A Novel Fat-Augmented Omentum-Based Construct for Unilateral and Bilateral Free-Flap Breast Reconstruction in Underweight and Normal Weight Women Receiving Nipple or Skin-Sparing Mastectomies.

BACKGROUND: Autologous tissue has proven advantages, however it is often not an option for women of low or normal body mass index (BMI). Omentum has been used sparingly, typically as a pedicled flap to correct breast deformities, but is considered suboptimal for full breast reconstruction. We developed a new construct, the omental fat-augmented free flap (O-FAFF) as an alternative for breast reconstruction. METHODS: O-FAFF involves laparoscopic omentum harvesting, creation of an acellular dermal matrix shell for its encasement, and lipoinjection to augment volume. The gastroepiploic vessels are microsurgically anastomosed to internal mammary vessels. Tissue and O-FAFF construct weights as well as outcomes are reported. RESULTS: Thirty-four consecutive women (50 breasts) received O-FAFF breast reconstruction after 18 unilateral and 16 bilateral mastectomies (10 non-nipple-sparing, 40 nipple-sparing). Thirty-seven were immediate and 13 were revisions of previous breast reconstructions. Patient mean age was 48.2 (range 23-73) years and mean BMI was 22.3 (range 17.6-32.4) kg/m2. Mean follow-up was 14.8 (range 3-33) months. The median weight of the omentum was 161.7 g (range 81-852, interquartile range [IQR] 102) and the mean ratio of fat to omentum weight was 0.73 (range 0.22-1.38) and 1.97 (range 0.24-3.8) for unilateral and bilateral cases, respectively. Postoperative pain scores and oral morphine equivalent consumption were more favorable for the O-FAFF group compared with controls (p < 0.001). Follow-up breast MRI demonstrated intact perfusion and no fat necrosis. CONCLUSIONS: The O-FAFF is ideally suited for women of lower BMI and could dramatically increase the number of women who are candidates for autologous breast reconstruction.

Trastuzumab Emtansine for Residual Invasive HER2-Positive Breast Cancer.

BACKGROUND: Patients who have residual invasive breast cancer after receiving neoadjuvant chemotherapy plus human epidermal growth factor receptor 2 (HER2)-targeted therapy have a worse prognosis than those who have no residual cancer. Trastuzumab emtansine (T-DM1), an antibody-drug conjugate of trastuzumab and the cytotoxic agent emtansine (DM1), a maytansine derivative and microtubule inhibitor, provides benefit in patients with metastatic breast cancer that was previously treated with chemotherapy plus HER2-targeted therapy. METHODS: We conducted a phase 3, open-label trial involving patients with HER2-positive early breast cancer who were found to have residual invasive disease in the breast or axilla at surgery after receiving neoadjuvant therapy containing a taxane (with or without anthracycline) and trastuzumab. Patients were randomly assigned to receive adjuvant T-DM1 or trastuzumab for 14 cycles. The primary end point was invasive disease-free survival (defined as freedom from ipsilateral invasive breast tumor recurrence, ipsilateral locoregional invasive breast cancer recurrence, contralateral invasive breast cancer, distant recurrence, or death from any cause). RESULTS: At the interim analysis, among 1486 randomly assigned patients (743 in the T-DM1 group and 743 in the trastuzumab group), invasive disease or death had occurred in 91 patients in the T-DM1 group (12.2%) and 165 patients in the trastuzumab group (22.2%). The estimated percentage of patients who were free of invasive disease at 3 years was 88.3% in the T-DM1 group and 77.0% in the trastuzumab group. Invasive disease-free survival was significantly higher in the T-DM1 group than in the trastuzumab group (hazard ratio for invasive disease or death, 0.50; 95% confidence interval, 0.39 to 0.64; P<0.001). Distant recurrence as the first invasive-disease event occurred in 10.5% of patients in the T-DM1 group and 15.9% of those in the trastuzumab group. The safety data were consistent with the known safety profile of T-DM1, with more adverse events associated with T-DM1 than with trastuzumab alone. CONCLUSIONS: Among patients with HER2-positive early breast cancer who had residual invasive disease after completion of neoadjuvant therapy, the risk of recurrence of invasive breast cancer or death was 50% lower with adjuvant T-DM1 than with trastuzumab alone. (Funded by F. Hoffmann-La Roche/Genentech; KATHERINE ClinicalTrials.gov number, NCT01772472 .).

Patient perspectives on window of opportunity clinical trials in early-stage breast cancer.

PURPOSE: Window of opportunity trials (WOT) are increasingly common in oncology research. In WOT participants receive a drug between diagnosis and anti-cancer treatment, usually for the purpose of investigating that drugs effect on cancer biology. This qualitative study aimed to understand patient perspectives on WOT. METHODS: We recruited adults diagnosed with early-stage breast cancer awaiting definitive therapy at a single-academic medical center to participate in semi-structured interviews. Thematic and content analyses were performed to identify attitudes and factors that would influence decisions about WOT participation. RESULTS: We interviewed 25 women diagnosed with early-stage breast cancer. The most common positive attitudes toward trial participation were a desire to contribute to research and a hope for personal benefit, while the most common concerns were the potential for side effects and how they might impact fitness for planned treatment. Participants indicated family would be an important normative factor in decision-making and, during the COVID-19 pandemic, deemed the absence of family members during clinic visits a barrier to enrollment. Factors that could hinder participation included delay in standard treatment and the requirement for additional visits or procedures. Ultimately, most interviewees stated they would participate in a WOT if offered (N = 17/25). CONCLUSION: In this qualitative study, interviewees weighed altruism and hypothetical personal benefit against the possibility of side effect from a WOT. In-person family presence during trial discussion, challenging during COVID-19, was important for many. Our results may inform trial design and communication approaches in future window of opportunity efforts.

Dilemma in management of hemorrhagic myositis in dermatomyositis.

Dermatomyositis (DM) is a rare inflammatory disorder affecting the muscle and skin. DM patients can present with spontaneous muscle hemorrhage, a potentially fatal complication. The best practice for management of hemorrhagic myositis in these patients remains unclear. Here we discuss the case of a patient who presented with progressive muscle weakness and intermittent rash that was diagnosed with dermatomyositis. During admission, she developed spontaneous hemorrhagic myositis of the right pectoralis major treated with surgical evacuation. She also developed a spontaneous left anterior thigh hematoma which was treated conservatively. She recovered and showed no evidence of recurrent bleeding at either location. We performed a literature review and identified ten cases of spontaneous hemorrhage in DM patients, with a 60% mortality rate among reported cases. Given the high mortality rate associated with spontaneous hemorrhage in DM patients, it is important for physicians to be aware of the diagnosis, workup, and management strategies.

Pretreatment Tattoo Marking of Suspicious Axillary Lymph Nodes: Reliability and Correlation with Sentinel Lymph Node.

BACKGROUND: Tattooing is an alternative method for marking biopsied axillary lymph nodes (ALNs) before initiation of treatments for newly diagnosed breast cancer. Detection of black ink-stained nodes is performed under direct visualization at surgery and is combined with sentinel node (SLN) mapping procedures. METHODS: Women with newly diagnosed breast cancer who underwent fine or core-needle biopsy of suspicious ALNs were recruited. The nodal cortex and perinodal soft tissue was injected with 0.1-1.0 ml of Spot™ (GI Supply) black ink under ultrasound guidance. Intraoperatively, black stained nodes were removed along with SLNs, noting concordance between the two. RESULTS: Sixty-six evaluable patients were enrolled (2013-2017). Nineteen received surgery first (Group 1) and 47 neoadjuvant therapy (NAT, Group 2). The average number of nodes tattooed was 1.16 for Group 1 and 1.04 for Group 2. The average interval from tattoo to surgery was 21 days (range 1-62) for Group 1 and 148 days (range 71-257) for Group 2. The tattooed node(s) were visually identified at surgery and corresponded to the sentinel lymph node(s) in 98.5% of cases (18/19 in Group 1 and 47/47 in Group 2). Of the 14 patients in Group 2 whose nodes remained positive following NAT, the tattooed node was the SLN associated with carcinoma. CONCLUSIONS: Tattooing is an alternative method for marking biopsied ALNs. Tattooed nodes coincided with SLNs in 98.5% of cases. This technique is advantageous, because it allows for fewer procedures and lower costs compared with other methods.

Current Strategies for the Management of Locoregional Breast Cancer Recurrence.

Advances in the treatment of breast cancer have decreased the rate of isolated locoregional recurrences (ILRRs) over time. Surgery, radiation therapy, and systemic therapies are used to manage these failure events and their associated poor prognosis. Operable ipsilateral breast tumor recurrences (IBTRs) are treated by either salvage mastectomy or, in select cases, repeat lumpectomy. Axillary nodal recurrences and postmastectomy chest wall relapses are commonly amenable to surgical resection, too. Repeat sentinel node mapping may be undertaken after IBTRs and chest wall recurrences. Aberrant lymphatic drainage, especially after previous mastectomy, is frequently observed. Adjuvant radiation is recommended for most ILRR cases; the dose and volume must be adjusted for prior to receipt of therapy. Implementation of adjuvant systemic therapies after ILRR should be based on the expression of molecular markers in the recurrent tumor. Administration of chemotherapy for estrogen receptor-negative ILRR is indicated, since it significantly decreases the rate of distant metastases.

Rising Bilateral Mastectomy Rates Among Neoadjuvant Chemotherapy Recipients in California From 1998 to 2012.

OBJECTIVE: To study the impact of rising bilateral mastectomy rates among neoadjuvant chemotherapy (NAC) recipients in California. BACKGROUND: NAC for operable breast cancer (BC) can downstage disease and facilitate breast conservation. We assessed trends in NAC use and surgical procedures in California from January 1, 1998 to December 31, 2012 using statewide population-based cancer registry data. METHODS: A total of 236,797 females diagnosed with stage I-III BC were studied. Information regarding NAC, adjuvant chemotherapy (aCT), breast conserving surgery (BCS), bilateral mastectomy (BLM), and unilateral mastectomy (ULM) was abstracted from the medical records. Multivariable polytomous logistic regression was used to estimate odds ratios (OR) of receiving NAC and of type of surgery after NAC. RESULTS: Approximately, 40.1% (94,980) of patients received chemotherapy: 87% (82,588) aCT and 13.0% (12,392) NAC. NAC use more than doubled over time and increased with stage (Stage I, 0.7%; Stage III, 29.9%). Multivariable predictors of NAC treatment were stage (III), younger age (<40 yrs), Black or Hispanic race/ethnicity versus non-Hispanic White (OR 1.10, 95% confidence interval (CI) 1.05-1.16), and care at a National Cancer Institute (NCI)-designated center (OR 1.70, CI 1.58-1.82). Most NAC recipients (68.4%) had mastectomies, and 14.3% of them underwent BLM. In contrast, 47.9% aCT patients had mastectomies with 7.3% BLM. The only independent predictor of BCS after NAC was care at a NCI-designated center (OR 1.28, CI 1.10-1.49), and of BLM, age <40 years versus 50 to 64 years (OR 2.59, CI 2.21-3.03), or residence in the highest socioeconomic neighborhood quintile versus lowest (OR 2.10, CI 1.67-2.64). CONCLUSIONS: NAC use remains low. Predictors of surgery type after NAC were sociodemographic rather than clinical, raising concern for disparities in care access.

Oncologic Procedures Amenable to Fluorescence-guided Surgery.

OBJECTIVE: Although fluorescence imaging is being applied to a wide range of cancers, it remains unclear which disease populations will benefit greatest. Therefore, we review the potential of this technology to improve outcomes in surgical oncology with attention to the various surgical procedures while exploring trial endpoints that may be optimal for each tumor type. BACKGROUND: For many tumors, primary treatment is surgical resection with negative margins, which corresponds to improved survival and a reduction in subsequent adjuvant therapies. Despite unfavorable effect on patient outcomes, margin positivity rate has not changed significantly over the years. Thus, patients often experience high rates of re-excision, radical resections, and overtreatment. However, fluorescence-guided surgery (FGS) has brought forth new light by allowing detection of subclinical disease not readily visible with the naked eye. METHODS: We performed a systematic review of clinicatrials.gov using search terms "fluorescence," "image-guided surgery," and "near-infrared imaging" to identify trials utilizing FGS for those received on or before May 2016. INCLUSION CRITERIA: fluorescence surgery for tumor debulking, wide local excision, whole-organ resection, and peritoneal metastases. EXCLUSION CRITERIA: fluorescence in situ hybridization, fluorescence imaging for lymph node mapping, nonmalignant lesions, nonsurgical purposes, or image guidance without fluorescence. RESULTS: Initial search produced 844 entries, which was narrowed down to 68 trials. Review of literature and clinical trials identified 3 primary resection methods for utilizing FGS: (1) debulking, (2) wide local excision, and (3) whole organ excision. CONCLUSIONS: The use of FGS as a surgical guide enhancement has the potential to improve survival and quality of life outcomes for patients. And, as the number of clinical trials rise each year, it is apparent that FGS has great potential for a broad range of clinical applications.

Intraoperative Tumor Detection Using a Ratiometric Activatable Fluorescent Peptide: A First-in-Human Phase 1 Study.

BACKGROUND: Positive surgical margins remain a significant challenge in breast cancer surgery. This report describes the use of a novel, first-in-human ratiometric activatable cell-penetrating peptide in breast cancer surgery. METHODS: A two-part, multi-institutional phase 1 trial of AVB-620 with a 3+3 dose escalation and dose-expansion cohorts was conducted. The patients received an infusion of AVB-620 2-20 h before planned lumpectomy/mastectomy and sentinel node biopsy/axillary dissection. Imaging analysis was performed on images obtained from the surgical field as well as post-excision surgical specimens. Pathology reports were obtained to correlate imaging results with histopathologic data. Information on physical adverse events and laboratory abnormalities were recorded. RESULTS: A total of 27 patients received infusion of AVB-620 and underwent surgical excision of breast cancer. The findings showed no adverse events or laboratory values attributable to infusion of AVB-620. The 8-mg dose was selected from the dose-escalation cohort for use with the expansion cohort based on imaging data. Region-of-interest (ROI) imaging analysis from the 8-mg cohort demonstrated measurable changes between pathology confirmed tumor-positive and tumor-negative tissue. CONCLUSION: Intraoperative imaging of surgical specimens after infusion with AVB-620 allowed for real-time tumor detection. Infusion of AVB-620 is safe and may improve intraoperative detection of malignant tissue during breast cancer operations.

Poor Prognosis After Second Locoregional Recurrences in the CALOR Trial.

BACKGROUND: Isolated locoregional recurrences (ILRRs) of breast cancer confer a significant risk for the development of distant metastasis. Management practices and second ILRR events in the Chemotherapy as Adjuvant for LOcally Recurrent breast cancer (CALOR) trial were investigated. METHODS: In this study, 162 patients with ILRR were randomly assigned to receive postoperative chemotherapy or no chemotherapy. Descriptive statistics characterize outcomes according to local therapy and the influence of hormone receptor status on subsequent recurrences. Competing risk regression models, Kaplan-Meier estimates, and Cox proportional hazards models were used to evaluate associations between treatment, site of second recurrence, and outcome. RESULTS: The median follow-up period was 4.9 years. Of the 98 patients who received breast-conserving primary surgery 89 had an ipsilateral-breast tumor recurrence. Salvage mastectomy was performed for 73 patients and repeat lumpectomy for 16 patients. Another eight patients had nodal ILRR, and one patient had chest wall ILRR. Among 64 patients whose primary surgery was mastectomy, 52 had chest wall/skin ILRR, and 12 had nodal ILRR. For 15 patients, a second ILRR developed a median of 1.6 years (range 0.08-4.8 years) after ILRR. All second ILRRs occurred for patients with progesterone receptor-negative ILRR. Death occurred for 7 (47 %) of 15 patients with a second ILRR and 19 (51 %) of 37 patients with a distant recurrence. As shown in the multivariable analysis, the significant predictors of survival after either a second ILRR or distant recurrence were chemotherapy for the primary cancer (hazard ratio [HR], 3.55; 95 % confidence interval [CI], 1.15-10.9; p = 0.03) and the interval (continuous) from the primary surgery (HR, 0.87; 95 % CI, 0.75-1.00; p = 0.05). CONCLUSIONS: Second ILRRs represented about one third of all recurrence events after ILRR, and all were PR-negative. These second ILRRs and distant metastases portend an unfavorable outcome.

Clinical Utility of the 12-Gene DCIS Score Assay: Impact on Radiotherapy Recommendations for Patients with Ductal Carcinoma In Situ.

OBJECTIVE: The aim of this study was to determine the impact of the results of the 12-gene DCIS Score assay on (i) radiotherapy recommendations for patients with pure ductal carcinoma in situ (DCIS) following breast-conserving surgery (BCS), and (ii) patient decisional conflict and state anxiety. METHODS: Thirteen sites across the US enrolled patients (March 2014-August 2015) with pure DCIS undergoing BCS. Prospectively collected data included clinicopathologic factors, physician estimates of local recurrence risk, DCIS Score results, and pre-/post-assay radiotherapy recommendations for each patient made by a surgeon and a radiation oncologist. Patients completed pre-/post-assay decisional conflict scale and state-trait anxiety inventory instruments. RESULTS: The analysis cohort included 127 patients: median age 60 years, 80 % postmenopausal, median size 8 mm (39 % ≤5 mm), 70 % grade 1/2, 88 % estrogen receptor-positive, 75 % progesterone receptor-positive, 54 % with comedo necrosis, and 18 % multifocal. Sixty-six percent of patients had low DCIS Score results, 20 % had intermediate DCIS Score results, and 14 % had high DCIS Score results; the median result was 21 (range 0-84). Pre-assay, surgeons and radiation oncologists recommended radiotherapy for 70.9 and 72.4 % of patients, respectively. Post-assay, 26.4 % of overall recommendations changed, including 30.7 and 22.0 % of recommendations by surgeons and radiation oncologists, respectively. Among patients with confirmed completed questionnaires (n = 32), decision conflict (p = 0.004) and state anxiety (p = 0.042) decreased significantly from pre- to post-assay. CONCLUSIONS: Individualized risk estimates from the DCIS Score assay provide valuable information to physicians and patients. Post-assay, in response to DCIS Score results, surgeons changed treatment recommendations more often than radiation oncologists. Further investigation is needed to better understand how such treatment changes may affect clinical outcomes.

Lymph Node Ratio Analysis After Neoadjuvant Chemotherapy is Prognostic in Hormone Receptor-Positive and Triple-Negative Breast Cancer.

BACKGROUND: Lymph node ratios (LNR), the proportion of positive lymph nodes over the number excised, both defined as ranges and single ratio values are prognostic of outcome. Little is known of the prognostic value of LNR after neoadjuvant chemotherapy (NAC) according to molecular subtype. METHODS: From 2003 to 2014, patients who underwent definitive surgery after NAC were identified. LNR was calculated for node-positive patients who received axillary dissection or had at least 6 nodes removed. DFS was calculated using the Kaplan-Meier log rank test for yp N0-3 status, LNR categories (LNRC) ≤0.20 (low), 0.21-0.65 (intermediate), >0.65 (high), and single LNR values. RESULTS: Of 428 NAC recipients, 263 were node negative and 165 (38.6 %) node positive: ypN1 = 97 (58.8 %), ypN2 = 43 (26.1 %), and ypN3 = 25 (15.2 %). Among node-positive cancers, the median number of LN removed was 14 (range, 6-51) and the median LNR was 0.22 (range, 0.03-1.0). Nodal stage was inversely associated with 5-year DFS: 91.5 % (ypN0), 74.5 % (ypN1), 49.8 % (ypN2), and 50.7 % (ypN3) (p < 0.001). LNRC was similarly inversely associated with DFS: 69.1 % (low), 71.4 % (intermediate), 49.3 % (high) (p < 0.001). Significant associations between LNRC and DFS were demonstrated in hormone receptor (HR)-positive and triple negative breast cancer (TNBC) subtypes, p = 0.02 and p = 0.003. A single-value LNR ≤ 0.15 in node-positive, HR-positive (94.1 vs 67.7 %; p = 0.04) and TNBC (94.1 vs 47.8 %; p = 0.001) groups was also significant. CONCLUSIONS: Residual nodal disease after NAC, analyzed by LNRC or LNR = 0.15 cutoff value, is prognostic and can discriminate between favorable and unfavorable outcomes for HR-positive and TNBC cancers.

Protecting Nipple Perfusion by Devascularization and Surgical Delay in Patients at Risk for Ischemic Complications During Nipple-Sparing Mastectomies.

BACKGROUND: Indications for nipple-sparing mastectomy (NSM) are expanding; however, high-risk patients have more ischemic complications. Surgical devascularization of the nipple-areolar complex (NAC) prior to NSM can reduce complications. This study reports perfusion patterns and complications in high-risk patients undergoing 2-stage NSM. METHODS: Surgical devascularization of the NAC was performed 3-6 weeks prior to NSM in 28 women. Risk factors included ptosis, obesity, smoking, prior breast surgery, and radiation. Using indocyanine green (ICG)-based fluorescence and an infrared camera, blood inflow was visualized intraoperatively. NAC perfusion patterns were classified as: V1, underlying breast; V2, surrounding skin; V3 = V1 + V2, or V4, capillary fill following devascularization. Ischemic complications were analyzed. RESULTS: Baseline perfusion for 54 breasts was 35 % V1, 32 % V2, and 33 % V3. Increasing ptosis was associated with V1 pattern: 86 % for grade 3, 31 % for grade 2, and 18 % for grade 1. Postdevascularization epidermolysis was observed in 63 % of V1 baseline, 41 % of V2, and 22 % of V3 (P = .042) and after NSM in 26 % for V1, 7 % for V2, and 6 % for V3 (P = .131). Ptosis was significantly associated with epidermolysis postdevascularization (P = .002) and NSM (P = .002). Smoking and BMI ≥30 were related to increased ischemic complications. Two or more risk factors were associated with postdevascularization ischemic changes (P = .026), but were not significant after NSM. Nipple loss was not observed, but 2 patients underwent partial areolar resection. CONCLUSION: Adaptive circulatory changes after devascularization allow tissues to tolerate the additional ischemic challenge of mastectomy. Our findings support extending 2-staged operations to high-risk women previously considered unsuitable for NSM.

Addressing inherited predisposition for breast cancer in transplant recipients.

Consideration of prophylactic mastectomy surgery following transplantation requires complex medical decision-making, and bias against elective surgery exists because of concern for post-operative complications. Prevention of cancer in transplant recipients is of utmost importance, given the risks of treating malignancy in an immunosuppressed patient. We present a patient case and review of the literature to support a thorough pre-transplantation evaluation of family history and consideration of prophylactic interventions to safeguard the quality of life of transplant recipients. J. Surg. Oncol. 2016;113:605-608. © 2016 Wiley Periodicals, Inc.

Chemotherapy for isolated locoregional recurrence of breast cancer (CALOR): a randomised trial.

BACKGROUND: Patients with isolated locoregional recurrences (ILRR) of breast cancer have a high risk of distant metastasis and death from breast cancer. We aimed to establish whether adjuvant chemotherapy improves the outcome of such patients. METHODS: The CALOR trial was a pragmatic, open-label, randomised trial that accrued patients with histologically proven and completely excised ILRR after unilateral breast cancer who had undergone a mastectomy or lumpectomy with clear surgical margins. Eligible patients were enrolled from hospitals worldwide and were centrally randomised (1:1) to chemotherapy (type selected by the investigator; multidrug for at least four courses recommended) or no chemotherapy, using permuted blocks, and stratified by previous chemotherapy, oestrogen-receptor and progesterone-receptor status, and location of ILRR. Patients with oestrogen-receptor-positive ILRR received adjuvant endocrine therapy, radiation therapy was mandated for patients with microscopically involved surgical margins, and anti-HER2 therapy was optional. The primary endpoint was disease-free survival. All analyses were by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00074152. FINDINGS: From Aug 22, 2003, to Jan 31, 2010, 85 patients were randomly assigned to receive chemotherapy and 77 were assigned to no chemotherapy. At a median follow-up of 4·9 years (IQR 3·6-6 ·0), 24 (28%) patients had disease-free survival events in the chemotherapy group compared with 34 (44%) in the no chemotherapy group. 5-year disease-free survival was 69% (95% CI 56-79) with chemotherapy versus 57% (44-67) without chemotherapy (hazard ratio 0·59 [95% CI 0·35-0·99]; p=0·046). Adjuvant chemotherapy was significantly more effective for women with oestrogen-receptor-negative ILRR (pinteraction=0·046), but analyses of disease-free survival according to the oestrogen-receptor status of the primary tumour were not statistically significant (pinteraction=0·43). Of the 81 patients who received chemotherapy, 12 (15%) had serious adverse events. The most common adverse events were neutropenia, febrile neutropenia, and intestinal infection. INTERPRETATION: Adjuvant chemotherapy should be recommended for patients with completely resected ILRR of breast cancer, especially if the recurrence is oestrogen-receptor negative. FUNDING: US Department of Health and Human Services, Swiss Group for Clinical Cancer Research (SAKK), Frontier Science and Technology Research Foundation, Australian and New Zealand Breast Cancer Trials Group, Swedish Cancer Society, Oncosuisse, Cancer Association of South Africa, Foundation for Clinical Research of Eastern Switzerland (OSKK), Grupo Español de Investigación en Cáncer de Mama (GEICAM), and the Dutch Breast Cancer Trialists' Group (BOOG).

Patient-derived xenografts of triple-negative breast cancer reproduce molecular features of patient tumors and respond to mTOR inhibition.

INTRODUCTION: Triple-negative breast cancer (TNBC) is aggressive and lacks targeted therapies. Phosphatidylinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathways are frequently activated in TNBC patient tumors at the genome, gene expression and protein levels, and mTOR inhibitors have been shown to inhibit growth in TNBC cell lines. We describe a panel of patient-derived xenografts representing multiple TNBC subtypes and use them to test preclinical drug efficacy of two mTOR inhibitors, sirolimus (rapamycin) and temsirolimus (CCI-779). METHODS: We generated a panel of seven patient-derived orthotopic xenografts from six primary TNBC tumors and one metastasis. Patient tumors and corresponding xenografts were compared by histology, immunohistochemistry, array comparative genomic hybridization (aCGH) and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) sequencing; TNBC subtypes were determined. Using a previously published logistic regression approach, we generated a rapamycin response signature from Connectivity Map gene expression data and used it to predict rapamycin sensitivity in 1,401 human breast cancers of different intrinsic subtypes, prompting in vivo testing of mTOR inhibitors and doxorubicin in our TNBC xenografts. RESULTS: Patient-derived xenografts recapitulated histology, biomarker expression and global genomic features of patient tumors. Two primary tumors had PIK3CA coding mutations, and five of six primary tumors showed flanking intron single nucleotide polymorphisms (SNPs) with conservation of sequence variations between primary tumors and xenografts, even on subsequent xenograft passages. Gene expression profiling showed that our models represent at least four of six TNBC subtypes. The rapamycin response signature predicted sensitivity for 94% of basal-like breast cancers in a large dataset. Drug testing of mTOR inhibitors in our xenografts showed 77 to 99% growth inhibition, significantly more than doxorubicin; protein phosphorylation studies indicated constitutive activation of the mTOR pathway that decreased with treatment. However, no tumor was completely eradicated. CONCLUSIONS: A panel of patient-derived xenograft models covering a spectrum of TNBC subtypes was generated that histologically and genomically matched original patient tumors. Consistent with in silico predictions, mTOR inhibitor testing in our TNBC xenografts showed significant tumor growth inhibition in all, suggesting that mTOR inhibitors can be effective in TNBC, but will require use with additional therapies, warranting investigation of optimal drug combinations.