Adjuvant trastuzumab emtansine in HER2-positive breast cancer patients with HER2-negative residual invasive disease in KATHERINE

Switching to T-DM1 remains justified in patients with HER2-negative residual invasive breast cancer after neoadjuvant therapy

Reductions in HER2-protein IHC intensity and HER2-gene amplification in residual invasive breast cancer following neoadjuvant therapy for HER2-positive breast cancer have been described and are associated with worse outcomes. T-DM1 requires initial binding to HER2 for activity, so concerns have been raised regarding T-DM1 activity when changes are sufficient to classify residual disease as HER2-negative. The KATHERINE trial assessed HER2 status of residual disease from 845 patients with HER2-positive status on pretherapy biopsies, of which 70 were negative on retesting. With 8 years of median follow-up, 7-year IDFS was 60.3 % with trastuzumab compared to 95.2 % with T-DM1, consistent with clinically meaningful benefit from T-DM1 in these 70 patients.

Interaction between redox regulation, immune activation, and response to treatment in HER2+ breast cancer

In HER2+ breast cancer (BC), neoadjuvant therapy represents an ideal scenario for translational research, considering pathological complete response (pCR) as an endpoint. In these patients, achieving pCR after neoadjuvant therapy is associated with a better prognosis. However, biomarkers are needed to tailor optimal treatment for each patient. Evaluating tumour-infiltrating lymphocytes (TILs) has gained attention in predicting pCR. In the context of metastatic disease, TILs also appear to play a role in predicting outcomes. The interaction between the presence of TILs and reactive oxygen species (ROS) remains an area to be explored. ROS are critical for tumour cell homeostasis, and different levels can trigger differential biological responses in cancer cells and their microenvironment. Nevertheless, the influence of ROS on treatment efficacy and prognosis in patients with HER2+ BC remains to be elucidated. In this article, we reviewed the interplay between treatment response, immune system activation, and ROS production in HER2+ BC and suggested novel areas of intervention and research. We also present a bioinformatic analysis demonstrating that the altered expression of several redox-related genes could be associated with the prevalence of immune cell populations in the tumour microenvironment and with patient survival. New biomarkers are thus suggested and should be further explored to tailor the best treatment to each patient.

CAR-macrophage therapy for HER2-overexpressing advanced solid tumors: a phase 1 trial

Chimeric antigen receptor (CAR) macrophages (CAR-Ms) mediate antitumor immunity via phagocytosis, cytokine release, activation of the tumor microenvironment and antigen presentation. We report results from a non-prespecified interim analysis of a first-in-human, phase 1 clinical trial of CT-0508, an anti-human epidermal growth factor receptor 2 (HER2) CAR-M in patients with advanced HER2-overexpressing tumors. Fourteen patients were treated across two different regimens. Patients with breast cancer and gastroesophageal cancer were primarily enrolled and had to have demonstrated overexpression of HER2 according to the American Society of Clinical Oncology/College of American Pathologists guidelines (HER2 immunohistochemistry 3+ or immunohistochemistry 2+/in situ hybridization-amplified). No lymphodepletion chemotherapy was used before infusion. The primary endpoints were safety and CAR-M manufacturability. Secondary endpoints included cellular kinetics and efficacy using objective response rate, overall survival, progression-free survival and duration of response. No dose-limiting toxicities, severe cytokine release syndrome (≥grade 3) or immune effector cell-associated neurotoxicity syndrome were observed; 44% (n = 4 of 9, 95% confidence interval = 14-79%) of HER2 3+ tumors achieved stable disease as best overall response 8 weeks after treatment. No meaningful activity was observed in the HER2 2+ population (n = 5). Correlative analyses of serial biopsies confirmed that CT-0508 traffics to and remodels the tumor microenvironment, resulting in expansion of CD8+ T cells. These findings demonstrate the preliminary safety, tolerability and manufacturing feasibility of CT-0508 for HER2+ tumors. ClinicalTrials.gov registration: NCT04660929 .

Impact of loss of HER2 positivity following neoadjuvant therapy in HER2-positive breast cancer patients on long-term prognosis: A systematic review and meta-analysis

AIMS

The primary objective was to assess the impact of HER2 loss after neoadjuvant therapy on the long-term prognosis of patients with HER2-positive breast cancer.

METHODS

We extracted relevant studies from PubMed and Cochrane Library and performed systematic review and meta-analysis. The key eligibility criteria for the studies were as follows: included HER2-positive early breast cancer cases undergoing neoadjuvant therapy, available data on HER2 status before and after neoadjuvant therapy, and reported recurrence-related outcomes (disease-free survival/invasive disease-free survival/relapse-free survival) or overall survival.

RESULTS

Of 915 studies that were initially identified, 8 met the eligibility criteria and were included in the meta-analysis for the recurrence-related outcomes (1,917 patients with HER2 loss: 411 [21.4 %] or HER2 retained: 1,506 [78.6 %]); 4 of them reported data on overall survival (606 patients with HER2 loss: 243 [40.1 %] or HER2 retained: 363 [59.9 %]). The average follow-up duration, based on data from five out of eight studies that reported this information, was 51.6 months. HER2 loss was significantly associated with worse recurrence-related outcomes (hazards ratio [HR] 1.85, 95 % confidence interval [CI] 1.31-2.61, p = 0.0005) and worse overall survival (HR 2.37, 95 % CI 1.27-4.41, p = 0.0065). No heterogeneity or publication bias was observed in the meta-analysis.

CONCLUSIONS

This study demonstrated that compared with patients with HER2 retained, those with HER2 loss had significantly higher risk of disease recurrence and worse prognosis. These findings implied the possible use of HER2 loss as a prognostic factor in patients with HER2-positive early breast cancer. Reassessment of HER2 status after neoadjuvant therapy could be valuable in predicting prognosis and may lead to reconsideration of the rational subsequent treatment.

Retesting of oestrogen receptor, progesterone receptor and HER2 status of invasive carcinoma of the breast after neoadjuvant chemotherapy

AIMS

There is no consensus on whether oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status should be assessed after neoadjuvant chemotherapy. This study assessed the frequency of changes in ER, PR and HER2 status after neoadjuvant chemotherapy.

METHODS AND RESULTS

Of 353 patients who had neoadjuvant chemotherapy and anti-HER2 treatment, receptors were assessed in 185 residual carcinomas. Eight per cent of carcinomas that were ER-negative in the core biopsy were ER-positive in the excision compared with 1.5% of controls. All were HER2-positive in the core biopsy and 23% were HER2-negative in the excision compared with 0% of controls. Controls were cases tested in the core biopsy and subsequent surgical resection with no neoadjuvant treatment. Of 589 patients who had neoadjuvant chemotherapy alone, receptors were assessed in 495 residual carcinomas. Six per cent of carcinomas that were ER-negative in the core biopsy were ER-positive in the excision (mainly ER-low positive) compared with 1.5% of controls. All were HER2-negative in the core biopsy and 6% were HER2-positive in the excision (mainly immunohistochemistry score 2+ and HER2 gene amplified) compared with 2% of controls.

CONCLUSIONS

Negative to positive changes in receptor status after neoadjuvant chemotherapy are infrequent and the positive result in the excision is often weakly positive. These results imply that repeat assessment after neoadjuvant chemotherapy and surgery could influence the subsequent treatment in a small proportion of patients.

Survival with Trastuzumab Emtansine in Residual HER2-Positive Breast Cancer

BACKGROUND

Patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer with residual invasive disease after neoadjuvant systemic therapy have a high risk of recurrence and death. The primary analysis of KATHERINE, a phase 3, open-label trial, showed that the risk of invasive breast cancer or death was 50% lower with adjuvant trastuzumab emtansine (T-DM1) than with trastuzumab alone.

METHODS

We randomly assigned patients with HER2-positive early breast cancer with residual invasive disease in the breast or axilla after neoadjuvant systemic treatment with taxane-based chemotherapy and trastuzumab to receive T-DM1 or trastuzumab for 14 cycles. Here, we report the prespecified final analysis of invasive disease-free survival and the second interim analysis of overall survival.

RESULTS

With a median follow-up of 8.4 years, T-DM1 sustained the improvement in invasive disease-free survival over trastuzumab (unstratified hazard ratio for invasive disease or death, 0.54; 95% confidence interval [CI], 0.44 to 0.66). Seven-year invasive disease-free survival was 80.8% with T-DM1 and 67.1% with trastuzumab (difference, 13.7 percentage points). T-DM1 also led to a significantly lower risk of death than trastuzumab (unstratified hazard ratio, 0.66; 95% CI, 0.51 to 0.87; P = 0.003). Seven-year overall survival was 89.1% with T-DM1 and 84.4% with trastuzumab (difference, 4.7 percentage points). Adverse events of grade 3 or higher were noted in 26.1% of the patients in the T-DM1 group and 15.7% of those in the trastuzumab group.

CONCLUSIONS

As compared with trastuzumab, T-DM1 improved overall survival with sustained improvement in invasive disease-free survival among patients with HER2-positive early breast cancer with residual invasive disease after neoadjuvant therapy. (Funded by F. Hoffmann-La Roche/Genentech; KATHERINE ClinicalTrials.gov number, NCT01772472.).

Change in Biomarker Profile After Neoadjuvant Chemotherapy is Prognostic and Common Among Patients with HER2+ Breast Cancer

BACKGROUND

Rates of pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) for breast cancer have improved, especially among human epidermal growth factor 2-positive (HER2+) and triple-negative subtypes. The frequency and significance of biomarker profile change in residual disease are unclear. This study aimed to determine the rate of biomarker profile changes after NAC and the impact on clinical outcomes in a contemporary cohort.

METHODS

Upon institutional review board approval, the study identified 634 consecutive patients treated with NAC between 2010 and 2022 at two academic institutions. The study cohort was focused on patients with residual disease who underwent biomarker profile retesting. Biomarker profile change for each subtype was compared across groups using Fisher-Irwin tests. Cox Proportional Hazards Model and Kaplan-Meier plots were performed to evaluate the association of changed versus unchanged biomarker profile with event-free survival.

RESULTS

Biomarker retesting was performed for 259 (61.4 %) of 422 patients with residual disease. Biomarker profile change occurred in 18.1 % overall and was significantly higher among those with pre-NAC HER2+ disease (32.7 %, 17/52) than among those with HER2-disease (14.5 %, 30/207) (p = 0.004). Conversion of pre-NAC biomarker profiles of HR+HER2- and HR+HER2+ to triple-negative breast cancer (TNBC) post-NAC may be associated with worse event-free survival, hazard ratios of 2.23 (95 % confidence interval [CI], 0.90-5.53; p = 0.08), trending toward significance, and 36.7 (95 % CI, 2.2-610.8; p = 0.01), respectively.

CONCLUSIONS

The results from one of the largest contemporary cohorts demonstrated that biomarker profile change in patients with residual disease after NAC was common. Furthermore, specific biomarker profile change in residual disease may have prognostic value. These findings strengthen the rationale for routine re-testing of biomarkers in residual disease after NAC.

Invasive disease-free survival and brain metastasis rates in patients treated with neoadjuvant chemotherapy with trastuzumab and pertuzumab

Patients with HER2(+) early breast cancer (EBC) receiving neoadjuvant systemic therapy (NAST) have poorer outcomes if they have residual disease (RD). We analyzed IDFS and brain metastasis (BM) rates in patients with HER2(+) EBC treated with NAST and report the outcomes of patients with HER2(-) RD. Patients with HER2(+) EBC who received NAST between 1 Jan 2019 and 31 Jan 2022 were reviewed. IDFS was defined as the time from surgery until first occurrence of invasive breast cancer recurrence, distant recurrence, or death from any cause. The total cohort was 594 patients. pCR (ypT0/isN0) was achieved in 325(55%) and RD was seen in 269(45%) patients. In 269 patients with RD, 45(17%) did not have HER2 retesting and were excluded. In the remaining 224 patients, 143(64%) were HER2(+) and 81(36%) were HER2(-). With a median follow up of 24 months, 8 patients developed BM at initial recurrence, 4/325(1.2%) with pCR and 4/143(2.8%) with HER2(+) RD. IDFS events occurred in 22/594(3%) patients; 14/269(5%) in RD and 8/325(2%) in pCR (p = 0.04). There was no difference in IDFS between 9/143(6%) patients with HER2(+) RD or 5/81(6%) with HER2(-) RD (p = 0.10). Patients with RD had higher IDFS events than those with pCR. In those with RD, 36% lost HER2(+) status; IDFS events appeared similar in those with HER2(+) RD versus those with HER2(-) RD. The BM events seen in those with RD and pCR highlights the need for more effective therapy in NAST and adjuvant setting to minimize BM risk.

TOWARDS Study: Patient-Derived Xenograft Engraftment Predicts Poor Survival in Patients With Newly Diagnosed Triple-Negative Breast Cancer

PURPOSE

Assessing risk of recurrence for nonmetastatic triple-negative breast cancer (TNBC) is a key determinant of therapeutic strategy. The best predictor of recurrence risk is failure to achieve a pathologic complete response after preoperative chemotherapy, but it imperfectly correlates with the definitive end points of relapse-free and overall survival (OS). The inability to accurately predict recurrence has led to increasingly toxic treatment regimens for patients with early-stage TNBC. Better assays for recurrence risk are needed to tailor aggressive therapy for patients who need it and avoid overtreatment and unnecessary toxicity for those at low risk. The purpose of this study was to determine if patient-derived xenograft (PDX) engraftment of newly diagnosed breast tumors can serve as an accurate predictor of recurrence and death from breast cancer.

METHODS

This study was a blinded noninterventional trial comprising 80 patients with newly diagnosed, nonmetastatic, estrogen receptor (ER)-negative or ER-low breast cancer.

RESULTS

PDX engraftment was strongly associated with relapse in 1 year: 8 of 18 (44.4%) patients whose tumors engrafted relapsed versus 1 of 62 (1.6%) patients whose tumors did not engraft (P < .0001). Patients whose tumors engrafted had a hazard ratio (HR) for relapse of 17.5. HRs for OS and breast cancer-specific survival in PDX+ patients were 21.1 and 39.5, respectively.

CONCLUSION

We report that the ability of a tumor to engraft as a PDX predicts early recurrence by serving as a functional readout of aggressiveness and prospectively identifies the most devastating tumors. This provides new opportunity to develop surrogate assays, such as biomarkers of engraftment, which will extend the clinical feasibility of this finding.

3-year invasive disease-free survival with chemotherapy de-escalation using an 18F-FDG-PET-based, pathological complete response-adapted strategy in HER2-positive early breast cancer (PHERGain): a randomised, open-label, phase 2 trial

BACKGROUND

PHERGain was designed to assess the feasibility, safety, and efficacy of a chemotherapy-free treatment based on a dual human epidermal growth factor receptor 2 (HER2) blockade with trastuzumab and pertuzumab in patients with HER2-positive early breast cancer (EBC). It used an 18fluorine-fluorodeoxyglucose-PET-based, pathological complete response (pCR)-adapted strategy.

METHODS

PHERGain was a randomised, open-label, phase 2 trial that took place in 45 hospitals in seven European countries. It randomly allocated patients in a 1:4 ratio with centrally confirmed, HER2-positive, stage I-IIIA invasive, operable breast cancer with at least one PET-evaluable lesion to either group A, where patients received docetaxel (75 mg/m2, intravenous), carboplatin (area under the curve 6 mg/mL per min, intravenous), trastuzumab (600 mg fixed dose, subcutaneous), and pertuzumab (840 mg loading dose followed by 420 mg maintenance doses, intravenous; TCHP), or group B, where patients received trastuzumab and pertuzumab with or without endocrine therapy, every 3 weeks. Random allocation was stratified by hormone receptor status. Centrally reviewed PET was conducted at baseline and after two treatment cycles. Patients in group B were treated according to on-treatment PET results. Patients in group B who were PET-responders continued with trastuzumab and pertuzumab with or without endocrine therapy for six cycles, while PET-non-responders were switched to receive six cycles of TCHP. After surgery, patients in group B who were PET-responders who did not achieve a pCR received six cycles of TCHP, and all patients completed up to 18 cycles of trastuzumab and pertuzumab. The primary endpoints were pCR in patients who were group B PET-responders after two treatment cycles (the results for which have been reported previously) and 3-year invasive disease-free survival (iDFS) in patients in group B. The study is registered with ClinicalTrials.gov (NCT03161353) and is ongoing.

FINDINGS

Between June 26, 2017, and April 24, 2019, a total of 356 patients were randomly allocated (71 patients in group A and 285 patients in group B), and 63 (89%) and 267 (94%) patients proceeded to surgery in groups A and B, respectively. At this second analysis (data cutoff: Nov 4, 2022), the median duration of follow-up was 43·3 months (range 0·0-63·0). In group B, the 3-year iDFS rate was 94·8% (95% CI 91·4-97·1; p=0·001), meeting the primary endpoint. No new safety signals were identified. Treatment-related adverse events and serious adverse events (SAEs) were numerically higher in patients allocated to group A than to group B (grade ≥3 62% vs 33%; SAEs 28% vs 14%). Group B PET-responders with pCR presented the lowest incidence of treatment-related grade 3 or higher adverse events (1%) without any SAEs.

INTERPRETATION

Among HER2-positive EBC patients, a PET-based, pCR-adapted strategy was associated with an excellent 3-year iDFS. This strategy identified about a third of patients who had HER2-positive EBC who could safely omit chemotherapy.

FUNDING

F Hoffmann-La Roche.

Neoadjuvant pertuzumab plus trastuzumab in combination with chemotherapy for human epidermal growth factor receptor 2 positive breast cancer: a real-world retrospective single-institutional study in China

INTRODUCTION

Real-world studies on neoadjuvant dual anti-HER2 therapy combined with chemotherapy for breast cancer (BC) are scarce in China. This study aimed to evaluate the efficacy and safety of neoadjuvant dual anti-HER2 therapy combined with chemotherapy in a real-world setting. Moreover, differences in estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and proliferation cell nuclear antigen (Ki-67) expression pre- and post-neoadjuvant therapy were analyzed.

METHODS

Clinical and pathological data of patients with HER2-positive BC who received neoadjuvant dual anti-HER2 therapy combined with chemotherapy at Liaoning Cancer Hospital & Institute, China, between September 2021 and September 2023, were retrospectively reviewed.

RESULTS

Among 179 included patients, a pathologic complete response (pCR) was achieved in 109 patients (60.9%). The univariate analysis results indicated that the hormone receptor (HR) status (P = 0.013), HER2 status (P = 0.003), and cycles of targeted treatment (P = 0.035) were significantly correlated with pCR. Subsequent multivariable analysis showed that HR negative and HER2 status 3 + were independent predictive factors of pCR. Anemia was the most common adverse event (62.0%), and the most common grade 3-4 adverse event was neutropenia (6.1%). The differences in HER2 (34.5%) and Ki-67 (92.7%) expression between core needle biopsy and the residual tumor after neoadjuvant therapy were statistically significant, whereas the differences were insignificant in terms of ER or PR status.

CONCLUSIONS

The combination of neoadjuvant trastuzumab and pertuzumab with chemotherapy showed good efficiency, and the toxic side effects were tolerable in patients with BC. In cases where pCR was not achieved after neoadjuvant therapy, downregulation of HER2 and Ki-67 expressions was observed.

Evolution of HER2 expression between pre-treatment biopsy and residual disease after neoadjuvant therapy for breast cancer

INTRODUCTION

We have previously found that HER2 expression is dynamic, and can change from the primary breast tumor to matched recurrences. With this work, we aimed to assess the dynamics of HER2 during neoadjuvant treatment.(NAT).

METHODS

We reviewed HER2 expression in pre- and post-treatment samples from consecutive patients with early-stage breast cancer that received NAT and underwent surgery at Dana-Farber Brigham Cancer Center between 01/2016-08/2022. The primary outcome was evolution of HER2 expression from pre- to post-NAT specimens in patients with residual disease.

RESULTS

Among 1613 patients receiving NAT, 1080 had residual disease at surgery. A total of 319 patients (29.5%) experienced a change in HER2 expression (HER2 0 vs. HER2-low vs. HER2-positive) from the pre-treatment sample to residual disease, with roughly equal distribution between decreased (50.5%) and increased HER2 expression (49.5%). Similar rates of change in HER2 expression were observed with anthracycline-based (31.8%) or taxane/platinum-based regimens (32.4%). Patients with HER2-0 or HER2-low tumors at diagnosis were likelier to experience a change in HER2 expression post-NAT compared to HER2-positive (32.3% vs. 21.3%, p < 0.001). Changes in HER2 expression post-NAT were prognostic among patients with HER2-positive tumors at diagnosis (3-year recurrence-free survival for change vs. no change: 71.6% vs. 89.6%, p = 0.006) but not among those with HER2-negative tumors at diagnosis (3-year recurrence-free survival for change vs. no change: 79.3% vs. 81.1%, p = 0.31).

CONCLUSIONS

Nearly 30% of patients with early-stage breast cancer showed a change in HER2 expression after NAT. Changes in HER2 expression post-NAT were only prognostic in the setting of HER2-positive tumors becoming HER2-negative at surgery.

Combinatorial Approaches for Chemotherapies and Targeted Therapies With Radiation: United Efforts to Innovate in Patient Care

Combinatorial therapies consisting of radiation therapy (RT) with systemic therapies, particularly chemotherapy and targeted therapies, have moved the needle to augment disease control across nearly all disease sites for locally advanced disease. Evaluating these important combinations to incorporate more potent therapies with RT will aid our understanding of toxicity and efficacy for patients. This article discusses multiple disease sites and includes a compilation of contributions from expert Red Journal editors from each disease site. Leveraging improved systemic control with novel agents, we must continue efforts to study novel treatment combinations with RT.

Branched pegylated linker-auristatin to control hydrophobicity for the production of homogeneous minibody-drug conjugate against HER2-positive breast cancer

Trastuzumab emtansine (Kadcyla®) was the first antibody-drug conjugate (ADC) approved by the Food and Drug Administration in 2013 against a solid tumor, and the first ADC to treat human epidermal growth factor receptor 2 positive (HER2+) breast cancer. However, this second generation ADC is burden by several limitations included heterogeneity, limited activity against heterogeneous tumor (regarding antigen expression) and suboptimal tumor penetration. To address this, different development strategies are oriented towards homogeneous conjugation, new drugs, optimized linkers and/or smaller antibody formats. To reach better developed next generation ADCs, a key parameter to consider is the management of the hydrophobicity associated with the linker-drug, increasing with and limiting the drug-to-antibody ratio (DAR) of the ADC. Here, an innovative branched pegylated linker was developed, to control the hydrophobicity of the monomethyl auristatin E (MMAE) and its cathepsin B-sensitive trigger. This branched pegylated linker-MMAE was then used for the efficient generation of internalizing homogeneous ADC of DAR 8 and minibody-drug conjugate of DAR 4, targeting HER2. Both immunoconjugates were then evaluated in vitro and in vivo on breast cancer models. Interestingly, this study highlighted that the minibody-MMAE conjugate of DAR 4 was the best immunoconjugate regarding in vitro cellular internalization and cytotoxicity, gamma imaging, ex vivo biodistribution profile in mice and efficient reduction of tumor size in vivo. These results are very promising and encourage us to explore further fragment-drug conjugate development.

Prognostic impact of reduced HER2 protein expression in post-neoadjuvant therapy resection specimens: A single institution experience and review of the literature

BACKGROUND

Retesting for Human epidermal growth factor receptor-2 (HER2) in post-neoadjuvant therapy resection is variable, and data is conflicting regarding the prognostic significance of changes in HER2 expression pre and post therapy.

METHODS

We identified 104 patients with localized HER2 IHC 3+ breast cancer who received neoadjuvant trastuzumab(T)/pertuzumab(P) containing chemotherapy at Yale Cancer Center between 2012 and 2022. Patients were divided into 3 cohorts by response and HER2 IHC in the residual disease: Cohort 1 pathologic complete response (pCR), Cohort 2 pre-treatment IHC 3+/post treatment IHC 1+/2+, and Cohort 3 pre-treatment IHC 3+/post-treatment IHC 3+. Kaplan-Meier survival analysis was performed to assess recurrence free survival at 36 months.

RESULTS

The overall pCR rate was 62.5% (65/104), while 37.5% (39/104) of patients had residual disease (RD). Among patients with RD, 58.9% (23/39) remained IHC 3+ and 41.1% (16/39) had reduced HER2 expression IHC1+ or 2+. In patients with HER2 IHC 3+ RD, 26% (6/23) developed local recurrence or distant metastasis while none of patients with post NAT HER2 IHC 1+ or 2+ RD had relapse (p = 0.0309). In patients with pCR, 6.15% (4/65) had recurrence. Kaplan-Meier survival analysis revealed superior disease-free survival in patients with reduced HER2 IHC expression compared to those with remained IHC 3+ (log rank p = 0.004).

CONCLUSION

We conclude that reduced HER2 expression by IHC following neoadjuvant treatment was associated with lower recurrence rates in HER2 IHC 3+ breast cancer. If confirmed, RD HER2 IHC expression could be used as a prognostic biomarker to stratify patients in adjuvant trials and identify patients who may benefit from more intensive adjuvant therapy and post therapy surveillance.

Real world data on the demographic and clinicopathological profile and management of patients with early-stage HER2-positive breast cancer and residual disease treated with adjuvant trastuzumab emtansine (KARMA study)

INTRODUCTION

Trastuzumab emtansine (T-DM1) significantly improves invasive disease-free survival and reduces the risk of recurrence in patients with HER2-positive early breast cancer (EBC) with residual disease (RD). The KARMA study aimed to describe the characteristics and management of these patients in clinical practice in Spain.

MATERIAL AND METHODS

We conducted a multicentre retrospective study in patients with HER2-positive EBC with RD following neoadjuvant treatment (NeoT) and who had received ≥1 dose of T-DM1 as adjuvant treatment. The primary endpoint was the evaluation of sociodemographic and clinicopathological characteristics of these patients.

RESULTS

A total of 114 patients were included (March-July 2020). At diagnosis, most tumours were infiltrating ductal carcinoma (IDC) (93.9 %), grade 2 (56.1 %), and hormone receptor (HR)-positive (79.8 %). Over 75 % of patients had disease in operable clinical stages (T1-3 N0-1). In the neoadjuvant setting, 86.8 % of patients received trastuzumab plus pertuzumab, and 23.6 % achieved radiological complete response. Breast-conserving surgery was performed in 55.8 % of patients. Surgical specimens showed that 89.5 % of patients had IDC, 49.1 % grade 2, 84.1 % HR-positive, and 8.3 % HER2-negative disease. Most patients had RD classified as RCB-II and Miller/Payne grade 3/4. Grade 3 treatment-related adverse events (trAEs) occurred in 5.3 % of patients. No grade 4/5 AEs occurred. Over 95 % of patients were free of invasive-disease during T-DM1 adjuvant treatment.

CONCLUSION

The KARMA study describes the characteristics of patients with HER2-positive EBC with RD after NeoT and the real-life management of a T-DM1 adjuvant regimen, which showed a manageable safety profile in line with the KATHERINE trial data.

Changes in HER2 status and survival outcomes in patients with non-pathological complete response after neoadjuvant targeted treatment

To study the changes in human epidermal growth factor receptor 2 (HER2) expression in patients with HER2-positive breast cancer before and after neoadjuvant treatment. The clinicopathologic data of 499 patients with HER2-positive breast cancer who completed neoadjuvant treatment and surgery at the Fourth Hospital of Hebei Medical University from 2018 to 2021 were retrospectively analyzed. According to the new adjuvant regimen, 298 patients were divided into the trastuzumab + pertuzumab combined chemotherapy group (dual target group), and 201 patients were divided into the trastuzumab combined chemotherapy group (single target group).The effect of different neoadjuvant regimens on HER2 status was analyzed by comparing HER2 expression before and after treatment. A total of 255 of 499 neoadjuvant patients with HER2-positive breast cancer achieved a pathological complete response (pCR). pCR was achieved in 60.07% (179/298) of the dual target group and 37.81% (76/201) of the single target group, and the difference was statistically significant (χ² = 23.795, P < .001). Among 244 cases of HER2-positive breast cancer that did not reach pCR (non-pCR), there was a certain negative conversion rate of HER2 expression after neoadjuvant treatment, and the overall negative conversion rate was 13.11% (32/244). The negative conversion rates of the dual target group was 17.65% (21/119) and single target group was 8.80% (11/125), (χ² = 4.188, P = .041). The DFS of 499 patients in the pCR group was 98.43% (251/255), which was significantly higher than that in the non-pCR group 92.21% (225/244), (χ² = 8.536, P = .003). Only 2 (0.20%) of 32 patients with negative HER2 had recurrence and metastasis. Neoadjuvant treatment had an effect on the expression status of HER2, especially in the dual target group. For patients with negative HER2, the optimal treatment strategy remains to be explored, but continued anti-HER2 treatment is still recommended.

Treatment of Early Breast Cancer: The 18th St. Gallen International Breast Cancer Consensus Conference against the Background of Current German Treatment Recommendations

This year's 18th St. Gallen (SG) consensus conference on the treatment of early breast cancer (SGBCC: St. Gallen International Breast Cancer Conference) focused on practice-oriented questions. The individual situation and risk-benefit assessment were discussed in great detail. As in previous years, a German working group of leading breast cancer experts presented the results of the international SGBCC 2023 against the background of German treatment recommendations - especially the updated treatment recommendations of the Arbeitsgemeinschaft Gynäkologische Onkologie e. V. (AGO) - for everyday clinical practice in Germany. The German treatment recommendations of AGO are based on the current evidence. The comparison with the clinical approach in Germany has proven useful, as the SGBCC panel consists of experts from different countries and disciplines. That is why country-specific characteristics can be incorporated into the SGBCC recommendations.

Biomarker Data from the Phase III KATHERINE Study of Adjuvant T-DM1 versus Trastuzumab for Residual Invasive Disease after Neoadjuvant Therapy for HER2-Positive Breast Cancer

PURPOSE

In KATHERINE, adjuvant T-DM1 reduced risk of disease recurrence or death by 50% compared with trastuzumab in patients with residual invasive breast cancer after neoadjuvant therapy (NAT) comprised of HER2-targeted therapy and chemotherapy. This analysis aimed to identify biomarkers of response and differences in biomarker expression before and after NAT.

EXPERIMENTAL DESIGN

Exploratory analyses investigated the relationship between invasive disease-free survival (IDFS) and HER2 protein expression/gene amplification, PIK3CA hotspot mutations, and gene expression of HER2, PD-L1, CD8, predefined immune signatures, and Prediction Analysis of Microarray 50 intrinsic molecular subtypes, classified by Absolute Intrinsic Molecular Subtyping. HER2 expression on paired pre- and post-NAT samples was examined.

RESULTS

T-DM1 appeared to improve IDFS versus trastuzumab across most biomarker subgroups, except the HER2 focal expression subgroup. High versus low HER2 gene expression in residual disease was associated with worse outcomes with trastuzumab [HR, 2.02; 95% confidence interval (CI), 1.32-3.11], but IDFS with T-DM1 was independent of HER2 expression level (HR, 1.01; 95% CI, 0.56-1.83). Low PD-L1 gene expression in residual disease was associated with worse outcomes with trastuzumab (HR, 0.66; 95% CI, 0.44-1.00), but not T-DM1 (HR, 1.05; 95% CI, 0.59-1.87). PIK3CA mutations were not prognostic. Increased variability in HER2 expression was observed in post-NAT versus paired pre-NAT samples.

CONCLUSIONS

T-DM1 appears to overcome HER2 resistance. T-DM1 benefit does not appear dependent on immune activation, but these results do not rule out an influence of the tumor immune microenvironment on the degree of response.

Recent Advances in Optimizing Radiation Therapy Decisions in Early Invasive Breast Cancer

Adjuvant whole breast irradiation after breast-conserving surgery is a well-established treatment standard for early invasive breast cancer. Screening, early diagnosis, refinement in surgical techniques, the knowledge of new and specific molecular prognostic factors, and now the standard use of more effective neo/adjuvant systemic therapies have proven instrumental in reducing the rates of locoregional relapses. This underscores the need for reliably identifying women with such low-risk disease burdens in whom elimination of radiation from the treatment plan would not compromise oncological safety. This review summarizes the current evidence for radiation de-intensification strategies and details ongoing prospective clinical trials investigating the omission of adjuvant whole breast irradiation in molecularly defined low-risk breast cancers and related evidence supporting the potential for radiation de-escalation in HER2+ and triple-negative clinical subtypes. Furthermore, we discuss the current evidence for the de-escalation of regional nodal irradiation after neoadjuvant chemotherapy. Finally, we also detail the current knowledge of the clinical value of stromal tumor-infiltrating lymphocytes and liquid-based biomarkers as prognostic factors for locoregional relapse.