Induction of complementary immunogenic necroptosis and apoptosis cell death pathways inhibits cancer metastasis and relapse

Interactions of light-sensitive drugs and materials with Cerenkov radiation-emitting radiopharmaceuticals generate cytotoxic reactive oxygen species (ROS) to inhibit localized and disseminated cancer progression, but the cell death mechanisms underlying this radionuclide stimulated dynamic therapy (RaST) remain elusive. Using ROS-regenerative nanophotosensitizers coated with a tumor-targeting transferrin-titanocene complex (TiO2-TC-Tf) and radiolabeled 2-fluorodeoxyglucose (18FDG), we found that adherent dying cells maintained metabolic activity with increased membrane permeabilization. Mechanistic assessment of these cells revealed that RaST activated the expression of RIPK-1 and RIPK-3, which mediate necroptosis cell death. Subsequent recruitment of the nuclear factors kappa B and the executioner mixed lineage kinase domain-like pseudo kinase (MLKL) triggered plasma membrane permeabilization and pore formation, respectively, followed by the release of cytokines and immunogenic damage-associated molecular patterns (DAMPs). In immune-deficient breast cancer models with adequate stroma and growth factors that recapitulate the human tumor microenvironment, RaST failed to inhibit tumor progression and the ensuing lung metastasis. A similar aggressive tumor model in immunocompetent mice responded to RaST, achieving a remarkable partial response (PR) and complete response (CR) with no evidence of lung metastasis, suggesting active immune system engagement. RaST recruited antitumor CD11b+, CD11c+, and CD8b+ effector immune cells after initiating dual immunogenic apoptosis and necroptosis cell death pathways in responding tumors in vivo. Over time, cancer cells upregulated the expression of negative immune regulating cytokine (TGF-β) and soluble immune checkpoints (sICP) to challenge RaST effect in the CR mice. Using a signal-amplifying cancer-imaging agent, LS301, we identified latent minimal residual disseminated tumors in the lymph nodes (LNs) of the CR group. Despite increased protumor immunogens in the CR mice, RaST prevented cancer relapse and metastasis through dynamic redistribution of ROS-regenerative TiO2 from bones at the early treatment stage to the spleen and LNs, maintaining active immunity against cancer progression and migration. This study reveals the immune-mechanistic underpinnings of RaST-mediated antitumor immune response and highlights immunogenic reprogramming of tumors in response to RaST. Overcoming apoptosis resistance through complementary necroptosis activation paves the way for strategic drug combinations to improve cancer treatment.

Frequency of Hepatic Metastatic Disease in Patients with Stage IV Breast Cancer Is Similar for Steatotic and Non-Steatotic Livers

Background

Breast cancer is the most common non-cutaneous malignancy and the second leading cause of cancer mortality in the United States. Breast cancer is a heterogeneous disease; diagnosis at an early stage renders it potentially curable, whereas advanced metastatic disease carries a worse prognosis.

Objectives

To investigate whether hepatic steatosis (HS) is associated with liver metastases in patients with newly diagnosed stage IV female breast cancer patients (either de novo metastatic breast cancer or recurrent metastatic breast cancer) using non-contrast computed tomography (CT) as a marker of HS.

Design

Retrospective analysis.

Methods

We retrospectively identified 168 patients with stage IV breast cancer with suitable imaging from a prospectively maintained oncologic database. Three radiologists manually defined hepatic regions of interest on non-contrast CT images, and attenuation data were extracted. HS was defined as a mean attenuation <48 Hounsfield units. The frequency of hepatic metastatic disease was calculated for patient with and without HS. Relationships between HS and various patient (age, body mass index, race) and tumor (hormone receptor status, HER2 status, tumor grade) characteristics were also analyzed.

Results

There were 4 patients with liver metastasis in the HS group (41 patients) versus 20 patients with liver metastases in the non-HS group (127 patients). The difference in frequencies of liver metastases among patients with (9.8%) versus without (15.7%) hepatic steatosis (odds ratio = 1.72 [0.53-7.39]) was not statistically significant (P = .45). Body mass index was significantly higher (P = .01) among patients with hepatic steatosis (32.2 ± 7.3 vs 28.8 ± 7.1 kg/m2). Otherwise, there were no significant differences between patients with versus without HS with respect to regarding age, race, hormone receptor status, HER2 status, or tumor grade.

Conclusion

The frequency of hepatic metastatic disease in patients with stage IV breast cancer is similar for steatotic and non-steatotic livers.

Genomic Complexity Predicts Resistance to Endocrine Therapy and CDK4/6 Inhibition in Hormone Receptor-Positive (HR+)/HER2-Negative Metastatic Breast Cancer

PURPOSE

Clinical biomarkers to identify patients unlikely to benefit from CDK4/6 inhibition (CDK4/6i) in combination with endocrine therapy (ET) are lacking. We implemented a comprehensive circulating tumor DNA (ctDNA) analysis to identify genomic features for predicting and monitoring treatment resistance.

EXPERIMENTAL DESIGN

ctDNA was isolated from 216 plasma samples collected from 51 patients with hormone receptor-positive (HR+)/HER2-negative (HER2-) metastatic breast cancer (MBC) on a phase II trial of palbociclib combined with letrozole or fulvestrant (NCT03007979). Boosted whole-exome sequencing (WES) was performed at baseline and clinical progression to evaluate genomic alterations, mutational signatures, and blood tumor mutational burden (bTMB). Low-pass whole-genome sequencing was performed at baseline and serial timepoints to assess blood copy-number burden (bCNB).

RESULTS

High bTMB and bCNB were associated with lack of clinical benefit and significantly shorter progression-free survival (PFS) compared with patients with low bTMB or low bCNB (all P < 0.05). Dominant APOBEC signatures were detected at baseline exclusively in cases with high bTMB (5/13, 38.5%) versus low bTMB (0/37, 0%; P = 0.0006). Alterations in ESR1 were enriched in samples with high bTMB (P = 0.0005). There was a high correlation between bTMB determined by WES and bTMB determined using a 600-gene panel (R = 0.98). During serial monitoring, an increase in bCNB score preceded radiographic progression in 12 of 18 (66.7%) patients.

CONCLUSIONS

Genomic complexity detected by noninvasive profiling of bTMB and bCNB predicted poor outcomes in patients treated with ET and CDK4/6i and identified early disease progression before imaging. Novel treatment strategies including immunotherapy-based combinations should be investigated in this population.

Abstract P3-06-06: Real-world analysis of adverse events of patients with triple negative breast cancer receiving therapy per KEYNOTE-522

Background: KEYNOTE-522 was a randomized, double-blind, placebo-controlled phase 3 trial which resulted in the FDA approval of pembrolizumab with neoadjuvant chemotherapy for patients (pts) with newly diagnosed, high-risk, early-stage triple negative breast cancer (TNBC). Given the improvement in pathological complete response (pCR) and event-free survival rates, this regimen has emerged as standard-of-care (SOC) therapy. Adverse events in pts on this treatment regimen in clinical practice is unknown and understanding the real-world toxicity of this regimen is critical.

Methods: In this IRB approved retrospective, single-center study we examined pts with early-stage TNBC who received planned treatment per KEYNOTE-522 per SOC from 2021-present. This regimen includes a year of pembrolizumab combined with 4 cycles of neoadjuvant carboplatin/paclitaxel followed by 4 cycles of doxorubicin/cyclophosphamide. Number and length of treatment delays, treatment related toxicities of all grades, and pCR rate were collected from the electronic medical record.

Results: Of the 87 identified pts, 2 were excluded due to locally recurrent or metastatic disease and 6 did not receive immunotherapy due to concerns for toxicity or patient preference. Of the 79 pts who initiated treatment with chemotherapy and immunotherapy, median age of the cohort was 52 (27-77). 9 pts had a BRCA1 mutation and 1 pt had a BRCA2 mutation. 41 (51.9%) had T1-2 disease and 38 (48.1%) had T3-4 disease. 37 (46.8%) pts had N0 disease and 42 (53.2%) had N1-3 disease. 15 pts had baseline comorbidities, including heart disease, kidney disease, type II DM, and/or peripheral neuropathy. 68 pts (86.1%) had baseline ECOG 0, 9 (11.4%) had ECOG 1, and 2 (2.5%) had ECOG 2. At the time of analysis, 70 pts (88.6%) were receiving active treatment, of which 47 (67.1%) had completed ≥50% of the planned neoadjuvant therapy. Of pts completing ≥50% of planned neoadjuvant therapy and pts off therapy (N=56), 31 (55.4%) had 1 or more hospitalizations and 23 (41.1%) had 1 or more emergency room visits. 30 pts had treatment delays (53.6%) and 21 pts (37.5%) had dose reductions. Rates of adverse events are presented in Table 1. Of the 79 analyzed pts, 35 have undergone surgery. pCR rate was 45.7% (N=16). 8 (22.9%) pts had RCB-I, 4 (11.4%) pts had RCB-II, 3 (8.6%) pts had RCB-III, and 4 (11.4%) pts had residual disease without RCB calculation. Updated analysis will be included at time of presentation.

Conclusions: In this single-center retrospective study of pts receiving chemoimmunotherapy for TNBC, we found higher rates of grade 3 toxicity, including nausea, fatigue, neutropenia, diarrhea, peripheral neuropathy, and hypothyroidism, and lower pCR rate than was reported in the KEYNOTE-522 trial. This may reflect a more heterogeneous population of pts treated in routine clinical practice who are typically less fit than pts on clinical trials. Additionally, pts in this study had higher T stages (48.1% with T3-4 disease vs 26.0% in trial) and node positive disease (53.7% with N1-3 disease vs 48.8% in trial). Limitations include immaturity of data and small sample size; however, these data warrant validation through longer-term follow-up and multicenter validation.

Adverse Events in pts receiving Keynote-522 regimen as SOC and on clinical trial

Citation Format: Mara Hofherr, Jennifer Hedgecorth, Foluso O. Ademuyiwa, Lindsay L. Peterson, Nusayba A. Bagegni, Rama Suresh, Ashley Frith, Ron Bose, Katherine Weilbaecher, Cynthia Ma, Andrew A. Davis, Katherine K. Clifton. Real-world analysis of adverse events of patients with triple negative breast cancer receiving therapy per KEYNOTE-522 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-06-06.

Abstract PD13-09: PD13-09 Clinical outcomes of patients with HR+ HER2- advanced breast cancer with early progression on CDK4/6 inhibitors

Background: CDK4/6 inhibitors (CDK4/6i) paired with endocrine therapy (ET) are considered first-line (1L) therapy for patients (pts) with HR+ HER2- advanced breast cancer (aBC). A minority of pts will demonstrate primary resistance to CDK4/6i, as characterized by early progression. Thymidine kinase 1 (TK1) is a cell-cycle regulated enzyme downstream of CDK4/6 and involved in nucleotide metabolism during DNA synthesis. Prior studies have shown TK1 may serve as a biomarker of response to CDK4/6i, with early TK1 activity (TK1a) suppression after initiation of CDK 4/6i therapy associated with improved PFS. Lack of TK1a suppression may be associated with primary resistance to CDK4/6i. In this study, we aim to analyze response to subsequent lines of therapy and overall survival (OS) of pts with early progression on 1L CDK4/6i. Methods: Pts with HR+ HER2- aBC from a phase II trial of an alternative schedule of palbociclib (palbo alt dosing trial NCT 3007979) and from a retrospective palbociclib study were included in this analysis. Pts in the palbo alt dosing trial underwent baseline and C1D15 TK1a analysis after initiation on CDK4/6i. C1D15 TK1a suppression was defined at TK1a &lt; 30 Du/L. Pts in the retrospective palbociclib study included pts receiving palbo as part of their standard of care 1L therapy for HR+ HER2- aBC at Washington University in Saint Louis from 2016 to 2021. Clinical information, including treatment start and stop dates on each of the next-line therapies, were collected from the electronic medical record. PFS was estimated by the treatment duration on a specified treatment regimen. Early progression on CDK4/6i was defined as PFS &lt; 6 mo. Best response was defined as next line of therapy with the numerically longest PFS. OS was defined as time to death from the initiation of CDK4/6i. Results: Of the 54 pts enrolled on the palbo alt dosing trial, 51 pts were evaluable for clinical benefit and 46 pts were evaluable for TK1a suppression rate at C1D15. 7 pts (15.2%) were found without TK1a suppression at C1D15. This lack of TK1a suppression on palbo was associated with a significantly shorter PFS (median PFS=3.1 mo) compared to not reached in pts with TK1a suppression at C1D15. We conducted clinical analysis on N=26 pts who exhibited early progression on CDK4/6i which included 10 pts from the palbo alt dosing trial and 16 from the retrospective study. The average subsequent line of therapies in this cohort was 3, with the most common second line (2L) therapy being chemotherapy (N=17, 65.4%) and ET (N=8, 30.8%). The median PFS for pts receiving 2L chemotherapy and ET was 4.09 mo and 3.64 mo, respectively. 10 pts received both chemotherapy and ET with 7 (70.0%) achieving best response with chemotherapy compared to 3 pts (30.0%) who achieved best response with ET. The median OS for the cohort was 14.6 mo. Conclusions: Early progression on CDK4/6i is associated with a particularly poor prognosis. In our cohort, the median OS was far below the expected median OS for pts receiving 1L palbo as reported in the PALOMA-2 trial (14.6 mo vs 53.9 mo). Early progression on CDK4/6i is associated with more aggressive disease which may respond more favorably to chemotherapy, as demonstrated by best response to therapy. Further prospective studies are warranted to explore this treatment approach.

Citation Format: Katherine K. Clifton, Shana N. Thomas, Jingqin Luo, Jing Xi, Nusayba A. Bagegni, Foluso O. Ademuyiwa, Rama Suresh, Ashley Frith, Andrew A. Davis, Ron Bose, Katherine Weilbaecher, Whitney L. Hensing, Timothy Pluard, Massimo Cristofanilli, Hyo S. Han, Adam M. Brufsky, Kevin Kalinsky, Shom Goel, Seth A. Wander, Lindsay L. Peterson, Cynthia Ma. PD13-09 Clinical outcomes of patients with HR+ HER2- advanced breast cancer with early progression on CDK4/6 inhibitors [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD13-09.

Abstract P3-06-07: Phase Ib/II study to evaluate safety and tolerability of cabiralizumab in combination with nivolumab and neoadjuvant chemotherapy in patients with localized triple-negative breast cancer

Background: Neoadjuvant immune checkpoint inhibition (ICI) in combination with chemotherapy is approved for patients with high-risk, early-stage triple-negative breast cancer (TNBC) based on improved outcomes in the KEYNOTE-522 trial. However, some patients have primary resistant disease and do not achieve a pathological complete response (pCR), while others experience significant toxicity. Tumor-associated macrophages (TAMs) are a potential resistance mechanism for ICIs and are dependent on colony-stimulating factor 1 receptor (CSF1R). Therefore, we examined the addition of cabiralizumab, a CSF1R inhibitor, to neoadjuvant paclitaxel, carboplatin, and nivolumab to assess the safety, tolerability, and changes in the tumor microenvironment (TME) in patients with early-stage TNBC. Methods: This is a phase Ib/II, single-institution, randomized controlled clinical trial (NCT04331067) in patients with newly diagnosed Stage II-III TNBC. The primary endpoints include: (1) to determine the safety of a 12-week neoadjuvant regimen of paclitaxel (80 mg/m2 IV q week) + carboplatin (AUC5 IV q3 weeks) + nivolumab (240 mg IV q2 weeks) with or without cabiralizumab (4 mg/kg IV q2 weeks) and (2) to evaluate the effect of cabiralizumab on TAMs and changes in tumor infiltrating lymphocytes (TILs) in the TME between baseline and an on-treatment biopsy after 4 weeks of therapy. Adjuvant treatment is per investigator’s choice. Secondary objectives include evaluation of pCR rate and recurrence-free survival. Paired tissue and bone marrow biopsies are collected for evaluation of the TME and disseminated tumor cells, respectively. The study was designed to enroll 50 patients, including a 12-patient safety lead-in cohort. Here, we report the planned interim analysis of the safety lead-in cohort. Results: Between December 2020 and May 2022, we enrolled 12 patients to the safety lead-in, including 6 patients in each arm. 5 of 12 patients (41.7%) enrolled are underrepresented minorities, including 4 Black patients and 1 Hispanic patient. 2 of 6 patients in the nivolumab arm experienced grade 3 severe toxicity, including 1 patient who developed sepsis and 1 who developed peripheral neuropathy. 3 of 6 patients in the nivolumab + cabiralizumab arm developed grade 3 severe toxicity including 2 patients who experienced myositis and 1 patient who developed periorbital edema. Of the first 10 patients enrolled, 5 had a pCR (2 pCR in cabiralizumab arm, 3 pCR in non-cabiralizumab arm) and 3 had non-pCR (1 RCB-1 and 1 RCB-3 in cabiralizumab arm, 1 RCB-1 in non-cabiralizumab arm). 2 patients came off study prior to surgery (1 due to toxicity and 1 due to missing study visits). Data from the final 2 patients still on treatment will be available at the time of presentation. Discussion: Full safety, pathologic, and clinical response data in the safety lead-in cohort for patients with early-stage TNBC receiving neoadjuvant chemotherapy + nivolumab with or without cabiralizumab, will be presented.

Citation Format: Andrew A. Davis, Leonel Hernandez-Aya, Jingqin Luo, Mateusz Opyrchal, Foluso O. Ademuyiwa, Nusayba A. Bagegni, Katherine K. Clifton, Jill Anderson, Trish Hammerschmidt, Leslie Nehring, David DeNardo, Mark Watson, Rebecca Aft, Cynthia Ma, Katherine Weilbaecher. Phase Ib/II study to evaluate safety and tolerability of cabiralizumab in combination with nivolumab and neoadjuvant chemotherapy in patients with localized triple-negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-06-07.

A phase II study of palbociclib plus letrozole plus trastuzumab as neoadjuvant treatment for clinical stages II and III ER+ HER2+ breast cancer (PALTAN)

Patients with ER+/HER2+ breast cancer (BC) are less likely to achieve pathological complete response (pCR) after chemotherapy with dual HER2 blockade than ER-/HER2+ BC. Endocrine therapy plus trastuzumab is effective in advanced ER+/HER2+ BC. Inhibition of CDK4/6 and HER2 results in synergistic cell proliferation reduction. We combined palbociclib, letrozole, and trastuzumab (PLT) as a chemotherapy-sparing regimen. We evaluated neoadjuvant PLT in early ER+/HER2+ BC. Primary endpoint was pCR after 16 weeks. Research biopsies were performed for whole exome and RNA sequencing, PAM50 subtyping, and Ki67 assessment for complete cell cycle arrest (CCCA: Ki67 ≤ 2.7%). After 26 patients, accrual stopped due to futility. pCR (residual cancer burden-RCB 0) was 7.7%, RCB 0/I was 38.5%. Grade (G) 3/4 treatment-emergent adverse events occurred in 19. Among these, G3/4 neutropenia was 50%, hypertension 26.9%, and leucopenia 7.7%. Analysis indicated CCCA in 85% at C1 day 15 (C1D15), compared to 27% at surgery after palbociclib was discontinued. Baseline PAM50 subtyping identified 31.2% HER2-E, 43.8% Luminal B, and 25% Luminal A. 161 genes were differentially expressed comparing C1D15 to baseline. MKI67, TK1, CCNB1, AURKB, and PLK1 were among the genes downregulated, consistent with CCCA at C1D15. Molecular Signatures Database gene-sets analyses demonstrated downregulated processes involved in proliferation, ER and mTORC1 signaling, and DNA damage repair at C1D15, consistent with the study drug's mechanisms of action. Neoadjuvant PLT showed a pCR of 7.7% and an RCB 0/I rate of 38.5%. RNA sequencing and Ki67 data indicated potent anti-proliferative effects of study treatments. ClinicalTrials.gov- NCT02907918.

Abstract P2-13-01: Phase 2 study of neoadjuvant palbociclib, letrozole, and trastuzumab in patients with ER+ HER2+ breast cancer (PALTAN)

Background Patients (pts) with ER+ HER2+ breast cancer (BC) are less likely to achieve pathological complete response (pCR) after neoadjuvant chemotherapy with dual HER2 blockade than pts with ER- HER2+ BC. Endocrine therapy (ET) plus trastuzumab is effective in advanced ER+ HER2+ BC, but pCR rate is low in the neoadjuvant setting. Inhibition of CDK4/6 and HER2 results in synergistic reduction in cell proliferation in preclinical studies. We therefore combined ET with CDK4/6 inhibition and trastuzumab in ER+ HER2+ BC as a chemotherapy-sparing regimen. Methods We evaluated the efficacy of palbociclib, letrozole, trastuzumab (PLT) in the neoadjuvant setting for pts with stages II or III ER+ HER2+ BC. Primary endpoint was pCR after 16 weeks of therapy. We assumed null of 15% pCR and pCR ≥ 30% warrants further investigation. To achieve 80% power at 1-sided 0.05 significance, 48 pts were to be enrolled. Evaluable population included pts who completed Cycle (C) 1 unless discontinued due to treatment-emergent adverse events (TEAEs) prior to completing C1. All who received one dose on study were considered evaluable for toxicity. Biopsies were collected at baseline (BL), C1 day 15 (C1D15), and surgery for RNA sequencing and central Ki67 assessment, for PAM50 subtype distribution, complete cell cycle arrest (CCCA: Ki67 ≤2.7%) at C1D15 and surgery, and treatment induced signaling changes. Results Accrual stopped early due to futility. 26 pts accrued were evaluable for efficacy and toxicity. pCR (residual cancer burden- [RCB] 0) was 7.7% (95% CI 0.9 - 25.1%) and RCB 0/I was 38.5% (95% CI 20.2 - 59.4%). TEAEs (n= 337) were seen in all pts (71.5% grade [G] 1, 19.3% G2, 8.6% G3, 0.6% G4); the most common were leukopenia (7.7%), neutropenia (7.1%), anemia (5.9%). G3/4 TEAEs occurred in 19 pts (73.1%). Among the 19, incidence of G3/4 neutropenia was 50%, hypertension 26.9%, leucopenia 7.7%. TEAEs (hypertension, ventricular tachycardia, pulmonary edema) leading to treatment discontinuation were reported in 1 pt. Two pts had at least one SAE. No treatment-related deaths occurred. Pt reported outcomes using NCI PRO-CTCAE revealed no differences in appetite, nausea, respiratory symptoms, edema, palpitations, rashes and dry skin, or concentration from BL to end of C4. Pts had worsening hair loss from BL to end of C4. Ki67 analysis indicated CCCA in 78% at C1D15, compared to 18% at surgery after only P had been discontinued approximately 4 weeks prior to surgery. RNA sequencing was performed on available biopsies collected at BL (N=16), C1D15 (N=5), and surgery (N=2) from 16 pts. Among 16 BL samples, PAM50 subtyping identified 5 (31.3%) basal-like, 2 (12.5%) HER2-E, 6 (37.5%) Lum B, and 3 (18.8%) normal. Subtype switching to Lum A at C1D15 (N=3, 1 each with HER2-E, Lum B, and normal at BL) or normal (N=2, 1 basal and 1 HER2-E at BL) was observed. 161 genes were differentially expressed (FDR p&lt;0.05); 145 downregulated and 16 upregulated comparing C1D15 to BL. MKI67, TK1, CCNB1, AURKB, PLK1 were among the downregulated genes, consistent with CCCA for majority of the samples at C1D15 by Ki67. Analysis of the Molecular Signatures Database Hallmark gene-sets comparing C1D15 and BL samples demonstrated downregulated biological processes involved in proliferation (E2F targets, G2M checkpoint, MYC targets, mitotic spindle), signaling (Estrogen response, mTORC1 signaling), and DNA damage (DNA repair) at C1D15, consistent with the mechanisms of action of the study drugs. E2F targets were higher in BL samples of RCB II/III, compared to RCB I (FDR p=0.042). Conclusions PALTAN did not meet its primary endpoint of pCR. Neoadjuvant PLT showed a pCR of 7.7% but was well tolerated. RNA sequencing and Ki67 data indicated potent anti-proliferative effects of study treatments, despite significant heterogeneity of intrinsic subtypes. Clinical trial information: NCT02907918.

Citation Format: Foluso O Ademuyiwa, Donald Northfelt, Tracey O'Connor, Ellis Levine, Jingqin Luo, Yu Tao, Jeremy Hoog, Marie Laury, Tracy Summa, Trish Hammerschmidt, Zhanfang Guo, Ashley Frith, Katherine Weilbaecher, Mateusz Opyrchal, Rebecca Aft, Katherine Clifton, Rama Suresh, Nusayba Bagegni, Ian S Hagemann, Cynthia X Ma. Phase 2 study of neoadjuvant palbociclib, letrozole, and trastuzumab in patients with ER+ HER2+ breast cancer (PALTAN) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-01.

Organ-on-a-chip model of vascularized human bone marrow niches

Bone marrow niches (endosteal and perivascular) play important roles in both normal bone marrow function and pathological processes such as cancer cell dormancy. Unraveling the mechanisms underlying these events in humans has been severely limited by models that cannot dissect dynamic events at the niche level. Utilizing microfluidic and stem cell technologies, we present a 3D in vitro model of human bone marrow that contains both the perivascular and endosteal niches, complete with dynamic, perfusable vascular networks. We demonstrate that our model can replicate in vivo bone marrow function, including maintenance and differentiation of CD34+ hematopoietic stem/progenitor cells, egress of neutrophils (CD66b+), and niche-specific responses to doxorubicin and granulocyte-colony stimulating factor. Our platform provides opportunities to accelerate current understanding of human bone marrow function and drug response with high spatial and temporal resolution.

Genetic Counseling and Testing in African American Patients With Breast Cancer: A Nationwide Survey of US Breast Oncologists

PURPOSE

To determine if physicians' self-reported knowledge, attitudes, and practices regarding genetic counseling and testing (GCT) vary by patients' race.

METHODS

We conducted a nationwide 49-item survey among breast oncology physicians in the United States. We queried respondents about their own demographics, clinical characteristics, knowledge, attitudes, practices, and perceived barriers in providing GCT to patients with breast cancer.

RESULTS

Our survey included responses from 277 physicians (females, 58.8%; medical oncologists, 75.1%; academic physicians, 61.7%; and Whites, 67.1%). Only 1.8% indicated that they were more likely to refer a White patient than refer an African American patient for GCT, and 66.9% believed that African American women with breast cancer have lower rates of GCT than White women. Regarding perceived barriers to GCT, 63.4% of respondents indicated that African American women face more barriers than White women do and 21% felt that African American women require more information and guidance during the GCT decision-making process than White women. Although 32% of respondents indicated that lack of trust was a barrier to GCT in all patients, 58.1% felt that this was a greater barrier for African American women (P < .0001). Only 13.9% believed that noncompliance with GCT is a barrier for all patients, whereas 30.6% believed that African American women are more likely than White women to be noncompliant (P < .0001).

CONCLUSION

We demonstrated that racial differences exist in oncology physicians' perceived barriers to GCT for patients with breast cancer. This nationwide survey will serve as a basis for understanding physicians' determinants of GCT for African American women and highlights the necessity of education and interventions to address bias among physicians. Awareness of such physician biases can enable further work to address inequities, ultimately leading to improved GCT equity for African American women with breast cancer.

Management of bone metastasis and cancer treatment-induced bone loss during the COVID-19 pandemic: An international perspective and recommendations

Optimum management of patients with cancer during the COVID-19 pandemic has proved extremely challenging. Patients, clinicians and hospital authorities have had to balance the risks to patients of attending hospital, many of whom are especially vulnerable, with the risks of delaying or modifying cancer treatment. Those whose care has been significantly impacted include patients suffering from the effects of cancer on bone, where delivering the usual standard of care for bone support has often not been possible and clinicians have been forced to seek alternative options for adequate management. At a virtual meeting of the Cancer and Bone Society in July 2020, an expert group shared experiences and solutions to this challenge, following which a questionnaire was sent internationally to the symposium's participants, to explore the issues faced and solutions offered. 70 respondents, from 9 countries (majority USA, 39%, followed by UK, 19%) included 50 clinicians, spread across a diverse range of specialties (but with a high proportion, 64%, of medical oncologists) and 20 who classified themselves as non-clinical (solely lab-based). Spread of clinician specialty across tumour types was breast (65%), prostate (27%), followed by renal, myeloma and melanoma. Analysis showed that management of metastatic bone disease in all solid tumour types and myeloma, adjuvant bisphosphonate breast cancer therapy and cancer treatment induced bone loss, was substantially impacted. Respondents reported delays to routine CT scans (58%), standard bone scans (48%) and MRI scans (46%), though emergency scans were less affected. Delays in palliative radiotherapy for bone pain were reported by 31% of respondents with treatments often involving only a single dose without fractionation. Delays to, or cancellation of, prophylactic surgery for bone pain were reported by 35% of respondents. Access to treatments with intravenous bisphosphonates and subcutaneous denosumab was a major problem, mitigated by provision of drug administration at home or in a local clinic, reduced frequency of administration or switching to oral bisphosphonates taken at home. The questionnaire also revealed damaging delays or complete stopping of both clinical and laboratory research. In addition to an analysis of the questionnaire, this paper presents a rationale and recommendations for adaptation of the normal guidelines for protection of bone health during the pandemic.

Abstract PS12-13: Balixafortide (a CXCR4 antagonist) plus eribulin in HER2 negative metastatic breast cancer: Final analysis from the Phase 1 single arm trial

Background: Balixafortide (B) is a potent, selective antagonist of the chemokine receptor CXCR4. High CXCR4 levels correlate with aggressive metastatic phenotypes and poor prognosis in metastatic breast cancer (MBC). Efficacy and safety data were published recently from the Phase 1 trial investigating B + eribulin (E) in patients with HER2 negative MBC1. We report the final safety and efficacy analyses from this trial, including an assessment of dose-response and adverse events of particular interest (AEPIs) (e.g. neutropenia, peripheral neuropathy).

Methods: In this single-arm, dose escalation trial, patients (pts) received E + increasing doses of B using a 3+3 design in 3 parts: Part I cohorts received low B doses (0.5−1mg/kg) + increasing E doses (1.1−1.4mg/m2); Part II dose-escalation cohort for B (1−5.5mg/kg) + 1.4mg/m2 E; Expanded Cohort (EC) to confirm safety and efficacy of B 5.5mg/kg + 1.4mg/m2 E. Most cohorts received E on days 2 and 9, and B on days 1−3 and 8−10 of 21-day cycles.

Results: At entry, all 56 women (age range 33−82 years) were HER2 negative, CXCR4 positive. Most pts were Caucasian and heavily pretreated in the metastatic setting (line of chemotherapy on study: 29% 2nd line, 50% 3rd line, 21% 4th line). 75% were hormone receptor positive and 23% had triple negative breast cancer.

A linear dose-exposure was observed over the entire dose range tested for B. Cmax and AUC for E were within published ranges.

Safety findings (including AEPIs) remained similar to those reported previously1.

No dose-limiting toxicities were confirmed; therefore, the maximum tolerated dose of B was not reached. The highest B dose evaluated was 5.5mg/kg; pharmacokinetic evaluation showed that further protocolled dose increments of B would not have provided a sufficient increase in plasma levels. In addition, the objective response rate in Part II was 3-fold greater than published for eribulin alone which suggested that the anti-tumor activity of B was worthy of further exploration at 5.5mg/kg in the EC.

Efficacy data for the trial are shown in the table.

These data suggest a potential dose-response relationship for B across all efficacy endpoints, with efficacy being numerically greatest in the EC. While PFS and OS should be interpreted with caution in single arm trials, these data suggest potential benefit for this combination. Further analyses will be presented.

Responses were observed regardless of line of chemotherapy on study or extent of CXCR4 expression and were numerically higher in hormone receptor positive patients.

Conclusions: A consistent dose response effect for B + E was suggested across all efficacy endpoints for heavily pretreated pts with HER2 negative MBC. When these results are compared with published data for E monotherapy in similar populations, the EC consistently shows numerically greater benefit for all efficacy endpoints2, 3.

The safety and tolerability of B + E appear comparable to published data on E or B alone, particularly for neutropenia and peripheral neuropathy1.

These results suggest that B + E could potentially provide a new treatment option in heavily pretreated patients with HER2 negative MBC. A Phase 3 trial exploring efficacy and safety of B 5.5mg/kg + E is ongoing.

1. Pernas S et al. Lancet Oncol. 2018; 19: 812−242. Cortes J et al. Lancet. 2011; 377: 914−9233. Kaufman PA et al. J Clin Oncol. 2015; 33: 594−601

Part II(N=21)Expanded Cohort(N=24)Overall Efficacy Population(N=54)Objective Response Rate (95% CI)33% (15−57)38% (19−59)30% (18−44)median duration in months (IQR)2.8 (1.4−3.3)4.4 (3.1−5.3)3.2 (2.2−4.5)Clinical Benefit Rate (95% CI)43% (22−66)63% (41−81)44% (31−59)median duration in months (IQR)5.4 (4.2−6.7)8.1 (6.3−10.8)6.9 (5.4−10.3)median PFS in months (95% CI)4.2 (3−5.4)6.2 (2.9−8.1)4.6 (3.2–5.7)median OS in months (95% CI)10.4 (7.7−18.4)18 (12.2–27.2)16.8 (10.6–18.4)Landmark OS estimate12 months (95% CI)40% (19−60)75% (53−88)60% (45−72)18 months (95% CI)30% (12−50)50% (29−68)42% (29−55)24 months (95% CI)20% (6−39)33% (16−52)25% (14−37)CI: confidence interval; IQR: interquartile range; OS: overall survival; PFS: progression free survival

Citation Format: Peter A. Kaufman, Sonia Pernas, Miguel Martin, Marta Gil-Martin, Patricia Gomez Pardo, Sara Lopez-Tarruella, Luis Manso, Eva Ciruelos, Jose Alejandro Perez-Fidalgo, Cristina Hernando, Foluso O Ademuyiwa, Katherine Weilbaecher, Ingrid A Mayer, Timothy J. Pluard, Maria Martinez Garcia, Francois Ringeisen, Daniela Schmitter, Javier Cortes. Balixafortide (a CXCR4 antagonist) plus eribulin in HER2 negative metastatic breast cancer: Final analysis from the Phase 1 single arm trial [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS12-13.

Abstract PS2-09: Next generation sequencing (NGS) in older adults with breast cancer using tissue-based and circulating tumor DNA (ctDNA) assays

Background: With advances in next generation sequencing (NGS) and now approved targeted therapy in breast cancer, genomic testing to identify potentially actionable mutations has become a common practice in patients (pts) with advanced breast cancer using both ctDNA and traditional tissue-based assays. Less is known regarding physician practice patterns in obtaining NGS testing and the practical implications of testing in older adults with breast cancer.Methods: Pts with advanced breast cancer underwent molecular profiling using a plasma-based ctDNA NGS assay (Guardant360® or Tempus®) between 5/2015 and 5/2020 at Siteman Cancer Center. Pts with advanced breast cancer who underwent genomic profiling using a tissue-based NGS assay (Tempus®) between 12/2017 and 5/2020 at this institution were also included. Clinicopathological histories were obtained from the medical record. Correlations were examined using a Fisher’s exact test.Results: During 5/15-5/20, 244 pts underwent ctDNA testing and 147 pts had a tissue-based NGS assay performed. There was no significant difference between the number of pts ≥ 65 years-old who underwent ctDNA testing (n=78, 32.0%) and tissue testing (n=37, 25.2%). There was no statistically significant difference between date of metastatic diagnosis and date of NGS testing between the older and younger cohorts. In pts who underwent tissue-based NGS testing, there was no significant difference between site of tissue tested (distant recurrence vs local) in the older and younger cohorts. The most common clinical managements following both ctDNA and tissue-based testing are presented in Table 1. Out of the 391 pts who underwent testing, 27 pts had both ctDNA and tissue-based NGS performed. Pts ≥ 65 were less likely to have both assays performed (n=3, 11.1%; p&lt;0.05). In pts undergoing both assays, there were high concordance rates of ESR1 (81.5%) and PIK3CA (81.5%) mutations. Mean time between tissue and plasma collection for NGS testing in pts undergoing both assays was 356.4 days.

Conclusion: Older adults, who are typically less likely to be included in clinical trials, may still benefit from NGS to reveal potentially targetable mutations. It is reassuring in our cohort that older adults had ctDNA and tissue-based NGS performed at similar rates as part of standard of care treatment. The clinical management following NGS testing was also not significantly different in the older adult cohort. Older adults were less likely to have both tissue and ctDNA testing performed however, given the high concordance rates between tests, this may be less clinically relevant.

Table 1clinical management following NGS testing≥65 years-old&lt;65 years-oldp valueno actionable mutations41 (35.7%)123 (44.6%)p=0.1testing results saved for potential future use27 (23.5%)45 (16.3%)p=0.1change in management15 (13.0%)41 (14.9%)p=0.6

Citation Format: Katherine K Clifton, Jingqin Luo, Yu Tao, Jennifer Saam, Thereasa Rich, Timothy Rearden, Anna Roshal, Ashley Frith, Caron Rigden, Foluso Ademuyiwa, Katherine Weilbaecher, Leonel Hernandez Aya, Lindsay Peterson, Nusayba Bagegni, Rama Suresh, Ron Bose, Tanya Wildes, Mateusz Opyrchal, Cynthia Ma. Next generation sequencing (NGS) in older adults with breast cancer using tissue-based and circulating tumor DNA (ctDNA) assays [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS2-09.

Mutation profile differences in younger and older patients with advanced breast cancer using circulating tumor DNA (ctDNA)

PURPOSE

Little is known regarding the mutation profiles of ctDNA in the older adult breast cancer population. The objective of this study is to assess differences in mutation profiles in the older adult breast cancer population using a ctDNA assay as well as assess utilization of testing results.

METHODS

Patients with advanced breast cancer underwent molecular profiling using a plasma-based ctDNA NGS assay (Guardant360) between 5/2015 and 10/2019 at Siteman Cancer Center. The profiling results of a multi-institutional database of patients with advanced breast cancer who had undergone molecular profiling were obtained. Associations between mutations and age group (≥ 65 vs. < 65) were examined using a Fisher's exact test.

RESULTS

In the single-institutional cohort, 148 patients (69.2%) were < 65 years old and 66 patients (30.8%) ≥ 65 years old. ATM, BRAF, and PIK3CA mutations were found more frequently in older patients with ER + HER2- breast cancers (p < 0.01). In the multi-institutional cohort, 5367 (61.1%) were < 65 years old and 3417 (38.9%) ≥ 65 years old. ATM, PIK3CA, and TP53 mutations were more common in the older cohort (p < 0.0001) and MYC and GATA3 mutations were less common in the older cohort (p < 0.0001). CtDNA testing influenced next-line treatment management in 40 (19.8%) patients in the single-institutional cohort.

CONCLUSION

When controlling for subtype, results from a single institution were similar to the multi-institutional cohort showing that ATM and PIK3CA were more common in older adults. These data suggest there may be additional molecular differences in older adults with advanced breast cancers.

Abstract P2-16-03: Neoadjuvant treatment of triple negative breast cancer patients with docetaxel and carboplatin to assess anti-tumor activity

Background: Anthracycline- and taxane-based neoadjuvant chemotherapy (NAT) in triple negative breast cancer (TNBC) patients yields a pathological complete response (pCR) rate of approximately 45%. Anthracyclines can lead to long-term toxicities including congestive heart failure and leukemia. TNBC patients achieving pCR have excellent long-term outcomes irrespective of NAT regimen. This study was designed to evaluate the efficacy of a non-anthracycline NAT regimen with carboplatin and docetaxel in TNBC. Correlative studies include detecting and tracking plasma circulating tumor DNA (ctDNA) to determine if it will predict clinical outcomes, and whole exome sequencing (WES) on tissue samples to decipher the genomic architecture of those who achieve pCR versus those who do not. Methods: This is a joint analysis of two identical multicenter trials. Eligible patients with AJCC 7 clinical stages II and III TNBC received docetaxel 75mg/m2 and carboplatin AUC 6 every 3 weeks X 6 cycles. Following NAT, all patients underwent definitive surgery. The primary endpoint is pCR (no invasive tumor in the breast and axilla). Secondary objectives include evaluating ctDNA as a prognostic biomarker that may be used in identifying TNBC patients at a high risk of disease relapse, and evaluating differences in the genomic architecture between pCR and non-pCR patients. Patients have a research biopsy at baseline, cycle 1 day 3 (optional), and at definitive surgery for those with residual disease. Plasma for ctDNA is collected at baseline, cycle 1 day 3, at definitive surgery, and every 6 months for 5 years. Results: Between 2014 and 2019, 103 patients have been registered. Median age is 53 years (range 25-74), 27.2%: African-American, 77.7%: clinical stage II. Ninety-nine have completed NAT and have had surgery. In the intent to treat population, the preliminary pCR rate is 46.5% (95% CI 36.9% - 56.2%). Nine (8.7%) have developed recurrent disease, and 7 (6.8%) have died. Preliminary ctDNA results from 6 patients (4 non-pCR, 2 pCR) show that ctDNA is detectable in 67%. We identified 627 somatic variants by exome analysis. Of these, 10 variants overlapped with the Swift panel (Accel-Amplicon™ 56G Oncology Panel v2) used for ctDNA sequencing and variant detection. TP53 variants were identified in all 6 patients’ tumor tissue samples. At least one TP53 variant was identified in 4 patients’ baseline pre-chemotherapy ctDNA. Both pCR patients had either no detectable ctDNA TP53 mutations, or clearance of ctDNA following chemotherapy. Three non-PCR patients had persistent TP53 mutations in ctDNA during the treatment course. WES and ctDNA analysis on all patients is currently ongoing. Conclusions: We report a very encouraging pCR rate of 46.5% in TNBC patients with carboplatin and docetaxel NAT. This rate is similar to observed rates with anthracycline- and taxane-based NAT and may represent an option for treatment for TNBC patients. Correlative genomic and ctDNA studies are ongoing. Clinical trial information: NCT02124902 & NCT02547987.

Citation Format: FOLUSO O ADEMUYIWA, Mothaffar F Rimawi, Tracy Summa, Jingqin Luo, Tao Wang, Rama Suresh, Lindsay Peterson, Michael Naughton, Ashley Frith, Leonel Hernandez-Aya, Katherine Weilbaecher, Cynthia Ma, Aadel A Chaudhuri, Yang-Yang Feng, Zachary L Skidmore, Obi L Griffith, Malachi Griffith, Matthew Ellis. Neoadjuvant treatment of triple negative breast cancer patients with docetaxel and carboplatin to assess anti-tumor activity [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-16-03.

Abstract P1-19-13: A phase II trial assessing the safety of an alternative dosing schedule of palbociclib (palbo) in hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC): Alt Dose Palbo

Introduction: Palbo is approved in combination with an aromatase inhibitor or fulvestrant (FUL) for the treatment of HR+ HER2- MBC. The incidence of grade (G) 3/4 neutropenia (ANC) approaching 66% has been observed in phase 3 trials of palbo. We hypothesize that an alternative schedule of palbo, 5 days on/2 days off every 7 days, reduces the severity of neutropenia, therefore allowing continued weekly dosing and less dose reduction and discontinuation. Methods: A single arm phase II study (Alt Dose Palbo) was conducted in patients (pts) with HR+ HER2- MBC who had ≤1 prior systemic therapy in the metastatic setting (NCT03007979). Pts were treated with palbo 125 mg daily on a 5 days on/2 days off every 7-day schedule, along with letrozole (LET) or FUL per treating physician. Goserelin was administered if premenopausal. The primary objective was to determine the rate of G3/4 ANC within the first 29 days of treatment. Secondary objectives included determining the rate of G3/4 ANC during all cycles, rate of palbo dose reduction/interruption/discontinuation, adverse event (AE) profile per CTCAE v5, progression free survival (PFS), objective response rate (ORR) and clinical benefit rate (CBR) by RECIST 1.1. The sample size of 47 was calculated to provide 90% power based on one-sample binomial exact test at a 5% alpha level to test the one-sided null hypothesis of G3/4 ANC rate &gt;62% versus the alternative of &lt;40%. If G3/4 ANC was not observed in 24 or more pts, this alternative dosing will be deemed to have a better toxicity profile than standard schedule. Results: Between July 2017 to June 2019, 48 pts were enrolled at 2 institutions. 3 pts withdrew/went off during cycle 1 unrelated to the study, leaving 45 pts (33 LET, 12 FUL) with a median age of 63 (range: 34-87) years and visceral metastases in 23 (51%). Prior (neo) adjuvant chemotherapy and endocrine therapy (ET) were received in 20 (44%) and 25 (56%) pts, respectively. Six (13%) had 1 prior ET in the metastatic setting. 19 (42%) had primary or secondary endocrine resistance defined according to the ESMO advanced breast cancer guideline prior to enrollment to the study. As of July 1, 2019, with a median follow up of 9.5 months, 28 (62%) pts are still receiving study drug. 42 pts were evaluable for toxicities. There were no G4 AEs. Nine (21%) and 15 (36%) pts experienced G3 ANC in cycle 1 (up to day 29), and all cycles, respectively. 33 pts in cycle 1 and 27 pts in all cycles, did not experience G3/4 ANC during all cycles, exceeding the predefined boundary for better tolerability of this schedule. Palbo was dose reduced in 10 (23.8%) pts. Two (4.8%) discontinued palbo due to AE (one with G3 ANC not recovering to G1 in 2 wks and the other died (G5 event) with acute subdural hematoma with concurrent G3 thrombocytopenia). The common treatment related AEs are shown in the Table 1. The ORR was 48% (2 CR, 10 PR, 95% Wilson CI: 30-66.5%) among 25 evaluable pts. The CBR (defined by CR or PR or stable disease for at least 24 wks) was 76.74% (33 of 43 evaluable pts, 95% Wilson CI: 62.3-86.9%). PFS has not been evaluated. Conclusion: The Alt Dose Palbo trial with palbo scheduled at 5 days on/2 days off every 7 days, with no weeks off therapy, met its primary endpoint with reduced G3/4 ANC. Survival data is not yet mature and will be updated at the presentation. However, preliminary efficacy data appears comparable to prior report. Encouraging data from this study should be confirmed in a randomized study.

Table 1C1 D1-29 AEG1G2G3TotalWBC decreased26%50%17%93%ANC decreased10%43%21%74%Anemia38%12%0%50%Fatigue29%0%0%29%Platelets decreased14%0%2%17%Nausea12%2%0%14%All cycle AEG1G2G3TotalWBC decreased19%50%26%95%ANC decreased5%40%36%81%Anemia50%21%2%74%Fatigue36%5%0%40%Nausea26%2%0%29%Platelets decreased24%0%2%26%Alopecia21%0%0%21%Mucositis19%0%0%19%Hot flashes17%2%0%19%Constipation14%0%0%14%Arthralgia12%2%0%14%AST elevated10%0%2%12%Anorexia12%0%0%12%ALT elevated7%0%5%12%

Citation Format: Jairam Krishnamurthy, Jingqin Luo, Foluso Ademuyiwa, Rama Suresh, Caron Rigden, Timothy Reardon, Katherine Weilbaecher, Ashley Frith, Anna Roshal, Pavan Tandra, Mathew Cherian, Tracy Summa, Shana Thomas, Leonel Hernandez-Aya, Lindsay Peterson, Cynthia Ma. A phase II trial assessing the safety of an alternative dosing schedule of palbociclib (palbo) in hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC): Alt Dose Palbo [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-19-13.

Abstract P6-08-14: Assessing the effectiveness of the NCCN genetic testing guidelines in identifying African American breast cancer patients with deleterious genetic mutations

Purpose: Approximately 10% of breast cancers are hereditary. Identifying women at high risk for hereditary breast and ovarian cancer allows for early detection, prevention, and individualized disease management for those diagnosed with breast cancer. There is limited data about breast cancer genetic risks among African Americans (AA) as the majority of the large studies have been conducted in European Americans. We examined the distribution of deleterious genetic mutations in AA breast cancer patients, and evaluated the effectiveness of the National Comprehensive Cancer Network (NCCN) guidelines for identifying AA women at high risk for deleterious genetic mutations. Methods: AA participants with breast cancer underwent an interview regarding health and family history, and a 30-gene saliva test. Medical records were accessed to determine whether participants had received prior genetic testing as part of usual care, results of previous testing, and cancer characteristics. Results: Two hundred and fifty participants were enrolled between February 2016 and May 2018. Twenty (8.0%) had a deleterious mutation in one of the 30 genes; BRCA2 had the highest frequency (40.0%). 187 (74.8%) met eligibility for testing based on NCCN guidelines. Only 110 (58.8%) of participants eligible for genetic testing, according to guidelines, had received prior testing as part of routine care. Using the 30-gene test, we identified deleterious mutations in 17 of 187 (9.1%) of those who met NCCN criteria for testing, and three of 63 (4.8%) of those who did not meet criteria for testing nonetheless had a deleterious mutation associated with breast cancer. Conclusions: Our results indicate that a large proportion of African American breast cancer patients who meet criteria for genetic testing do not receive it as part of routine care. Even in women who do not meet testing guidelines, nearly 5% have a known deleterious mutation associated with breast cancer.

Citation Format: Foluso O Ademuyiwa, Patricia Salyer, Yinjiao Ma, Sherri Fisher, Graham Colditz, Katherine Weilbaecher, Laura J Bierut. Assessing the effectiveness of the NCCN genetic testing guidelines in identifying African American breast cancer patients with deleterious genetic mutations [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-14.

Abstract GS5-07: International pooled analysis of the prognostic impact of disseminated tumor cells from the bone marrow in early breast cancer: Results from the PADDY study

Introduction

As early breast cancer might relapse even after complete removal of breast and lymphnodes, the disease must persist in secondary sites. The detection of disseminated tumor cells (DTC) in the bone marrow (BM) has been described as a surrogate of residual disease. Various trials showed an impaired prognosis of DTC positive early breast cancer (EBC) patients. The PADDY (Pooled Analysis of DTC Detection in Early Breast Cancer) study is a large international pooled analysis that aimed to assess the prognostic impact of DTC detection in patients with EBC.

Methods

A pre-specified protocol was followed, and centers known to practice BM sampling for DTC detection were contacted for individual patient data. Patients with EBC, with available follow-up data and BM sampling before any anti-cancer treatment were eligible. BM aspirates were collected at the time of primary surgery. DTC were identified by antibody (A45-B/B3, AE1/AE3, 2E11 and E29) staining against cytokeratin. The DTC status was compared to other prognostic factors using the chi-squared test. Univariate log-rank test and multivariate cox regression were used to compare survival of DTC positive versus DTC negative patients.

Results

Individual data from 10,320 patients (11 centers from Europe and USA) were included with a median follow-up of 91 months. Of all patients, 2,823 (27.4 %) were DTC positive. DTC detection was associated with higher tumor grade, higher T stage, nodal positivity, ER and PR negativity, and HER2 positivity (all p&lt;0.001). In univariate analyses, overall, breast cancer specific, disease-free and distant disease-free survival (OS, BCSS, DFS, DDFS) were significantly shorter in DTC positive patients with p-values of &lt;0.001. Multivariate analyses showed the DTC status to be an independent prognostic marker for OS, BCSS, DFS and DDFS with hazard ratios (HR) and 95%-confidence intervals (CI) of 1.23 (95%-CI: 1.06-1.42, p=0.007), 1.38 (95%-CI: 1.11-1.72, p=0.004), 1.29 (95%-CI: 1.10-1.50, p=0.001) and 1.32 (95%-CI: 1.10-1.58, p=0.003), respectively.

Conclusions

Detection of DTC in the bone marrow is an independent prognostic marker in patients with non-metastatic breast cancer. Further studies should investigate the impact of DTC on metastatic cancer progression and their role for clinical decision making.

Citation Format: Hartkopf AD, Brucker SY, Taran F-A, Harbeck N, von Au A, Naume B, Pierga J-Y, Hoffmann O, Beckmann MW, Rydén L, Fehm T, Aft R, Montserrat S, Walter V, Rack B, Schuetz F, Borgen E, Ta M-H, Bittner A-K, Fasching P, Fernö M, Krawczyk N, Weilbaecher K, Margelí M, Hahn M, Jueckstock J, Domschke C, Bidard F-C, Kasimir-Bauer S, Schoenfisch B, Kurt AG, Wallwiener M, Gebauer G, Wallwiener D, Janni W, Pantel K. International pooled analysis of the prognostic impact of disseminated tumor cells from the bone marrow in early breast cancer: Results from the PADDY study [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 GS5-07.

Abstract PD1-02: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Cortes J, Martin M, Pernas S, Gomez Pardo P, Lopez-Tarruella S, Gil-Martin M, Manso L, Ciruelos E, Perez-Fidalgo JA, Hernando C, Ademuyiwa FO, Weilbaecher K, Mayer I, Pluard TJ, Martinez Garcia M, Vahdat L, Wach A, Barker D, Romagnoli B, Kaufman PA. Withdrawn [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 PD1-02.

Retrospective Analysis of Treatment Patterns and Effectiveness of Palbociclib and Subsequent Regimens in Metastatic Breast Cancer

Background: Cyclin-dependent kinase (CDK) 4/6 inhibitors are now the standard of care for hormone receptor-positive (HR+), HER2-negative (HER-) metastatic breast cancer (MBC). However, guidelines are lacking regarding their optimal sequencing with other available agents. This study examines physician practice patterns and treatment outcomes of palbociclib and subsequent therapies in a real-world setting. Methods: A retrospective chart review was conducted for consecutive patients with MBC who received palbociclib between February 2015 and August 2017 at the Alvin J. Siteman Cancer Center. Kaplan-Meier method was used to generate time-to-event curves and estimate median progression-free survival (mPFS). Log-rank test was used to compare differences. Results: A total of 200 patients, with a median age of 59.4 years and a follow-up of 19.5 months, were included. Palbociclib was most frequently combined with letrozole (73.5%), followed by fulvestrant (25%), anastrozole (1%), and tamoxifen (0.5%). Most patients received palbociclib in the endocrine-resistant setting (n=42, n=50, and n=108 in the first-, second-, and subsequent-line settings, respectively), and the fraction of patients receiving palbociclib as first- or second-line therapy increased in recent months (P=.0428). mPFS was 20.7, 12.8, and 4.0 months with palbociclib administered in the first-, second-, and subsequent-line settings, respectively (P<.0001). Incidences of grade 3/4 neutropenia (41.5%) and dose reductions (29%) were comparable to reports in the literature. Among patients whose disease progressed on palbociclib (n=104), the most frequent next-line treatment was capecitabine (n=21), followed by eribulin (n=16), nab-paclitaxel (n=15), and exemestane + everolimus (n=12). mPFS with hormone therapy alone or in combination with targeted agents (n=32) after first-, second-, and subsequent-line palbociclib was 17.0, 9.3, and 4.2 months, respectively (P=.04). mPFS with chemotherapy (n=70) was not reached, 4.7, and 4.1 months after first-, second-, and subsequent-line palbociclib, respectively (P=.56). Conclusions: Palbociclib is effective for HR+/HER2- MBC in real-world practice. Hormone therapy alone or in combination with targeted agents remains an effective option after palbociclib progression.

Circulating Receptor Activator of Nuclear Factor-κB (RANK), RANK ligand (RANKL), and Mammographic Density in Premenopausal Women

The receptor activator of nuclear factor-κB (RANK) pathway plays essential roles in breast development. Mammographic density is a strong risk factor for breast cancer, especially in premenopausal women. We, therefore, investigated the associations of circulating RANK and soluble RANK ligand (sRANKL) with mammographic density in premenopausal women. Mammographic density was measured as volumetric percent density in 365 cancer-free premenopausal women (mean age, 47.5 years) attending screening mammogram at the Washington University School of Medicine (St. Louis, MO). We used linear regression models adjusted for confounders, to compare the least-square means of volumetric percent density across tertiles of circulating RANK and sRANKL. Furthermore, because RANKL levels in mammary tissue are modulated by progesterone, we stratified analyses by progesterone levels. The mean volumetric percent density increased across tertiles of circulating RANK from 8.6% in tertile 1, to 8.8% in tertile 2, and 9.5% in tertile 3 (P _trend = 0.02). For sRANKL, the mean volumetric percent density was 8.5% in tertile 1, 9.4% in tertile 2, and 9.0% in tertile 3 (P _trend = 0.30). However, when restricted to women with higher progesterone levels, the mean volumetric percent density increased from 9.1% in sRANKL tertile 1 to 9.5% in tertile 2, and 10.1% in tertile 3 (P _trend = 0.01). Circulating RANK was positively associated with volumetric percent density, while circulating sRANKL was positively associated with volumetric percent density among women with higher progesterone levels. These findings support the inhibition of RANKL signaling as a pathway to reduce mammographic density and possibly breast cancer incidence in high-risk women with dense breasts.

Abstract P2-02-14: Circulating tumor DNA predicts clinical outcome in early stage triple negative breast cancer

Background- Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer as these patients have the highest risk of recurrence and death. Only 35% of TNBC patients achieve a pathologic complete response (pCR) following neoadjuvant chemotherapy. Patients who do not achieve pCR have a 27% risk of distant recurrence and ultimate death at 3 years compared to 9% for pCR. Unidentified micrometastases are responsible for ultimate overt progression and death. Developing strategies to identify patients with minimal residual disease following curative treatment is an unmet need. Circulating tumor DNA (ctDNA) can characterize and monitor advanced cancers. In this study, we sought to assess if ctDNA can predict clinical outcome in TNBC.

Methods-Biospecimens were obtained from patients with stages II and III TNBC enrolled on a neoadjuvant trial (NCT02124902). Patients have a research biopsy and plasma for ctDNA collected at baseline, cycle 1 day 3, definitive surgery for those with residual disease, and at recurrence for those who relapse. Plasma for ctDNA is also collected every 6 months for 5 years after treatment. Patients receive docetaxel and carboplatin every 3 weeks X 6 cycles. Surgery is 3-5 weeks after chemotherapy. Six patients' serial tumor samples and germline DNA were studied by whole exome sequencing. The median sequencing depth was 90.13x. Sequencing was performed on samples with high cellularity (≥50%). All 6 patients also had serial ctDNA analyzed using Swift Biosciences Accel-Amplicon™ 56G Oncology Panel v2. After identifying somatic mutations in each breast tumor series, we determined the subset of mutations that intersected with the regions targeted by the Swift 56 gene panel. We then evaluated whether corresponding mutations could be detected in ctDNA, and if ctDNA predicted clinical outcome.

Results-Four of the 6 patients were non-pCR with residual disease following chemotherapy. We identified 627 somatic variants by exome analysis that were called by at least two somatic variant callers and passed additional quality filtering steps. Of these, 10 variants overlapped with the Swift panel. TP53 variants were identified in all 6 patients' tumor tissue samples. At least one TP53 variant was identified in 4 patients' baseline pre-chemotherapy ctDNA samples. Both pCR patients had either no detectable ctDNA TP53 mutations (NTN007-ref. in baseline tumor tissue was 19.58% variant allele frequency [VAF]); or clearance of ctDNA following chemotherapy from 4.45% VAF at baseline to 0.06% following chemotherapy (NTN004-ref. in baseline tumor tissue 37.34% VAF). Three non-PCR patients had persistent TP53 mutations in ctDNA during the treatment course. One non-pCR patient did not have detectable mutations in ctDNA. The only patient with recurrent disease whose ctDNA TP53 mutation persisted during the treatment course (baseline VAF-1.65%, cycle 1 day 3-0.78%, definitive surgery-0.09%), was found to have a higher ctDNA VAF at recurrence (29.55%).

Conclusion-In this pilot study, mutation tracking by ctDNA is sensitive and distinguishes pCR from non-pCR in TNBC patients receiving neoadjuvant chemotherapy. ctDNA also identifies recurrence following curative therapy. Evaluating ctDNA as a biomarker of outcome in TNBC is warranted.

Citation Format: Ademuyiwa F, Feng Y-Y, Skidmore Z, Kunisaki J, Walker J, Fulton R, Krysiak K, Skinner T, Weilbaecher K, Ma C, Griffith O, Griffith M. Circulating tumor DNA predicts clinical outcome in early stage triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-02-14.

Abstract P1-07-11: Tumor genomic profiling of triple negative breast cancer during neoadjuvant chemotherapy: Results from a prospective trial of carboplatin and docetaxel

Background-The clonal evolution and effect of neoadjuvant chemotherapy on the mutational landscape of triple negative breast cancer (TNBC) is unknown. Inability to eradicate TNBC may be due to clonal progression and selection of cells fundamentally resistant to chemotherapy.In this study, we sought to decipher the genomic architecture of TNBC serially during neoadjuvant chemotherapy to distinguish pre- versus post-chemotherapy genotypes.

Methods-Tumor specimens were obtained from patients with stages II and III TNBC enrolled on an ongoing prospective neoadjuvant co-clinical trial (NCT02124902). Patients have a research biopsy at baseline, cycle 1 day 3 (optional), and at definitive surgery for those with residual disease. Patients are treated with docetaxel 75mg/m2 and carboplatin AUC6 cycled every 3 weeks X six cycles. Definitive surgery is 3-5 weeks after chemotherapy. The primary endpoint is pathologic complete response rate. Correlative studies include development of patient derived xenografts, evaluation of genomic signatures of resistance and response, and comparison of chemotherapy responses between xenografts and host patients. Five patients' serial tumor samples and germline DNA were studied by exome and transcriptome sequencing. Three of these patients had an additional on-treatment sample at cycle 1 day 3. Two patients lacked residual disease samples- one was not banked and the other could not be accurately genotyped due to low cellularity. The median sequencing depth was 90.13x. Sequencing was performed on either fresh frozen or formalin-fixed paraffin-embedded samples with high cellularity (≥50%). After identifying somatic mutations in each tumor series, we evaluated whether each mutation was persistent, emergent, or cleared by comparing pre- and post-treatment (and when possible, on-treatment) samples.

Results-All five patients had response to neoadjuvant chemotherapy based on caliper-based and pathologic (residual cancer burden I or II) measurements. All residual disease remained TNBC by standard immunohistochemistry and all samples were basal-like from PAM50 gene expression analysis. We identified 908 somatic mutations, including the expected variants in TP53 which persisted in all post-treatment samples. Non-silent somatic variants were identified in other breast cancer-related genes, including GATA1, FBXO11, PIK3R1, AXIN2, ARID1B, BRCA2, and RBCC1. In spite of the clinico-pathologic evidence of response, we observed little change in clonal architecture, as derived from the purity-corrected variant allele fractions between baseline, cycle 1 day 3, and post-chemotherapy samples. Copy number alterations were likewise stable and transcriptional-based assessment indicated that patterns of mutant allele expression in driver genes were retained throughout the course of treatment.

Conclusion-In TNBC patients undergoing neoadjuvant platinum-based chemotherapy, there were no apparent shifts in the prevalence of known breast cancer specific somatic variants during or after chemotherapy. Despite pathologic response, core genomic features appear to be preserved in TNBC patients with residual disease following chemotherapy, likely accounting for high rates of relapse in these patients.

Citation Format: Ademuyiwa FO, Miller CA, Li T, Sanati S, Ma CX, Weilbaecher K, Ellis MJ, Mardis ER. Tumor genomic profiling of triple negative breast cancer during neoadjuvant chemotherapy: Results from a prospective trial of carboplatin and docetaxel [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-07-11.

Differences in the mutational landscape of triple-negative breast cancer in African Americans and Caucasians

BACKGROUND

Triple-negative breast cancer (TNBC) occurs at higher frequency in African Americans compared with Caucasians. It is unclear if the biology of TNBC is different in African American versus Caucasians. In this study, we sought to evaluate racial differences in the molecular pathology of TNBC.

METHODS

Using data from The Cancer Genome Atlas, we identified TNBC patients with information on race. We analyzed differences in clinical characteristics, tumor somatic mutations, and gene expression patterns by race from whole exome and microarray data.

RESULTS

1104 patients were identified, of which 178 had TNBC. TNBC was more frequent in African Americans than Caucasians (33.3 vs 14.9%). Although more African Americans than Caucasians overall were classified as basal-like from PAM50 gene expression (34.8 vs 16.1%), no differences in the TNBC cohort were observed. Median tumor somatic mutation counts were higher in African Americans versus Caucasians (39.5 vs 34), but no racial differences in the mutation counts in TNBC were observed. Somatic mutation analysis revealed racial differences in specific high prevalence genes in all patients (TP53 46% in African Americans vs 27% in Caucasians; PIK3CA 23% in African Americans vs 34% in Caucasians; and MLL3 12% in African Americans vs 6% in Caucasians). TNBC patients did not have any specific high prevalence genes associated with racial differences. There were no racial differences in gene expression patterns in selected genes involved in breast cancer biology. Overall, African Americans had shorter TTP and worse DFS. Racial differences in clinical outcomes were not observed in TNBC.

CONCLUSION

The mutational landscape of TNBC is similar between African Americans and Caucasians. The higher frequency of TNBC in African Americans is therefore not associated with a different genomic profile of commonly established tumor regulatory pathway genes. Other modifiable factors may exist that contribute to the racial disparity in TNBC.

Abstract CT091: A neoadjuvant co-clinical trial in triple-negative breast cancer patients with genomic discovery analysis

Background: Patients with TNBC who do not achieve a pathologic complete response (pCR) or near pCR have high rates of relapse, due to chemotherapy resistance, within the first few years after their diagnosis. Molecular biomarkers predictive for chemotherapy sensitivity are lacking. This ongoing trial is evaluating carboplatin and docetaxel in the neoadjuvant setting to determine whether these drugs will increase the pCR rate compared to historical controls. Correlative studies include exome and transcriptome sequencing on samples acquired from patients as a means to decipher the genomic architecture and clonal evolution of those who achieved a pCR compared to those who did not. The simultaneous development of patient derived xenografts (PDX) from host tumors is also planned.

Methods: Patients with clinical stage 2 or 3 histologically confirmed TNBC will receive six cycles of neoadjuvant carboplatin AUC 6 and docetaxel 75 mg/m2 every 3 weeks, followed by definitive surgery. Forty-one eligible patients will be treated according to this protocol, permitting us to attain a power of 83% to detect our expected pCR rate of 54% compared to the historical 35% rate, based on a two-sided exact binomial test at the 4.8% significance level. Eligibility: tumor size at least 2 cm, adequate organ and bone marrow function, no bilateral or inflammatory breast cancer, no invasive cancer within 5 years, ECOG performance status of ? 2, no prior sentinel lymph node biopsy. Tissue collection for xenografting and correlative studies will occur at baseline, at cycle 1 day 3, and at surgery. The primary objective is to determine the pCR rate, defined as the absence of invasive cancer in breast or nodes at definitive surgery. Secondary and exploratory objectives include xenografting rates, evaluation of mutational signatures of chemotherapy resistance and response, and comparison of chemotherapy responses between patients and their xenografts. The study was activated on 7/7/2014 and is still recruiting. Twenty (48.8% of planned 41) patients have been enrolled and have had baseline tissue banked. Fourteen patients have completed protocol therapy. Three patients have tissue at all 3 time points (9 samples), and are presently being studied by exome and transcriptome sequencing.

Citation Format: Foluso O. Ademuyiwa, Shunqiang Li, Jingqin Luo, Tracy Skinner, Jason Hoshower, Cynthia X. Ma, Katherine Weilbaecher, Michael Naughton, Leonel Hernandez-Aya, Elaine R. Mardis, Matthew J. Ellis. A neoadjuvant co-clinical trial in triple-negative breast cancer patients with genomic discovery analysis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT091.

Abstract 3285: HTLV-1 viral oncogene Hbz induces leukemia with osteolytic bone involvement in mice

Adult T-cell leukemia/lymphoma (ATL) develops in a subset of patients infected with the HTLV-1 virus. Most ATL patients become refractory to chemotherapy and have a median survival time of 6 months. Although uncommon in hematologic malignancies, 80% of ATL patients develop osteolytic lesions and hypercalcemia of malignancy. Bone resident and metastatic tumors release paracrine factors that modulate the bone microenvironment to facilitate disease progression and decrease survival. HTLV-1 encodes 2 viral oncogenes, Tax and Hbz. Tax is critical to ATL development and regulates tumor growth and proliferation in part through trans-activation of NFκB and CREB. We have previously shown Tax expression driven by the Granzymbe B promoter is sufficient for the development of leukemia/lymphoma with osteolytic lesions and hypercalcemia. We and others have shown that Tax alters the expression of paracrine factors that modulate the bone microenvironment through effects on bone forming osteoblasts (OB) and bone resorping osteoclasts (OC). Tax is expressed in early lymphocyte transformation with low expression in advanced ATL. HBZ is expressed early in lymphocyte transformation and throughout ATL progression. We hypothesize that in ATL cells, HTLV-1 viral oncogenes Tax and Hbz cooperate to modulate bone metabolism in a paracrine manner to enhance ATL tumor growth and progression. Mice with Granzyme B driven Hbz expression (T and NK cells) develop leukemia/lymphoproliferative disease in lymph nodes correlating with increased spleen weight. We found that lymphoproliferative disease is also present in the bone marrow. Hbz mice have decreased trabecular bone at 18 months by microCT and radiographic analysis. These data suggest Hbz can alter bone metabolism. Future studies will define the effects of Hbz on bone formation, OB and OC specific effects and tumor progression. Understanding HTLV-1 oncogene modulation of the bone microenvironment will uncover critical pathways in tumor/bone cross talk enabling the development of novel targeted therapies for ATL patients.

Citation Format: Alison Esser, Dan Rauch, Jingyu Xiang, John Harding, Nicole Kohart, Patrick Green, Stefan Niewiesk, Thomas Rosol, Lee Ratner, Katherine Weilbaecher. HTLV-1 viral oncogene Hbz induces leukemia with osteolytic bone involvement in mice. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3285.

Abstract 659: Macrophage Beta3 Integrin Deficiency Promotes Atherosclerosis Development Through ERK-Dependent Signaling

Atherosclerosis is a chronic inflammation of the arterial wall caused by accumulation of cholesterol. This complex process involves endothelial and smooth muscle cells as well as the recruitment and differentiation of circulating monocytes. Integrins are membrane-bound molecules that are involved in signaling between cells and the extracellular matrix, thereby influencing intracellular signaling and cytoskeletal stability. We and others have described the in vivo consequences of germline deletion of the β3 integrin in inflammation, atherosclerosis and cancer. However, the distinct pathophysiological consequences of its tissue-specific deletion in macrophage function in development of atherosclerotic lesions remain mostly elusive. Our aim was to characterize for the first time the phenotype of mice with tissue-specific deletion of β3 integrin in macrophages (LyzMCre) under high fat diet (HFD) condition on atherosclerotic prone backgrounds (ApoE-/- and LDLr-/-), and to elucidate the signaling mechanism involved using in vitro methods. Tissue specific β3 integrin deficiency in macrophages alone is sufficient to cause increased lesion formation in the aorta of mice on HFD on both backgrounds used suggesting an important atheroprotective role played by this integrin. β3 integrin-deficient bone marrow-derived macrophages (BMDM) treated with oxLDL in vitro demonstrated a strong cholesterol uptake and increased foam cell formation. We identified that β3 integrin deficiency in macrophages caused an early activation of Ras followed by ERK phosphorylation, deficient cholesterol efflux and decreased expression of cholesterol transporter (ABCA1) which is a major regulator of cellular cholesterol. Inhibition of the ERK pathway reduced foam cell formation of macrophages at least partially by restoring expression of ABCA1. Taken together, our results show that macrophage β3 integrin is an important signaling molecule for cellular activation. Its deficiency showed important functional consequences in regard to inflammation and atherosclerosis that could be possibly modulated by interfering with downstream signaling.

Dickkopf-related protein 1 (Dkk1) regulates the accumulation and function of myeloid derived suppressor cells in cancer

Tumor-stroma interactions contribute to tumorigenesis. Tumor cells can educate the stroma at primary and distant sites to facilitate the recruitment of heterogeneous populations of immature myeloid cells, known as myeloid-derived suppressor cells (MDSCs). MDSCs suppress T cell responses and promote tumor proliferation. One outstanding question is how the local and distant stroma modulate MDSCs during tumor progression. Down-regulation of β-catenin is critical for MDSC accumulation and immune suppressive functions in mice and humans. Here, we demonstrate that stroma-derived Dickkopf-1 (Dkk1) targets β-catenin in MDSCs, thus exerting immune suppressive effects during tumor progression. Mice bearing extraskeletal tumors show significantly elevated levels of Dkk1 in bone microenvironment relative to tumor site. Strikingly, Dkk1 neutralization decreases tumor growth and MDSC numbers by rescuing β-catenin in these cells and restores T cell recruitment at the tumor site. Recombinant Dkk1 suppresses β-catenin target genes in MDSCs from mice and humans and anti-Dkk1 loses its antitumor effects in mice lacking β-catenin in myeloid cells or after depletion of MDSCs, demonstrating that Dkk1 directly targets MDSCs. Furthermore, we find a correlation between CD15(+) myeloid cells and Dkk1 in pancreatic cancer patients. We establish a novel immunomodulatory role for Dkk1 in regulating tumor-induced immune suppression via targeting β-catenin in MDSCs.

Effects of neoadjuvant chemotherapy with or without zoledronic acid on pathological response: A meta-analysis of randomised trials

Purpose

The addition of bisphosphonates to adjuvant therapy improves survival in postmenopausal breast cancer (BC) patients. We report a meta-analysis of four randomised trials of neoadjuvant chemotherapy (CT) +/− zoledronic acid (ZA) in stage II/III BC to investigate the potential for enhancing the pathological response.

Methods

Individual patient data from four prospective randomised clinical trials reporting the effect of the addition of ZA on the pathological response after neoadjuvant CT were pooled. Primary outcomes were pathological complete response in the breast (pCRb) and in the breast and lymph nodes (pCR). Trial-level and individual patient data meta-analyses were done. Predefined subgroup-analyses were performed for postmenopausal women and patients with triple-negative BC.

Results

pCRb and pCR data were available in 735 and 552 patients respectively. In the total study population ZA addition to neoadjuvant CT did not increase pCRb or pCR rates. However, in postmenopausal patients, the addition of ZA resulted in a significant, near doubling of the pCRb rate (10.8% for CT only versus 17.7% with CT+ZA; odds ratio [OR] 2.14, 95% confidence interval [CI] 1.01–4.55) and a non-significant benefit of the pCR rate (7.8% for CT only versus 14.6% with CT+ZA; OR 2.62, 95% CI 0.90–7.62). In patients with triple-negative BC a trend was observed favouring CT+ZA.

Conclusion

This meta-analysis shows no impact from the addition of ZA to neoadjuvant CT on pCR. However, as has been seen in the adjuvant setting, the addition of ZA to neoadjuvant CT may augment the effects of CT in postmenopausal patients with BC.

Suppression of β3-integrin in mice triggers a neuropilin-1-dependent change in focal adhesion remodelling that can be targeted to block pathological angiogenesis

Anti-angiogenic treatments against αvβ3-integrin fail to block tumour growth in the long term, which suggests that the tumour vasculature escapes from angiogenesis inhibition through αvβ3-integrin-independent mechanisms. Here, we show that suppression of β3-integrin in mice leads to the activation of a neuropilin-1 (NRP1)-dependent cell migration pathway in endothelial cells via a mechanism that depends on NRP1's mobilisation away from mature focal adhesions following VEGF-stimulation. The simultaneous genetic targeting of both molecules significantly impairs paxillin-1 activation and focal adhesion remodelling in endothelial cells, and therefore inhibits tumour angiogenesis and the growth of already established tumours. These findings provide a firm foundation for testing drugs against these molecules in combination to treat patients with advanced cancers.

Summary: Targeting both β3-integrin and neuropilin-1 prevents anti-angiogenic treatment escape.

Real-time intravital imaging establishes tumor-associated macrophages as the extraskeletal target of bisphosphonate action in cancer

Recent clinical trials have shown that bisphosphonate drugs improve breast cancer patient survival independent of their antiresorptive effects on the skeleton. However, because bisphosphonates bind rapidly to bone mineral, the exact mechanisms of their antitumor action, particularly on cells outside of bone, remain unknown. Here, we used real-time intravital two-photon microscopy to show extensive leakage of fluorescent bisphosphonate from the vasculature in 4T1 mouse mammary tumors, where it initially binds to areas of small, granular microcalcifications that are engulfed by tumor-associated macrophages (TAM), but not tumor cells. Importantly, we also observed uptake of radiolabeled bisphosphonate in the primary breast tumor of a patient and showed the resected tumor to be infiltrated with TAMs and to contain similar granular microcalcifications. These data represent the first compelling in vivo evidence that bisphosphonates can target cells in tumors outside the skeleton and that their antitumor activity is likely to be mediated via TAMs.

SIGNIFICANCE

Bisphosphonates are assumed to act solely in bone. However, mouse models and clinical trials show that they have surprising antitumor effects outside bone. We provide unequivocal evidence that bisphosphonates target TAMs, but not tumor cells, to exert their extraskeletal effects, offering a rationale for use in patients with early disease.

Comparative effectiveness on survival of zoledronic acid versus pamidronate in multiple myeloma

Zoledronic acid and pamidronate are the two bisphosphonates approved in the United States to reduce multiple myeloma skeletal complications. Little prior evidence exists comparing survival outcomes between the two. We evaluated the incidence of skeletal-related events and overall survival in patients with myeloma treated with zoledronic acid versus pamidronate using a cohort of 1018 United States veterans. At a median follow-up of 26.9 months, patients receiving zoledronic acid had a 22% reduction in risk of death compared to pamidronate (hazard ratio 0.78; 95% confidence interval, 0.67-0.92). The benefit persisted after controlling for potential confounders. Adjusted Cox modeling with inverse probability weighting and propensity score matching supported these findings. Zoledronic acid was also associated with a 25% decrease in skeletal-related events. Zoledronic acid is associated with increased overall survival and decreased skeletal-related events compared to pamidronate in patients with multiple myeloma and should become the preferred bisphosphonate.

Acute Depletion of Endothelial β3-Integrin Transiently Inhibits Tumor Growth and Angiogenesis in Mice

Rationale:

The dramatic upregulation of αvβ3-integrin that occurs in the vasculature during tumor growth has long suggested that the endothelial expression of this molecule is an ideal target for antiangiogenic therapy to treat cancer. This discovery led to the development of small-molecule inhibitors directed against αvβ3-integrin that are currently in clinical trials. In 2002, we reported that β3-integrin−knockout mice exhibit enhanced tumor growth and angiogenesis. However, as β3-integrin is expressed by a wide variety of cells, endothelial cell–specific contributions to tumor angiogenesis are muddied by the use of a global knockout of β3-integrin function.

Objective:

Our aim was to examine the endothelial-specific contribution β3-integrin makes to tumor growth and angiogenesis.

Methods and Results:

We have crossed β3-integrin–floxed (β3-floxed) mice to 2 endothelial-specific Cre models and examined angiogenic responses in vivo, ex vivo, and in vitro. We show that acute depletion of endothelial β3-integrin inhibits tumor growth and angiogenesis preventatively, but not in already established tumors. However, the effects are transient, and long-term depletion of the molecule is ineffective. Furthermore, long-term depletion of the molecule correlates with many molecular changes, such as reduced levels of focal adhesion kinase expression and a misbalance in focal adhesion kinase phosphorylation, which may lead to a release from the inhibitory effects of decreased endothelial β3-integrin expression.

Conclusions:

Our findings imply that timing and length of inhibition are critical factors that need to be considered when targeting the endothelial expression of β3-integrin to inhibit tumor growth and angiogenesis.

Abstract OT2-6-12: A randomized pacebo-controlled phase II trial evaluating the effect of hedgehog inhibitor LDE225 on bone marrow disseminated tumor cells in women with early stage estrogen receptor negative and HER2 negative breast cancer

Background: 20% of invasive breast cancers are triple negative (TN). Chemotherapy improves the outcome for a subset of these patients. Recurrence rates of 40-50% have been reported in those patients who do not achieve a complete pathological response to neoadjuvant therapy. Currently, there are no targeted therapies to TN cancers. Data suggest that micrometastases or disseminated tumor cells (DTCs) that persist despite chemotherapy are enriched with cells that have stem cell-like features. The Hedgehog (Hh) signaling pathway, which is involved in modulating epithelial-mesenchymal transition and maintenance of breast cancer stem cells, is an attractive therapeutic target for patients with TN tumors. In preclinical models, we have shown that Hh inhibition reduced breast cancer growth and metastasis.

Trial Design: This is a placebo-controlled, double blinded, randomized phase II trial in early stage TN breast cancer patients with detectable DTCs in their bone marrow (BM) at the completion of all therapy. LDE225 is administered at 400 mg orally daily for a 28 day cycle for 20 cycles. After 6 cycles, BM will be collected for analysis.

Specific Aims: The primary endpoint is the elimination of DTCs after 6 cycles of LDE225. Additional endpoints include: 2-year disease-free survival (DFS) and overall survival (OS), effect on BM Ptch1 gene expression, toxicity profile of LDE225, DFS and OS in patients with no DTCs at screening versus DTC-positive patients in the placebo arm.

Eligibility: Patients with ER-/Her2- stage I-III invasive breast cancers who have completed all therapy and have detectable DTCs, as defined by a molecular based assay for DTCs performed in a CLIA-licensed facility are eligible.

Statistical Methods: Based on preliminary data, 60% of patients in the LDE225 arm are expected to be Ptch1 positive, and 50% of these patients are expected eliminate DTCs after 6 cycles of treatment. The expected clearance rate in the remaining 40% of the LDE225 arm is 5% with an overall clearance rate of 32%. In the placebo arm, the expected clearance rate is 5% regardless of Ptch1 status. A sample of 68 patients, 34 in each treatment arm, will have power ∼ 0.8 at a 0.05 significance level, after adjusting for one interim analysis, to detect a difference in DTC clearance rate of 32% in the LDE225 arm versus 5% in the placebo arm. Assuming that 40% of patients screened have detectable DTCs, approximately 170 patients will be screened to identify 68 with detectable DTCs.

Enrollment will be suspended for 3 months after the first 6 patients have been randomized to LDE225 therapy to allow time to document toxicity and adverse events. One interim analysis will be conducted after 50% of the patients have completed 6 months on study. The proportion of patients who are DTC-positive at 6 months will be estimated. The power of the study power to achieve its primary goal will be calculated conditional on results obtained to that point. The significance level of the final analysis will be adjusted to 0.048 in order to maintain an overall 0.05 significance level.

Accrual: Accrual is anticipated to begin August 2013. Target = 34 per arm. NCT01757327.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT2-6-12.

Effect of (Neo)adjuvant zoledronic acid on disease-free and overall survival in clinical stage II/III breast cancer

BACKGROUND

Despite neoadjuvant/adjuvant chemotherapy, women with resectable stage II/III breast cancer (BC) have high risk of recurrent disease. Recent data suggest that zoledronic acid (ZOL) therapy concurrent with adjuvant treatments may improve cancer-related outcomes in patients with BC.

METHODS

Disease-free survival (DFS; secondary end point) and overall survival (OS; tertiary end point) were evaluated in 119 women with stage II/III BC randomised to intravenous ZOL 4 mg every 3 weeks for 1 year or no ZOL (control) starting with the first chemotherapy cycle.

RESULTS

At 61.9 months' median follow-up, there was no significant difference in recurrence or survival between study arms. However, time to recurrence or death (DFS) was significantly different between subgroups defined by oestrogen receptor (ER) status (interaction P=0.010 for DFS and 0.025 for OS). Hazard ratios (HRs) for disease recurrence and death were significantly less among patients with ER-negative (ER(-)) tumours who received ZOL vs no ZOL (DFS: HR=0.361, 95% confidence interval (CI) 0.148, 0.880; OS: HR=0.375, 95% CI 0.143, 0.985).

CONCLUSION

ZOL administered with chemotherapy may improve DFS and OS in a subset of BC patients with ER(-) tumours. This study was not powered to compare subgroups of patients; thus, these findings should be considered hypothesis generating.

CD8+ T cells regulate bone tumor burden independent of osteoclast resorption

Blockade of osteoclast (OC) activity efficiently decreases tumor burden as well as associated bone erosion in immune-compromised animals bearing human osteolytic cancers. In this study, we showed that modulation of antitumor T-cell responses alters tumor growth in bone, regardless of OC status, by using genetic and pharmacologic models. PLCγ2(-/-) mice, with dysfunctional OCs and impaired dendritic cell (DC)-mediated T-cell activation, had increased bone tumor burden despite protection from bone loss. In contrast, Lyn(-/-) mice, with more numerous OCs and a hyperactive myeloid population leading to increased T-cell responses, had reduced tumor growth in bone despite enhanced osteolysis. The unexpected tumor/bone phenotype observed in PLCγ2(-/-) and Lyn(-/-) mice was transplantable, suggesting the involvement of an immune component. Consistent with this hypothesis, T-cell activation diminished skeletal metastasis whereas T-cell depletion enhanced it, even in the presence of zoledronic acid, a potent antiresorptive agent. Importantly, injection of antigen-specific wild-type cytotoxic CD8(+) T cells in PLCγ2(-/-) mice or CD8(+) T-cell depletion in Lyn(-/-) mice normalized tumor growth in bone. Our findings show the important contribution of CD8(+) T cells in the regulation of bone metastases regardless of OC status, thus including T cells as critical regulators of tumor growth in bone.

Abstract LB-159: Bisphosphonates are internalised by myeloid derived suppressor cells (MDSCs) in vivo in a mouse model of breast cancer

Zoledronic acid (Zometa; ZOL), a nitrogen-containing bisphosphonate (N-BP), has become the standard treatment for metastatic bone disease due to its ability to inhibit osteoclast-mediated resorption. The molecular target of ZOL in osteoclasts is FPP synthase, an enzyme of the mevalonate pathway. Inhibition of this enzyme prevents the synthesis of isoprenoid lipids necessary for the prenylation of small GTPases such as Rho, Rac and Rap, thereby causing the accumulation of the unprenylated form of these proteins and fundamentally affecting cell function and survival. ZOL and other N-BPs have anti-tumour effects in some preclinical models of skeletal and non-skeletal tumours, and, more recently, have tantalising effects on patient survival in some clinical trials. However, the exact mechanisms responsible for these anti-tumour effects in vivo are still unknown, and the extent to which N-BPs are internalised by cells other than osteoclasts (such as immune cells) is unclear. We have sought to address this question in the 4T1 murine breast cancer model using a novel, fluorescently-labeled N-BP (AF647-RIS). 24 hours after a subcutaneous injection, using flow cytometry we have demonstrated for the first time the cellular uptake of this N-BP by Gr1+CD11b+ myeloid-derived suppressor cells (MDSCs), as well as by CD14+F4/80+ monocytes/macrophages (TAMs) in mammary tumours, whole blood, liver, spleen and bone marrow. Uptake of N-BP was not detectable in the tumour cells or other cell types. Furthermore, 7 days after a single injection of a clinically relevant dose of ZOL into tumour-bearing mice, we detected a significant reduction in MDSC number in the spleen.

It remains unknown whether ZOL affects protein prenylation in MDSCs or TAMs in vivo. Currently available methods to detect changes in protein prenylation, using western blotting to detect unprenylated small GTPases, are too insensitive to detect subtle effects of N-BPs on prenylation in cells in vivo. Importantly, we have now optimised a new, highly sensitive enzyme-based approach to detect the accumulation of unprenylated proteins in cell and tissue extracts from N-BP-treated animals. Additional studies are now in the very final stages to determine conclusively whether a clinically-relevant dose of ZOL inhibits protein prenylation in MDSCs and TAMs in 4T1 mice.

In summary, we provide the first conclusive evidence that N-BPs can be internalized in vivo by MDSC and other myeloid cells such as TAMs. Given the important role of these cells in the progression of tumour growth and metastasis, our studies will finally clarify the mechanism underlying the preclinical, and potentially clinical, anti-tumour activity of these agents.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-159. doi:10.1158/1538-7445.AM2011-LB-159

Abstract P3-02-12: Effect of Platelet Function Inhibition on Circulating Tumor Cells in Patients with Metastatic Breast Cancer: A Randomized Phase II Trial

Background: Tumor-recruited platelets have been implicated in tumor cell survival in the circulation, and in tumor cell arrest and adhesion at distant metastatic sites. Tumor cells activate platelets through a variety of mechanisms including the generation of thrombin and ADP. Blockade of platelet activation and aggregation can inhibit metastasis in animal models. Clopidogrel (Plavix) inhibits ADP mediated platelet activation through blockade of the P2Y12 receptor. Aspirin blocks thromboxane production and can partially disrupt thrombin and ADP mediated activation of platelets. We hypothesized that disruption of platelet function and aggregation will result in a decrease in circulating tumor cells (CTC) number. We evaluated the impact of platelet inhibitors clopidogrel and aspirin on CTC in women with metastatic breast cancer.

Methods: Eligible patients had a diagnosis of metastatic breast cancer, had no contraindications to receive aspirin or clopidogrel, and were on a planned anti-neoplastic treatment break or were on stable endocrine therapy for at least 2 months. Maintenance zoledronic acid and/or trastuzumab was allowed. Patients were randomized to receive either aspirin and clopidogrel or no treatment. CTC was measured at baseline, 2 weeks, 1 month, and monthly thereafter. CTC determinations were made via the CellSearch® assay from Veridex®. Platelet aggregation in whole blood using VerifyNow® P2Y12 and aspirin cartridges was performed on all samples to monitor drug compliance. The primary endpoint was proportion of patients with detectable CTC at 1 month.

Results: 48 patients were enrolled, 22 and 19 remained on study at 1 month for the no treatment and treatment arms. Patient characteristics: the median age was 56, 58% of patients were ER positive, 35% were Her2 positive, the median number of organs involved with metastasis was 2, and the median time since diagnosis of metastasis was approximately 22 months. Baseline CTC was ≥1 in 65% of patients and was ≥5 in 13% of patients. Proportion of patients with CTC ≥1 at time of study completion was compared between groups using Fisher's Exact Test and showed no difference between groups. Mean CTC was compared using non-parametric testing and was not different at any time point; however, the no treatment group's mean CTC increased more rapidly over time compared to the treatment group. Medication compliance as monitored by platelet function testing was outstanding. Clopidogrel and aspirin were well tolerated with no patients developing an SAE related to bleeding. Discussion: There was no statistically significant difference between patients who received anti-platelet therapy and those who did not with respect to the primary endpoint, proportion of detectable CTC at one month. In this population of patients with treated metastatic breast cancer, the CTC numbers were lower than expected, which likely decreased our ability to detect a difference in CTC number with anti-platelet therapy. Aspirin and clopidogrel were well tolerated in patients with metastatic breast cancer. Future studies addressing the utility of CTC in clinical settings as well as the potential role for anti-platelet therapy in breast cancer are needed.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-02-12.

Abstract P6-14-04: Effect of Zoledronic Acid on Disease-Free Survival and Overall Survival in Women with Clinic Stage II/III Undergoing Neoadjuvant Chemotherapy for Breast Cancer

Background: We conducted a randomized Phase II study examining the effect zoledronic acid (ZA) on disseminated tumor cells (DTC) in women undergoing neoadjuvant chemotherapy (Lancet Oncology11:421). We now report on the effect of ZA administered concurrently with neoadjuvant/adjuvant chemotherapy on disease-free survival and overall survival in this patient population.

Methods: Between March 2003-2006, 120 women with newly diagnosed clinical stage II/III breast cancer were randomized to either ZA 4 mg IV every 3 weeks for 1 year starting with the first cycle of chemotherapy or no bisphosphonate. 4 cycles of epirubicin (75 mg/m2)/docetaxel (75 mg/m2) were given prior to surgery and 2 cycles in the adjuvant setting. Eligible patients received adjuvant endocrine therapy and trastuzumab. Disease-free survival was defined as the time from trial registration to first detectable recurrence. Overall survival was defined as the time from trial registration to date of breast-cancer related death. Data was analyzed using Kaplan-Meier and Cox proportional hazard models.

Results: Of 120 patients randomized 119 patients were evaluable. Treatment arms were balanced for grade, menopausal status, and tumor biomarkers. Tumors of 55 (46.2%) women were estrogen-receptor (ER) positive/Her2-negative, 40 (33.6%) were ER-negative/Her2-negative and 24 (20.2%) were Her2-positive.With a median follow up of 61.9 (4.93-85.43) months, there was no significant difference in recurrence or survival between the ZA and no ZA groups (p=0.88, p=.92 respectively). Subgroup analysis demonstrated that time to recurrence and death was significantly different between patient groups based on ER-status and ZA treatment (p=.013 for recurrence, p=.013 for survival).

Months

Time to recurrence and hazard of death was similar in three of the subgroups, ER-positive/Her2-negative/control, ER-positive/Her2-negative/ZA, and ER-negative/Her2-negative/ZA (p&gt;.05 for recurrence and p&gt;.05 for survival. ER-negative/Her2- negative patients in the no ZA treatment arm experienced a significantly decreased time to recurrence and survival compared to ER-positive patients (p=.0039, p=.0074, respectively). The hazard ratio of death for ER-negative/Her2-negative patients was reduced from 8.36 to 3.15 with ZA treatment. The estimated 5yr survival for ER-positive/Her2-negative/control, ER-positive/Her2-negative/ZA, ER-negative/Her2-negative/control, ER-negative/Her2-negative/ZA were 96.6%, 80.0%, 63.2% and 81.0% respectively.

Discussion: ZA administered with chemotherapy conferred a disease-free survival and overall survival benefit to a subset of breast cancer patients with ER-negative/Her2-negative tumors. Longer follow-up may be required to determine if there is a benefit in other tumor subgroups. Larger studies are warranted to examine the effects of ZA in patients at high risk of developing metastatic disease.

A role for the epithelial microenvironment at tumor boundaries: evidence from Drosophila and human squamous cell carcinomas

Recent work has shown an increasing appreciation for the importance of the tumor environment, most commonly the overlying stroma. Less emphasis has been placed on the importance of local communication between transformed cells and their neighbors within the epithelium at tumor boundaries. We previously reported a Drosophila model that highlighted the importance of local interactions within the epithelial microenvironment: Src-transformed cells (Csk-deficient) were influenced by their immediate normal neighbors. The result was a consistent change in 'border cells' at the edge of transformed patches including delocalized p120-catenin and E-cadherin as well as invasive migration through the basal lamina. Here we show that the invasive properties of the boundary cells depend on up-regulation of Drosophila matrix metalloproteinase-1 as assessed by promoter activity, protein levels, in situ enzymatic activity, and tests of genetic modifier activity. Further, we provide evidence that these events at tumor borders may be evolutionarily conserved. We detected changes in 'boundary cells' within histological sections of human squamous cell carcinomas that were similar to those observed in Drosophila: both E-cadherin and p120-catenin exhibited normal junctional localization at the centers of the tumors but were reduced or delocalized at the boundary. Further, matrix metalloproteinase-2 was up regulated within these same boundary cells. These results support the view that local cell-cell interactions within the epithelial microenvironment impact tumor invasion and progression.

Effect of zoledronic acid on disseminated tumour cells in women with locally advanced breast cancer: an open label, randomised, phase 2 trial

BACKGROUND

Treatment with bisphosphonates decreases bone loss and can increase disease-free survival in patients with breast cancer. The aim of our study was to assess the effect of zoledronic acid on clearance of disseminated tumour cells (DTCs) from the bone marrow in women undergoing neoadjuvant chemotherapy for breast cancer.

METHODS

Patients were recruited for this open-label, phase 2 randomised trial between March 17, 2003, and May 19, 2006, at a single centre. Eligible patients had clinical stage II-III (> or = T2 and/or > or = N1) newly diagnosed breast cancer, Eastern Cooperative Oncology Group performance status of 0 or 1, and normal cardiac, renal, and liver function. 120 women were randomly assigned, using allocation concealment, to receive 4 mg zoledronic acid intravenously every 3 weeks (n=60), or no zoledronic acid (n=60), for 1 year concomitant with four cycles of neoadjuvant epirubicin (75 mg/m(2)) plus docetaxel (75 mg/m(2)) and two cycles of adjuvant epirubicin plus docetaxel. The primary endpoint was the number of patients with detectable DTCs at 3 months. Final analysis was done 1 year after the last patient was enrolled. Analyses were done for all patients with available data at 3 months. This study is registered with ClinicalTrials.gov, number NCT00242203.

FINDINGS

Of the 120 patients initially enrolled, one withdrew after signing consent and one patient's baseline bone marrow was not available. Both of these patients were in the control group. At 3 months, 109 bone-marrow samples were available for analysis. In the zoledronic acid group, bone marrow was not collected from one patient because of disease progression, one patient was taken off study because of severe diarrhoea, and two patients had not consented at the time of surgery. In the control group, bone marrow was not collected from two patients because of disease progression, one patient withdrew consent, and three patients were not consented at the time of surgery. At baseline, DTCs were detected in 26 of 60 patients in the zoledronic acid group and 28 of 58 patients in the control group. At 3 months, 17 of 56 patients receiving zoledronic acid versus 25 of 53 patients who did not receive zoledronic acid had detectable DTCs (p=0.054). The most common grade 3-4 toxicities were infection (five of 60 patients in the zoledronic acid group and six of 59 in the control group) and thrombosis (five of 60 in the zoledronic acid and two of 59 in the control group). There was one documented case of osteonecrosis in the zoledronic acid group.

INTERPRETATION

Zoledronic acid administered with chemotherapy resulted in a decreased proportion of patients with DTCs detected in the bone marrow at the time of surgery. Our study supports the hypothesis that the antimetastatic effects of zoledronic acid may be through effects on DTCs.

FUNDING

Novartis Pharmaceuticals and Pfizer Inc.

The bisphosphonate zoledronic acid decreases tumor growth in bone in mice with defective osteoclasts

Bisphosphonates (BPs), bone targeted drugs that disrupt osteoclast function, are routinely used to treat complications of bone metastasis. Studies in preclinical models of cancer have shown that BPs reduce skeletal tumor burden and increase survival. Similarly, we observed in the present study that administration of the Nitrogen-containing BP (N-BP), zoledronic acid (ZA) to osteolytic tumor-bearing Tax+ mice beginning at 6 months of age led to resolution of radiographic skeletal lesions. N-BPs inhibit farnesyl diphosphate (FPP) synthase, thereby inhibiting protein prenylation and causing cellular toxicity. We found that ZA decreased Tax+ tumor and B16 melanoma viability and caused the accumulation of unprenylated Rap1a proteins in vitro. However, it is presently unclear whether N-BPs exert anti-tumor effects in bone independent of inhibition of osteoclast (OC) function in vivo. Therefore, we evaluated the impact of treatment with ZA on B16 melanoma bone tumor burden in irradiated mice transplanted with splenic cells from src(-/-) mice, which have non-functioning OCs. OC-defective mice treated with ZA demonstrated a significant 88% decrease in tumor growth in bone compared to vehicle-treated OC-defective mice. These data support an osteoclast-independent role for N-BP therapy in bone metastasis.

APT102, a novel adpase, cooperates with aspirin to disrupt bone metastasis in mice

Platelets contribute to the development of metastasis, the most common cause of mortality in cancer patients, but the precise role that anti-platelet drugs play in cancer treatment is not defined. Metastatic tumor cells can produce platelet alphaIIb beta3 activators, such as ADP and thromboxane A(2) (TXA(2)). Inhibitors of platelet beta3 integrins decrease bone metastases in mice but are associated with significant bleeding. We examined the role of a novel soluble apyrase/ADPase, APT102, and an inhibitor of TXA(2) synthesis, acetylsalicylic acid (aspirin or ASA), in mouse models of experimental bone metastases. We found that treatment with ASA and APT102 in combination (ASA + APT102), but not either drug alone, significantly decreased breast cancer and melanoma bone metastases in mice with fewer bleeding complications than observed with alphaIIb beta3 inhibition. ASA + APT102 diminished tumor cell induced platelet aggregation but did not directly alter tumor cell viability. Notably, APT102 + ASA treatment did not affect initial tumor cell distribution and similar results were observed in beta3-/- mice. These results show that treatment with ASA + APT102 decreases bone metastases without significant bleeding complications. Anti-platelet drugs such as ASA + APT102 could be valuable experimental tools for studying the role of platelet activation in metastasis as well as a therapeutic option for the prevention of bone metastases.