Trastuzumab-containing Therapy Research Articles

Beamion BCGC-1: A phase Ib/II trial of the HER2-selective tyrosine kinase inhibitor (TKI) zongertinib (BI 1810631) + trastuzumab deruxtecan (T-DXd) or trastuzumab emtansine (T-DM1) for patients with metastatic breast cancer (mBC) and metastatic gastric, gastroesophageal junction, or esophageal adenocarcinoma (mGEAC).

TPS509 Background: Approximately 15% of mGEAC tumors overexpress HER2. Currently, the HER2-targeted antibody-drug conjugate (ADC), T-DXd, is approved in mGEAC as a second-line or later-line treatment option following the failure of prior trastuzumab-containing therapy. Zongertinib (BI 1810631) is a novel, orally administered HER2-selective TKI that spares EGFR. In a Phase I trial (NCT04886804), zongertinib showed encouraging tolerability and efficacy in patients with HER2 aberration-positive advanced solid tumors, including mGEAC. Beamion BCGC-1 (NCT06324357) is a Phase Ib/II dose escalation/optimization trial investigating zongertinib plus T-DXd or T-DM1 in patients with HER2+ mGEAC or mBC. Here we focus on the mGEAC cohorts, in which patients will receive zongertinib in combination with T-DXd. Methods: Across the whole trial, approximately 240 patients will be enrolled from approximately 48 sites in 6 countries. In the mGEAC cohorts, approximately 80 patients with histologically/cytologically confirmed locally advanced/metastatic, unresectable, HER2-positive, pre-treated mGEAC will be enrolled. All patients must have investigator-assessed progression and documented HER2-positive disease (overexpressed and/or amplified; confirmed by immunohistochemistry and in situ hybridization). In Phase Ib, approximately 20 patients will receive escalating doses of zongertinib plus a fixed approved dose of T-DXd (6.4 mg/kg, once every 21 days). Dose escalation will be guided by a Bayesian Logistic Regression Model, with overdose control. In Phase Ib, the primary endpoint is the occurrence of dose-limiting toxicities (DLTs) during the maximum tolerated dose evaluation period (first 21-day cycle); secondary endpoints include objective response (RECIST v1.1), DLTs during the on-treatment period and pharmacokinetics. In Phase II, up to 60 patients with mGEAC will be randomized 1:1 to receive one of two zongertinib dose levels (dose levels informed by Phase Ib), plus a fixed approved dose of T-DXd. In Phase II, the primary endpoint is objective response; secondary endpoints include progression-free survival, disease control, treatment-emergent adverse events leading to dose reduction, pharmacokinetics and patient-reported outcomes. Patients will remain on treatment until disease progression, undue toxicity or any other protocol-defined stopping criterion. Enrollment is ongoing. Clinical trial information: NCT06324357 .

Abstract 6298: The value of routine trastuzumab-related cardiac toxicity monitoring in gastrointestinal cancers

Abstract Background: It is a common practice to monitor trastuzumab-related cardiac toxicity (TRCT) using left ventricular ejection fraction (LVEF) in patients who receive trastuzumab-containing therapy for human epidermal growth factor receptor 2 (HER2)-positive cancers. However, this monitoring approach does not appear cost effective in patients with HER2-positive gastrointestinal (GI) cancers given poor overall survival (OS). Here, we aim to examine the incidence of clinically significant TRCT in this target population. Methods: This is a retrospective cohort study of patients with advanced HER2-positive GI cancers who received trastuzumab-containing therapies (trastuzumab +/- pertuzumab, chemotherapy +/- immunotherapy + trastuzumab, trastuzumab deruxtecan) between 2011 and 2023. HER2 status was determined by immunohistochemistry, fluorescent in situ hybridization, and/or next generation sequencing. LVEF was estimated by serial transthoracic echocardiograms (TTE). Continuous variables were summarized as median and interquartile range (IQR). Paired Wilcoxon signed rank test was used to compare serial LVEF. OS was estimated using Kaplan-Meier method. Results: A total of 243 patients were included in this study with a median age of 64 (IQR: 55-70) years. 139 (57%) patients had esophageal or GEJ adenocarcinoma; 45 (19%) patients had gastric cancer; 37 (15%) patients had colorectal cancer; and the rest had other GI cancers. Median follow-up time was 18.6 (IQR: 9.2-36) months. Median OS from cancer diagnosis and the first dose of trastuzumab-containing therapy were 24.1 (95%CI: 20.2-30.2) and 11.7 (95%CI: 10.4-15.6) months, respectively. Patients received a median of 13 cycles of trastuzumab-containing therapy for a median duration of 4.1 (IQR: 1.4-10.1) months. The median number of TTE each patient had throughout therapy was 2 (IQR: 1-4). Median baseline LVEF was 61% (IQR: 56-65%) which was significantly higher (p<0.001) than the median lowest LVEF of 58% (IQR: 53-62%) during therapy, but not different (p=0.14) from the most recent median LVEF of 60% (IQR: 56-64%) after discontinuation of trastuzumab. Among 176 patients with serial LVEF data, 16 (9%) had > 10% LVEF drop; 7 (44%) of these 16 patients had LVEF recovery. None of the cardiovascular risk factors prior to trastuzumab treatment including hypertension, diabetes, hyperlipidemia, peripheral arterial disease, coronary artery disease, and stroke were significantly associated with the development of TRCT. Conclusion: The incidence of clinically significant LVEF drop appears low in patients with advanced GI cancers as post-treatment LVEF recovery to baseline was observed at the population level. The value of using TTE to monitor TRCT in these patients with short OS should be further assessed in the perspective of cost effectiveness. Citation Format: Samual R. Kosydar, Matteo Castrichini, Mojun Zhu, Hao Xie. The value of routine trastuzumab-related cardiac toxicity monitoring in gastrointestinal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6298.

ESMO update: upper gastrointestinal cancer

SummaryAt the European Society for Medical Oncology (ESMO) 2022 annual meeting, several pertinent studies in the field of upper gastrointestinal cancer were presented. The most practice-changing study appeared to be the Destiny-Gastric02 study evaluating trastuzumab–deruxtecan as a second-line treatment option in patients with Her2-positive gastric and gastroesophageal junction cancer. The median overall survival was 12.1 months with a confirmed overall response rate of 41.8%. 55.7% of patients experienced grade ≥ 3 events with nausea, vomiting, and fatigue being the most frequently observed. This study led to the approval of trastuzumab–deruxtecan as second-line therapy in patients with Her2-positive gastric and gastroesophageal junction tumors who have experienced disease progression after first-line trastuzumab-containing therapy.

Targeting FGFR Pathway Is Not an Effective Therapeutic Strategy in Patients with Unselected Metastatic Esophagogastric Cancer Resistant to Trastuzumab

Trastuzumab plus chemotherapy is the standard of care for the first-line treatment of patients with HER2+ advanced esophagogastric (EG) cancer. Nevertheless, patients frequently develop resistance. In preclinical models, we identified the overexpression of Fibroblast Growth Factor Receptor (FGFR) 3 as a mechanism potentially involved in trastuzumab-acquired resistance. FGFR inhibition could be a potential mechanism as a second-line treatment. In this Simon's two-stage phase 2, single arm study, patients with advanced EG cancer refractory to trastuzumab-containing therapies received pemigatinib, an inhibitor of FGFR. The primary end point was the 12-week progression-free survival rate. Translational analyses were performed on tissue and plasma samples. Eight patients were enrolled in the first stage. Although the 6-week disease control rate was 25%, only one patient achieved a stable disease after 12 weeks of treatment. The trial was discontinued before the second stage. Two out of six evaluable tumor samples expressed FGFR3. No FGFRs amplification was detected. HER2 amplification was lost in three out of eight patients. Three patients had an high Tumor Mutational Burden, and two of them are significantly long-term survivors. These results do not support the therapeutic efficacy of targeting FGFR in unselected patients with advanced EG cancer, who are refractory to trastuzumab-containing therapies.

Comparing treatment and outcomes in advanced esophageal, gastroesophageal junction, and gastric adenocarcinomas: a population-based study.

Treatment of advanced or metastatic esophageal adenocarcinoma (EAC) follows the guidelines for gastroesophageal junction adenocarcinoma (GEJC) and gastric adenocarcinoma (GAC), but patients with EAC are often excluded from clinical studies of GEJC/GAC. Here we describe treatment and survival of patients with advanced EAC, GEJC, and GAC to provide population-based evidence on distinctions and similarities between these populations. Retrospective cohort study of patients with unresectable advanced (cT4b) or metastatic (cM1) EAC, GEJC, or GAC (2015-2020) were selected from the Netherlands Cancer Registry. Overall survival (OS) was assessed using Kaplan-Meier methods, log-rank tests, and multivariable Cox regression. In all, 7391 patients were included (EAC: n = 3346, GEJC: n = 1246, and GAC: n = 2798). Patients with EAC were more often males and more often had ⩾2 metastatic locations. First-line systemic therapy was received by 42%, 47%, and 36% of patients with EAC, GEJC, and GAC, respectively. Median OS was 5.0, 5.1, and 4.0 months for all patients with EAC, GEJC, and GAC, respectively (p < 0.001). Median OS from start of first-line therapy of patients with human epidermal growth factor receptor 2 (HER2)-negative adenocarcinomas was 7.6, 7.8, and 7.5 months (p = 0.12) and of patients with HER2-positive carcinoma receiving first-line trastuzumab-containing therapy was 11.0, 13.3, and 9.5 months (p = 0.37) in EAC, GEJC, and GAC, respectively. After multivariable adjustment, no difference in OS for patients with EAC, GEJC, and GAC was observed. Despite differences in clinical characteristics and treatment strategies, survival between patients with advanced EAC, GEJC, and GAC was similar. We advocate that EAC patients should not be excluded from clinical trials for patients with molecularly similar GEJC/GAC.

The adverse effects of trastuzumab-containing regimes as a therapy in breast cancer: A piggy-back systematic review and meta-analysis.

Trastuzumab is a valuable therapy option for women with ERBB2(HER2)+ breast cancer tumours, often used in combination with chemotherapy and alongside other therapies. It is known to have adverse effects, but these have proved difficult to separate from the effects of other concurrent therapies patients are usually taking. This study aims to assess the adverse effects specifically attributable to trastuzumab, and whether they vary by patient subgroup or concurrent therapies. As registered on PROSPERO (CRD42019146541), we used previous systematic reviews as well as the clinicaltrials.gov registry to identify randomised controlled trials in breast cancer which compared treatment regimes with and without trastuzumab. Neoadjuvant, adjuvant and metastatic settings were examined. Data was extracted from those which had, as of July 2022, reported adverse events. Risk of bias was assessed using ROB2. Primary outcomes were adverse events of any type or severity (excluding death). A standard random-effects meta-analysis was performed for each outcome independently. In order to ascertain whether adverse effects differed by individual factors such as age or tumour characteristics, or by use of trastuzumab concurrently with hormone therapy, we examined individual-level patient data for one large trial, HERA. 79 relevant trials were found, of which 20 contained comparable arms of trastuzumab-containing therapy and corresponding matched therapy without trastuzumab. This allowed a comparison of 8669 patients receiving trastuzumab versus 9556 receiving no trastuzumab, which gave a list of 25 statistically and clinically significant adverse effects related to trastuzumab alone: unspecified pain, asthenia, nasopharyngitis, skin disorders (mainly rash), dyspepsia, paraesthesia, infections (often respiratory), increased lacrimation, diarrhoea, myalgia, oedema (limb/peripheral), fever, nose bleeds, cardiac events, insomnia, cough, back pain, dyspnoea, chills, dizziness or vertigo, hypertension, congestive heart failure, increased levels of aspartate aminotransferase, gastrointestinal issues and dehydration. Analysis of individual patient-level data from 5102 patients suggested that nausea is slightly more likely for women taking trastuzumab who are ER+ /also taking hormone therapy than for those who are ER-/not taking hormone therapy; no other potential treatment-subgroup interactions were detected. We found no evidence for significantly increased rates of neutropenia, anaemia or lymphopenia in patients on trastuzumab-containing regimes compared to those on comparable regimes without trastuzumab. This meta-analysis should allow clinicians and patients to better identify and quantify the potential adverse effects of adding trastuzumab to their treatment regime for breast cancer, and hence inform their decision-making. However, limitations include serious risk of bias due to heterogeneity in reporting of the outcomes and the open-label nature of the trials.

Effects of Exercise on Cardiac Function Outcomes in Women Receiving Anthracycline or Trastuzumab Treatment for Breast Cancer: A Systematic Review and Meta-Analysis

Background: we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the efficacy of exercise training on cardiac function and circulating biomarkers outcomes among women with breast cancer (BC) receiving anthracycline or trastuzumab-containing therapy. Methods: PubMed, EMBASE, Cochrane Library, Web of Science and Scopus were searched. The primary outcome was change on left ventricular ejection fraction (LVEF). Secondary outcomes included diastolic function, strain imaging and circulating biomarkers. Results: Four RCTs were included, of those three were conducted during anthracycline and one during trastuzumab, involving 161 patients. All trials provided absolute change in LVEF (%) after a short to medium-term of treatment exposure (≤6 months). Pooled data revealed no differences in LVEF in the exercise group versus control [mean difference (MD): 2.07%; 95% CI: −0.17 to 4.34]. Similar results were observed by pooling data from the three RCTs conducted during anthracycline. Data from trials that implemented interventions with ≥36 exercise sessions (n = 3) showed a significant effect in preventing LVEF decline favoring the exercise (MD: 3.25%; 95% CI: 1.20 to 5.31). No significant changes were observed on secondary outcomes. Conclusions: exercise appears to have a beneficial effect in mitigating LVEF decline and this effect was significant for interventions with ≥36 exercise sessions.

A phase Ib/II, multicenter, open-label, dose-escalation, and dose-expansion study evaluating trastuzumab deruxtecan (T-DXd, DS-8201) monotherapy and combinations in patients with HER2-overexpressing gastric cancer (DESTINY-Gastric03).

TPS261 Background: For patients (pts) with HER2-overexpressing metastatic gastric cancer, trastuzumab + chemotherapy is a standard first-line option but provides only a modest overall survival (OS) benefit vs chemotherapy. T-DXd is an antibody-drug conjugate consisting of an anti-HER2 antibody, cleavable tetrapeptide-based linker, and a membrane-permeable topoisomerase I inhibitor payload. Results from a phase 1 trial showed promising antitumor activity (confirmed objective response rate [ORR], 43.2%) in pts with heavily pretreated HER2+ metastatic gastric cancer who received T-DXd (5.4 or 6.4 mg/kg; Shitara K, et al. Lancet Oncol. 2019;20:827-836). Here we describe the phase 1b/2 DESTINY-Gastric03 trial (NCT04379596) evaluating T-DXd monotherapy and combinations in pts with HER2-overexpressing gastric cancer. Methods: This is an open-label, multicenter, 2-part, phase 1b/2 study in pts with HER2-overexpressing (immunohistochemistry [IHC] 3+ or IHC 2+/in situ hybridization positive) locally advanced, unresectable or metastatic gastric or gastroesophageal junction cancer. In part 1 (dose escalation), pts who had received prior trastuzumab-containing therapy will be assigned to 1 of 5 arms: (1) T-DXd + 5-fluorouracil (5-FU); (2) T-DXd + capecitabine (C); (3) T-DXd + durvalumab; (4) T-DXd + 5-FU or C + oxaliplatin (Ox); or (5) T-DXd + 5-FU or C + durvalumab. In part 2 (dose expansion), pts with no prior treatment for metastatic disease will be randomized across 4 arms: (1) T-DXd; (2) trastuzumab + 5-FU or C + Ox or cisplatin; (3) T-DXd + 5-FU or C ± Ox; or (4) T-DXd + 5-FU or C + durvalumab. In part 2, pts will be stratified by HER2 status. Primary endpoints are safety, determination of recommended phase 2 doses (part 1), and investigator-assessed confirmed ORR per RECIST v1.1 (part 2). Secondary endpoints include confirmed ORR (part 1), disease control rate, duration of response, progression-free survival (all per investigator), OS, safety (part 2), pharmacokinetics, and immunogenicity. Clinical trial information: NCT04379596.

Primary Trastuzumab Resistance After (Neo)adjuvant Trastuzumab-containing Treatment for Patients With HER2-positive Breast Cancer in Real-world Practice

BackgroundIt is difficult to define patients with primary trastuzumab resistance (PTR) after (neo)adjuvant trastuzumab with minimal data and understanding of the actual prevalence, prognosis, and potential treatment strategies in the real-world setting. Patients and MethodsThe medical records of 1096 patients with human epidermal growth factor receptor 2-positive early-stage breast cancer who had received (neo)adjuvant trastuzumab-containing treatment from 2010 to 2016 in the Cancer Hospital and Chinese Academy of Medical Sciences were reviewed. PTR was defined as recurrence during adjuvant trastuzumab or within 12 months from their last (neo)adjuvant trastuzumab dosage. The cutoff date for data collection was September 1, 2018, with a median follow-up time of 46 months. ResultsA total of 126 recurrences were observed, and 75 (6.8%; 75/1096) of them were categorized as PTR; the remaining were non-PTR. The prognosis of patients in the PTR group was much inferior to those in the non-PTR group (27 months vs. not reached; P < .01). As expected, patients with PTR did possess a much lower response rate to first-line trastuzumab-containing therapy (27.3% vs. 61.9%; P = .02). Subgroup analyses indicated that patients in the PTR group seemed to get little survival benefit from the reuse of trastuzumab compared with those without trastuzumab (26 months vs. 28 months; P = .80). However, in the non-PTR group, re-treatment with trastuzumab in the metastatic setting prolonged the survival of patients compared to those without trastuzumab (not reached vs. 34 months; P = .04). ConclusionThis study verified the rationality of present definition of PTR after (neo)adjuvant trastuzumab. Patients with PTR did have a poor prognosis. Further research and clinical trials are required to establish the best treatment patterns for these patients.

A phase II trial of the FGFR inhibitor pemigatinib in patients with metastatic esophageal-gastric junction/gastric cancer trastuzumab resistant: the FiGhTeR trial.

Background:Prognosis of patients affected by metastatic esophageal–gastric junction (EGJ) or gastric cancer (GC) remains dismal. Trastuzumab, an anti-HER2 monoclonal antibody, is the only targeted agent approved for the first-line treatment of patients with HER2-overexpressing advanced EGJ or GC in combination with chemotherapy. However, patients invariably become resistant during this treatment. We recently identified the overexpression of fibroblast growth factor (FGF) receptor 3 (FGFR3) as a molecular mechanism responsible for trastuzumab resistance in GC models, providing the rationale for the inhibition of this receptor as a potential second-line strategy in this disease. Pemigatinib is a selective, potent, oral inhibitor of FGFR1, 2, and 3.Methods:The FiGhTeR trial is a phase II, single-arm, open-label study to assess safety and activity of the FGFR inhibitor pemigatinib as second-line treatment strategy in metastatic EGJ/GC patients progressing under trastuzumab-containing therapies. The primary endpoint is the 12-week progression-free survival rate. Plasma and tumor tissue samples will be collected for translational research analyses at baseline, during treatment, and at progression on pemigatinib.Discussion:Co-alterations in genes coding for different tyrosine-kinase receptors are emerging as relevant mechanisms of acquired resistance to anti-HER2 therapeutic strategies in GC. In particular, our group has recently identified that in GC models the overexpression of FGFR3 sustains the acquired resistance to trastuzumab. This trial aims to assess the safety, tolerability and activity of the FGFR inhibitor pemigatinib as a second-line treatment in metastatic EGJ/GC patients refractory to first-line trastuzumab-containing therapies. Furthermore, this study offers the opportunity to prospectively study mechanisms and pathways involved in trastuzumab resistance.Protocol number:CRC2017_02EudraCT Number:2017-004522-14

Abstract P6-17-04: 3-year relapse-free survival of stage II-III HER2-neu positive breast cancer treated with pertuzumab and trastuzumab-containing neoadjuvant therapy compared to trastuzumab-containing therapy

Abstract Background: Pertuzumab (P) in combination with trastuzumab (H) based chemotherapy is FDA-approved as a standard neoadjuvant treatment for patients with clinical stage II-III HER2-positive (HER2+) breast cancer (BC). The goal of this study was to evaluate the pathologic complete response (pCR) rate for neoadjuvant HP-containing regimens compared to H-containing regimens and report the 3-year relapse-free survival (RFS) for patients who had a pCR compared to those with residual disease (RD). Methods: All patients with stage II-III non-inflammatory HER2+ BC who received neoadjuvant H-containing or HP-containing therapy and underwent definitive breast and axillary surgery were identified from 2005 to 2016 through an institutional database. Medical records were examined for patient demographics, breast cancer stage, pathology results, surgical outcomes, and treatment details. pCR was defined as ypT0/is, ypN0. RFS was defined as the interval from surgery to date of last followup or death from any cause. Descriptive statistics, Cox proportional hazards, and Kaplan-Meier estimates were used for statistical analysis. Results: Patient characteristics and results by pCR or RD status are shown in the table below. The median age was 51 (22-84) years for the HP group and 50 (21-87) years for the H group. The median follow-up time was 1.9 (0-4.2) years for the HP group and 5.3 (0.1-12) years for the H group. For the HP group, the 3-year RFS was 98% (95% CI: 95, 100) for the pCR group and 90% (95% CI: 83, 97) for the RD group; HR 0.17 (0.04, 0.82), p=0.012. For the H group, the 3-year RFS was 91% (95% CI: 88,94) for the pCR group and 75% (95% CI: 71-79) for the RD group; HR 0.31 (0.22, 0.44), p&amp;lt;0.0001. Among the 520 patients who achieved pCR and the 502 patients who had RD, the effect of HP vs. H was statistically significant (pCR: HR 0.24 (0.06, 1.00); p=0.015) (no pCR: HR 0.46 (0.22, 0.94); p=0.017). Conclusion: Patients who achieve pCR have an improved 3-year RFS compared to patients who have RD. Treatment with HP-containing neoadjuvant regimens is associated with a high 3-year RFS. VariableHP (n=215)H (n=807) pCR n=121RD n=94pCR n=399RD n= 408Age at Diagnosis&amp;lt;5043%46%46%51% ≥5057%54%54%49%Menopausal StatusPremenopausal46%50%53%57% Postmenopausal54%50%47%43%Clinical Stage at DiagnosisIIA40%29%34%29% IIB29%31%23%28% IIIA14%15%17%16% IIIB0%5%5%9% IIIC17%20%21%18%Clinical Nodal StatusNode (+)63%76%69%73% Node (-)37%24%31%27%Nuclear Grade1II25%32%22%28% III75%65%78%72%HR statusHR(+)52%74%52%67% HR(-)48%26%48%33%Adjuvant therapyTrastuzumab88%80%100%100% Trastuzumab and Pertuzumab3%5%0%0% Unknown9%15%20%0%11 patient in the HP pCR group had nuclear grade 1; 2 patients in the HP RD group had nuclear grade 1 tumors 2 2 patients received adjuvant TDM-1 on the NSABP B50 protocol Citation Format: Murthy RK, Raghavendra AS, Hess KR, Barcenas CH, Lim B, Moulder SL, Giordano SH, Mittendorf EA, Thompson A, Ueno NT, Valero V, Litton JK, Tripathy D, Chavez-Macgregor M. 3-year relapse-free survival of stage II-III HER2-neu positive breast cancer treated with pertuzumab and trastuzumab-containing neoadjuvant therapy compared to trastuzumab-containing 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 P6-17-04.

Abstract P4-03-10: Clinical observation of lapatinib versus continued use of trastuzumab for trastuzumab-resistant HER2-positive advanced breast cancer

Abstract Objective: To compare the efficacy, adverse effects and survival of lapatinib versus continued use of trastuzumab for trastuzumab-resistant human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer. Methods: Patients who began the regimen of lapatinib plus capecitabine (LC or LX) or trastuzumab beyond progression (TBP) between May 2013 and October 2016 were selected from the First Affiliated Hospital of Nanjing Medical University. All of their clinical data were recorded, including age, performance status, hormone receptor status, metastatic site, primary or acquired trastuzumab resistance, previous treatment and so on. They were followed up until death or April 30, 2017. The primary end point was progression-free survival (PFS). The efficacy and safety of the two regimens were evaluated according to Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1 and Common Terminology Criteria for Adverse Events (CTCAE) version 4.0, respectively. Data were analyzed by SPSS version 19.0. Results: In total, 95 patients were identified, including 40 treated with LX and 55 with TBP. Median follow-up time was 16.0 months. There was no difference in objective response rate (ORR) and disease control rate (DCR) between the two groups. By the end of follow-up, median PFS was 6.3 months with LX and 7.1 months with TBP (P=0.676). In patients with primary trastuzumab resisitance, longer PFS was observed in LX group compared with TBP group [median PFS: 8.0 months vs. 5.3 months, hazard ratio (HR)=0.416, 95% confidence interval (CI): 0.177-0.981, P=0.038]. The incident rate of new brain metastases during treatment was 2.5% in LX group and 10.9% in TBP group, respectively (P=0.233). Both regimens showed similar outcomes in baseline brain metastases. Grade 3-4 adverse effects included diarrhea 7.5%(3/40) and hand-foot syndrome 12.5%(5/40) in LX group, along with leukopenia 18.2%(10/55), thrombocytopenia 9.1%(5/55) and nausea/vomiting 3.6%(2/55) in TBP group. Conclusion: LX and TBP were similarly effective for patients with HER2-positive breast cancer progressing on prior trastuzumab-containing therapy. Both were well tolerated in general. Lapatinib tended to reduce the risk of disease progression in patients resistant to trastuzumab primarily. LX or TBP after local treatment appeared to show no difference in treating patients with brain metastases. Citation Format: Yin Y, Li W, Huang X, Wang J, Fu Z, Li J. Clinical observation of lapatinib versus continued use of trastuzumab for trastuzumab-resistant HER2-positive advanced breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-03-10.

Trastuzumab without chemotherapy in the adjuvant treatment of breast cancer: subgroup results from a large observational study

BackgroundThe topic of trastuzumab therapy without chemotherapy in early breast cancer (EBC) has been repeatedly discussed at international consensus meetings, but is compromised by the lack of solid evidence from clinical studies.MethodsAn observational study database of patients with EBC receiving trastuzumab-containing (neo)adjuvant therapy was screened to identify those patients who did not receive cytostatic agents.ResultsOf 3935 patients, 232 (6%) were identified who received no chemotherapy, being characterized by older age, worse performance status, and/or less aggressive histology. Relapse-free survival in this cohort was 84% (95% confidence interval [CI] 78–89%) at 3 years and 80% (95% CI 74–87%) at 5 years. However, these rates were significantly worse than those in the group of patients who received chemotherapy (hazard ratio 1.49; 95% CI 1.06–2.09; P = 0.022). A similar pattern was observed for overall survival, with marginally non-significant inferiority in the group receiving no chemotherapy (hazard ratio 1.56; 95% CI 1.00–2.44; P = 0.052). Survival rates in patients receiving no chemotherapy were 93% (95% CI 88–97%) and 87% (95% CI 81–93%) at 3 and 5 years, respectively. These findings were confirmed by a propensity score analysis accounting for selection bias.ConclusionsTrastuzumab plus chemotherapy should remain the preferred option in all patients with HER2-positive EBC with an indication for adjuvant treatment. However, a limited proportion of patients will need an alternative treatment approach, either because of contraindications or the patient’s preference. In these selected patients, trastuzumab monotherapy, eventually combined with endocrine agents, might be a reasonable option offering favorable long-term outcomes by addressing the high-risk profile associated with HER2-positive disease.

FcrR3A-158 Polymorphism and Stromal Tumor-Infiltrating Lymphocytes and Survival among Patients with Metastatic HER2-Positive Breast Cancer Receiving Trastuzumab-Based Treatment.

PurposeThe prognosis of human epidermal growth factor receptor 2 (HER2)-positive breast cancer has markedly improved since the introduction of trastuzumab. We aimed to evaluate the association between stromal tumor-infiltrating lymphocyte (sTIL) or FcrR polymorphisms and survival among patients with metastatic HER2-positive breast cancer who were treated with trastuzumab.MethodsA total of 56 women with recurrent or metastatic HER2-positive breast cancer who received the trastuzumab-taxane combination as first-line treatment were included in this retrospective analysis. The single-step multiplex allele-specific real-time polymerase chain reaction technique was employed for FcrR3A genotyping. sTILs were identified via immunohistochemical analysis of surgical (n=34, 60.7%) or biopsy specimens of metastatic lesions (n=22, 39.3%).ResultsWe classified patients based on the sTIL level (≤10% [n=44] or >10% [n=12]); high sTIL counts were more commonly observed in patients with hormone receptor-negative tumors than in those with hormone receptor-positive tumors (34.8% vs. 12.1%, p=0.02). There was a significant association between high sTIL levels and longer progression-free survival in comparison to low sTIL levels (median, 28.4 months vs. 16.8 months; p=0.03). With regard to the FcrR3A-158 genotype, patients were classified into the Phenylalanine/Phenylalanine group (23 patients, 41.1%), Phenylalanine/Valine group (23 patients, 41,1%), or Valine/Valine group (10 patients, 17.9%); these classifications were not associated with clinical outcomes.ConclusionHigh sTIL expression may be associated with better efficacy of trastuzumab-containing therapy in patients with metastatic HER2-positive breast cancer. However, this finding warrants further evaluation in the larger population.

Predictive value of quantitative HER2, HER3 and p95HER2 levels in HER2-positive advanced breast cancer patients treated with lapatinib following progression on trastuzumab.

Lapatinib is a HER1 and HER2 tyrosine kinase inhibitor (TKI) approved in second line treatment of advanced or metastatic breast cancer following progression on trastuzumab-containing therapy. Biomarkers for activity of lapatinib and other TKIs are lacking.Formalin-fixed, paraffin-embedded primary tumor samples were obtained from 189 HER2-positive patients treated with lapatinib plus capecitabine following progression on trastuzumab. The HERmark® Breast Cancer Assay was used to quantify HER2 protein expression. HER3 and p95HER2 protein expression was quantified using the VeraTag® technology.Overall survival (OS) was inversely correlated with HER2 (HR = 1.9/log; P = 0.009) for patients with tumors above the cut-off positivity level by the HERmark assay. OS was significantly shorter for those with above median HER2 levels (HR = 1.7; P = 0.015) and trended shorter for those below the cut-off level of positivity by the HERmark assay (HR = 1.7; P = 0.057) compared to cases with moderate HER2 overexpression. The relationship between HER2 protein expression and OS was best captured with a U-shaped parabolic function (P = 0.004), with the best prognosis at moderate levels of HER2 protein overexpression. In a multivariate model including HER2, increasing p95HER2 expression was associated with longer OS (HR = 0.35/log; P = 0.027). Continuous HER3 did not significantly correlate with OS.Patients with moderately overexpressed HER2 levels and high p95HER2 expression may have best outcomes while receiving lapatinib following progression on trastuzumab. Further study is warranted to explore the predictive utility of quantitative HER2 and p95HER2 in guiding HER2-directed therapies.

Circulating PD-L1 (programmed death-ligand 1) and outcomes in a HER2-positive metastatic breast cancer cohort treated with first-line trastuzumab.

1024 Background: Recently the immune checkpoint inhibitors (ICIs) have demonstrated efficacy across a wide variety of cancers, but have been less effective in breast cancer. PD-L1 (B7-H1, CD274) is a ligand produced by many tumor cells and some immune cells, and suppresses the T cell immune response. This allows tumor cells to escape immune detection. PD-L1 is used as a companion tumor tissue IHC biomarker for patient selection for some of the FDA-approved ICIs (pembrolizumab), but not for others (nivolumab, atezolizumab). Circulating PD-L1 has been detected in multiple myeloma, renal, lung, and gastric cancer, but not in breast cancer. Here we correlated serum PD-L1 levels with outcome in a HER2-positive metastatic breast cancer cohort treated with trastuzumab. Methods: Pretreatment serum was obtained from 63 metastatic breast cancer patients before starting first-line trastuzumab-containing therapy. A novel ELLA microfluidic channel immunoassay platform (ProteinSimple, San Jose, CA) was employed to quantitate serum PD-L1. Serum PD-L1 levels were analyzed using continuous, quartile, and dichotomous (25%, median, and 75%) cutpoints. Progression-free survival (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method. Results: On a continuous basis, patients with higher serum PD-L1 had a significantly reduced PFS (p = 0.045) and overall survival OS (p = 0.004) compared to patients with lower serum PD-L1 levels. Patients with the higher quartiles of serum PD-L1 also trended to have reduced PFS (0.11) and significantly reduced OS (p = 0.015) compared to the lower quartiles of serum PD-L1. Finally, using either the 25th or 75th percentile of serum PD-L1 as dichotomous cutpoint, patients with higher serum PD-L1 had significantly reduced OS (p = 0.04). Conclusions: Higher circulating PD-L1 levels were prognostic for reduced PFS and OS in HER2-positive metastatic breast cancer patients treated with first-line trastuzumab. Circulating PD-L1 deserves further study for prognostic and predictive biomarker utility in larger trials of immune checkpoint inhibitors and other immunotherapies in breast and other cancers. AA, LK contributed equally.

HER2/CEP17 Ratios and Clinical Outcome in HER2-Positive Early Breast Cancer Undergoing Trastuzumab-Containing Therapy.

BackgroundAdjuvant therapy comprising the HER2 receptor antagonist trastuzumab is associated with a significant improvement in disease-free and overall survival as compared to chemotherapy alone in localized HER2-positive breast cancer (BC). However, a subset of HER2-positive tumors seems to respond less favorably to trastuzumab. Various mechanisms have been proposed for trastuzumab resistance, such as high HER2 to Chromosome 17 FISH (HER2/CEP17) ratios and the possibility that single agent trastuzumab may not suffice to efficiently block HER2 downstream signaling thresholds. In a retrospective analysis we evaluated whether HER2/CEP17 ratios might have an impact on disease-free survival (DFS).MethodsClinical records of Stage I-III BC patients with HER2-positive tumors were reviewed at our institution from 2007–2013. We analyzed demographics, tumor characteristics including tumor size and grade, lymph node involvement and estrogen receptor expression as well as treatment with respect to chemotherapeutic regimens from the clinical charts. HER2/CEP17 ratios were determined by routine pathology analysis using in situ fluorescent hybridization (FISH). Upon statistical preview we defined three groups of HER2 amplification based on FISH ratio (2.2 to 4, >4 to 8, >8), in order to evaluate an association between HER2 gene amplification and DFS with trastuzumab containing therapies. DFS was analyzed using Cox-regression.ResultsA total of 332 patients with HER2-positive BC were reviewed. Median age was 54 (range 23–89) years. The majority of tumors were classified T1 (50%) or T2 (39%), node negative (52%) and of high grade G3 histology (70%). We identified 312 (94%) tumors as immunohistochemistry (IHC) score 3+ and HER2/CEP17 ratios were available from 278 patients (84%). 30% (N = 84) had tumors with high HER2/CEP17 ratios (>8). Univariate analysis found no correlation between outcome, age, histological grade, sequence as well as anthracycline content of chemotherapy. However, a prognostic impact was detected for tumor size (p = 0.02), nodal status (p<0.01), proliferation index (p<0.01), level (≥20%) of estrogen receptor expression (p = 0.03) and neoadjuvant therapeutic setting (p = 0.03), respectively. Importantly, univariate and multivariable analysis revealed that standard trastuzumab containing chemotherapy resulted in impaired disease free survival among tumors with FISH ratio >8 (p<0.01). Although less pronounced, a similar association was found also with respect to high HER2 gene copy numbers (>12) and DFS (p = 0.01).ConclusionsIn early BC patients, tumors with high HER2 amplification ratios (>8), may less likely respond to standard trastuzumab-containing therapies. Although, we obtained a similar effect for high HER2 gene copy numbers, this provides only an indirect speculation and not a proof that high HER2/CEP17 ratios may induce HER2 resistance.

Abstract 304: HER2 basal tumors have frequent mutation of HER3 and are more resistant to HER2-targeted therapy

Abstract Background: HER2 tumors are heterogeneous at both the clinical and molecular levels (Harris et al 2007, Varadan, AACR 2015). We and others have identified a distinct molecular subtype termed ‘HER2 basal’ that demonstrates lower response to preoperative trastuzumab and is characterized by overexpression of the ‘basal-like’ signature genes (Harris, CCR 2007; Carey, JCO 2015). We sought to better understand the molecular underpinnings of the HER2 basal phenotype by performing whole exome sequencing (WES) in a cohort of HER2 tumors treated with trastuzumab-containing preoperative therapy. Methods: A multicenter trial (BrUOG 211B) was conducted to determine predictors of pathologic complete response (pCR) to trastuzumab (T)-containing preoperative therapy. Sixty HER2+ Stage II-III patients were enrolled and assigned to either a single dose of T or nab-paclitaxel (N) followed by T+N+carboplatin (TNC). Fresh tumor core biopsies were taken at baseline and 2 weeks after the initial dose of T or N. PAM50 subtyping was performed using gene expression data from patient tumor biopsies and tumors were classified into HER2-Enriched, HER2-Luminal and HER2-Basal subtypes based on ER/PR IHC values and relative expression of the proliferation-associated genes within the PAM50 gene list. WES was performed on a total of 86 samples (49 baseline and 37 from the post brief-exposure timepoint), with each sample sequenced at an average depth of 90X. Somatic mutations (single nucleotide variants and short indels) were assessed using Genome Analysis Toolkit (GATK) UnifiedGenotyper followed by a robust pipeline comparing multiple databases to eliminate germline variants. Copy-number estimation was performed on the WES data using a novel algorithm, ‘ENVE’ (Varadan, Genome Med, 2015) that robustly identifies somatic copy-number alterations. Results: WES profiles of HER2 basal tumors (n = 6) revealed lower average copy number for HER2 (2.5 vs 5.8) and were less likely to have high-level amplification (&amp;gt;4 copies per cell) of other amplicons (e.g. 11q13, 20q13) with the exception of 8q24. The so-called ‘Myc’ amplicon was co-amplified in all subtypes relatively equally (3/6 in HER2-B, 11/19 in HER2-E, 10/23 in HER2-L). HER2-B tumors were also characterized by higher frequency of mutations in Rb (2/6 versus 1/42; P = 0.0376) and HER3 (4/6 vs 2/42; P = 0.0011) compared with other subtypes and frequent alteration of p53 (4/6 versus 17/42; P = 0.22). pCR to preop TNC was HER2-B 3/8, HER2-E 10/20, HER2-L 6/21, not significant in this small cohort. The presence of HER3 mutations suggests a potential mechanism for the previously reported poor clinical response to preoperative anti-HER2 therapy in HER2 basal tumors. Conclusions: The HER2 basal subtype is more likely to exhibit mutations in HER3 and is less likely to respond to trastuzumab-based therapy. Larger cohorts are required to confirm these findings and trials of other HER2 targeted agents in this subtype should be considered. Citation Format: Vinay Varadan, Salendra Singh, Hannah Gilmore, Shikha Parsai, George Somlo, Maysa Abu-Khalaf, William Sikov, Lyndsay N. Harris. HER2 basal tumors have frequent mutation of HER3 and are more resistant to HER2-targeted therapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 304.

Cardiac Surveillance Guidelines for Trastuzumab-Containing Therapy in Early-Stage Breast Cancer: Getting to the Heart of the Matter.

Trastuzumab-containing regimens for breast cancer have significantly improved survival both in the early-stage and metastatic settings.1-8 Nevertheless, given the early signals of cardiotoxicity, a prevailing concern exists regarding the risk of cardiotoxicity, defined as a decline in left ventricular ejection fraction (LVEF) both asymptomatic and symptomatic. This concern that LVEF decline would be an early and actionable surrogate for subsequent development of congestive heart failure (CHF) led to the design and implementation of specific eligibility criteria and LVEF surveillance guidelines for the pivotal randomized adjuvant trials. These guidelines were subsequently adopted as the standard of care. However, it is increasingly unclear whether these specific recommendations are justified for all patients. Resolution of this matter is critical for our community because adherence to these guidelines was recently proposed as a quality metric.9 This issue raises the general question of the level of evidence needed to accept a toxicity screening schedule as a quality indicator. If following these guidelines is not associated with improved outcomes, then adherence to them as a quality metric should be challenged. Cardiotoxicity screening can serve to illuminate this issue. Here, we review the historical events that led to the development of the current guidelines and highlight critical knowledge gaps with regard to the benefits of screening and intervention.

Long-term outcome of HER2 positive metastatic breast cancer patients treated with first-line trastuzumab

BackgroundTrastuzumab has changed the natural history of metastatic HER2 positive breast cancer. Some patients remain well and in remission for many years. There is currently no established duration after which trastuzumab in the advanced setting can be safely discontinued. This study aims to evaluate long-term efficacy and cardiac safety of trastuzumab when used as first-line treatment for patients with metastatic HER2 positive breast cancer. Patient and methodsWe retrospectively identified 215 patients with HER2 positive, locally advanced or metastatic breast cancer who commenced first line trastuzumab-containing therapy for metastatic disease between 2001 and 2010 at The Royal Marsden Hospital. ResultsThe median progression free survival for all patients was 12 months (95%CI: 10.3–14.6 months); 103 (48%) patients remained in remission beyond one year, 59 (27%) beyond two years and 25 (12%) beyond five years. The median overall survival was 2.6 years (95% confidence interval (CI): 2.2–3.3). The objective response rate (ORR) was 65% with 17 (8%) complete responses and 120 (57%) partial responses. Trastuzumab was well tolerated. Twenty eight (13%) patients recorded any grade of left ventricular dysfunction. There was no significant difference in cardiac toxicity between those patients on less than or more than one year of trastuzumab. ConclusionTrastuzumab is associated with long-term remissions in a significant proportion of patients with metastatic HER2 positive disease when used in the first-line advanced setting.