Metastatic HER2 Research Articles

Survival of patients with metastatic HER2 positive gastro-oesophageal cancer treated with second-line chemotherapy plus trastuzumab or ramucirumab after progression on front-line chemotherapy plus trastuzumab

BackgroundThe role of continuing anti-HER2 therapy beyond progression on front-line therapy in patients with metastatic HER2 positive gastro-oesophageal cancer (GEC) is unclear. Continued chemotherapy plus trastuzumab (CT) has never been compared with the current standard second-line treatment, chemotherapy plus ramucirumab (CR).MethodsThe Flatiron Health electronic health record derived database, a nationwide database comprising patient-level structured and unstructured data, curated via technology-enabled abstraction, was reviewed for patients with metastatic HER2 positive GEC who received first-line CT, followed by second-line CT or CR. Survival from second-line therapy (SST) and time to next therapy or death (TTNTD) were compared using Kaplan-Meier curves and logrank analysis.Results133 patients with metastatic HER2 positive GEC who received first-line CT were identified. 32 received second-line CR and 101 received CT. Median SST for patients treated with CT versus CR was 10.2 months (IQR 5.1–20.8) and 6.8 months (IQR 2.4–20.2), respectively (p=0.29). Median TTNTD for second-line CT versus CR was 4.9 months (IQR 2.8–9.8) and 5.1 months (IQR 2.3–7.5), respectively (p=0.65). Patients who received second-line CT were more likely to receive a multiagent chemotherapy backbone (76% vs 3%, p≤0.001).ConclusionsThis analysis showed no significant difference in SST for patients treated with second-line CT versus CR. Further studies are needed to clarify the role of trastuzumab in the second line, especially in patients with confirmed retention of HER2 positivity following progression.

Abstract 5027: Sequencing the tumor microenvironment and myeloid derived suppressor cells to understand response to immunotherapy in primary HER2 positive breast cancer

Abstract The purpose of this study is to identify how the epigenetic modulator entinostat reprograms myeloid derived suppressor cells (MDSCs) to prime the tumor microenvironment (TME) and modulate immunotherapy response. Early trials investigating single agent ICIs, anti-CTLA-4 and anti-PD-1/PD-L1, resulted in overall response rates of 5-20% in patients with metastatic HER2 positive breast cancer but little is understood about use of these therapies in patients with early stage/ primary disease. Suboptimal and inconsistent immune responsiveness is likely the result of multiple suppressive signals within the TME that provide a formidable barrier to T cell infiltration leading to an opportunity for TME modulation to potentially improve response. We and others have shown that immunosuppressive factors can be overcome by adding the class 1 histone deacetylase inhibitor, entinostat, to ICIs to reprogram MDSCs and upregulate T cell attracting signals within the TME. We hypothesize that gene expression signatures of reprogrammed MDSCs are predictive of response with subsequent immunotherapy treatment. To test this hypothesis, we used the neu-N syngeneic mouse model of HER2 positive breast cancer. We investigated differences in survival and tumor burden in response to combinations of entinostat with anti-PD-1 and anti-CTLA-4. Having previously identified MDSCs as important targets of entinostat that modulate response to ICIs, we used methods we developed to study MDSC function. Given the broad effects of entinostat on global gene expression including that of MDSCs, we used single cell RNA-seq (scRNA-seq) on primary tumors and isolated intratumoral MDSCs to determine what is driving changes in MDSC function in primary tumors. We plan to use data obtained from scRNA-seq to develop signatures of response and identify changes in responders vs. non-responders to help develop biomarkers of response in primary disease. Our results thus far show that treatment with entinostat + ICIs improves survival, and decreases tumor burden in primary tumors. Ex-vivo studies of MDSCs demonstrate changes in immunosuppressive capabilities of MDSCs and show differences in infiltration and function of granulocytic vs. monocytic MDSCs. We expect that evaluation of the ongoing sequencing data will identify more specific immune targets within primary TME and help us understand the importance of targeting MDSCs in early disease. We predict this work will identify additional candidate targets for therapeutic testing to convert breast cancers into immune responsive tumors, and that this will facilitate improved response to ICIs that will ultimately translate into improved survival of patients with breast cancer. Citation Format: Evanthia T. Roussos Torres, Christine Rafie, Emily Davis, Luciane T. Kagohara, Elana J. Fertig, Elizabeth M. Jaffee. Sequencing the tumor microenvironment and myeloid derived suppressor cells to understand response to immunotherapy in primary HER2 positive breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5027.

Anlotinib in Metastatic HER2 Negative Breast Cancer

Anlotinib in Metastatic HER2 Negative Breast Cancer

Stimulation of natural killer cells with a CD137-specific antibody enhances trastuzumab efficacy in xenotransplant models of breast cancer.

Trastuzumab, a monoclonal antibody targeting human epidermal growth factor receptor 2 (HER2; also known as HER-2/neu), is indicated for the treatment of women with either early stage or metastatic HER2(+) breast cancer. It kills tumor cells by several mechanisms, including antibody-dependent cellular cytotoxicity (ADCC). Strategies that enhance the activity of ADCC effectors, including NK cells, may improve the efficacy of trastuzumab. Here, we have shown that upon encountering trastuzumab-coated, HER2-overexpressing breast cancer cells, human NK cells become activated and express the costimulatory receptor CD137. CD137 activation, which was dependent on NK cell expression of the FcγRIII receptor, occurred both in vitro and in the peripheral blood of women with HER2-expressing breast cancer after trastuzumab treatment. Stimulation of trastuzumab-activated human NK cells with an agonistic mAb specific for CD137 killed breast cancer cells (including an intrinsically trastuzumab-resistant cell line) more efficiently both in vitro and in vivo in xenotransplant models of human breast cancer, including one using a human primary breast tumor. The enhanced cytotoxicity was restricted to antibody-coated tumor cells. This sequential antibody strategy, combining a tumor-targeting antibody with a second antibody that activates the host innate immune system, may improve the therapeutic effects of antibodies against breast cancer and other HER2-expressing tumors.

KEYNOTE-811 pembrolizumab plus trastuzumab and chemotherapy for HER2+ metastatic gastric or gastroesophageal junction cancer (mG/GEJC): A double-blind, randomized, placebo-controlled phase 3 study.

TPS4146 Background: Combination therapy with the anti-HER2 antibody trastuzumab with fluoropyrimidine and platinum is the current standard for patients with HER2+ mG/GEJc. We hypothesize that combination anti–PD-1 and anti-HER2 therapy will result in T-cell activation, augment ADCC, and potentiate antitumor immune response in HER2+ patients. This phase 2 study in HER2+ mG/GEJc demonstrated the safety and preliminary efficacy of trastuzumab/pembrolizumab/chemotherapy; the overall response rate was 87%, and the disease control rate was 100% Janjigian YY, ASCO GI 2019). KEYNOTE 811, a global, multicenter, randomized, placebo-controlled, phase 3 study, is underway. Methods: Key eligibility criteria are age ≥18 years; previously untreated unresectable or metastatic HER2+ (centrally confirmed IHC 3+ or IHC 2+/ISH >2.0) G/GEJ adenocarcinoma; life expectancy >6 months with RECIST v1.1 measurable disease; adequate organ function and performance status. Patients will be randomly assigned 1:1 to receive chemotherapy with pembrolizumab 200 mg IV flat dose or placebo with trastuzumab 6 mg/kg (after 8 mg/kg load) Q3W up to 2 years or until intolerable toxicity or disease progression. Investigator choice chemotherapy will include day 1 cisplatin 80 mg/m2 IV and /5-fluorouracil 800 mg/m2/day IV (days 1-5) or oxaliplatin 130 mg/m2 IV and capecitabine 1000 mg/m2 BID days 1-14 (Q3W). Primary end points are progression-free survival and overall survival. Secondary end points are objective response rate, duration of response, and safety and tolerability. Adverse events are graded per NCI CTCAE v4.0 and will be monitored for 30 or 90 days after treatment. Patients will be followed up for survival. Planned enrollment is approximately 692 patients. Clinical trial information: NCT03615326.

Phase 1 open label trial of intraperitoneal paclitaxel (IPP) in combination with intravenous cisplatin (C) and oral capecitabine (X) in patients with advanced gastric cancer and peritoneal metastases.

4061 Background: IPP is a potential treatment option in patients with gastric cancer with peritoneal metastasis. IPP with a dose of 20 mg/m2 is well tolerated in combination with S1; however, this has been achieved in a specific genetic pool (Japanese population), and S1 is not available in some countries. We investigated the Maximum Tolerated Dose (MTD) of IPP in addition to a standard chemotherapy combination in an Australian population. Methods: Study population included synchronous or metachronous metastatic HER-2 non-amplified gastric adenocarcinoma with histologically/cytologically proven peritoneal involvement and adequate organ function. Intra-peritoneal catheter was placed surgically. 3 + 3 standard dose-escalation design was used. MTD was defined as the highest dose level at which ≤ 33% of patients had Dose Limiting Toxicity (DLT). DLT was defined within the first 3 cycles. Recommended Phase-2 Dose was defined as equal to the MTD, or cohort-3 dose if MTD was not reached. Treatment: maximum of six 21-day cycles of C (80mg/m2 IV day 1) + X (1000mg/m2 PO BD days 1-14) + IPP (days 1 and 8). IPP doses for Cohort-1, 2 and 3 were 10, 20 and 30mg/m2 respectively. Primary endpoint was the MTD of IPP. Secondary endpoints included safety, tolerability, overall response rate, ascites response rate, progression free survival and overall survival. Results: 15 patients were recruited in 3 cohorts: 9 males (60%), median age at study entry: 61y (range 32-82). All had synchronous metastatic disease and were chemo-naïve. Cohort-1 expanded to 6 patients due to 1 DLT (grade 3 diarrhea), cohort-2 included 3 patients (no DLT) and cohort-3 was expanded to 6 patients as planned and 1 DLT occurred (febrile neutropenia). MTD was not reached and Recommended Phase 2 Dose was determined as 30mg/m2. 8 patients (53%) completed all 6 cycles of treatment. The last patient on the study has completed 3 cycles and is expected to complete 6 cycles by April 2019. No grade 4 or 5 toxicity was recorded. Conclusions: MTD of IPP was not reached. IPP is safe in combination with C + X and the Recommended Phase 2 Dose is 30 mg/m2. Survival data will be presented when available. Clinical trial information: ACTRN12614001063606.

Phase II clinical trial using anti-CD3 x anti-HER2 bispecific antibody armed activated T cells (HER2 BATs) for HER2-negative (0-2+) metastatic breast cancer.

1080 Background: This study presents a phase II cell therapy trial in 32 women with metastatic or locally advanced HER2- breast cancer (BrCa) who received infusions of anti-CD3 x anti-HER2 bispecific antibody armed activated T cells (BATs). This phase II study (NCT 01022138) was conducted to determine if BATs infusions could improve time to progression (TTP) and overall survival (OS), as well as to confirm the toxicity profile of BATs. Methods: The phase II included 32 patients with a median of 4 lines of therapy (7 TNBC and 25 HR/PR+ HER2- patients) with an average age of 52.5 years (range 28-75 years). Twenty-one patients had ≥3 lines of prior therapy and 11 patients had 1-2 lines. Peripheral blood mononuclear cells (PBMC) were stimulated with anti-CD3 antibody and expanded in IL-2, armed with HER2Bi, and aliquoted for the clinical trial. Patients received oncologist’s choice of chemotherapy (4 cycles/4 months) followed by 3 infusions of BATs given once per week for 3 weeks and a boost given 12 weeks after the 3rd infusion. Results: Fifteen of 32 (ORR of 46.8%) who had received any cells had stable disease (SD) at 1 month after the last infusion, and 8 of 15 (25%) had SD > 4 months. For patients who completed 3 or 4 infusions (17-83 x 109 BATs), 8 of 31 patients had TTP > 4 months. One patient completed 2 infusions (17 x 109 BATs). There were no dose limiting toxicities (DLTs). Tumor markers decreased in 13 of 23 (56.5%) patients with evaluable markers. The median OS was 13.8, 16.5, and 12.4 months for all, ER/PR+, and TNBC, respectively. OS for all patients with chemosensitive (chemoS) and chemoresistant (chemoR) disease was 14.6 and 8.6 months (NS), respectively. OS for chemoS and chemoR disease in HER2- ER/PR+ patients was 16.5 and 8.6 months (NS), respectively. OS for chemoS and chemoR disease in TNBC patients was 12.4 and 22.6 months, respectively (NS). The median TTP for all, HER2- ER/PR+, and TNBC patients was 2.7, 2.9, and 1.4 months, respectively. Increases in serum IL-2 and IL-12 were associated with BATs infusions. Conclusions: Targeting HER2- tumors was safe. There were trends toward improved survival in patients who were HER2-/ER/PR+ TNBC, patients who were chemoS, was associated with increased TTP and OS in all groups, and was associated with decreased tumor markers in those who received 4 infusions. Immune studies showed evidence for induction of adaptive immunity directed at breast cancer antigens. Targeting metastatic HER2- BrCa with BATs shows promise. Clinical trial information: NCT 01022138.

Assessing the tolerability and efficacy of first-line chemotherapy in elderly patients with metastatic HER2-ve breast cancer.

BackgroundIn metastatic breast cancer (MBC), there is no consensus regarding the optimal regimen sequence and whether adults >65 years old (OA) are at increased risk from chemotherapy toxicity. Treatment decisions are often driven by the ability to tolerate treatment and maintain the quality of life. This study was designed to assess current practice in an oncology hospital in the UK.MethodsRetrospective data were collected about treatments used for 87 OA with MBC in a single centre between 2009 and 2016 to assess the tolerability and efficacy of first-line chemotherapy. Student’s T-tests and Kaplan-Meier statistical methods were applied.Results70% of patients were commenced on standard dose (SD) of chemotherapy; 84% (21/25) of the anthracycline group (AG), 65% (20/31) of the capecitabine group (CG), 48% (10/21) of the taxane group (TG) and 100% (10/10) of other agents. 32% of patients had dose reductions; 16% in AG, 19% in TG and 58% in CG. Overall 30% of patients received six cycles of SD of chemotherapy; 36% in AG, 29% in CG and 14% in TG. 23% of patients suffered ≥grade 3 toxicity; 28% in AG, 29% in CG and 10% in TG. There were four treatment-related deaths; two in AG and one in both CG and TG. 61% of the CG received 6+ cycles with a mean on treatment time of 445 days (1–2,150). There was no statistical significance in progression- free survival (PFS) between groups. The median PFS for all patients was 244 days (87–381). Performance status, haemoglobin and estimated glomerular filtration rates prior to starting chemotherapy were all useful in predicting PFS.ConclusionsA relevant number of patients required dose reduction but dose-reduced chemotherapy was tolerated well. Anthracycline-based regimens were used in patients who had not received adjuvant chemotherapy. Capecitabine required the most dose reductions. Taxanes were generally started at reduced doses, resulting in fewer grade 3+ toxicities. As well as age, underlying physiological reserve, current performance status and co-morbidities should guide physicians who should consider lower starting doses in OA and recognise that dose reductions may be required to improve tolerability. The PFS of all regimens were similar in this study. This study highlights the need for further research to define the optimal first-line chemotherapy and starting dose in OA with MBC.

ULOGA INHIBITORA CDK4/6 U LIJEČENJU HORMONSKI OVISNOGA METASTATSKOG RAKA DOJKE NEGATIVNOG NA HER-2

ULOGA INHIBITORA CDK4/6 U LIJEČENJU HORMONSKI OVISNOGA METASTATSKOG RAKA DOJKE NEGATIVNOG NA HER-2

Abstract P6-18-11: Long-term responders to single-agent margetuximab, an Fc-modified anti-HER2 monoclonal antibody, in metastatic HER2+ breast cancer patients with prior anti-HER2 therapy

Abstract Background Margetuximab is an Fc-optimized anti-HER2 antibody that recognizes the same epitope as trastuzumab. Margetuximab has increased affinity for the activating CD16A Fc-receptor on NK cells and macrophages as well as decreased affinity for the inhibitory CD32B receptor compared to trastuzumab. In a Phase 1 study (NCT01148849) of 66 patients with relapsed or metastatic HER2+ cancer across multiple indications, margetuximab was well tolerated at all doses. Among 60 response-evaluable patients, confirmed partial response (PR) and stable disease (SD) were seen in 7 (12%) and 30 (50%) patients, respectively. Tumor reductions occurred in 18/23 (78%) evaluable breast cancer patients. Ex-vivo analyses of patient peripheral blood mononuclear cell samples confirmed margetuximab's ability to enhance antibody dependent cell-mediated cytotoxicity over that from trastuzumab. We report on 3 breast cancer patients with prior anti-HER2 therapy failure with durable (≥ 3.5 years) SD (1) or PR (2). Methods Enrolled patients had histologically/cytologically-confirmed carcinoma with documented HER2 overexpression by immunohistochemistry (2+ or 3+) and disease progression during/following last therapy. Eligibility included life expectancy ≥3 months; performance status ≤1; measurable disease by Response Criteria for Solid Tumors 1.1; adequate bone marrow, renal, hepatic function; and left ventricular ejection fraction ≥50%. Margetuximab was given by intravenous infusion at 0.1 – 6.0 mg/kg for 3 of every 4 weeks or once every 3 weeks (10 – 18 mg/kg). Results Three of 17 HER2 3+ metastatic breast cancer patients received long-term margetuximab. Patient 35 had 3 prior regimens (adjuvant doxorubicin+cyclophosphamide followed by docetaxol+trastuzumab; gemcitabine+vinorelbine; lapatinib+capecitabine) and received margetuximab at 10 mg/kg q3wk, 88 cycles to date, with PR achieved Cycle 1 Day 43, maintained 4.4 years. Patient 44 had 3 prior regimens for metastatic disease (docetaxel+trastuzumab+pertuzumab; doxorubicin+cyclophosphamide; lapatinib+capecitabine) and received margetuximab at 15 mg/kg q3wk, 79 cycles to date with SD for 4.3 years. Patient 50 had 4 prior regimens for recurrent/metastatic disease (tamoxifen; anastrozole; capecitabine+trastuzumab; lapatinib+capecitabine) and received margetuximab dose of 18 mg/kg q3wk with PR achieved Cycle 1 Day 43, maintained 3.5 years. Progression was noted at Cycle 57, and margetuximab continues at 63 cycles to date. No cardiac toxicities were found during long-term follow-up for these 3 patients and there were no treatment-related adverse events ≥Grade 3. Conclusions Margetuximab is well-tolerated without cardiac toxicities in long-term responders, with single-agent activity including durable responses in heavily pre-treated metastatic breast cancer. A Phase 3, randomized, multi-center clinical trial (SOPHIA; NCT02492711) is enrolling patients with metastatic breast cancer, comparing margetuximab plus chemotherapy to trastuzumab plus chemotherapy in patients who have received 1 to 3 lines of therapy for advanced disease. Citation Format: Im S-A, Bang Y-J, Oh D-Y, Giaccone G, Bauer T, Nordstrom J, Li H, Moore P, Hong S, Baughman J, Rock E, Burris H. Long-term responders to single-agent margetuximab, an Fc-modified anti-HER2 monoclonal antibody, in metastatic HER2+ breast cancer patients with prior anti-HER2 therapy [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 P6-18-11.

Abstract OT3-02-08: Genetic analysis in blood, urine, stool and tumor samples from patients with advanced or metastatic estrogen receptor positive and HER2 negative breast cancer receiving palbociclib and endocrine therapy (PROMISE)

Abstract Background: Combining cyclin dependent 4/6 kinase inhibitors (CDK4/6i) with endocrine therapy (ET) has resulted in clinically significant improvements in progression-free survival (PFS) in persons with hormone-receptor (HR)-positive metastatic breast cancer (MBC). However, nearly all patients will progress on CDK4/6i and ET and the mechanisms associated with primary and secondary resistance are mostly unknown. The identification of biomarkers associated with response to CDK4/6i is therefore a major research priority. PROMISE is a multicenter prospective cohort study designed to perform a comprehensive “omic” assessment of blood, tumor, urine and the fecal microbiome to identify alterations in molecular or cellular features associated with primary endocrine resistance (e.g. disease progression ≤ 12 months on treatment) and acquired resistance to CDK4/6i. Additionally, patient derived xenografts (PDX) and organoids are generated to test new drug strategies designed to reverse resistance to CDK4/6i and ET. Methods: Eligible participants include women for whom palbociclib is recommended in combination with either letrozole (first-line) or fulvestrant (second-line) therapy for HR-positive MBC. As of July 2018, 14 patients have been enrolled; the target accrual is 250 patients, who will be followed over the course of 36 months and followed for at least 12 months after the close of enrollment. Blood and tumor biopsies are obtained at baseline, at the end of cycle 2, and at progression. Whole exome sequencing (germline and tumor) and RNAseq (whole transcriptome) are performed on tumor samples in a CAP/CLIA lab (TEMPUS) and results will be provided back to all patients for later use. Additionally, PDX and organoids are generated from tumor biopsies at baseline and during progression. Blood, stool, and urine samples are collected for additional correlative studies. The primary objective of this trial is to identify novel genomic variants and pathways associated with early progression (≤ 12 months) among women with advanced HR-positive breast cancer treated with palbociclib and ET. Secondary objectives include identification of the biomolecular features within the gut (stool) microbiome and exploration of the metabolomics and proteomics of ER-positive MBC. Results from the interrogation of these biospecimens will be critical to gain insights into treatment resistance. Funding is provided by Mayo Clinic Center for Individualized Medicine, TEMPUS, and an ASCO Career Development Award (COS). ClinicalTrials.gov Identifier: NCT03281902. Citation Format: O'Sullivan CC, Suman VJ, Kalari KR, Moyer A, Sung J, Moreno-Aspitia A, Northfelt DW, Liu MC, Haddad TC, Chumsri S, Couch FJ, Weinshilboum RM, Wang L, Goetz MP. Genetic analysis in blood, urine, stool and tumor samples from patients with advanced or metastatic estrogen receptor positive and HER2 negative breast cancer receiving palbociclib and endocrine therapy (PROMISE) [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 OT3-02-08.

Abstract GS1-08: Genomic characterisation of metastatic breast cancer

Abstract Rationale: while large efforts have been done to characterize early breast cancer, little is known about the genomic landscape of metastatic breast cancer. In the present study, we performed whole exome sequencing of 800 metastatic breast cancers, in order to identify new candidate targets and better stratify patients eligible for innovative therapies. Patients and Methods: Patients were selected to present a metastatic breast cancer and to have received a biopsy in the context of precision medicine trials (SAFIR01, SAFIR02, PERMED, MOSCATO, SHIVA). Samples with >30% cancer cells, and normal DNA, were sequenced using Hiseq and Novaseq. Drivers were identified using MutSigCV. Actionability of somatic genetic alterations was determined based on OncoKB. Decomposition of mutational signatures was performed using deconstructSigs. Prognostic value was assessed using a cox model. TCGA database was used as comparator to identify gene alterations enriched in metastatic samples. Results: results presented in the current abstract are based on the first 629 patients analyzed.Sequencing was performed in 387 patients with HR+/Her2- breast cancer, 186 triple negative breast cancers, and 32 Her2-overexpressing breast cancers. only 9 patients received a pretreatment with a CDK4 inhibitor. 24 driver genes were significantly mutated. In patients with HR+/Her2- breast cancer, 11 genes were found more frequently mutated in the metastatic setting as compared to early stage breast cancer. This includes TP53 (29%), KMT2C (13%), NCOR1 (8%), NF1 (7%), RB1 (4%), C16orf3 (2%), FRG1 (6%), ESR1 (21%), RIC8A (4%), AKT1 (7%), PLSCR5 (2%). In addition, in the whole population, KRAS was found mutated in 3% of samples (G12A/C/R/V) while its frequency of mutation in early breast cancer is <1%. No gene alteration was found enriched in metastatic Her2+++ and TNBC. Copy number alterations were compared between metastatic and early breast cancer. 18 amplicons were found more frequently in HR+/Her2- metastatic breast cancers as compared to eBC. Among the genes enriched in metastatic samples, mutations in RB1 or NF1 were associated with a poor outcome ( median OS 9 and 13 months respectively, p=0.0038 and 0.01 respectively). 73% of patients presenting HR+/Her2- mBC had an actionable alteration, as compared to 55% of patients presenting HR+/Her2- eBC (p<0.01). Patients with HR+/Her2- mBC presented an enrichment of gene alterations in the MAPK/ERK pathway (37% vs 22%) and in the HRD pathway (22% vs 10%). When the analysis focuses on mTNBC; the proportion of patient presenting an actionable alteration was comparable to the eTNBC. 11 (6%) and 16 (9%) patients presented a somatic mutation or homozygous gene deletion on BRCA1 and PTEN respectively. We further assessed the mutational signatures in order to better understand which mutational processes could drive cancer progression. Metastatic HR+/Her2- mBC presented an increase in APOBEC, S3 (HRD), S10 (POLE-associated signature), S17 signatures as compared to early HR+/Her2- BC. Conclusion: the present study, based on 629 patients, identifies 11 driver gene alterations and four mutational processes enriched in HR+/Her2- metastatic breast cancers. Final results on 800 patients will be presented. Citation Format: Andre F, Filleron T, Ng C, Bertucci F, Letourneau C, Jacquet A, Piscuoglio S, Jimenez M, Bachelot T. Genomic characterisation of metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS1-08.

Abstract OT2-07-04: A phase 1b study of poziotinib in combination with T-DM1 in women with advanced or metastatic HER2-positive breast cancer

Abstract Background:Poziotinib represents a new class of irreversible quinazoline inhibitors of ErbB receptor tyrosine kinases that inhibit the proliferation of tumor cells in culture and in vivo by inhibiting HER-1 (EGFR), HER-2, HER-4. ErbB signaling plays important roles in the progression of HER2+ breast cancer. Poziotinib has promising clinical activity in breast cancer, and other solid tumors including lung, gastric, and colorectal cancers. Study SPI-POZ-101, is being conducted to evaluate the safety and efficacy of the combination of daily poziotinib and T-DM1, HER2 antibody-drug-conjugate every three weeks in patients with HER2+ advanced or metastatic breast cancer. Trial Objectives and Design: The primary objectives of the study are to determine the maximum tolerated dose (MTD) or maximum administered dose (MAD) of daily poziotinib plus T-DM1 (every 3 weeks) in women with advanced or metastatic HER2 positive breast cancer; and to evaluate the Objective Response Rate (ORR) in these patients. The secondary objectives include disease control rate (DCR), progression-free-survival (PFS), safety and pharmacokinetics at the MTD/MAD dose level of poziotinib plus T-DM1. In Part 1, the dose of poziotinib plus standard dose of T-DM1 (3.6 mg/kg IV) on Day 1 of each cycle will be determined using a “3+3” design with up to 3 escalating dose levels, 8, 10 and 12 mg with no DLT or to de-escalate to 6 mg with DLT observed in Cycle 1. Patients in current dose cohort, if not discontinued, will continue treatment until discontinuation of therapy. In Part 2 of the study, approximately 10 patients will be treated at the MTD/MAD to confirm dose for safety of the combination and to evaluate preliminary efficacy. Eligibility Criteria: The study will enroll female patients between 18 and 90 years with confirmed HER2 overexpression or gene-amplified tumor via immunohistochemistry [IHC] with IHC 3+ or IHC 2+ with confirmatory fluorescence in situ hybridization [FISH]+ or [ISH]+ and must have had at least 2 lines of anti-HER2 directed therapies either in the metastatic or early-stage disease setting. Patients must have adequate hematologic, hepatic, cardiac and renal functions and have at least one measurable lesion per RECIST 1.1 criteria. Exclusion criteria includes unstable CNS metastases or seizure disorder; anticancer chemotherapy, TKIs, biologics, immunotherapy, radiotherapy, or investigational treatment within 15 days; ≥ Grade 2 adverse events; known hypersensitivity to receptor tyrosine kinase inhibitors or any of the components of poziotinib tablets or T-DM1 IV solution. Statistical Methods: Part 1 of the study will enroll 3 to 6 patients at each dose using 3+3 design. Part 2 will enroll 10 patients at the MTD/MAD. The efficacy analysis will be conducted using the Evaluable Population based on RECIST 1.1. The Clopper-Pearson 95% confidence interval will be estimated using exact method based on binomial distribution. Target Accrual:Part 1: 6-18 patients Part 2: 10 patients ClinicalTrials.gov Identifier: NCT03429101 Contact Information: Spectrum Pharmaceuticals. SPI-POZ-101@sppirx.com Poziotinib is currently under clinical investigation and has not been approved for use in breast cancer. Citation Format: Bhat G, Potter D, Bharadwaj J, Khan N, Shabazz L, Tache J, Yang Z. A phase 1b study of poziotinib in combination with T-DM1 in women with advanced or metastatic HER2-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-07-04.

Abstract P5-03-15: Mechanism of activation of PPP1R1B drug-resistance gene in trastuzumab-resistant Her2+ breast cancer

Abstract Trastuzumab (Herceptin) resistance is a persistent challenge in the treatment of metastatic Her2+ breast cancer, with an average relapse time of 1 year after treatment. Human breast cancer cell-lines (SKBr3 and BT474) selected for trastuzumab resistance have a PPP1R1B gene (chr17:39,626,924-39,636,626) that is transcriptionally activated compared to their drug-sensitive counterparts. PPP1R1B codes for two related protein products, Darpp-32 (long) and t-Darpp (short), that are overexpressed in 50% of clinical breast cancer samples in comparison to normal breast tissue; reintroduction of t-Darpp into drug-sensitive cells confers drug resistance. The mechanism controlling overexpression of these transcripts is unknown. To gain insight into this mechanism we used ATAC-seq to map open chromatin areas in trastuzumab-resistant breast cancer cell lines and compared their open chromatin areas to those in the parental trastuzumab-sensitive counterparts. The PPP1R1B gene consists of 7 canonical exons. In each trastuzumab-resistant line there is two significantly increased open chromatin peaks, one within exon 2 and one within exon 3. We are performing deep sequencing (>200 million reads) to identify transcription factor footprints in these peaks. Furthermore, we performed RNA-seq analysis and identified genes that are similarly regulated in the resistant lines in comparison to their drug-sensitive counterparts. In summary, these results shed light on an area of high clinical importance and point to potential drug targets to be developed to overcome trastuzumab resistance in Her2+ breast cancer. Citation Format: Momand J, Murad R, Ma X, Geng S, Mortazavi A. Mechanism of activation of PPP1R1B drug-resistance gene in trastuzumab-resistant Her2+ breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-03-15.

Abstract P3-10-29: tRNA-derived fragments as novel predictive biomarkers for trastuzumab-resistant breast cancer

Abstract Background: Resistance to trastuzumab remains a common challenge to HER-2 positive breast cancer. Up until now, the underlying mechanism of trastuzumab resistance is still unclear. tRNA-derived small non-coding RNAs, a new class of small non-coding RNA (sncRNAs), have been observed to play an important role in cancer progression. However, the relationship between tRNA-derived fragments and trastuzumab resistance is still unknown. Methods:We detected the levels of tRNA-derived fragments expression in normal breast epithelial cell lines, trastuzumab-sensitive and -resistant breast cancer cell linesusing high-throughput sequencing.qRT-PCR was conducted to validate the differentially expressed fragments in serums from trastuzumab-sensitive and -resistant patients. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the power of specific tRNA-derived fragments.Progression-free survival (PFS) was analyzed using Cox-regression. Results:Our sequence results showed that tRNA-derived fragments were differentially expressed in the HBL-100, SKBR3, and JIMT-1 cell lines. tRF-30-JZOYJE22RR33 and tRF-27-ZDXPHO53KSN were found significantly upregulated in trastuzumab-resistant patients compared to sensitive individuals, and the ROC analysis showed that tRF-30-JZOYJE22RR33 and tRF-27-ZDXPHO53KSN were correlated with trastuzumab resistance. In a multivariate analysis, higher levels of tRF-30-JZOYJE22RR33 and tRF-27-ZDXPHO53KSN expression were associated with significantly shorter PFS in patients with metastatic HER-2 positive breast cancer. Conclusion: Our results suggest that tRF-30-JZOYJE22RR33 and tRF-27-ZDXPHO53KSN play important roles in trastuzumab resistance. Patients with high levels of tRF-30-JZOYJE22RR33 and tRF-27-ZDXPHO53KSN expression benefitted less from trastuzumab-based therapy than those that express lower-levels of these molecules. tRF-30-JZOYJE22RR33 and tRF-27-ZDXPHO53KSN may be potential biomarkers and intervention targets in the clinical treatment of trastuzumab-resistant breast cancer. Citation Format: Sun C, Li W, Wu H, Huang X, Li J, Fu Z, Tang J, Yin Y. tRNA-derived fragments as novel predictive biomarkers for trastuzumab-resistant breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-29.

Abstract P2-03-08: Preclinical evaluation of the PI3Kα/δ inhibitor, copanlisib in HER2+ breast cancer: A proof of concept study

Abstract Purpose: The PI3K-AKT-mTORC1/C2 pathway is frequently activated in HER2+ breast cancer and upregulation of this pathway is a key mechanism of trastuzumab resistance. However, attempts to indirectly target this pathway by using the allosteric mTOR inhibitor everolimus have had limited clinical success. Here, we present the results of a preclinical study of the PI3K α/δ (dominant) inhibitor copanlisib alone and in combination with T-DM1, in HER2 amplified cell lines including a model with acquired resistance to trastuzumab. Method: Anti-proliferative, apoptotic, cell cycle, and intracellular signaling effects of copanlisib alone and in combination with T-DM1 were evaluated in a panel of HER2 amplified (ER+ or ER-), and HER2 amplified/PIK3CA mutated cell lines, as well as trastuzumab-resistant breast cancer cell lines. Results: 1) Copanlisib inhibited PI3K, mTOR and their downstream signaling molecules in HER2 amplified/PIK3CA WT or PIK3CA mutated as well as in trastuzumab-resistant cell lines, 2) interestingly, copanlisib also inhibited RAS-MAPK signaling in the earlier time points, 3) copanlisib caused a strong differential growth inhibition in HER2 amplified BC cell lines by 3D-ON-TOP clonogenic assay and real-time monitoring in an IncuCyte Zoom. Inhibition was greater when copanlisib was combined with T-DM1, 4) administration of copanlisib induced cell cycle G0/G1 arrest and resulted in increased apoptosis in a dose-dependent manner, 5) unlike everolimus copanlisib blocked HIF1α accumulation in hypoxic condition and this blocking effect was reversed by prior treatment with the proteasome inhibitor, carfilzomib and 6) copanlisib also attenuated HER2 amplified cell migration, an important phenotypic feature for metastasis. Conclusions: Copanlisib is highly effective (blocks proliferation, induces apoptosis, and inhibits PI3K and its downstream signaling targets) in HER2 amplified breast cancer cell lines including trastuzumab-resistant and PIK3CA mutated cell lines. The addition of copanlisib to T-DM1 might represent an improved treatment strategy for patients with refractory metastatic HER2+ breast cancer. Citation Format: De P, Carlson JH, Dey N, Leyland-Jones B. Preclinical evaluation of the PI3Kα/δ inhibitor, copanlisib in HER2+ breast cancer: A proof of concept 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 P2-03-08.

Survival of patients with metastatic HER2 positive gastroesophageal cancer treated with second-line chemotherapy plus trastuzumab or ramucirumab after progression on frontline chemotherapy plus trastuzumab.

69 Background: Optimal second line treatment for patients with metastatic HER2 positive gastroesophageal cancer (Her2GE) is unknown. A retrospective study has suggested continuation of chemotherapy with trastuzumab (CT), as compared to chemotherapy alone, may improve outcomes. However, CT has never been compared to the current standard second-line treatment of chemotherapy plus ramucirumab (CR). Methods: The Flatiron Health EHR-derived database, a nationally representative database comprising patient-level structured and unstructured data, curated via technology-enabled abstraction, was reviewed for patients with metastatic Her2GE who received CT in the first line setting, followed by either second line CT or CR. Survival from second line therapy (SST) and time to next therapy or death (TTNTD) were compared using Kaplan-Meier curves and Log-Rank analysis. Demographics between treatment groups were compared using standard T tests and chi-squared analysis. Results: 135 patients were identified, of whom 34 received second-line CR and 101 received CT. Median SST for patients treated with CT was 10.2 months (m) [interquartile range (IQR) 5.1-20.8] and 6.8 m (IQR 3.2-20.2) for those treated with CR, p = 0.39. Median TTNTD for patients treated with CT versus CR was 4.9 m (IQR 2.8-9.8) and 4.8 m (IQR 2.3-7.5), respectively (p = 0.53). There was no difference between patients who received CT or CR in regards to average age (63 vs. 62, p = 0.72), average duration of first-line therapy (7.8 m vs. 9.1 m, p = 0.36), or percentage of patients with ECOG > 1 (15% vs. 22%, p = 0.50). Patients who received CT were more likely to receive a multiagent chemotherapy backbone (76% vs. 3%, p ≤ 0.001). Conclusions: This data suggest a non-significant trend towards increased SST for patients treated with second line CT versus CR. Further studies are needed to clarify optimal second-line treatment for this patient population.

Neratinib in Combination With Trastuzumab for the Treatment of Patients With Advanced HER2-positive Breast Cancer: A Phase I/II Study

BackgroundDespite the availability of several human epidermal growth factor receptor 2 (HER2)-directed treatments, many HER2-positive (HER2+) breast cancers eventually progress because of primary or acquired resistance. Patients and MethodsA 2-part, open-label, multicenter phase I/II study was conducted to determine the recommended dose of neratinib when administered with trastuzumab (part I), and to assess the antitumor activity of this combination in women with locally advanced or metastatic HER2+ breast cancer previously treated with at least 1 prior trastuzumab-based regimen (part II). Patients received oral neratinib (160 or 240 mg/d) once daily plus intravenous trastuzumab 4 mg/kg (loading dose) then 2 mg/kg weekly. Diarrhea prophylaxis was not permitted. The primary endpoint in part II was investigator-assessed 16-week progression-free survival (PFS). ResultsForty-five patients received neratinib plus trastuzumab (part I: neratinib 160 mg/d, n = 4; neratinib 240 mg/d, n = 4; part II: neratinib 240 mg/d, n = 37). In part I, there were no dose-limiting toxicities and the recommended neratinib dose was 240 mg/d. In part II, the 16-week PFS rate was 44.8% (90% confidence interval, 28.8%-59.6%), and the median PFS was 15.9 weeks (95% confidence interval, 15.1-31.3 weeks) in 28 evaluable patients. Three patients had durable clinical benefit lasting 9.4 to 9.7 years. Diarrhea was the most common adverse event (grade 3, n = 7 [15.6%]; grade 4, n = 0). No clinically significant cardiac toxicity was seen. ConclusionsNeratinib in combination with trastuzumab was well-tolerated and had encouraging antitumor activity in patients with advanced trastuzumab-pretreated HER2+ breast cancer. Durable responses can be achieved in some patients.

Risk factors for the development of brain metastases in patients with HER2-positive breast cancer

BackgroundPatients with metastatic human epidermal growth factor receptor 2-positive breast cancer (HER2+ BC) frequently experience brain metastases (BM). We aimed to define risk factors for the development of BM in patients with HER2+ BC and to report on their outcome.MethodsThis is a retrospective analysis of patients diagnosed with HER2+ BC between January 2000 and December 2014 at Institut Jules Bordet, Belgium. Statistical analyses were conducted with SAS V.9.4 using Kaplan-Meier method and Cox regression analyses.ResultsA total of 483 patients were included of whom 108 (22.4%) developed metastases and 52 (10.8%) BM. Among 96 metastatic patients without BM at diagnosis, 40 (41.7%) developed BM in the course of their disease. In multivariate analysis, risk factors for the development of BM were age ≤40 years (HR 2.10, 95 % CI 1.02 to 4.36), tumour size >2 cm (HR 4.94, 95% CI 1.69 to 14.47), nodal involvement (HR 3.48, 95% CI 1.47 to 8.25), absence or late start (≥6 months after initial diagnosis) of adjuvant anti-HER2 treatment (HR 3.79, 95% CI 1.52 to 9.43 or HR 2.65, 95% CI 1.03 to 6.82) and the development of lung metastases as first site of relapse (HR 6.97, 95% CI 3.41 to 14.24). Twenty-two patients with HER2+ BC and BM sent to our institute for further treatment were included in the outcome analysis. Asymptomatic patients at the time of BM diagnosis showed a better overall survival than symptomatic patients (HR 0.49, 95% CI 0.25 to 0.94).ConclusionA considerable number of patients with metastatic HER2+ BC will develop BM. Screening of patients with risk factors for BM might lead to early detection and better outcome. However, randomised controlled trials examining the use of MRI as a screening method for BM in patients with metastatic BC are warranted before such an approach can be recommended.

366TiP - The NAME trial: A direct comparison of oral navelbine given either classic or metronomic in metastatic HER2 neg breast cancer

366TiP - The NAME trial: A direct comparison of oral navelbine given either classic or metronomic in metastatic HER2 neg breast cancer