HER2-positive Early Breast Cancer Research Articles

Evaluation of Treatment and Recurrence-Free Survival in Patients with Early HER2-Positive Breast Cancer: Real-Life Data Comparing Public and Private Healthcare

Abstract Introduction The present study was designed to compare the treatment provided in private and public health care facilities for women positive for early breast cancer of the human epidermal growth factor receptor 2 (HER2) subtype, who received anti-HER2 therapy in neoadjuvant or adjuvant settings, with an evaluation of the recurrence-free survival (RFS) and pathological complete response (pCR) rates. Materials and Methods The current is a retrospective study carried out at the Instituto Brasileiro de Controle do Cancer (IBCC Oncologia), in the city of São Paulo, Brazil. We included patients treated between 2015 and 2020. Results The study included 472 medical records of early HER2-positive breast cancer patients treated in the public and private health care systems who received neoadjuvant or adjuvant treatments. The pathological complete response (pCR) was related to a lower recurrence rate and a longer recurrence-free survival (RFS). The results showed no statistically significant difference between the public and private health care systems in terms of RFS. Discussion Although the public health care patients were diagnosed with more advanced diseases than the private health care patients, both presented similar survival rates. In spite of the small number of patients evaluated, the dual HER2 blockade did not improve the clinical outcomes. These findings should be confirmed through studies with a larger number of patients and a longer follow-up period.

Survival following adjuvant trastuzumab-based treatment among older patients with HER2-positive early invasive breast cancer: A national population-based cohort study using routine data

BackgroundRandomised controlled trials (RCTs) reported adjuvant trastuzumab-based treatment improved overall survival (OS) among patients with HER2-positive early invasive breast cancer (EIBC). Few RCTs included older patients or those with comorbidity/frailty. This study aimed to determine whether the effect of adjuvant trastuzumab-based treatment on survival outcomes varies by patient age and fitness, using national data from routine care. MethodsWomen (50+ years) newly-diagnosed with HER2-positive EIBC between 2014 and 2019 were identified from England Cancer Registry data. Registration records were linked to Systemic Anti-Cancer Therapy data for treatment details and ONS death register for mortality details. A propensity score analysis employing the inverse probability of treatment weighting method was used to balance the patient variables across treatment groups. Cox models were used to evaluate whether the effect of treatment on OS was associated with patient age and fitness; competing risks regression models were used for breast cancer-specific survival (BCSS). Results5238 women initiated adjuvant trastuzumab-based treatment. Median follow-up was 56.7 months. Comparison with 3421 women who did not receive adjuvant trastuzumab highlighted differences at diagnosis in relation to age, fitness, grade, nodal involvement, surgery type and use of radiotherapy. Weighted survival analysis found trastuzumab was associated with improved OS (hazard ratio HR 0.56, 95 %CI: 0.45–0.70) and improved BCSS (subHR 0.62, 95 %CI: 0.47–0.82). We found no evidence of a difference in effect by age or patient fitness for either outcome. ConclusionIn this national dataset, adjuvant trastuzumab was associated with improvements in survival, with an OS effect size similar to RCT evidence. The effect size was not found to vary by patient age or fitness. Chronological age and fitness alone should not be barriers to receipt of effective adjuvant targeted treatment.

280P Personalized treatment approaches with HER2DX in early HER2-positive breast cancer: A precision tool for treatment decision-making

280P Personalized treatment approaches with HER2DX in early HER2-positive breast cancer: A precision tool for treatment decision-making

HER2DX Genomic Assay in HER2-Positive Early Breast Cancer Treated with Trastuzumab and Pertuzumab: A Correlative Analysis from the PHERGain Phase II Trial.

The purpose of this study was to assess the predictive capability of HER2DX assay following (neo)adjuvant trastuzumab-pertuzumab (HP)-based therapy in HER2-positive (HER2+) early breast cancer. HER2DX was analyzed in baseline pretreatment tumors from the PHERGain trial. Patients with stage I-IIIA HER2+ early breast cancer were randomized to group A [docetaxel, carboplatin, and HP (TCHP)] and group B (HP ± endocrine therapy). PET response was evaluated after two cycles. Group A received TCHP for six cycles regardless of PET response. Group B continued with HP ± endocrine therapy for six cycles (PET responders) or with TCHP for six cycles (PET nonresponders). The primary objective of this retrospective study was to associate the HER2DX pathologic complete response (pCR) score with pCR. The secondary objective was the association of the HER2DX risk score with 3-year invasive disease-free survival (iDFS). HER2DX was performed on 292 (82.0%) tumors. The overall pCR rate was 38.0%, with pCR rates of 56.4% in group A and 33.8% in group B. In multivariable analysis including treatment and clinicopathologic factors, the HER2DX pCR score (continuous variable) significantly correlated with pCR [OR, 1.29; 95% confidence interval (CI), 1.10-1.54; P < 0.001]. HER2DX-defined pCR-high, -med, and -low groups exhibited pCR rates of 50.4%, 35.8%, and 23.2%, respectively (pCR-high vs. pCR-low OR, 3.27; 95% CI, 1.54-7.09; P < 0.001). In patients with residual disease, the HER2DX high-risk group demonstrated numerically worse 3-year iDFS than the low-risk group (89.8% vs. 100%; HR, 2.70; 95% CI, 0.60-12.18; P = 0.197). HER2DX predicts pCR in the context of neoadjuvant HP-based therapy, regardless of chemotherapy addition, and might identify patients at higher risk of recurrence among patients with residual disease.

Genomic tests for risk stratification in patients with early human epidermal growth factor receptor 2-positive breast cancer.

The purpose of this review is to provide a comprehensive overview of human epidermal growth factor receptor 2 (HER2) genomic tests, particularly focusing on the most recent developments and looking at the future prospects of this field, yet to be thoroughly explored. HER2DX is a multifeatured assay, retrospectively proved to add prognostic information and to predict pathological complete response (pCR) in patients with HER2-positive early breast cancer (EBC) undergoing neoadjuvant treatment containing HER2-directed agents. Preliminary data have shown that the assay maintains its predictive capabilities even in the context of chemotherapy-free, anti-HER2 neoadjuvant regimens, potentially selecting patients suitable for treatment de-escalation, having highly HER2-driven malignancies. Multigene prognostic assays have become essential tools in the management of EBC, providing crucial information for risk stratification.

Cost-utility and budget impact analysis of neoadjuvant dual HER2 targeted therapy for HER2-positive breast cancer in Sri Lanka

This study aimed to assess the cost-utility and budget impact of dual to single HER2 targeted neoadjuvant therapy for HER2-positive breast cancer in Sri Lanka. A five-health state Markov model with lifetime horizon was used to assess the cost-utility of neoadjuvant trastuzumab (T) plus pertuzumab (P) or lapatinib (L) compared to single therapy of T with chemotherapy (C), in public healthcare system and societal perspectives. Input parameters were estimated using local data, network meta-analysis, published reports and literature. Costs were adjusted to year 2021 (1USD = LKR194.78). Five-year budget impact for public healthcare system was assessed. Incremental cost-effectiveness ratios in societal perspective for neoadjuvantLTC plus adjuvantT (strategy 3), neoadjuvantPTC plus adjuvantT (strategy 2), neoadjuvantLTC plus adjuvantLT (strategy 5), and neoadjuvantPTC plus adjuvantPT (strategy 4) compared to neoadjuvantTC plus adjuvantT (strategy 1) were USD2716, USD5600, USD6878, and USD12127 per QALY gained, respectively. One GDP per-capita (USD3815) was considered as the cost-effectiveness threshold for the analysis. Even though only the ICER for strategy 3 was cost-effective, uncertainty of efficacy parameter was revealed. For strategy 2 neoadjuvant PTC plus adjuvant T, a 25% reduction of neoadjuvant regimen cost was required to be cost effective for use in early HER2 positive breast cancer.

Diffusion-weighted imaging in addition to contrast-enhanced MRI in identifying complete response in HER2-positive breast cancer.

The aim of this study is to investigate the added value of diffusion-weighted imaging (DWI) to dynamic-contrast enhanced (DCE)-MRI to identify a pathological complete response (pCR) in patients with HER2-positive breast cancer and radiological complete response (rCR). This is a single-center observational study of 102 patients with stage I-III HER2-positive breast cancer and real-world documented rCR on DCE-MRI. Patients were treated between 2015 and 2019. Both 1.5 T/3.0 T single-shot diffusion-weighted echo-planar sequence were used. Post neoadjuvant systemic treatment (NST) diffusion-weighted images were reviewed by two readers for visual evaluation and ADCmean. Discordant cases were resolved in a consensus meeting. pCR of the breast (ypT0/is) was used to calculate the negative predictive value (NPV). Breast pCR-percentages were tested with Fisher's exact test. ADCmean and ∆ADCmean(%) for patients with and without pCR were compared using a Mann-Whitney U-test. The NPV for DWI added to DCE is 86% compared to 87% for DCE alone in hormone receptor (HR)-/HER2-positive and 67% compared to 64% in HR-positive/HER2-positive breast cancer. Twenty-seven of 39 non-rCR DWI cases were false positives. In HR-positive/HER2-positive breast cancer the NPV for DCE MRI differs between MRI field strength (1.5 T:50% vs. 3 T:81% [p = 0.02]). ADCmean at baseline, post-NST, and ∆ADCmean were similar between patients with and without pCR. DWI has no clinically relevant effect on the NPV of DCE alone to identify a pCR in early HER2-positive breast cancer. The added value of DWI in HR-positive/HER2-positive breast cancer should be further investigated taken MRI field strength into account. The residual signal on DWI after neoadjuvant systemic therapy in cases with early HER2-positive breast cancer and no residual pathologic enhancement on DCE-MRI breast should not (yet) be considered in assessing a complete radiologic response. Radiologic complete response is associated with a pathologic complete response (pCR) in HER2+ breast cancerbut further improvement is warranted. No relevant increase in negative predictive value was observed when DWI was added to DCE. Residualsignalon DW-images without pathologic enhancement on DCE-MRI, does not indicate a lower chance of pCR.

Concurrent epirubicin and trastuzumab use increases complete pathological response rate without additional cardiotoxicity in patients with human epidermal growth factor receptor 2-positive early breast cancer: A meta-regression analysis.

Due to cardiotoxicity concerns, the concurrent use of epirubicin and trastuzumab has not been fully studied. This study aimed to examine the cardiotoxicity and pathological complete response (pCR) rate associated with the concurrent regimens in patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (EBC). We conducted a systematic search for relevant literature in the NCBI/PubMed, the Cochrane database, and international conference abstracts for phase II or III randomized controlled trials between January 1, 2000, and February 28, 2021, focusing on the concurrent regimens in patients with HER2-positive EBC. To compare the risk of cardiotoxicity and the odds of the pCR rate, we performed linear meta-regression analyses to investigate the effects of multiple covariates. We analyzed 7 neoadjuvant trials involving the concurrent use of epirubicin and trastuzumab with 1797 patients. The median cumulative dose of epirubicin used was 300 mg/m2, with a total of 96 reported adverse cardiac events. The concurrent regimens did not result in a significant increase in cardiotoxicity compared to nonconcurrent regimens (risk ratio [RR] = 1.18, 95% confidence interval [CI] = 0.68-2.05). Compared with nonconcurrent or non-anthracycline-containing regimens, concurrent regimens were associated with a significant increase in the pCR rate (odds ratio = 1.48, 95% CI = 1.04-2.12). The linear fixed-effects meta-regression analysis indicated that in trials including more patients with hormone receptor-positive EBC, the RR of cardiotoxicity significantly increased with concurrent regimens, and the pCR rate became less significant. The combination of trastuzumab and a low dose of epirubicin positively impacted the pCR rate without a significant increase in cardiotoxicity. We recommend exploring concurrent regimens for HR-negative, HER2-positive tumors to enhance pCR rates, with caution advised for HR-positive tumors due to potential cardiotoxicity.

Pharmacological properties and clinical development overview of pertuzumab (genetical recombination), trastuzumab (genetical recombination) and vorhyaluronidase alfa (genetical recombination) (PHESGO® combination for ‍subcutaneous injection MA, IN)

Pertuzumab and trastuzumab are anti-HER2 humanized monoclonal antibodies with different mechanisms of action. Their combination is expected to suppress intracellular HER2 signaling additively or synergistically. Their combination is widely recommended worldwide and has been established as a standard of care for HER2-positive breast cancer. However, improvement is required because of the prolonged time of intravenous infusion. Vorhyaluronidase alfa (rHuPH20) depolymerizes hyaluronan in the subcutaneous connective tissue. It's reported to increase the permeability and absorption levels of drugs. PHESGO® combination for subcutaneous injection MA/IN (PHESGO®) is a fixed-dose combination of pertuzumab, trastuzumab, and rHuPH20. A confirmatory phase III study (FeDeriCa) was conducted following a dose-finding phase I study (BO30185). Patients with HER2-positive early breast cancer were randomly assigned to receive either intravenous infusion of pertuzumab and trastuzumab or subcutaneous injection of PHESGO®, in combination with chemotherapy, to compare the pharmacokinetics (PK), efficacy and safety. A phase II study (PHranceSCa) was also conducted to assess patients' preference and satisfaction. Based on these results, population PK analysis, and other data, PHESGO® obtained marketing approval in Japan in September 2023 with indications for "HER2-positive breast cancer" and "advanced or recurrent HER2-positive colorectal cancer that has progressed following cancer chemotherapy and is not amenable to curative resection". By reducing the administration time, PHESGO® is expected to contribute to various needs of patients and improvement of their daily lives. Since drug preparation is not required, it can provide convenience to healthcare professionals, leading to stress reduction of medical resources as well.

Exploring the feasibility and implications of cranioencephalic computed tomography in HER2-positive breast cancer: A pilot study

BackgroundBreast cancer has several subtypes, including HER2-positive breast cancer, which is characterized by overexpression of human epidermal growth factor receptor 2 (HER2), aggressiveness, poor prognosis, and high risk of recurrence and metastasis. Brain metastases are a common complication of HER2-positive breast cancer, but brain imaging is not included in the initial staging of this disease. This prospective pilot study aimed to evaluate the usefulness of brain computed tomography (CT) in the initial staging of HER2-positive breast cancer. Patients and methodsFifty-eight patients were enrolled and demographic, clinical, and breast cancer-specific data were collected after the informed consent and ethical approval were obtained. ResultsA descriptive analysis was performed. The median age of the patients was 55 years, and the majority had good performance status. Brain CT scans were performed at diagnosis, and no brain metastases were detected in early-stage patients. However, brain CT identified brain metastases in one advanced-stage patient with clinical suspicion. ConclusionsThis study suggests that brain CT may have limited utility in the initial staging of early HER2-positive breast cancer, while it could be a valuable tool in advanced cases. Further research is needed, including a higher number of patients to identify those with high risk, which may benefit from brain imaging.

Safety and efficacy analysis of neoadjuvant pertuzumab, trastuzumab and standard chemotherapy for HER2–positive early breast cancer: real–world data from NeoPowER study

BackgroundThe addition of pertuzumab (P) to trastuzumab (H) and standard chemotherapy (CT) as neoadjuvant treatment (NaT) for patients with HER2 + breast cancer (BC), has shown to increase the pathological complete response (pCR) rate, without main safety concerns. The aim of NeoPowER trial is to evaluate safety and efficacy of P + H + CT in a real–world population.MethodsWe retrospectively reviewed the medical records of stage II–III, HER2 + BC patients treated with NaT: who received P + H + CT (neopower group) in 5 Emilia Romagna institutions were compared with an historical group who received H + CT (control group). The primary endpoint was the safety, secondary endpoints were pCR rate, DRFS and OS and their correlation to NaT and other potential variables.Results260 patients were included, 48% received P + H + CT, of whom 44% was given anthraciclynes as part of CT, compared to 83% in the control group. The toxicity profile was similar, excluding diarrhea more frequent in the neopower group (20% vs. 9%). Three patients experienced significant reductions in left ventricular ejection fraction (LVEF), all receiving anthracyclines. The pCR rate was 46% (P + H + CT) and 40% (H + CT) (p = 0.39). The addition of P had statistically correlation with pCR only in the patients receiving anthra-free regimens (OR = 3.05,p = 0.047). Preoperative use of anthracyclines (OR = 1.81,p = 0.03) and duration of NaT (OR = 1.18,p = 0.02) were statistically related to pCR. 12/21 distant-relapse events and 14/17 deaths occurred in the control group. Patients who achieve pCR had a significant increase in DRFS (HR = 0.23,p = 0.009).ConclusionsAdding neoadjuvant P to H and CT is safe. With the exception of diarrhea, rate of adverse events of grade > 2 did not differ between the two groups. P did not increase the cardiotoxicity when added to H + CT, nevertheless in our population all cardiac events occurred in patients who received anthracycline-containing regimens. Not statistically significant, higher pCR rate is achievable in patients receiving neoadjuvant P + H + CT. The study did not show a statistically significant correlation between the addition of P and long-term outcomes.

Real-World Study of Adjuvant Biosimilar Trastuzumab-dkst for HER2-Positive Breast Cancer Treatment in a Brazilian Population.

Biological monoclonal antibodies play a pivotal role in cancer treatment, with biosimilars significantly enhancing their accessibility. In Brazil's ethnically diverse setting, real-world evidence is crucial for assessing the effectiveness and applicability of these therapies in routine clinical practice. We performed a multicentric, observational, prospective real-world study on biosimilar trastuzumab-dkst for adjuvant treatment of early HER2-positive breast cancer in Brazilian patients. Data were collected using a case-report form. Of the 176 recruited, we present data from the first 59 patients (mean age 51.7 ± 12.9years) who had completed treatment with trastuzumab-dkst. The mean time from diagnosis to the first adjuvant treatment with trastuzumab-dkst was 5.5 ± 2.7months. Of the patients, 59% of patients achieved at least a 30-month follow-up. The 31.7-month invasive disease-free survival rate (IDFS) was 94.5% (95% CI 83.9-98.2%) and median IDFS was not achieved, since only three patients had invasive disease recurrence. The overall survival rate was 100% until the last assessment. The observed adverse events were similar to those presented by other studies using biosimilar or reference trastuzumab. Four serious adverse events (8.5%) were observed. A reduction in left ventricular ejection fraction of at least 10% was observed in 16.9% of participants. There was no treatment interruption, and three participants (5.1%) had their trastuzumab-dkst dose reduced. Our study reinforces the existing pivotal data, underscoring the real-world efficacy and safety of biosimilar trastuzumab-dkst in the adjuvant treatment for early HER2-positive breast cancer. The preliminary long-term effectiveness and safety data we present further validate trastuzumab-dkst's role as a cost-saving alternative in oncological care. These findings have important implications for improving patient access to crucial treatments and for the more efficient use of healthcare resources. NCT03892655.

Neoadjuvant pegylated liposomal doxorubicin-containing chemotherapy in combination with trastuzumab and pertuzumab in patients with HER2-positive early breast cancer: A randomized phase II study (METIS).

596 Background: In the neoadjuvant phase, anti-HER2 therapy is usually delayed when combined with anthracycline-containing chemotherapy regimens, since conventional anthracycline and anti-HER2 agents cannot be given simultaneously. Pegylated liposomal doxorubicin (PLD) is a modified form of doxorubicin that can lower the risk of heart damage while preserving its anticancer activity. In this study, we aimed to explore whether PLD could replace conventional anthracycline and be used earlier with anti-HER2 agents to enhance neoadjuvant efficacy without increasing cardiotoxicity. Methods: The METIS study was an investigator-initiated, multicenter, open-label, randomized, phase II study conducted at 11 centers in China. Patients aged 18 to 70 years old with previously untreated stage II–III histologically documented HER2-positive breast cancer were randomly assigned (1:1) to receive PLD-containing or epirubicin-containing neoadjuvant chemotherapy. The PLD-containing regimen consisted of 4 cycles of PLD (35 mg/m2) and cyclophosphamide (600 mg/m2) every 3 weeks, followed by 4 cycles of a taxane of the investigator's choice (docetaxel, paclitaxel, or nab-paclitaxel). The epirubicin-containing regimen consisted of 4 cycles of epirubicin (90 mg/m2) and cyclophosphamide (600 mg/m2) every 3 weeks, followed by 4 cycles of a taxane of the investigator's choice. Both regimens included trastuzumab (8 mg/kg loading dose, then 6 mg/kg maintenance dose) and pertuzumab (840 mg loading dose, then 420 mg maintenance dose) every 3 weeks. Trastuzumab and pertuzumab were given with all chemotherapy cycles in the PLD-containing group, and with the taxane cycles only in the epirubicin-containing group. The primary end point was investigator-assessed total pathological complete response (tpCR) rate in the intention-to-treat population. Results: From August 2019 to March 2023, 156 were enrolled and randomly assigned to receive PLD-containing (n=80) or epirubicin-containing (n=76) treatment. At date of data analysis, the median follow-up duration was 16.3 months. The PLD-containing treatment group had a higher rate of pathological complete response (67.5%, 95% CI 56.1-77.6) than the epirubicin-containing group (48.7%, 95% CI 37.0-60.4), with a rate difference of 18.8% (p=0.033). Only one patient in the epirubicin-containing group experienced a grade 3 decrease in left ventricular ejection fraction, while none did in the PLD-containing group. Other adverse events were similar in both groups. Conclusions: A combination of PLD and cyclophosphamide with trastuzumab and pertuzumab, followed by a taxane, trastuzumab, and pertuzumab, significantly increased the rate of tpCR without more cardiotoxicity in neoadjuvant treatment for early-stage HER2-positive breast cancer patients. Clinical trial information: NCT04172259 .

Comparing the mutation profiles of primary HER2-positive breast cancers in patients with and without brain metastases.

e13018 Background: Brain metastasis is a frequent and devastating event of HER2-positive breast cancer. Identifying the driver genes of brain metastasis is important for the prevention and treatment of brain metastasis. In this study, we compared the gene mutation profiles of primary breast cancers between patients with and without brain metastases, aiming to identify new candidate genes associated with brain metastases. Methods: HER2-positive and lymph node-positive early breast cancers of 21 patients who eventually developed brain metastases (BM group) and 27 patients without any metastasis (NM group) at a minimum 5-year follow-up were retrieved from the Sun Yat-sen University Cancer Center. Whole-exome sequencing was performed on primary breast cancers (FFPE) and matched normal breast tissues or peripheral blood. Mutect2 was used to detect somatic mutations, and Fisher’s exact test was used to identify genes mutated at different frequencies in the BM and NM groups. The mRNA expression changes of genes mutated at higher frequencies in the BM group were further analyzed in 16-pair matched HER2-positive primary breast cancers and brain metastases using the public dataset (1). Results: The BM and NM groups exhibited similar TP53 (33.3% vs. 55.6%, p=0.15) and PIK3CA (23.8% vs. 25.9%, p=1) mutation rates. The mutation rates of AP3B1 (38.1% vs. 3.7%), DHTKD1 (23.8% vs. 0), ERCC6L2 (38.1% vs. 7.4%), DNAH5 (33.3% vs. 3.7%), ZNF207 (33.3% vs. 7.4%), SPATA31E1 (19.0% vs. 0), FAM111B (19.0% vs. 0), ATG3 (19.0% vs. 0), CDK14 (19.0% vs. 0), TUT4 (19.0% vs. 0), CCNB3 (19.0% vs. 0), MGA (19.0% vs. 0), CLCA1 (28.6% vs. 3.7%), BBS7 (28.5% vs. 3.7%) and GABRG1 (38.1% vs. 11.1%) were significantly (p&lt;0.05) higher in the BM group than in the NM group. Among these genes, CDK14 and TUT4 were significantly downregulated, and ZNF207 and FAM111B were significantly upregulated in brain metastases compared to their matched primary breast cancers. Conclusions: We identified several genes with higher mutation rates in primary breast cancer of patients who eventually developed brain metastases. These genes warrant further investigation in the development of brain metastases in HER2-positive breast cancer. 1. Cosgrove et al. NC 2022.

RNA-Seq based gene expression profiling of baseline and on-treatment breast tumors to predict response to HER2-directed therapy, without chemotherapy (TBCRC026).

530 Background: Robust biomarkers are needed to personalize treatment in early stage HER2-positive breast cancer. The TBCRC026 trial (n=83) demonstrated that early metabolic changes on FDG-PET/CT [&gt;40% decline in SULmax at day 15 post treatment initiation (C1D15); C1D15 SULmax] were associated with response to neoadjuvant trastuzumab/pertuzumab (HP), without chemotherapy, in an ER-negative, HER2-positive cohort (NCT01937117). We investigated the association of RNA sequencing (RNAseq)-based gene expression signatures (GES) at baseline and on-treatment (C1D15), with early metabolic change on PET/CT and clinical outcomes. Methods: RNAseq (664 GES) was performed on baseline (n=56) and C1D15 (n=31) tumor biopsies (25 paired samples available). Association with pCR following HP (secondary), PET/CT parameters and survival (exploratory) was studied. Gene expression changes between baseline and C1D15 samples were tested by Wilcoxon signed-rank test. Association between GES and PET/CT parameters and GES with pCR were evaluated using logistic regression models. Cox regressions were performed to study the association between PET/CT SULmax at C1D15 and a B cell signature and relapse-free survival (RFS). The likelihood ratio test was used to compare the prognostic ability of two nested Cox models. Results: Both RNAseq and clinical outcomes were available in 53/83 patients. HER2-enriched (HER2-E) intrinsic subtype comprised 71% (40/56) of cases at baseline and 61% (19/31) at D15; basal subtype for 27% (15/56) and 39% (12/31), respectively. pCR rate was 19% (10/53) with all but one exhibiting HER2-E subtype. One basal-like sample underwent pCR, with downregulation of HER2 amplicon and IgG signatures slightly more prominent. Gene expression changes from baseline to C1D15 were analyzed; ERBB2was downregulated after HP (p = 0.007), B cell signatures, CD4, CD8, natural killer cells and Treg cells were significantly upregulated at C1D15. GES associated with 40% decline in SULmax at C1D15 included ERBB2 amplicon genes ( ERBB2, GRB7) and correlation to the HER2-E subtype, whereas basal-like signatures were significantly associated with lack of response on PET at C1D15. Univariate logistic regression analysis suggested that FOS-JUN, fibroblast and B cell GES at baseline were significantly associated with pCR (p=&lt;0.05). Finally, the addition of a B cell signature improved the prognostic value of C1D15 SULmax on PET/CT for RFS (p &lt; 0.05). Conclusions: In this unique cohort with ER-negative, HER2-positive breast cancer treated with neoadjuvant HP without chemotherapy, HER2-E tumors and those with increased immune signaling were more likely to respond to HER2-directed therapy. Combining C1D15 SULmax on PET/CT and a B cell signature provided improved prognostic information and should be further explored as candidate biomarkers in this setting. Clinical trial information: NCT01937117 .

A prospective phase II study of neoadjuvant therapy guided by personalized drug-testing on patient-derived tumor-like cell clusters for early breast cancer.

e12625 Background: Individual tumors of breast cancer patients possess unique characteristics that may influence their neoadjuvant therapy (NAT) response to specific cytotoxic agents and treatment choices. Therefore, it is essential to have a platform that can assist in the personalized selection of chemotherapy for individual patients. Previously, we reported an in vitro model called patient-derived tumor-like cell clusters (PTC), which can structurally and functionally recapitulate original tumors. Retrospective research has shown that PTC hold potential as reliable pre-clinical drug testing model for guiding NAT therapeutic options in early breast cancer patients. Methods: This prospective, phase II, open-label study aimed to validate the efficacy of drug screening on patient-derived tumor-like cell clusters (PTCs). TNBC and HER2 positive patients received neoadjuvant therapy based on subtype and personalized drug testing on PTCs. TNBC patients were treated based on drug testing, receiving either TA (taxanes combined with anthracyclines) or TP (taxanes combined with carboplatin). HER2 positive patients received treatment based on drug testing, including THP (taxanes, trastuzumab and pertuzumab) or TCbHP (taxanes, carboplatin, trastuzumab, and pertuzumab). Sample size calculation was performed using Fleming's two-stage design. For TNBC patients, if 10 or more out of 20 patients achieved pCR in the first stage, an additional 26 patients would be enrolled in the second stage. For HER2-positive patients, the sample size was same with TNBC patients. The study was approved by the Ethics Committee of Peking University People's Hospital in Beijing and was registered on ClinicalTrials.gov (NCT04750122, NCT04836156). This time, we report the results of the first stage. Results: Among 20 enrolled TNBC patients in the first stage, 15 achieved pCR with the rate of 75%. 17 patients (85%) had RCB 0-I score while 3 patients (15%) had an RCB-II score. 14 patients received TP as it demonstrated greater sensitivity in vitro. Out of these 14 patients, 10 patients (71.4%) achieved pCR. Six patients received TA as it was more effective in drug testing. Among these patients, 5 (83.3%) patients achieved pCR. Out of 20 enrolled HER2-positive patients, 16 achieved pCR, resulting in a pCR rate of 80%. Six patients received THP treatment based on their sensitivity to this regimen in drug testing. Among these patients, 5 (83.3%) achieved a pCR. 14 patients who were sensitive to TCbHP but not to THP in drug testing received TCbHP treatment. Among these patients, 11 (78.6%) achieved pCR. The non-pCR patients had 2 RCB-II score and the ORR was 100% for all 14 patients. Conclusions: Our results demonstrate that personalized drug testing on PTCs can effectively guide the choice of neoadjuvant therapy for early TNBC and HER2-positive breast cancer patients. Clinical trial information: NCT04750122 , NCT04836156 .

Interim FDG-PET/CT for predicting response of HER2-positive breast cancer to neoadjuvant therapy: ECOG-ACRIN EA1211/DIRECT trial.

TPS614 Background: Strategies to optimize treatment decision-making in early stage HER2-positive breast cancer are a priority. Recent studies suggest that early metabolic changes on FDG-PET/CT predict response to HER2-directed therapy. The TBCRC026 trial showed that participants not obtaining a 40% reduction in SULmax by cycle 1 day 15 (C1D15) following neoadjuvant trastuzumab/pertuzumab (HP) were unlikely to obtain pCR [negative predictive value (NPV) 91%]. This trial aims to validate FDG-PET/CT as a neoadjuvant interim (niFDG-PET/CT) imaging integral biomarker in patients treated with standard HER2-directed regimens (NCT05710328). Methods: Trial design: EA1211/DIRECT is a multicenter, single-arm, primary imaging phase 2 study enrolling patients with stage II/III HER2-positive breast cancer. Patients undergo standard skull base-thigh FDG-PET/CT at baseline and C1D15 and receive standard of care pertuzumab-based neoadjuvant therapy followed by surgery. Eligibility: Age ≥18 years, ECOG performance status 0-2, stage IIa-IIIc, untreated HER2-positive breast cancer with known hormone receptor status, suitable to undergo FDG-PET/CT imaging and neoadjuvant therapy. Statistical methods: ΔSULmaxD15 will be computed as: (D15 SULmax – baseline SULmax)/baseline SULmax. The primary objective is to estimate the NPV of niFDG-PET/CT for pCR using ΔSULmaxD15 of the primary breast cancer at a threshold of 40%. NPV is defined as the probability that pCR will not be achieved by participants with ΔSULmaxD15 &lt;40%. Secondary endpoints include evaluating sensitivity, specificity, and positive predictive value of ΔSULmaxD15 of the primary breast cancer at a threshold of 40% and ability of the niFDG-PET/CT biomarker to predict 3-year event free survival (EFS). Sample size: We expect that 50% of patients will not reach the ΔSULmax threshold of 40% and a pCR rate of 40-60%. The proposed sample size is 210 participants, adjusted to 235 to account for missing data in 10% of cases. Computation of exact, two-sided 95% confidence intervals (CI) for NPV determined the lower limit of the CI is at least 80% when the true NPV is at least 88%. The lower limit is 84% when the true NPV has the value of 91%, which was estimated in the TBCRC026 study. Current status: EA1211/DIRECT was activated in May 2023 across the NCI National Clinical Trials Network (NCTN) and is anticipated to complete in March 2025. Those interested in the clinical trial can email ea1211team@ecog-acrin.org. The EA1211/DIRECT trial is the first step in implementing a Response-Guided Treatment Strategy by validating the ΔSULmax threshold of 40% as the optimum cut point across standard of care HER2-directed neoadjuvant regimens. If EA1211/DIRECT meets its objectives, the results will be used to design clinical utility studies, thus hoping to change practice. Clinical trial information: NCT05710328 .

Patient-derived tumor cell clusters (PTC) guiding-neoadjuvant therapy of HER2-positive breast cancer: A prospective randomized phase II clinical trial.

581 Background: In a previous study, the patient-derived tumor-like cell clusters (PTC) were confirmed to be an accurate medicine effect-predicting model in vitro for clinical practice (1). We designed this prospective randomized phase II trial to research if this PTC-guiding strategy could improve the effect of neoadjuvant therapy in human epidermal growth factor receptor 2 (HER2) positive breast cancer (NCT05103293). Methods: We enrolled HER2-positive early breast cancer patients planning for neoadjuvant therapy to accept the PTC-guiding regimen as an experimental group or regimens of the physician's choice as a control group randomly. All eligible patients in the experimental group would receive medicine-sensitive testing by PTC then accepted the regimen with the highest PTC killing rate (30% as the lowest cut-off value) from the three candidate regimens (Cyclophosphamide combined with epirubicin -- Docetaxel combined with trastuzumab and pertuzumab, EC-THP, Docetaxel and carboplatin with trastuzumab and pertuzumab, TCbHP and Docetaxel with trastuzumab and pyrotinib, THPy). The primary endpoint is pathological complete response (pCR) in two groups using superiority odd ratio Fisher's exact test (one-sided alpha =0.05, power of 80%, and superiority margin at 0.1). The secondary endpoints are Miller-Payne (MP) grade 4~5 proportion, objective response rate (ORR), disease-free survival (DFS), and overall survival (OS). Results: Finally, 86 patients were enrolled in this study, 44 in the experimental and 42 in the control groups. The experimental group had 65.9% of pCR, significantly higher than 42.9% in the control group (Hazard ratio=0.388, P=0.033). The PTC-guiding treatment also considerably increased MP 4~5 proportion (79.5% vs. 59.4%, Hazard ratio=0.283, P=0.009) and objective response rate (90.9% vs 71.4%, Hazard ratio=0.250, P=0.027). After a two-year medium follow-up, the disease-free survival of the PTC-guiding treatment group was 84.1% higher than 71.4% of the control group without a significant difference (Log Rank, P=0.106). The two groups had similar overall survival (Log Rank, P=0.958). Furthermore, the PTC-guiding strategy significantly impacted pCR in univariate and multivariate regression analyses but not survival. Conclusions: In this trial, we concluded that the PTC-guiding neoadjuvant therapy could improve the effect, including pCR, MP score, and ORR in HER2-positive breast cancer. 1. Yin et al., Sci.Transl. 2020. Clinical trial information: NCT05103293 .

The predictive role of Ki67 in pathological complete response (pCR) and invasive disease-free survival (IDFS) in HER2-positive breast cancer: A retrospective study of 246 cases.

e12610 Background: While Ki67 is a routine diagnostic measure for early hormone receptor positive breast cancer, it is not integrated into the standard procedure for patients with Human Epidermal Growth Factor Receptor 2 (HER2)-positive breast cancer patients, given the substantial risk linked to HER2 expression alone. Consequently, the predictive significance of Ki67 in achieving pathological complete response (pCR) or invasive disease-free survival (IDFS) in this subgroup remains uncertain. Methods: This retrospective, bi-centric analysis focused on HER2-positive early breast cancer patients undergoing neoadjuvant chemotherapy from 2015 to 2023. We assessed the correlation between Ki67 values and the achievement of pathological complete response (pCR, defined as ypT0/is, pN0). Multivariable logistic regression analyzed the independent association of various clinical parameters, including Ki67, with pCR. Ki67 values were categorized into risk groups (low &lt;15%, intermediate 15.1-35%, high &gt;35%) following the GepardTrio data [1]. Kaplan-Meier estimator calculated differences in overall and invasive disease-free survival. Results: The study included 246 HER2-positive early breast cancer patients with known Ki67 expression, followed for a median of 42 months. The median age was 52 years. Final nodal status was pN0 in 80.5%, pN1 in 15%, and pN2 in 3.3%. Hormone receptor positivity was observed in 66% of patients. 147 patients (60%) achieved pCR. Median Ki67 was 30. When categorized, 13% were low, 41.5% intermediate, and 45.5% high risk. No correlation between Ki67 and pCR was observed (p=0.25). HER2 IHC score 3+ significantly increased pCR compared to IHC 2+ (62.2% vs. 44.6%, p=0.023). Hormone receptor-positive tumors had a lower pCR rate (52.7% vs. 72.4%, p=0.0016. 5-year overall survival was 96.5% for pCR and 83.8% for non-pCR (p=0.008). 5-year invasive disease-free survival showed no difference between low Ki67 (89.5%), intermediate Ki67 (79.9%), and high Ki67 (80.9%) groups (p=0.77). Conclusions: In this study, Ki67 did not predict pCR in HER2-positive breast cancer, providing no additional clinical value. HER2 IHC score and hormone receptor status were predictive indicators for pCR. Ki67 expression appears to lack additional value in HER2-positive breast cancer, considering resource implications. 1. Denkert C et al: Ann Oncol. 2013 Nov;24(11):2786-93. doi: 10.1093/annonc/mdt350. Epub 2013 Aug 22. PMID: 23970015.

Pathological and clinical outcomes following neoadjuvant dual HER2 therapy for early-stage breast cancer: An Australian institutional real-world experience.

There has been significant progress made in developing novel targeted therapies in the neoadjuvant setting for non-metastatic HER2-positive breast cancer, which may be used in combination with conventional chemotherapy to optimise pathological responses at surgery. However, these therapies, particularly the chemotherapeutic components, may portend significant and long-lasting toxicity. Hence, de-escalation of treatment intensity has been an area of interest and was evaluated in the phase II NeoSphere study. Herein, we report the real-world pathological and survival outcomes from neoadjuvant taxane and dual HER2 blockade recorded at our centre. This was a retrospective cohort study of patients receiving neoadjuvant pertuzumab, trastuzumab and taxane chemotherapy for non-metastatic HER2-positive breast cancer at a single centre in Sydney, Australia. We collected data pertaining to baseline demographic characteristics, pathological response rates, post-surgical prescribing patterns and also undertook survival analyses for invasive disease-free survival (iDFS) as well as exploratory analyses for correlations between pre-specified clinicopathologic factors and pathological response at surgery. Our population was largely similar at baseline to the NeoSphere study. 71 patients were included in the final analysis. 61% achieved a pathological complete response (pCR). Three patients received conventional chemotherapy in the adjuvant setting. 92% of included patients were alive and disease-free at 3 years of follow-up. Only 3 events of recurrence or death were recorded at a median follow-up of 32 months. No significant difference in iDFS was noted between patients achieving pCR and those with residual disease at surgery. This study demonstrates that de-escalated adjuvant treatment for HER2-positive early breast cancer achieved favourable pathological and long-term outcomes comparable to large trials, some utilising more intensive chemotherapeutic components.