of 62 years. ILC tumor classification included classic (67%), pleomorphic (23%) and mixed (10%) subtypes with a median tumor size of 2.0 cm (0.6-6.0). Ninety-seven percent of tumors were estrogen receptor-positive, 74% progesterone receptor-positive. Median ODX recurrence score was 15 (0-34) with an ODX 10-yr risk of 10% (3-23). ODX risk classification was: Low (N=26), Intermediate (N=12), and High (N=1). There was no difference in ODX recurrence score or risk classification between ILC subtypes (p=0.52 and p=0.35, respectively). Adjuvant chemotherapy was used in 26% (TC N=8, AC N=1, FEC 100 N=1). Tumor size or ILC tumor subtype were not significant for adjuvant chemotherapy use while tumor grade (p=0.046), ODX recurrence score (22.8 vs 13.6, p<0.0001), ODX risk classification (p=0.009) and ODX 10 year risk (15.9 vs 9.0, p<0.0001) were significant. With a median follow up of 16.5 months, there were no recurrences or tumor-related deaths.

Conclusions: ODX testing on early stage node-negative ILC may serve as a useful adjunct when counseling patients on the decision for adjuvant therapy. The long-term impact on recurrence or survival in patients with ILC who receive adjuvant chemotherapy based on ODX recurrence score remains undetermined and warrants further testing.

Side-population cells in luminal-type breast cancer have tumour-initiating cell properties, and are regulated by HER2 expression and signalling

BACKGROUND

The expression of side-population (SP) cells and their relation to tumour-initiating cells (T-ICs) have been insufficiently studied in breast cancer (BC). We therefore evaluated primary cell cultures derived from patients and a panel of human BC cell lines with luminal- or basal-molecular signatures for the presence of SP and BC stem cell markers.

METHODS

The SPs from luminal-type BC were analysed for BC T-IC characteristics, including human epidermal growth factor receptor 2 (HER2), ERalpha, IGFBP7 expression and their ability to initiate tumours in non-obese diabetic severe combined immunodeficiency (NOD/SCID) mice. Pharmacological modulators were used to assess the effects of HER2 signalling and breast cancer-resistance protein (BCRP) expression on SPs.

RESULTS

The SP was more prevalent in the luminal subtype of BC compared with the basal subtype. HER2 expression was significantly correlated with the occurrence of an SP (r(2)=0.75, P=0.0003). Disappearance of SP in the presence of Ko143, a specific inhibitor of the ATP-binding cassette transporter BCRP, suggests that BCRP is the predominant transporter expressed in this population. The SP also decreased in the presence of HER2 signalling inhibitors AG825 or trastuzumab, strengthening the notion that HER2 contributed to the SP phenotype, likely through downstream AKT signalling. The SP cells from luminal-type MCF-7 cells with enforced expression of HER2, and primary cells with luminal-like properties from a BC patient, displayed enrichment in cells capable of repopulating tumours in NOD/SCID mice. Engraftment of SP cells was inhibited by pretreatment with AG825 or by in vivo treatment with trastuzumab.

INTERPRETATION

Our findings indicate an important role of HER2 in regulating SP and hence T-ICs in BC, which may account for the poor responsiveness of HER2-positive BCs to chemotherapy, as well as their aggressiveness.

Margin Assessment in Breast Conservation for Ductal Carcinoma In Situ

IntroductionBreast conserving surgery in the setting of ductal carcinoma in situ (DCIS) produces many challenges. Re-excision rates for close or negative margins after lumpectomy are common due to difficulty in intraoperative margin status assessment. The objective of this study was to review our experience with various margin assessment techniques in the setting of a preoperative diagnosis of DCIS on core needle biopsy (CNB).MethodsA prospectively gathered database of surgically-treated breast cancer patients was reviewed for patients with a diagnosis of DCIS as the most significant lesion on CNB from 1997 to 2009. Of 425 patients with a diagnosis of DCIS by CNB, 231 patients underwent a lumpectomy. Patients' age, tumor characteristics, type of surgery, margin assessment technique, and follow up data were recorded.Results231 patients underwent a lumpectomy following a CNB of DCIS. 138 patients (59.7%) had intra-operative touch prep (TP) analysis of all 6 margins, 39 patients (16.9%) underwent intra-operative gross evaluation of margins, 53 (22.9%) patients had no intra-operative analysis, and one patient (0.4%) had a frozen section analysis. Success at achieving negative margins (&gt;2mm) with initial lumpectomy was 66.7% (92/138) for TP analysis, 56.4% (22/39) for gross evaluation, and 52.8% (28/53) for no margin assessment. These percentages did not reach statistical significance by odds ratios (TP to Gross p= 0.24, TP to None p=0.08, Gross to None p=0.73). After excluding patients that required mastectomy following an unsuccessful lumpectomy, ipsilateral breast recurrence rates were 6.3% (8/127) for the touch prep patients after a mean follow up of 4.0 years, 0.0% (0/31) for the gross evaluation patients after a mean follow up of 1.9 years, and 10.5% (4/38) for the patients with no intraoperative assessment after a mean follow up of 3.8 years. Characteristics of each group are listed in Table 1.ConclusionsReexcision for close or positive margins is required for a significant percentage of patients who undergo lumpectomy after a preoperative diagnosis of DCIS on CNB. Although intraoperative TP analysis had the highest success of preventing reexcision, long term data suggest that recurrence rates between intraoperative TP and gross evaluation are both acceptable with short term follow up.Table 1: Characteristics of patients undergoing lumpectomy with a preoperative diagnosis of DCIS on CNBMargin AssessmentTouch PrepGrossNoneFrozenNumber of cases13839531Patient Median Age59.758.956.359.8Cases not needing Reexcision66.7%(92/138)56.4% (22/39)52.8% (28/53)0%(0/1)Cases that received mastectomy8.0%(11/138)20.5%(8/39)26.4%(14/53)100%(1/1)DCIS Grade3- 512- 631- 22Unk- 23- 162- 151- 5Unk- 33-252-201- 7Unk- 13- 02- 01- 1Unk- 0Cases with Necrosis50%(69/138)53.9%(21/39)62.3%(33/53)0%(0/1)Cases upgraded to Invasive Cancer12.3%(17/138)15.4%(6/39)35.9%(19/53)0%(0/1)ReceivedRadiation after lumpectomy85.0%(108/127)67.7% (21/31)76.3%(29/38)0%(0/1)ReceivedTamoxifen after lumpectomy34.7%(44/127)25.8%(8/31)31.2%(12/38)0%(0/1)Ipsilateral breastRecurrence after lumpectomy6.3%(8/127)0%(0/31)10.5% (4/38)0%(0/1)Follow up after lumpectomy (years)4.0(0-10.6)1.9(0.19-5.6)3.8(0.17-9.4)6.0 

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4122.

Neoadjuvant Intratumoral Injection of Dendritic Cells in Breast Cancer

Backround: Autologous intratumoral dendritic cell injections were used to modulate the tumor reduction effects of standard neoadjuvant chemotherapy. Dendritic cells are important in the regulation of T cell immunity and have been shown to have activity in cancer patients. The neoadjuavant combination therapy was designed to expose dendritic cells to tumor cell apoptosis leading to induction of tumor antigen-specific responses.Methods: Seventeen women with stage II or III breast cancer with breast tumors at least 3 cm in size and had a confirmed initial breast biopsy were entered into this trial from August 2007 through 2009. All patients participating in the clinical trial had tumors that expressed either carcinoembryonic antigen (CEA) or survivin and were HER2-neu negative. They received 4 cycles of paclitaxel at 175 mg/m2 followed by 4 cycles of doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2 (AC) in a bi-weekly dose dense fashion. Pegfilgrastim 6 mg subcutaneous injection was administered 24 hours after each cycle of chemotherapy. Autologous intratumoral dendritic cell injections were administered one week following the first three paclitaxel treatments. All patients consented to a pre-treatment biopsy and a second tumor biopsy after 4 cycles of paclitaxel to evaluate responses to the intratumoral dendritic cell injections. The endpoints of this trial included assessment of clinical and pathologic response in the breast, safety of the intratumoral dendritic cell injection, evaluation of tumor response, and induction of T cell responses to tumor antigens.Results: Fourteen patients are evaluable for response. The median age was 51.5, the median tumor size was 5.6 cm, and 64 % were estrogen receptor positive. A complete clinical response was observed in 57%, a partial response in 36%, and one stable disease response. A pathologic complete response with no evidence of tumor in the breast was confirmed in 2 patients (14 %). Treatment was well tolerated with no incidence of toxicity observed related to the intratumoral dendritic cell injections. Grade 3/4 hematologic toxicity was as expected for the chemotherapy. Other grade 3/4 toxicity related to the chemotherapy included fatigue, hand-foot, infection, mucositis, and hypocalcemia.Discussion: Combination neoadjuvant therapy with dose-dense paclitaxel followed by AC and autologous intratumoral dendritic cell injections administered between the first three cycles of paclitaxel is safe with no toxicity observed related to the intratumoral dendritic cell injections. Immune response to the treatment is being evaluated by proliferation and interferon-gamma production by peripheral blood mononuclear cells in response to tumor cell lysates, survivin, and CEA. Initial evaluation indicates that treatment resulted in generation of tumor specific responses in more than half of all treated patients.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4128.