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Predictive biomarkers of response to human epidermal growth factor receptor 2 (HER2)-directed therapy are essential to inform treatment decisions. The TBCRC026 trial reported that early declines in tumor SUVs corrected for lean body mass (SUL max ) on 18 F-FDG PET/CT predicted a pathologic complete response (pCR) to HER2 therapy with neoadjuvant trastuzumab and pertuzumab (HP) without chemotherapy in estrogen receptor (ER)-negative, HER2-positive breast cancer. We hypothesized that 18 F-FDG PET/CT SUL max parameters would predict recurrence-free survival (RFS) and overall survival (OS). Methods: Patients with stage II/III ER-negative, HER2-positive breast cancer received neoadjuvant HP ( n = 88). pCR after HP alone was 22% (18/83), additional nonstudy neoadjuvant therapy was administered in 28% (25/88), and the majority received adjuvant therapy per physician discretion. 18 F-FDG PET/CT was performed at baseline and at cycle 1, day 15 (C1D15). RFS and OS were summarized using the Kaplan-Meier method and compared between subgroups using logrank tests. Associations between 18 F-FDG PET/CT (≥40% decline in SUL max between baseline and C1D15, or C1D15 SUL max ≤ 3) and pCR were evaluated using Cox regressions, where likelihood ratio CIs were reported because of the small numbers of events. Results: Median follow-up was 53.7 mo (83/88 evaluable), with 6 deaths and 14 RFS events. Estimated RFS and OS at 3 y was 84% (95% CI, 76%-92%) and 92% (95% CI, 87%-98%), respectively. A C1D15 SUL max of 3 or less was associated with improved RFS (hazard ratio [HR], 0.36; 95% CI, 0.11-1.05; P = 0.06) and OS (HR, 0.14; 95% CI, 0.01-0.85; P = 0.03), the latter statistically significant. The association of an SUL max decline of at least 40% (achieved in 59%) with RFS and OS did not reach statistical significance. pCR was associated with improved RFS (HR, 0.25; 95% CI, 0.01-1.24; P = 0.10) but did not reach statistical significance. Conclusion: For the first time, we report a potential association between a C1D15 SUL max of 3 or less on 18 F-FDG PET/CT and RFS and OS outcomes in patients with ER-negative, HER2-positive breast cancer receiving neoadjuvant HP alone. If confirmed in future studies, this imaging-based biomarker may facilitate early individualization of therapy., (© 2023 by the Society of Nuclear Medicine and Molecular Imaging.)

Background: We aimed to examine circulating tumor DNA (ctDNA) and its association with residual cancer burden (RCB) using an ultrasensitive assay in patients with triple-negative breast cancer (TNBC) receiving neoadjuvant chemotherapy., Patients and Methods: We identified responders (RCB 0/1) and matched non-responders (RCB 2/3) from the phase II TBCRC 030 prospective study of neoadjuvant paclitaxel versus cisplatin in TNBC. We collected plasma samples at baseline, 3 weeks and 12 weeks (end of therapy). We created personalized ctDNA assays utilizing MAESTRO mutation enrichment sequencing. We explored associations between ctDNA and RCB status and disease recurrence., Results: Of 139 patients, 68 had complete samples and no additional neoadjuvant chemotherapy. Twenty-two were responders and 19 of those had sufficient tissue for whole-genome sequencing. We identified an additional 19 non-responders for a matched case-control analysis of 38 patients using a MAESTRO ctDNA assay tracking 319-1000 variants (median 1000 variants) to 114 plasma samples from 3 timepoints. Overall, ctDNA positivity was 100% at baseline, 79% at week 3 and 55% at week 12. Median tumor fraction (TFx) was 3.7 × 10 -4 (range 7.9 × 10 -7 -4.9 × 10 -1 ). TFx decreased 285-fold from baseline to week 3 in responders and 24-fold in non-responders. Week 12 ctDNA clearance correlated with RCB: clearance was observed in 10 of 11 patients with RCB 0, 3 of 8 with RCB 1, 4 of 15 with RCB 2 and 0 of 4 with RCB 3. Among six patients with known recurrence, five had persistent ctDNA at week 12., Conclusions: Neoadjuvant chemotherapy for TNBC reduced ctDNA TFx by 285-fold in responders and 24-fold in non-responders. In 58% (22/38) of patients, ctDNA TFx dropped below the detection level of a commercially available test, emphasizing the need for sensitive tests. Additional studies will determine whether ctDNA-guided approaches can improve outcomes., (Copyright © 2023 European Society for Medical Oncology. Published by Elsevier Ltd. All rights reserved.)

Purpose: Chemotherapy-related amenorrhea (CRA) is a surrogate for ovarian toxicity and associated risk of infertility and premature menopause. Here, we compare CRA rate with paclitaxel (T)-trastuzumab (H) to that with ado-trastuzumab emtansine (T-DM1)., Methods: Patients with T1N0 HER2 + early-stage breast cancer (eBC) enrolled on the ATEMPT trial and were randomized 3:1 to T-DM1 3.6 mg/kg IV every (q) 3 weeks (w) × 17 vs. T 80 mg/m 2 with H IV qw × 12 (4 mg/kg load → 2 mg/kg), followed by H (6 mg/kg IV q3w × 13). Enrollees who self-reported as premenopausal were asked to complete menstrual surveys at baseline and every 6-12 months for 60 months. 18-month CRA (no periods reported during prior 6 months on 18-month survey) was the primary endpoint of this analysis., Results: Of 512 ATEMPT enrollees, 123 who began protocol therapy and answered baseline and at least one follow-up menstrual survey were premenopausal at enrollment. 76 had menstrual data available at 18 months without having received a gonadotropin-releasing hormone agonist or undergone hysterectomy and/or oophorectomy. Median age was 45 (range 23-53) among 18 who had received TH and 46 (range 34-54) among 58 who had received T-DM1. The 18-month rate of CRA was 50% after TH and 24% after T-DM1 (p = 0.045)., Conclusion: Amenorrhea at 18 months was less likely in recipients of adjuvant T-DM1 than TH. Future studies are needed to understand how T-DM1 impacts risk of infertility and permanent menopause, and to assess amenorrhea rates when T-DM1 is administered after standard HER2-directed chemotherapy regimens., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: The ATEMPT trial was designed to determine if treatment with trastuzumab emtansine (T-DM1) caused less toxicity than paclitaxel plus trastuzumab (TH) and yielded clinically acceptable invasive disease-free survival (iDFS) among patients with stage I human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC)., Methods: Patients with stage I centrally confirmed HER2+ BC were randomly assigned 3:1 to T-DM1 or TH and received T-DM1 3.6 mg/kg IV every 3 weeks for 17 cycles or T 80 mg/m 2 IV with H once every week × 12 weeks (4 mg/kg load →2 mg/kg), followed by H × 39 weeks (6 mg/kg once every 3 weeks). The co-primary objectives were to compare the incidence of clinically relevant toxicities (CRTs) in patients treated with T-DM1 versus TH and to evaluate iDFS in patients receiving T-DM1., Results: The analysis population includes all 497 patients who initiated protocol therapy (383 T-DM1 and 114 TH). CRTs were experienced by 46% of patients on T-DM1 and 47% of patients on TH ( P = .83). The 3-year iDFS for T-DM1 was 97.8% (95% CI, 96.3 to 99.3), which rejected the null hypothesis ( P < .0001). Serially collected patient-reported outcomes indicated that patients treated with T-DM1 had less neuropathy and alopecia and better work productivity compared with patients on TH., Conclusion: Among patients with stage I HER2+ BC, one year of adjuvant T-DM1 was associated with excellent 3-year iDFS, but was not associated with fewer CRT compared with TH., Competing Interests: Sara TolaneyConsulting or Advisory Role: Novartis, Pfizer, Merck, Lilly, Nektar, NanoString Technologies, AstraZeneca, Puma Biotechnology, Genentech, Eisai, Sanofi, Celldex, Bristol Myers Squibb, Paxman, Seattle Genetics, Odonate Therapeutics, AbbVie, Silverback Therapeutics, G1 Therapeutics, OncoPep, Kyowa Hakko Kirin, Samsung Bioepis, CytomX Therapeutics, Daiichi Sankyo, Athenex, Immunomedics/Gilead, Mersana, CertaraResearch Funding: Genentech/Roche, Merck, Exelixis, Pfizer, Lilly, Novartis, Bristol Myers Squibb, Eisai, AstraZeneca, NanoString Technologies, Cyclacel, Nektar, Immunomedics, Odonate Therapeutics, Sanofi, Seattle GeneticsTravel, Accommodations, Expenses: AstraZeneca, Lilly, Merck, Nektar, Novartis, Pfizer, Genentech/Roche, Immunomedics, Eisai, NanoString Technologies, Puma Biotechnology, Celldex Chau DangHonoraria: Puma Biotechnology, eviCore healthcareConsulting or Advisory Role: Puma Biotechnology, eviCore healthcareResearch Funding: Genentech/Roche, Puma Biotechnology Denise YardleyConsulting or Advisory Role: Novartis, Biotheranostics, Bristol Myers Squibb, G1 Therapeutics, Athenex, Immunomedics, Sanofi/Aventis, R-Pharm, LillySpeakers' Bureau: Novartis, Genentech/Roche, Genentech/RocheResearch Funding: Genentech/Roche, Novartis, MedImmune, Lilly, Medivation, Pfizer, Tesaro, Macrogenics, AbbVie, Merck, Clovis Oncology, Amgen, Biomarin, Biothera, Dana Farber Cancer Hospital, Incyte, Innocrin Pharma, Nektar, NSABP Foundation, Odonate Therapeutics, PolyphorTravel, Accommodations, Expenses: Novartis, Genentech/Roche Steven IsakoffConsulting or Advisory Role: AbbVie, OncoPep, Puma Biotechnology, Seattle Genetics, NovartisResearch Funding: Genentech, PharmaMar, AbbVie, OncoPep, Merck, AstraZeneca/MedImmune, Outcomes4Me Vicente ValeroHonoraria: Genentech/Roche, Merck, NovartisConsulting or Advisory Role: Genentech/Roche, Novartis, MerckTravel, Accommodations, Expenses: Genentech/Roche Therese MulveyConsulting or Advisory Role: Outcomes4Me Ron BoseConsulting or Advisory Role: GenentechResearch Funding: Puma Biotechnology Antonio WolffConsulting or Advisory Role: Ionis PharmaceuticalsResearch Funding: Biomarin, CelldexPatents, Royalties, Other Intellectual Property: Antonio Wolff has been named as inventor on one or more issued patents or pending patent applications related to methylation in breast cancer and has assigned his rights to JHU and participates in a royalty sharing agreement with JHUOpen Payments Link: https://openpaymentsdata.cms.gov/physician/357301/summary Katherine Reeder-HayesResearch Funding: Pfizer Hope RugoHonoraria: Puma Biotechnology, MylanConsulting or Advisory Role: SamsungResearch Funding: Macrogenics, OBI Pharma, Eisai, Pfizer, Novartis, Lilly, Genentech, Merck, Immunomedics, Odonate Therapeutics, Daiichi Sankyo, Seattle Genetics, Sermonix Pharmaceuticals, AstraZenecaTravel, Accommodations, Expenses: Pfizer, Novartis, Macrogenics, Mylan, Daiichi Sankyo, AstraZeneca Spain, MerckOpen Payments Link: https://openpaymentsdata.cms.gov/summary Bhuvaneswari RamaswamyConsulting or Advisory Role: Eisai Lowell HartHonoraria: Novartis, Daiichi Sankyo, AstraZeneca, Seattle Genetics, G1 Therapeutics, Veracyte, Karyopharm TherapeuticsConsulting or Advisory Role: Genentech/Roche, Amgen, G1 Therapeutics, Merck, Seattle GeneticsSpeakers' Bureau: Bristol Myers Squibb, Lilly, Pfizer, Genentech, AstraZeneca, NovartisResearch Funding: Novartis, Genentech/Roche, Bristol Myers Squibb, G1 Therapeutics, Seattle Genetics Vijayakrishna GadiLeadership: SEngine Precision MedicineStock and Other Ownership Interests: Sengine precision medicine, Novilla, 3rdEyeBio, New Equilibrium BiosciencesConsulting or Advisory Role: Seattle Genetics, Puma Biotechnology, Novartis, SanofiSpeakers' Bureau: Seagen, bioTheranosticsResearch Funding: Genentech/Roche, SignalOne Bio, AgendiaTravel, Accommodations, Expenses: NovartisOpen Payments Link: https://openpaymentsdata.cms.gov/physician/2511 Bryan SchneiderHonoraria: Lilly, Research to Practice Paul MarcomConsulting or Advisory Role: Genentech/Roche, ImmunomedicsResearch Funding: Novartis, Genentech/Roche, AstraZeneca, Verily, Glycomimetics, MillenniumOpen Payments Link: https://openpaymentsdata.cms.gov/physician/237508/summary Kathy AlbainConsulting or Advisory Role: Novartis, Pfizer, Myriad Genetics, Genomic Health, Agendia, Genentech/RocheResearch Funding: Seattle GeneticsOther Relationship: Puma Biotechnology Nadine TungResearch Funding: AstraZeneca Rita NandaConsulting or Advisory Role: Merck, Genentech/Roche, Pfizer, Macrogenics, Daiichi Sankyo, Athenex, Aduro Biotech, ION Pharma, Seattle Genetics, ImmunomedicsResearch Funding: Corcept Therapeutics, Celgene, Merck, Seattle Genetics, Genentech/Roche, Odonate Therapeutics, Pfizer, AstraZeneca, AbbVie, ImmunomedicsOther Relationship: G1 Therapeutics Rachel JankowitzHonoraria: EisaiConsulting or Advisory Role: Merck Mothaffar RimawiConsulting or Advisory Role: Macrogenics, Daiichi Sankyo, Seattle Genetics, GenentechResearch Funding: Pfizer Vandana AbramsonEmployment: HCA HealthcareConsulting or Advisory Role: Eisai, Daiichi Sankyo, AbbvieResearch Funding: Genentech/Roche, Lilly Paula PohlmannLeadership: Immunonet BioSciencesStock and Other Ownership Interests: Immunonet BioSciencesHonoraria: Dava Oncology, OncLive/MJH Life Sciences, Frontiers—PublisherConsulting or Advisory Role: Personalized Cancer Therapy, OncoPlex Diagnostics, Immunonet BioSciences, Pfizer, HERON, Puma Biotechnology, Sirtex Medical, Caris Life Sciences, Juniper Pharmaceuticals, Bolt BiotherapeuticsSpeakers' Bureau: Genentech/RocheResearch Funding: Genentech/Roche, Fabre-Kramer, Advanced Cancer Therapeutics, Caris Centers of Excellence, Pfizer, Pieris Pharmaceuticals, Cascadian Therapeutics, Bolt Biotherapeutics, Byondis, SeagenPatents, Royalties, Other Intellectual Property: United States Patent no. 8486413, United States Patent no. 8501417, United States Patent no. 9023362, United States Patent no. 9745377, Patent application Catherine Van PoznakResearch Funding: BayerPatents, Royalties, Other Intellectual Property: UpToDate Andres Forero-TorresEmployment: Seattle GeneticsStock and Other Ownership Interests: Seattle Genetics Minetta LiuResearch Funding: Eisai, Seattle Genetics, Novartis, Roche/Genentech, GRAIL, Merck, Tesaro, Menarini Silicon Biosystems, Genomic HealthTravel, Accommodations, Expenses: GRAIL, Merck, Menarini Silicon Biosystems, Pfizer, Genomic Health, AstraZeneca, Ionis Pharmaceuticals Kathryn RuddyPatents, Royalties, Other Intellectual Property: My husband is a co-inventor of technology licensed by Mayo Clinic to AliveCor (MountainView, CA), which makes a smartphone-enabled remote ECG monitoring system Richard GelberResearch Funding: AstraZeneca, Novartis, Roche, Merck, PfizerTravel, Accommodations, Expenses: Roche, AstraZeneca, Novartis Bill BarryEmployment: Rho Ann PartridgePatents, Royalties, Other Intellectual Property: I receive small royalty payments for co-authoring the breast cancer survivorship section of UpToDateTravel, Accommodations, Expenses: Novartis Eric WinerHonoraria: Genentech/Roche, Genomic HealthConsulting or Advisory Role: Leap Therapeutics, Seattle Genetics, Jounce Therapeutics, GlaxoSmithKline, Carrick Therapeutics, Lilly, G1 Therapeutics, Syros Pharmaceuticals, Genentech/Roche, Gilead Sciences, Zymeworks, AthenexResearch Funding: GenentechOther Relationship: InfiniteMD Ian KropEmployment: AMAG Pharmaceuticals, Freeline TherapeuticsLeadership: AMAG Pharmaceuticals, Freeline TherapeuticsStock and Other Ownership Interests: AMAG Pharmaceuticals, Freeline Therapeutics, VertexHonoraria: Genentech/Roche, AstraZeneca, CelltrionConsulting or Advisory Role: Genentech/Roche, Seattle Genetics, Daiichi Sankyo, Macrogenics, Taiho Pharmaceutical, Context Therapeutics, Novartis, Merck, Ionis Pharmaceuticals, Bristol Myers Squibb, AstraZenecaResearch Funding: Genentech, PfizerNo other potential conflicts of interest were reported.

Purpose: Predictive biomarkers to identify patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer who may benefit from targeted therapy alone are required. We hypothesized that early measurements of tumor maximum standardized uptake value corrected for lean body mass (SULmax) on 18 F-labeled fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) would predict pathologic complete response (pCR) to pertuzumab and trastuzumab (PT)., Patients and Methods: Patients with stage II or III, estrogen receptor-negative, HER2-positive breast cancer received four cycles of neoadjuvant PT. 18 F-labeled fluorodeoxyglucose positron emission tomography-computed tomography was performed at baseline and 15 days after PT initiation (C1D15). Eighty evaluable patients were required to test the null hypothesis that the area under the curve of percent change in SULmax by C1D15 predicting pCR is ≤ 0.65, with a one-sided type I error rate of 10%., Results: Eighty-eight women were enrolled (83 evaluable), and 85% (75 of 88) completed all four cycles of PT. pCR after PT alone was 22%. Receiver operator characteristic analysis of percent change in SULmax by C1D15 yielded an area under the curve of 0.72 (80% CI, 0.64 to 0.80; one-sided P = .12), which did not reject the null hypothesis. However, between patients who obtained pCR and who did not, a significant difference in median percent reduction in SULmax by C1D15 was observed (63.8% v 41.8%; P = .004) and SULmax reduction ≥ 40% was more prevalent (83% v 52%; P = .03; positive predictive value, 31%). Participants not obtaining a 40% reduction in SULmax by C1D15 were unlikely to obtain pCR (negative predictive value, 91%)., Conclusion: Although the primary objective was not met, early changes in SULmax predict response to PT in estrogen receptor-negative and HER2-positive breast cancer. Once optimized, this quantitative imaging strategy may facilitate tailoring of therapy in this setting., Competing Interests: Roisin M. ConnollyResearch Funding: Genentech/Roche, Puma Biotechnology, Novartis, Merck, MacrogenicsOther Relationship: Pfizer Lilja SolnesConsulting or Advisory Role: ProgenicsResearch Funding: AAA/Novartis, Progenics Vandana AbramsonEmployment: HCA HealthcareConsulting or Advisory Role: Eisai, Daiichi Sankyo, AbbvieResearch Funding: Genentech/Roche, Lilly Lisa A. CareyResearch Funding: Innocrin Pharma, Syndax, Immunomedics, Novartis, NanoString Technologies, Abbvie, Seattle GeneticsPatents, Royalties, Other Intellectual Property: Royalty-sharing agreement, investorship interest in licensed IP to startup company, Falcon Therapeutics, that is designing neural stem cell-based therapy for glioblastoma multiformeUncompensated Relationships: Sanofi, Novartis, G1 Therapeutics, Genentech/Roche, GlaxoSmithKline, Exact Sciences, AstraZeneca/Daiichi Sankyo, Aptitude HealthOpen Payments Link: https://openpaymentsdata.cms.gov/physician/179671 Minetta C. LiuResearch Funding: Eisai, Seattle Genetics, Novartis, Roche/Genentech, GRAIL, Merck, Tesaro, Menarini Silicon Biosystems, Genomic HealthTravel, Accommodations, Expenses: Grail, Merck, Menarini Silicon Biosystems, Pfizer, Genomic Health, AstraZeneca, Ionis Pharmaceuticals Mothaffar RimawiConsulting or Advisory Role: Macrogenics, Daiichi Sankyo, Seattle Genetics, GenentechResearch Funding: Pfizer Jennifer SpechtHonoraria: Nektar, Genomic Health, Daiichi SankyoConsulting or Advisory Role: Genomic Health, Nektar, Daiichi SankyoResearch Funding: Pfizer, Nektar, Merck, Myriad Pharmaceuticals, Cascadian Therapeutics, Pfizer, Minerva Biotechnologies, Seattle Genetics, Novartis, Chalasani, Xencor, Johns Hopkins University, Genentech, Dana-Farber Cancer Institute, NCITravel, Accommodations, Expenses: Nektar Anna Maria StornioloEmployment: Sophren Therapeutics, Q32Bio IncLeadership: Sophren Therapeutics, Q32Bio IncStock and Other Ownership Interests: Gilead Sciences, Moderna Therapeutics, Merck, Lilly, Gilead, Pfizer, Meridian Bioscience IncConsulting or Advisory Role: Q32bio, Tri-I TDI, Deerfield Management, Atlas Venture, Boston PharmaceuticalsResearch Funding: QUE Oncology, Pfizer Vicente ValeroHonoraria: Genentech/Roche, Merck, NovartisConsulting or Advisory Role: Genentech/Roche, Novartis, MerckTravel, Accommodations, Expenses: Genentech/Roche Christos VaklavasEmployment: Flatiron HealthHonoraria: Guidepoint GlobalConsulting or Advisory Role: Daiichi SankyoResearch Funding: Genentech, Roche, Pfizer, Incyte, Pharmacyclics, Novartis, TRACON Pharma, Innocrin Pharma, Zymeworks, H3 BiomedicineOther Relationship: Puma Biotechnology, Takeda, Daiichi SankyoUncompensated Relationships: GenentechOpen Payments Link: https://openpaymentsdata.cms.gov/physician/1306968 Ian E. KropEmployment: AMAG Pharmaceuticals, Freeline TherapeuticsLeadership: AMAG Pharmaceuticals, Freeline TherapeuticsStock and Other Ownership Interests: AMAG Pharmaceuticals, Freeline Therapeutics, VertexHonoraria: Genentech/Roche, AstraZeneca, CelltrionConsulting or Advisory Role: Genentech/Roche, Seattle Genetics, Daiichi Sankyo, Macrogenics, Taiho Pharmaceutical, Context Therapeutics, Novartis, Merck, Ionis Pharmaceuticals, Bristol Myers Squibb, AstraZenecaResearch Funding: Genentech, Pfizer Eric P. WinerHonoraria: Genentech/Roche, Genomic HealthConsulting or Advisory Role: Leap Therapeutics, Seattle Genetics, Jounce Therapeutics, GlaxoSmithKline, Carrick Therapeutics, Lilly, G1 Therapeutics, Syros Pharmaceuticals, Genentech/Roche, Gilead Sciences, ZymeworksResearch Funding: Genentech, AstraZenecaOther Relationship: InfiniteMD Antonio C. WolffConsulting or Advisory Role: Ionis PharmaceuticalsResearch Funding: Biomarin, CelldexPatents, Royalties, Other Intellectual Property: Antonio Wolff has been named as inventor on one or more issued patents or pending patent applications relating to methylation in breast cancer, and has assigned his rights to JHU, and participates in a royalty sharing agreement with JHUOpen Payments Link: https://openpaymentsdata.cms.gov/physician/357301/summary Ashley Cimino-MathewsEmployment: Vivante HealthHonoraria: Bristol Myers Squibb, RocheResearch Funding: Bristol Myers Squibb Ben H. ParkLeadership: LoxoStock and Other Ownership Interests: Loxo, CelcuityHonoraria: AstraZenecaConsulting or Advisory Role: Horizon Discovery, Foundation Medicine, Loxo, Casdin Capital, H3 Biomedicine, Jackson Laboratory for Genomic Medicine, Lilly, Celcuity, Sermonix Pharmaceuticals, PathovaxResearch Funding: Abbvie, Pfizer, GE Healthcare, LillyPatents, Royalties, Other Intellectual Property: Royalties paid through inventions at Johns Hopkins University by Horizon Discovery LtdTravel, Accommodations, Expenses: Lilly, LoxoUncompensated Relationships: Tempus Richard L. WahlStock and Other Ownership Interests: ProgenicsHonoraria: Siemens Healthineers, Bristol Myers Squibb, Jubilant DraxImage, Actinium Medical Advisory BoardConsulting or Advisory Role: Clarity PharmaceuticalsResearch Funding: Whiterabbit AI, Siemens Healthineers, Bristol Myers Squibb, Actinium PharmaceuticalsTravel, Accommodations, Expenses: Siemens Healthineers, Actinium PharmaceuticalsOther Relationship: Society of Nuclear Medicine Vered StearnsResearch Funding: Abbvie, Pfizer, Novartis, Puma Biotechnology, BioceptOther Relationship: ImmunomedicsNo other potential conflicts of interest were reported.

Background: HER2-positive (+) breast cancers, defined by HER2 overexpression and/or amplification, are often addicted to HER2 to maintain their malignant phenotype. Yet, some HER2+ tumors do not benefit from anti-HER2 therapy. We hypothesize that HER2 amplification levels and PI3K pathway activation are key determinants of response to HER2-targeted treatments without chemotherapy., Patients and Methods: Baseline HER2+ tumors from patients treated with neoadjuvant lapatinib plus trastuzumab [with endocrine therapy for estrogen receptor (ER)+ tumors] in TBCRC006 (NCT00548184) were evaluated in a central laboratory for HER2 amplification by fluorescence in situ hybridization (FISH) (n = 56). HER2 copy number (CN) and FISH ratios, and PI3K pathway status, defined by PIK3CA mutations or PTEN levels by immunohistochemistry were available for 41 tumors. Results were correlated with pathologic complete response (pCR; no residual invasive tumor in breast)., Results: Thirteen of the 56 patients (23%) achieved pCR. None of the 11 patients with HER2 ratio <4 and/or CN <10 achieved pCR, whereas 13/45 patients (29%) with HER2 ratio ≥4 and/or CN ≥10 attained pCR (P = 0.0513). Of the 18 patients with tumors expressing high PTEN or wild-type (WT) PIK3CA (intact PI3K pathway), 7 (39%) achieved pCR, compared with 1/23 (4%) with PI3K pathway alterations (P = 0.0133). Seven of the 16 patients (44%) with HER2 ratio ≥4 and intact PI3K pathway achieved pCR, whereas only 1/25 (4%) patients not meeting these criteria achieved pCR (P = 0.0031)., Conclusions: Our findings suggest that there is a clinical subtype in breast cancer with high HER2 amplification and intact PI3K pathway that is especially sensitive to HER2-targeted therapies without chemotherapy. A combination of HER2 FISH ratio and PI3K pathway status warrants validation to identify patients who may be treated with HER2-targeted therapy without chemotherapy., (© The Author(s) 2019. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Purpose: Predictive biomarkers to identify patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer who may benefit from targeted therapy alone are required. We hypothesized that early measurements of tumor maximum standardized uptake values corrected for lean body mass (SULmax) on [ 18 F]fluorodeoxyglucose positron emission tomography/computed tomography would predict pathologic complete response (pCR) to neoadjuvant pertuzumab and trastuzumab (PT)., Patients and Methods: Patients with stage II/III, estrogen receptor-negative, HER2-positive breast cancer received four cycles of neoadjuvant PT. [ 18 F]Fluorodeoxyglucose positron emission tomography/computed tomography was performed at baseline and 15 days after PT initiation (C1D15). Eighty evaluable patients were required to test the null hypothesis that the area under the curve of percentage of change in SULmax by C1D15 predicting pCR is less than or equal to 0.65, with a one-sided type I error rate of 10%., Results: Eighty-eight women were enrolled (83 evaluable), and 85% (75 of 88) completed all four cycles of PT. pCR after PT alone was 34%. Receiver operating characteristic analysis yielded an area under the curve of 0.76 (90% CI, 0.67 to 0.85), which rejected the null hypothesis. Between patients who obtained pCR versus not, a significant difference in median percent reduction in SULmax by C1D15 was observed (63.8% v 33.5%; P < .001), an SULmax reduction greater than or equal to 40% was more prevalent (86% v 46%; P < .001; negative predictive value, 88%; positive predictive value, 49%), and a significant difference in median C1D15 SULmax (1.6 v 3.9; P < .001) and higher proportion of C1D15 SULmax less than or equal to 3 (93% v 38%; P < .001; negative predictive value, 94%; positive predictive value, 55%) were observed., Conclusion: Early changes in SULmax predict response to four cycles of PT in estrogen receptor-negative, HER2-positive breast cancer. Once optimized, this quantitative imaging strategy may facilitate a more tailored approach to therapy in this setting.

Background: Breast cancer patient-derived xenograft (BC-PDX) models represent a continuous and reproducible source of circulating tumor cells (CTCs) for studying their role in tumor biology and metastasis. We have previously shown the utility of BC-PDX models in the study of CTCs by immunohistochemistry (IHC) on serial paraffin sections and manual microscopic identification of cytokeratin-positive cells, a method that is both low-throughput and labor-intensive. We therefore aimed to identify and characterize CTCs from small volume mouse blood samples and examined its practical workflow in a study of BC-PDX mice treated with chemotherapy using an automated imaging platform, the AccuCyte®-CyteFinder® system., Methods: CTC analysis was conducted using blood from non-tumor bearing SCID/Beige mice spiked with human breast cancer cells, BC-PDX-bearing mice, and BC-PDX mice treated with vehicle or chemotherapeutic agent(s). After red blood cell lysis, nucleated cells were mixed with transfer solution, processed onto microscope slides, and stained by immunofluorescence. The CyteFinder automated scanning microscope was used to identify CTCs, defined as nucleated cells that were human cytokeratin-positive, and mouse CD45-negative. Disaggregated primary BC-PDX tumors and lung metastatic nodules were processed using the same immunostaining protocol. Collective expression of breast cancer cell surface markers (EpCAM, EGFR, and HER2) using a cocktail of target-specific antibodies was assessed. CTCs and disaggregated tumor cells were individually retrieved from slides using the CytePicker® module for sequence analysis of a BC-PDX tumor-specific PIK3CA mutation., Results: The recovery rate of human cancer cells spiked into murine blood was 83 ± 12%. CTC detection was not significantly different from the IHC method. One-third of CTCs did not stain positive for cell surface markers. A PIK3CA T1035A mutation present in a BC-PDX tumor was confirmed in isolated single CTCs and cells from dissociated metastatic nodules after whole genome amplification and sequencing. CTC evaluation could be simply implemented into a preclinical PDX therapeutic study setting with substantial improvements in workflow over the IHC method., Conclusions: Analysis of small volume blood samples from BC-PDX-bearing mice using the AccuCyte-CyteFinder system allows investigation of the role of CTCs in tumor biology and metastasis independent of surface marker expression.

Purpose: CDK4/6 inhibitors are used to treat estrogen receptor (ER)-positive metastatic breast cancer (BC) in combination with endocrine therapy. PALLET is a phase II randomized trial that evaluated the effects of combination palbociclib plus letrozole as neoadjuvant therapy., Patients and Methods: Postmenopausal women with ER-positive primary BC and tumors greater than or equal to 2.0 cm were randomly assigned 3:2:2:2 to letrozole (2.5 mg/d) for 14 weeks (A); letrozole for 2 weeks, then palbociclib plus letrozole to 14 weeks (B); palbociclib for 2 weeks, then palbociclib plus letrozole to 14 weeks (C); or palbociclib plus letrozole for 14 weeks. Palbociclib 125 mg/d was administered orally on a 21-days-on, 7-days-off schedule. Core-cut biopsies were taken at baseline and 2 and 14 weeks. Coprimary end points for letrozole versus palbociclib plus letrozole groups (A v B + C + D) were change in Ki-67 (protein encoded by the  MKI67 gene; immunohistochemistry) between baseline and 14 weeks and clinical response (ordinal and ultrasound) after 14 weeks. Complete cell-cycle arrest was defined as Ki-67 less than or equal to 2.7%. Apoptosis was characterized by cleaved poly (ADP-ribose) polymerase., Results: Three hundred seven patients were recruited. Clinical response was not significantly different between palbociclib plus letrozole and letrozole groups ( P = .20; complete response + partial response, 54.3% v 49.5%), and progressive disease was 3.2% versus 5.4%, respectively. Median log-fold change in Ki-67 was greater with palbociclib plus letrozole compared with letrozole (-4.1 v -2.2; P < .001) in the 190 evaluable patients (61.9%), corresponding to a geometric mean change of -97.4% versus -88.5%. More patients on palbociclib plus letrozole achieved complete cell-cycle arrest (90% v 59%; P < .001). Median log-fold change (suppression) of cleaved poly (ADP-ribose) polymerase was greater with palbociclib plus letrozole versus letrozole (-0.80 v -0.42; P < .001). More patients had grade 3 or greater toxicity on palbociclib plus letrozole (49.8% v 17.0%; P < .001) mainly because of asymptomatic neutropenia., Conclusion: Adding palbociclib to letrozole significantly enhanced the suppression of malignant cell proliferation (Ki-67) in primary ER-positive BC, but did not increase the clinical response rate over 14 weeks, which was possibly related to a concurrent reduction in apoptosis.

Purpose: To assess pertuzumab plus trastuzumab and an aromatase inhibitor (AI) in patients with human epidermal growth factor receptor 2 (HER2)-positive and hormone receptor-positive metastatic/locally advanced breast cancer (MBC/LABC)., Patients and Methods: The PERTAIN trial (NCT01491737) is an ongoing randomized, open-label, multicenter-80 sites and eight countries-phase II trial. Patients have HER2-positive, hormone receptor-positive MBC/LABC and no prior systemic therapy with the exception of endocrine. Random assignment was 1:1 to intravenous pertuzumab (840 mg loading dose followed by 420 mg every 3 weeks) plus trastuzumab (8 mg/kg followed by 6 mg/kg every 3 weeks), and oral anastrozole (1 mg every day) or letrozole (2.5 mg every day), or trastuzumab and an AI. Induction intravenous docetaxel every 3 weeks or paclitaxel every week could be administered for 18 to 24 weeks at the investigator's discretion (decided before but given after random assignment). Primary end point was progression-free survival (PFS). Patients were stratified by whether they received induction chemotherapy and their time since adjuvant hormone therapy., Results: One hundred twenty-nine patients were randomly assigned per arm (February 2012 to October 2014; intent-to-treat populations); 75 in one arm and 71 in the other were chosen to receive induction chemotherapy. Stratified median PFS was 18.89 months (95% CI, 14.09 to 27.66 months) in the pertuzumab plus trastuzumab arm and 15.80 months (95% CI, 11.04 to 18.56 months) in the trastuzumab arm (stratified hazard ratio, 0.65; 95% CI, 0.48 to 0.89; P = .0070). Serious adverse events (AEs) were reported for 42 (33.1%) of 127 and 24 (19.4%) of 124 patients in the safety populations of the pertuzumab plus trastuzumab and trastuzumab arms, respectively. Rates of grade ≥ 3 AEs were 64 (50.4%) of 127 and 48 (38.7%) of 124, respectively. There were no deaths as a result of AEs., Conclusion: PERTAIN met its primary PFS end point. Pertuzumab plus trastuzumab and an AI is effective for the treatment of HER2-positive MBC/LABC. The safety profile was consistent with previous trials of pertuzumab plus trastuzumab.

Importance: Chemotherapy may induce alopecia. Although scalp cooling devices have been used to prevent this alopecia, efficacy has not been assessed in a randomized clinical trial., Objectives: To assess whether a scalp cooling device is effective at reducing chemotherapy-induced alopecia and to assess adverse treatment effects., Design, Setting, and Participants: Multicenter randomized clinical trial of women with breast cancer undergoing chemotherapy. Patients were enrolled from December 9, 2013, to September 30, 2016. One interim analysis was planned to allow the study to stop early for efficacy. Data reported are from the interim analysis. This study was conducted at 7 sites in the United States, and 182 women with breast cancer requiring chemotherapy were enrolled and randomized., Interventions: Participants were randomized to scalp cooling (n = 119) or control (n = 63). Scalp cooling was done using a scalp cooling device., Main Outcomes and Measures: The primary efficacy end points were successful hair preservation assessed using the Common Terminology Criteria for Adverse Events version 4.0 scale (grade 0 [no hair loss] or grade 1 [<50% hair loss not requiring a wig] were considered to have hair preservation) at the end of 4 cycles of chemotherapy by a clinician unaware of treatment assignment, and device safety. Secondary end points included wig use and scores on the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30, Hospital Anxiety and Depression Scale, and a summary scale of the Body Image Scale., Results: At the time of the interim analysis, 142 participants were evaluable. The mean (SD) age of the patients was 52.6 (10.1) years; 36% (n = 51) received anthracycline-based chemotherapy and 64% (n = 91) received taxane-based chemotherapy. Successful hair preservation was found in 48 of 95 women with cooling (50.5%; 95% CI, 40.7%-60.4%) compared with 0 of 47 women in the control group (0%; 95% CI, 0%-7.6%) (success rate difference, 50.5%; 95% CI, 40.5%-60.6%). Because the 1-tailed P value from the Fisher exact test was <.001, which crossed the superiority boundary (P = .0061), the data and safety monitoring board recommended study termination on September 26, 2016. There were no statistically significant differences in changes in any of the scales of quality of life from baseline to chemotherapy cycle 4 among the scalp cooling and control groups. Only adverse events related to device use were collected; 54 adverse events were reported in the cooling group, all grades 1 and 2. There were no serious adverse device events., Conclusions and Relevance: Among women with stage I to II breast cancer receiving chemotherapy with a taxane, anthracycline, or both, those who underwent scalp cooling were significantly more likely to have less than 50% hair loss after the fourth chemotherapy cycle compared with those who received no scalp cooling. Further research is needed to assess longer-term efficacy and adverse effects., Trial Registration: clinicaltrials.gov Identifier: NCT01986140.

Background: Observational and experimental data support a potential breast cancer chemopreventive effect of green tea., Methods: We conducted an ancillary study using archived blood/urine from a phase IB randomised, placebo-controlled dose escalation trial of an oral green tea extract, Polyphenon E (Poly E), in breast cancer patients. Using an adaptive trial design, women with stage I-III breast cancer who completed adjuvant treatment were randomised to Poly E 400 mg (n = 16), 600 mg (n = 11) and 800 mg (n = 3) twice daily or matching placebo (n = 10) for 6 months. Blood and urine collection occurred at baseline, and at 2, 4 and 6 months. Biological endpoints included growth factor [serum hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF)], lipid (serum cholesterol, triglycerides), oxidative damage and inflammatory biomarkers., Results: From July 2007-August 2009, 40 women were enrolled and 34 (26 Poly E, eight placebo) were evaluable for biomarker endpoints. At 2 months, the Poly E group (all dose levels combined) compared to placebo had a significant decrease in mean serum HGF levels (-12.7% versus +6.3%, P = 0.04). This trend persisted at 4 and 6 months but was no longer statistically significant. For the Poly E group, serum VEGF decreased by 11.5% at 2 months (P = 0.02) and 13.9% at 4 months (P = 0.05) but did not differ compared to placebo. At 2 months, there was a trend toward a decrease in serum cholesterol with Poly E (P = 0.08). No significant differences were observed for other biomarkers., Conclusions: Our findings suggest potential mechanistic actions of tea polyphenols in growth factor signalling, angiogenesis and lipid metabolism., (© 2014 The British Dietetic Association Ltd.)

Background: Brain metastasis from breast cancer presents a significant threat to women's health and quality of life. Capecitabine and sunitinib have shown some activity in this setting; therefore, we conducted a single-arm phase II trial with these agents., Methods: Patients with breast cancer and central nervous system (CNS) metastases received whole-brain radiotherapy concurrently with capecitabine (1,000 mg/m(2) per day for 14 consecutive days), followed by concomitant capecitabine (2,000 mg/m(2) per day for 2 weeks followed by a 1-week break) and sunitinib (37.5 mg daily, continuously). The primary endpoint was progression-free survival (PFS)., Results: Of 25 planned patients that would be required to detect a 4-month improvement (from 5 to 9 months) in median PFS with 80% power, 12 were enrolled, and the study was then closed for slow accrual. Median PFS was 4.7 months, and median overall survival was 10 months. In the CNS, 25% had progressive disease, and 83% experienced extra-CNS progression. The most common side effects were fatigue and nausea., Conclusion: In 12 evaluable patients studied, concurrent capecitabine and whole-brain radiation followed by capecitabine and sunitinib did not extend PFS over historical rates and was associated with significant toxicity. Our study was small and closed due to slow accrual., (©AlphaMed Press; the data published online to support this summary is the property of the authors.)

Purpose: Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate comprising the humanized monoclonal antibody trastuzumab linked to DM1, a highly potent cytotoxic agent. A population pharmacokinetic (PK) analysis was performed to estimate typical values and interindividual variability of T-DM1 PK parameters and the effects of clinically relevant covariates., Methods: Serum samples were collected from 671 patients with human epidermal growth factor receptor 2-positive locally advanced or metastatic breast cancer (MBC) who received single-agent T-DM1 in five phase I to phase III studies. Nonlinear mixed-effects modeling with the first-order conditional estimation method was used., Results: A linear two-compartment model with first-order elimination from the central compartment described T-DM1 PKs in the clinical dose range. T-DM1 elimination clearance was 0.676 L/day, volume of distribution in the central compartment (V c) was 3.127 L, and terminal elimination half-life was 3.94 days. Age, race, region, and renal function did not influence T-DM1 PK. Given the low-to-moderate effect of all statistically significant covariates on T-DM1 exposure, none of these covariates is expected to result in a clinically meaningful change in T-DM1 exposure., Conclusions: T-DM1 PK properties are consistent and predictable in patients. A further refinement of dose based on baseline covariates other than body weight for the current 3.6 mg/kg regimen would not yield clinically meaningful reductions in interindividual PK variability in patients with MBC.

Studies on well characterized, large populations of estrogen receptor (ER)/progesterone receptor (PgR)/HER2-negative [triple-negative (TN)] breast cancer (BC) patients with long-term follow-up are lacking. In this study, we analyze clinical outcomes of TN BC and implications of epidermal growth factor receptor (EGFR) expression. Clinical and biologic features, time to first recurrence (TTFR), and overall survival (OS) were compared in 253 TN versus 1,036 ER positive, PgR positive, HER2-negative [estrogen-driven (ED)] BC. Compared to ED, TN tumors were larger (p = 0.02), more proliferative (high S-phase 54 vs. 17 %, p < 0.0001), more aneuploid (64 vs. 43 %, p < 0.0001) and more likely EGFR positive (≥10 fmol/mg by radioligand-binding assay, 49 vs. 7 %, p < 0.0001). Among TN, EGFR-positive BC were larger (p = 0.0018), more proliferative (p < 0.0001), and more aneuploid, (p < 0.0001) than EGFR-negative BC. Adjuvant-treated TN patients had shorter TTFR (p = 0.0003), and OS (p = 0.0017), than ED patients. However, in untreated patients, no differences in TTFR and OS were observed at 8 years median follow-up. Among TN patients, EGFR expression was not associated with worse outcome. TN tumors have a worse outcome in systemically treated patients but not in untreated patients. EGFR expression, does not predict for worse long-term survival.

Epidemiologic data support an inverse association between green tea intake and breast cancer risk, and numerous experimental studies have shown the antitumor effects of its main component, epigallocatechin gallate (EGCG). We conducted a phase IB dose escalation trial in women with a history of stage I to III hormone receptor-negative breast cancer of an oral green tea extract, polyphenon E (Poly E) 400, 600, 800 twice daily or matching placebo for 6 months. The primary endpoint was to determine the maximum tolerated dose (MTD), defined as the dose that causes 25% dose-limiting toxicity (DLT, grade ≥II). Assignment to dose level was based upon an adaptive design, the continual reassessment method. A mammogram and random core biopsy of the contralateral breast were obtained at baseline and 6 months and serial blood/urine collections every 2 months for biomarker analyses. Forty women were randomized: 10 to placebo, 30 to Poly E (16 at 400 mg, 11 at 600 mg, 3 at 800 mg). There was one DLT at 400 mg (grade III rectal bleeding), three DLTs at 600 mg (grade II weight gain, grade III indigestion and insomnia), and one DLT at 800 mg (grade III liver function abnormality). The DLT rate at 600 mg was 27% (3 of 11). Pharmacologic levels of total urinary tea polyphenols were achieved with all three dose levels of Poly E. Using a novel phase I trial design, we determined the MTD for Poly E to be 600 mg twice daily. This study highlights the importance of assessing toxicity for any chemopreventive agent being developed for chronic use in healthy individuals.

We studied resistance to endocrine and HER2-targeted therapies using a xenograft model of estrogen receptor positive (ER)/HER2-overexpressing breast cancer. Here, we report a novel phenotype of drug resistance in this model. MCF7/HER2-18 xenografts were treated with endocrine therapy alone or in combination with lapatinib and trastuzumab (LT) to inhibit HER2. Archival tumor tissues were stained with hematoxylin and eosin and with mucicarmine. RNA extracted from tumors at early time points and late after acquired resistance were analyzed for mucin4 (MUC4) expression by microarray and quantitative reverse transcriptase-PCR. Protein expression of the MUC4, ER, and HER2 signaling pathways was measured by immunohistochemistry and western blotting. The combination of the potent anti-HER2 regimen LT with either tamoxifen (Tam + LT) or estrogen deprivation (ED + LT) can cause complete eradication of ER-positive/HER2-overexpressing tumors in mice. Tumors developing resistance to this combination, as well as those acquiring resistance to endocrine therapy alone, exhibited a distinct histological and molecular phenotype-a striking increase in mucin-filled vacuoles and upregulation of several mucins including MUC4. At the onset of resistance, MUC4 mRNA and protein were increased. These tumors also showed upregulation and reactivation of HER2 signaling, while losing ER protein and the estrogen-regulated gene progesterone receptor. Mucins are upregulated in a preclinical model of ER-positive/HER2-overexpressing breast cancer as resistance develops to the combination of endocrine and anti-HER2 therapy. These mucin-rich tumors reactivate the HER2 pathway and shift their molecular phenotype to become more ER-negative/HER2-positive.

Endocrine therapy in patients with breast cancer can be limited by the problem of resistance. Preclinical studies suggest that complete blockade of the estrogen receptor (ER) combined with inhibition of the epidermal growth factor receptor can overcome endocrine resistance. We tested this hypothesis in a phase II neoadjuvant trial of anastrozole and fulvestrant combined with gefitinib in postmenopausal women with newly diagnosed ER-positive breast cancer. After a baseline tumor core biopsy, patients were randomized to receive anastrozole and fulvestrant or anastrozole, fulvestrant, and gefitinib (AFG) for 3 weeks. After a second biopsy at 3 weeks, all patients received AFG for 4 months and surgery was done if the tumor was operable. The primary endpoint was best clinical response by RECIST criteria and secondary endpoints were toxicity and change in biomarkers. The study closed after 15 patients were enrolled because of slow accrual. Median patient age was 67 years and median clinical tumor size was 7 cm. Four patients had metastatic disease present. Three patients withdrew before response was assessed. In the remaining 12 patients, there were two complete clinical responses (17%), three partial responses (25%), five had stable disease (41%), and two (17%) had progressive disease. Most common adverse events were rash in four patients, diarrhea in four, joint symptoms in three, and abnormal liver function tests in three. There were no grade 4 toxicities and all toxicities were reversible. At 3 weeks, cell proliferation as measured by Ki-67 was significantly reduced in the AFG group (P value = 0.01), with a parallel reduction in the expression of the Cyclin D1 (P value = 0.02). RNA microarray data showed a corresponding decrease in the expression of cell cycle genes. These results suggest that AFG was an effective neoadjuvant therapy and consistently reduced proliferation in ER-positive tumors.

Purpose: Phosphatase and tensin homolog (PTEN) loss or activating mutations of phosphoinositol-3 (PI3) kinase (PIK3CA) may be associated with trastuzumab resistance. Trastuzumab, the humanized human epidermal growth factor receptor 2 (HER2) monoclonal antibody, and lapatinib, an epidermal growth factor receptor/HER2 tyrosine kinase inhibitor, are both established treatments for HER2-overexpressing breast cancers. Understanding of the cellular response to HER2-targeted therapies is needed to tailor treatments and to identify patients less likely to benefit., Methods: We evaluated the effect of trastuzumab or lapatinib in three HER2-overexpressing cell lines. We confirmed the in vitro observations in two neoadjuvant clinical trials in patients with HER2 overexpression; 35 patients received trastuzumab as a single agent for the first 3 weeks, then docetaxel every 3 weeks for 12 weeks (trastuzumab regimen), whereas 49 patients received lapatinib as a single agent for 6 weeks, followed by trastuzumab/docetaxel for 12 weeks before primary surgery (lapatinib regimen). Apoptosis, Ki67, p-MAPK, p-AKT, and PTEN were assessed by immunohistochemistry. Genomic DNA was sequenced for PIK3CA mutations., Results: Under low PTEN conditions, in vitro data indicate that lapatinib alone and in combination with trastuzumab was effective in decreasing p-MAPK and p-AKT levels, whereas trastuzumab was ineffective. In the clinical trials, we confirmed that low PTEN or activating mutation in PIK3CA conferred resistance to the trastuzumab regimen (P = .015), whereas low PTEN tumors were associated with a high pathologic complete response rate (P = .007)., Conclusion: Activation of PI3 kinase pathway is associated with trastuzumab resistance, whereas low PTEN predicted for response to lapatinib. These observations support clinical trials with the combination of both agents.

We hypothesized that a subset of sporadic triple negative (TN) breast cancer patients whose tumors have defective DNA repair similar to BRCA1-associated tumors are more likely to exhibit up-regulation of DNA repair-related genes, anthracycline-sensitivity, and taxane-resistance. We derived a defective DNA repair gene expression signature of 334 genes by applying a previously published BRCA1-associated expression pattern to three datasets of sporadic TN breast cancers. We confirmed a subset of 69 of the most differentially expressed genes by quantitative RT-PCR, using a low density custom array (LDA). Next, we tested the association of this DNA repair microarray signature expression with pathologic response in neoadjuvant anthracycline trials of FEC (n = 50) and AC (n = 16), or taxane-based TET chemotherapy (n = 39). Finally, we collected paraffin-fixed, formalin-embedded biopsies from TN patients who had received neoadjuvant AC (n = 28), and tested the utility of the LDA to discriminate response. Correlation between RNA expression measured by the microarrays and 69-gene LDA was ascertained. This defective DNA repair microarray gene expression pattern was significantly associated with anthracycline response and taxane resistance, with the area under the ordinary receiver operating characteristic curve (AUC) of 0.61 (95% CI = 0.45-0.77), and 0.65 (95% CI = 0.46-0.85), respectively. From the FFPE samples, the 69-gene LDA could discriminate AC responders, with AUC of 0.79 (95% CI = 0.59-0.98). In conclusion, a promising defective DNA repair gene expression signature appears to differentiate TN breast cancers that are sensitive to anthracyclines and resistant to taxane-based chemotherapy, and should be tested in clinical trials with other DNA-damaging agents and PARP-1 inhibitors.

Not all breast cancers respond to tamoxifen, and many develop resistance despite initial benefit. We used an in vivo model of estrogen receptor (ER)-positive breast cancer (MCF-7 xenografts) to investigate mechanisms of this resistance and develop strategies to circumvent it. Epidermal growth factor receptor (EGFR) and HER2, which were barely detected in control estrogen-treated tumors, increased slightly with tamoxifen and were markedly increased when tumors became resistant. Gefitinib, which inhibits EGFR/HER2, improved the antitumor effect of tamoxifen and delayed acquired resistance, but had no effect on estrogen-stimulated growth. Phosphorylated levels of p42/44 and p38 mitogen-activated protein kinases (both downstream of EGFR/HER2) were increased in the tamoxifen-resistant tumors and were suppressed by gefitinib. There was no apparent increase in phosphorylated AKT (also downstream of EGFR/HER2) in resistant tumors, but it was nonetheless suppressed by gefitinib. Phosphorylated insulin-like growth factor-IR (IGF-IR), which can interact with both EGFR and membrane ER, was elevated in the tamoxifen-resistant tumors compared with the sensitive group. However, ER-regulated gene products, including total IGF-IR itself and progesterone receptor, remained suppressed even at the time of acquired resistance. Tamoxifen's antagonism of classic ER genomic function was retained in these resistant tumors and even in tumors that overexpress HER2 (MCF-7 HER2/18) and are de novo tamoxifen-resistant. In conclusion, EGFR/HER2 may mediate tamoxifen resistance in ER-positive breast cancer despite continued suppression of ER genomic function by tamoxifen. IGF-IR expression remains dependent on ER but is activated in the tamoxifen-resistant tumors. This study provides a rationale to combine HER inhibitors with tamoxifen in clinical studies, even in tumors that do not initially overexpress EGFR/HER2.

Background: Human epidermal growth factor receptor 2 (HER2) is a member of the HER signaling pathway. HER inhibitors partially block HER signaling and tumor growth in preclinical breast cancer models. We investigated whether blockade of all HER homo- and heterodimer pairs by combined treatment with several inhibitors could more effectively inhibit tumor growth in such models., Methods: Mice carrying xenograft tumors of HER2-overexpressing MCF7/HER2-18 (HER2-transfected) or BT474 (HER2-amplified) cells were treated with estrogen supplementation or estrogen withdrawal, alone or combined with tamoxifen. One to three HER inhibitors (pertuzumab, trastuzumab, or gefitinib) could also be added (n > or = 8 mice per group). Tumor volumes, HER signaling, and tumor cell proliferation and apoptosis were assessed. Results were analyzed with the t test or Wilcoxon rank sum test and survival analysis methods. All statistical tests were two-sided., Results: Median time to tumor progression was 21 days for mice receiving estrogen and 28 days for mice receiving estrogen and pertuzumab (difference = 7 days; P = .001; hazard ratio [HR] of progression in mice receiving estrogen and pertuzumab versus mice receiving estrogen = 0.27, 95% confidence interval [CI] = 0.09 to 0.77). Addition of gefitinib and trastuzumab to estrogen and pertuzumab increased this time to 49 days (difference = 21 days; P = .004; HR of progression = 0.28, 95% CI = 0.10 to 0.76). MCF7/HER2-18 tumors disappeared completely and did not progress (for > or = 189 days) after combination treatment with pertuzumab, trastuzumab, and gefitinib plus tamoxifen (19 of 20 mice) or plus estrogen withdrawal (14 of 15 mice). Both combination treatments induced apoptosis and blocked HER signaling and proliferation in tumor cells better than any single agent or dual combination. All BT474 tumors treated with pertuzumab, trastuzumab, and gefitinib disappeared rapidly, regardless of endocrine therapy, and no tumor progression was observed for 232 days., Conclusion: Combined treatment with gefitinib, trastuzumab, and pertuzumab to block signals from all HER homo- and heterodimers inhibited growth of HER2-overexpressing xenografts statistically significantly better than single agents and dual combinations.

HER-2/neu in breast cancer is associated with tamoxifen resistance, but little data exist on its interaction with estrogen deprivation or fulvestrant. Here, we used an in vivo xenograft model of estrogen receptor (ER)-positive breast cancer with HER-2/neu overexpression (MCF7/HER-2/neu-18) to investigate mechanisms of growth inhibition and treatment resistance. MCF7/HER-2/neu-18 tumors were growth inhibited by estrogen deprivation and with fulvestrant, but resistance developed in 2 to 3 months. Inhibited tumors had reductions in ER, insulin-like growth factor-I receptor (IGF-IR), phosphorylated HER-2/neu (p-HER-2/neu), and phosphorylated p42/44 mitogen-activated protein kinase (p-MAPK). p27 was increased especially in tumors sensitive to estrogen deprivation. Tumors with acquired resistance to these therapies had complete loss of ER, increased p-HER-2/neu, increased p-MAPK, and reduced p27. In contrast, IGF-IR and phosphorylated AKT (p-AKT) levels were markedly reduced in these resistant tumors. The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib, which can block EGFR/HER-2/neu signaling, significantly delayed the emergence of resistance to both estrogen deprivation and fulvestrant. Levels of p-MAPK and p-AKT decreased with gefitinib, whereas high ER levels were restored. Eventually, however, tumors progressed in mice treated with gefitinib combined with estrogen deprivation or fulvestrant accompanied again by loss of ER and IGF-IR, increased p-HER-2/neu, high p-MAPK, and now increased p-AKT. Thus, estrogen deprivation and fulvestrant can effectively inhibit HER-2/neu-overexpressing tumors but resistance develops quickly. EGFR/HER-2/neu inhibitors can delay resistance, but reactivation of HER-2/neu and signaling through AKT leads to tumor regrowth. Combining endocrine therapy with EGFR/HER-2/neu inhibitors should be tested in clinical breast cancer, but a more complete blockade of EGFR/HER-2/neu may be optimal.

Estrogen receptor (ER), mediating estrogen-signaling stimuli, is a dominant regulator and a key therapeutic target in breast cancer etiology and progression. Endocrine therapy, blocking the ER pathway, is one of the most important systemic therapies in breast cancer management, but de novo and acquired resistance is still a major clinical problem. New research highlights the role of both genomic and nongenomic ER activities and their intimate molecular crosstalk with growth factor receptor and other signaling kinase pathways in endocrine resistance. These signaling pathways, when overexpressed and/or hyperactivated, can modulate both activities of ER, resulting in endocrine resistance. Thus, these signal transduction receptors and signaling molecules may serve as both predictive markers and novel therapeutic targets to circumvent endocrine resistance. Compelling experimental and clinical evidence suggest that the epidermal growth factor/HER2/neu receptor (EGFR/HER2) pathway might play a distinct role in endocrine resistance, and especially in resistance to selective estrogen receptor modulators (SERMs) such as tamoxifen. Results from preclinical studies of treatment combinations with various endocrine therapy drugs together with several potent anti-EGFR/HER2 inhibitors are very promising, and clinical trials to see whether this new strategy is effective in patients are now ongoing.