Correlation between postoperative treatment selection and prognosis determined using the Oncotype DX® test data: a retrospective multicenter study in Japan

PURPOSE

Oncotype DX® is a frequently used multigene assay for hormone receptor-positive breast cancers. However, limited evidence is available regarding its application in Japan owing to the lack of insurance coverage. Therefore, we conducted this large-scale, retrospective study by collecting data from nine Japanese institutes and assessed postoperative treatment choice and prognosis by using Oncotype DX®.

METHODS

Six hundred thirty-two patients who underwent breast surgery and whose recurrence score (RS) data were available were included. They were divided into RS 0-25 and RS ≥ 26 groups. The groups were compared in terms of clinicopathological factors, treatment options, and prognosis.

RESULTS

After the median follow-up period of 10.1 years, the disease-free survival (DFS) rates were significantly better in the RS 0-25 group (p = 0.02). Per the recurrent event type, there was no significant intergroup difference in locoregional recurrence (p = 0.139). However, a trend toward better distant DFS was observed in the RS 0-25 group (p = 0.08). Overall survival was also significantly better in this group (p = 0.027). Considering chemotherapy use, DFS worsened among chemotherapy-treated patients with an RS of 0-25 and those with an RS ≥ 26 who did not receive chemotherapy (p < 0.001). Seven (1.35%) chemotherapy-treated patients with an RS of 0-25 showed disease recurrence.

CONCLUSIONS

This study presents the largest database-derived prognostic data in Japanese patients, utilizing the Oncotype DX® treatment selection. Further studies are needed to determine the impact on treatment choice, considering the clinical risk, and the need for additional postoperative treatment.

Efficacy of Nursing Interventions Using Motivational Interviewing Aimed at Weight Loss in Overweight/Obese Breast Cancer Patients Undergoing Endocrine Therapy

OBJECTIVE

Obesity adversely impacts breast cancer treatment and outcomes. This study assessed the efficacy of nurses' motivational interviews (MI) in promoting weight loss among breast cancer patients.

METHODS

Motivational Interviewing was performed at 4, 8, and 12 weeks from baseline in 27 overweight/ obese breast cancer patients receiving adjuvant endocrine therapy. An average weight loss rate of 5% at week 12 was the threshold for determining whether MI intervention was clinically meaningful. Clinical and sociodemographic variables were gathered from medical records and self-administered questionnaires. Body weight, body mass index (BMI), physical activity time, sedentary time, self-efficacy for weight loss, and mood scores were evaluated at baseline, 4, 8, 12, and 24 weeks.

RESULTS

Significant reductions in body weight were observed throughout compared with baseline; 51.9% of participants attained the 5% weight loss target, but the average weight loss rate was 3.9% at week 12. BMI notably decreased at 8, 12, and 24 weeks compared with baseline. Physical activity increased significantly at 12 weeks, while sedentary time decreased at 8 and 24 weeks.

CONCLUSIONS

Nursing-administered MI did not achieve the goal of 5% weight loss at week 12. However, it increased physical activity and reduced sedentary time, showing potential for promoting healthier habits.

Survival trends and patient characteristics between 2004 and 2016 for breast cancer in Japan based on the National Clinical Database-Breast Cancer Registry

This is a prognostic report by the Japanese Breast Cancer Society on breast cancer extracted from the National Clinical Database-Breast Cancer Registry of Japan. Here, we present a summary of 457,878 breast cancer cases registered between 2004 and 2016. The median follow-up duration was 5.6 years. The median age at the start of treatment was 59 years (5-95%: 38-82 years) and increased from 57 years between 2004 and 2008 to 60 years between 2013 and 2016. The proportion of patients with Stage 0-II disease increased from 74.5% to 78.3%. The number of cases with estrogen and progesterone receptor positivity increased from 74.8% to 77.9% and 60.5% to 68.1%, respectively. Regarding (neo-)adjuvant chemotherapy, the taxane (T) or taxane-cyclophosphamide (C) regimen increased by 2.4% to 8.2%, but the (fluorouracil (F)) adriamycin (A)-C-T/(F) epirubicin (E)C-T and (F)AC/(F)EC regimens decreased by 18.6% to 15.2% and 13.5% to 5.0%, respectively. Regarding (neo-)adjuvant anti-human epidermal growth factor-2 (HER2)-targeted therapy, the use of trastuzumab increased from 4.6% to 10.5%. The rate of sentinel lymph node biopsy increased from 37.1% to 60.7%, while that of axillary dissection decreased from 54.5% to 22.6%. Improvements in disease-free and overall survival were observed in patients with HER2-positive breast cancer, but there was no apparent trend in patients with hormone receptor-positive, HER2-negative, or triple-negative breast cancers.

2020 Annual Report of National Clinical Database-Breast Cancer Registry: 10-year mortality of elderly breast cancer patients in Japan

The Japanese Breast Cancer Society initiated the breast cancer registry in 1975, which transitioned to the National Clinical Database-Breast Cancer Registry in 2012. This annual report presents data from 2020 and analyzes the ten-year mortality rates for those aged 65 and older. We analyzed data from 93,784 breast cancer (BC) cases registered in 2020 and assessed 10-year mortality rates for 36,279 elderly patients diagnosed between 2008 and 2012. In 2020, 99.4% of BC cases were females with a median age of 61. Most (65%) were diagnosed at early stages (Stage 0 or I). Breast-conserving surgery rates varied with stages: 58.5% at cStage I, 30.8% at cStage II, and 13.1% at cStage III. Sentinel lymph node biopsy was done in 73.6% of cases, followed by radiotherapy in 70% of those post-conserving surgery and chemotherapy in 21.1% post-surgery. Pathology showed that 63.4% had tumors under 2.0 cm, 11.7% had pTis tumors, and 77.3% had no axillary lymph node metastasis. ER positivity was seen in 75.1%, HER2 in 14.3%, and 30% had a Ki67 positivity rate above 30%. Across all stages and subtypes, there was a trend where the 10-year mortality rates increased for individuals older than 65 years. In Stage I, many deaths were not directly linked to BC and, for those with HER2-type and triple-negative BC, breast cancer-related deaths increased with age. Within Stage II, patients older than 70 years with luminal-type BC often experienced deaths not directly linked to BC, whereas patients below 80 years with HER2-type and triple-negative BC, likely had breast cancer-related deaths. In Stage III, breast cancer-related deaths were more common, particularly in HER2 and triple-negative BC. Our prognostic analysis underscores distinct mortality patterns by stage, subtype, and age in elderly BC patients. It highlights the importance of personalized treatment strategies, considering subtype-specific aggressiveness, age-related factors, and comorbidities.

Identifying prognostic biomarkers for palbociclib add-on therapy in fulvestrant-resistant breast cancer using cell-free DNA sequencing

BACKGROUND

The FUTURE trial (UMIN000029294) demonstrated the safety and efficacy of adding palbociclib after fulvestrant resistance in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced and metastatic breast cancer (ABC/MBC). In this planned sub-study, cancer panel sequencing of cell-free DNA (cfDNA) was utilized to explore prognostic and predictive biomarkers for further palbociclib treatment following fulvestrant resistance.

MATERIALS AND METHODS

Herein, 149 cfDNA samples from 65 patients with fulvestrant-resistant disease were analysed at the time of palbociclib addition after fulvestrant resistance (baseline), on day 15 of cycle 1, and at the end of treatment using the assay for identifying diverse mutations in 34 cancer-related genes.

RESULTS

During the course of treatment, mutations in ESR1, PIK3CA, FOXA1, RUNX1, TBX3, and TP53 were the most common genomic alterations observed. Analysis of genomic mutations revealed that before fulvestrant introduction, baseline PIK3CA mutations were marginally lower in metastatic aromatase inhibitor (AI)-treated patients compared to adjuvant AI-treated patients (P = 0.063). Baseline PIK3CA mutations were associated with poorer progression-free survival [hazard ratio: 1.62, P = 0.04]. Comparative analysis between baseline and early-changing gene mutations identified poor prognostic factors including early-changing MAP3K1 mutations (hazard ratio: 4.66, P = 0.04), baseline AR mutations (hazard ratio: 3.53, P = 0.04), and baseline PIK3CA mutations (hazard ratio: 3.41, P = 0.02). Notably, the relationship between ESR1 mutations and mutations in PIK3CA, MAP3K1, and TP53 weakened as treatment progressed. Instead, PIK3CA mutations became correlated with TP53 and FOXA1 mutations.

CONCLUSIONS

Cancer panel testing for cfDNA identified prognostic and predictive biomarkers for palbociclib add-on therapy after acquiring fulvestrant resistance in patients with HR+/HER2- ABC/MBC.

Investigating the immunological function of alpha-2-glycoprotein 1, zinc-binding in regulating tumor response in the breast cancer microenvironment

BACKGROUND

Alpha-2-glycoprotein 1, zinc-binding (ZAG), a secreted protein encoded by the AZGP1 gene, is structurally similar to HLA class I. Despite its presumed immunological function, little is known about its role in tumor immunity. In this study, we thus aimed to determine the relationship between the expression of AZGP1/ZAG and the immunological profiles of breast cancer tissues at both the gene and protein level.

METHODS

Using a publicly available gene expression dataset from a large-scale breast cancer cohort, we conducted gene set enrichment analysis (GSEA) to screen the biological processes associated with AZGP1. We analyzed the correlation between AZGP1 expression and immune cell composition in breast cancer tissues, estimated using CIBERSORTx. Previously, we evaluated the infiltration of 11 types of immune cells for 45 breast cancer tissues using flow cytometry (FCM). ZAG expression was evaluated by immunohistochemistry on these specimens and analyzed for its relationship with immune cell infiltration. The action of ZAG in M1/M2 polarization models using primary cultures of human peripheral blood mononuclear cells (PBMC)-derived macrophage (Mφ) was analyzed based on the expression of M1/M2 markers (CD86, CD80/CD163, MRC1) and HLA class I/II by FCM.

RESULTS

AZGP1 expression was negatively correlated with multiple immunological processes and specific immune cell infiltration including Mφ M1 using GSEA and CIBERSORTx. ZAG expression was associated with decreased infiltration of monocytes/macrophages, non-classical monocytes, and myeloid-derived suppressor cells in tumor tissues assessed using FCM. In in vitro analyses, ZAG decreased the expression of CD80, CD163, MRC1, and HLA classes I/II in the M1 polarization model and the expression of CD163 and MRC1 in the M2 polarization model.

CONCLUSION

ZAG is suggested to be a novel immunoregulatory factor affecting the Mφ phenotype in breast cancer tissues.

BRCA1/2 reversion mutations in a pan-cancer cohort

Tumor sensitivity to platinum (Pt)-based chemotherapy and poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors is increased by homologous recombination deficiency-causing mutations; in particular, reversion mutations cause drug resistance by restoring protein function. Treatment response is predicted by breast cancer susceptibility gene 1/2 (BRCA1/2) mutations; however, BRCA1/2 reversion mutations have not been comprehensively studied in pan-cancer cohorts. We aimed to characterize BRCA1/2 reversion mutations in a large pan-cancer cohort of Japanese patients by retrospectively analyzing sequencing data for BRCA1/2 pathogenic/likely pathogenic mutations in 3738 patients with 32 cancer types. We identified somatic mutations in tumors or circulating cell-free DNA that could restore the ORF of adverse alleles, including reversion mutations. We identified 12 (0.32%) patients with somatic BRCA1 (n = 3) and BRCA2 (n = 9) reversion mutations in breast (n = 4), ovarian/fallopian tube/peritoneal (n = 4), pancreatic (n = 2), prostate (n = 1), and gallbladder (n = 1) cancers. We identified 21 reversion events-BRCA1 (n = 3), BRCA2 (n = 18)-including eight pure deletions, one single-nucleotide variant, six multinucleotide variants, and six deletion-insertions. Seven (33.3%) reversion deletions showed a microhomology length greater than 1 bp, suggesting microhomology-mediated end-join repair. Disease course data were obtained for all patients with reversion events: four patients acquired mutations after PARP-inhibitor treatment failure, two showed somatic reversion mutations after disease progression, following Pt-based treatment, five showed mutations after both treatments, one patient with pancreatic cancer and BRCA1 reversion mutations had no history of either treatment. Although reversion mutations commonly occur in BRCA-associated cancers, our findings suggest that reversion mutations due to Pt-chemotherapy might be correlated with BRCA1/2-mediated tumorigenesis even in non-BRCA-associated histologies.

Annual report of the Japanese Breast Cancer Registry for 2019

This is an annual report by the Japanese Breast Cancer Society regarding the clinical data on breast cancer extracted from the National Clinical Database-Breast Cancer Registry (NCD-BCR) of Japan. Here, we present an updated summary of 98,300 breast cancer cases registered in 2019. The median age at cancer diagnosis was 61 years (interquartile range 49-72 years), and 30.6% of the breast cancer patients were premenopausal. Of the 93,840 patients without distant metastases, 14,118 (15.0%) and 42,047 (44.8%) were diagnosed with stage 0 and I disease, respectively. Breast-conserving surgery was performed in 42,080 (44.8%) patients. Regarding axillary procedures, 62,677 (66.8%) and 7371 (7.9%) patients underwent sentinel node biopsy and axillary node dissection after biopsy, respectively. Whole breast irradiation was administered to 29,795 (70.8%) of the 42,080 patients undergoing breast-conserving surgery. Chest wall irradiation was administered to 5524 (11.1%) of the 49,637 patients who underwent mastectomy. Of the 6912 clinically lymph node-negative patients who received preoperative therapy, 5250 (76.0%) and 427 (6.2%) underwent sentinel node biopsy and axillary node dissection after biopsy, respectively; however, 602 (8.7%) patients initially underwent axillary node dissection without biopsy.

Changes in cell-free DNA after short-term palbociclib and fulvestrant treatment for advanced or metastatic hormone receptor-positive and human epidermal growth factor 2-negative breast cancer

PURPOSE

Here, we investigated the potential predictive and elucidating efficacy of cell-free DNA (cfDNA) changes on clinical outcomes and biological effects, respectively, after short-term palbociclib and fulvestrant treatment for patients with hormone receptor (HR)-positive and human epidermal growth factor 2 (HER2)-negative advanced or metastatic breast cancer (ABC).

METHODS

In this secondary analysis of the Japan Breast Cancer Research Group-M07 (FUTURE) trial, blood cfDNA was obtained before palbociclib treatment and on day 15 of cycle one (28-day cycle). Target enrichment was performed using next-generation sequencing; progression-free survival (PFS) was compared based on cfDNA changes between baseline and day 15 of cycle one after combination therapy.

RESULTS

Fifty-six patients (112 paired blood samples) were examined. The median follow-up time was 8.9 months. PIK3CA (30.4%, 17/56), FOXA1 (30.4%, 17/56), and ESR1 (28.6%, 16/56) were most frequently mutated at baseline. The number of mutated genes was significantly decreased on day 15 compared with that at baseline (paired t test: P value = 0.025). No significant difference was observed in PFS (decrease group, 7.9 m vs the others, 9.3 m; log-rank P value = 0.75; hazard ratio, 1.13; 95% confidence interval, 0.53-2.41). Among patients without previous aromatase inhibitor treatment (n = 15), three (20%) had ESR1 mutations after progression to fulvestrant.

CONCLUSION

No significant association was observed between changes in mutated genes after short-term palbociclib and fulvestrant treatment and disease progression; a significant reduction in cfDNA mutation level was observed on day 15 of cycle one. Clinical meanings of cfDNA should be investigated in the future trials.

Computed diffusion-weighted imaging with a low-apparent diffusion coefficient-pixel cut-off technique for breast cancer detection

OBJECTIVE

This study aimed to compare the image quality and diagnostic performance of computed diffusion-weighted imaging (DWI) with low-apparent diffusion coefficient (ADC)-pixel cut-off technique (cDWI cut-off) and actual measured DWI (mDWI).

METHODS

Eighty-seven consecutive patients with malignant breast lesions and 72 with negative breast lesions who underwent breast MRI were retrospectively evaluated. Computed DWI with high b-values of 800, 1200, and 1500 s/mm2 and ADC cut-off thresholds of none, 0, 0.3, and 0.6 (×10-3 mm2/s) were generated from DWI with two b-values (0 and 800 s/mm2). To identify the optimal conditions, two radiologists evaluated the fat suppression and lesion reduction failure using a cut-off technique. The contrast between breast cancer and glandular tissue was evaluated using region of interest analysis. Three other board-certified radiologists independently assessed the optimised cDWI cut-off and mDWI data sets. Diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

When an ADC cut-off threshold of 0.3 or 0.6 (× 10-3 mm2/s) was applied, fat suppression improved significantly (p < .05). The contrast of the cDWI cut-off with a b-value of 1200 or 1500 s/mm2 was better than the mDWI (p < .01). The ROC area under the curve for breast cancer detection was 0.837 for the mDWI and 0.909 for the cDWI cut-off (p < .01).

CONCLUSION

The cDWI cut-off provided better diagnostic performance than mDWI for breast cancer detection.

ADVANCES IN KNOWLEDGE

Using the low-ADC-pixel cut-off technique, computed DWI can improve diagnostic performance by increasing contrast and eliminating un-suppressed fat signals.

Treatment with trastuzumab deruxtecan in patients with HER2-positive breast cancer and brain metastases and/or leptomeningeal disease (ROSET-BM)

Therapeutic options for breast cancer patients with brain metastases (BM)/leptomeningeal carcinomatosis (LMC) are limited. Here, we report on the effectiveness and safety of trastuzumab deruxtecan (T-DXd) in human epidermal growth factor receptor 2-positive breast cancer patients with BM. Data were analyzed for 104 patients administered T-DXd. Overall response rate (ORR), progression-free survival (PFS), overall survival (OS), intracranial (IC)-ORR, and IC-PFS were evaluated. ORR by investigator assessment was 55.7% (total population). Median PFS was 16.1 months; 12-month OS rate was 74.9% (total population). Median time-to-treatment failure was 9.7 months. In 51 patients with BM imaging, IC-ORR and median IC-PFS by independent central review were 62.7% and 16.1 months, respectively. In 19 LMC patients, 12-month PFS and OS rates were 60.7% and 87.1%, respectively. T-DXd showed effectiveness regarding IC-ORR, IC-PFS, PFS, and OS in breast cancer patients with BM/active BM, and sustained systemic and central nervous system disease control in LMC patients.Trial Registration: UMIN000044995.

Efficacy and safety of pegfilgrastim biosimilar MD-110 in patients with breast cancer receiving chemotherapy: Single-arm phase III

INTRODUCTION

Pegfilgrastim is indicated to decrease the incidence of chemotherapy-induced febrile neutropenia. It is the first granulocyte-colony stimulating factor approved for prophylactic use regardless of carcinoma type and is marketed in Japan as G-LASTA (Kyowa Kirin Co., Ltd., Tokyo, Japan). MD-110 is a biosimilar of pegfilgrastim. This phase III, multicenter, open-label, single-arm study investigated the efficacy and safety of MD-110 in early-stage breast cancer patients receiving neoadjuvant or adjuvant myelosuppressive chemotherapy.

METHODS

A total of 101 patients received the study drug. Each patient received docetaxel 75 mg/m2 and cyclophosphamide 600 mg/m2 (TC) for four cycles on day 1 of each cycle. MD-110 (3.6 mg) was administered subcutaneously on day 2 of each cycle. The primary efficacy endpoint was the duration of severe neutropenia during cycle 1 (days with absolute neutrophil count < 500/mm3 ). The safety endpoints were adverse events and the presence of antidrug antibodies.

RESULTS

The mean (SD) duration of severe neutropenia for MD-110 was 0.2 (0.4) days. The upper limit of the two-sided 95% confidence interval for the mean duration of severe neutropenia was 0.2 days, below the predefined threshold of 3.0 days. The incidence of febrile neutropenia, the secondary efficacy endpoint, was 6.9% (7/101). Adverse events, occurring in more than 50% of patients, were alopecia, constipation, and malaise, which are common side effects of TC chemotherapy. Antidrug antibodies were negative in all patients.

CONCLUSION

MD-110 was effective against chemotherapy-induced neutropenia. No additional safety concern, compared with the originator, was observed in patients with breast cancer receiving TC chemotherapy.(JapicCTI-205230).

Analysis of prognosis in different subtypes of invasive lobular carcinoma using the Japanese National Cancer Database-Breast Cancer Registry

PURPOSE

Many studies have shown that the prognosis of invasive lobular carcinoma (ILC) is better than that of invasive ductal carcinoma (IDC). However, both disorders exhibit different prognoses according to molecular subtype, and the prognosis of ILC subtypes might depend on their hormone receptor positivity rate. This study clarified the prognosis of ILC and IDC in each subtype and examined the effectiveness of adjuvant chemotherapy (CT) in luminal ILC.

METHODS

We planned the analysis using data from the Breast Cancer Registry in Japan. Because it was presumed that there are differences in characteristics between ILC and IDC, we created matched cohorts using exact matching to compare their prognoses. We compared the prognosis of ILC and IDC for each subtype. We also compared the prognosis of luminal ILC between the CT and non-CT groups.

RESULTS

For all subtypes, the disease-free survival (DFS) and overall survival (OS) of ILC were poorer than those of IDC. In the analysis by each subtype, no statistically significant difference was found in DFS and OS in luminal human epidermal growth factor 2 (HER2), HER2, and triple-negative cohorts; however, luminal ILC had significantly poorer DFS and OS than luminal IDC. The CT effects on the prognosis of luminal ILC were greater in more advanced cases.

CONCLUSION

Luminal ILC had a poorer prognosis than luminal IDC, contributing to the worse prognosis of ILC than that of IDC in the overall cohort. Different therapeutic approaches from luminal IDC are essential for a better prognosis of luminal ILC.

Efficacy of probiotics and trimebutine maleate for abemaciclib-induced diarrhea: A randomized, open-label phase II trial (MERMAID, WJOG11318B)

BACKGROUND

Abemaciclib-induced diarrhea (AID) impairs quality of life (QOL) and treatment adherence in patients with breast cancer. Supportive treatment with loperamide is associated with constipation. We hypothesized that probiotics and trimebutine maleate (TM) would decrease the frequency of AID without causing constipation.

METHODS

Hormone receptor-positive, human epidermal growth factor 2-negative advanced breast cancer patients were randomized into the probiotic Bifidobacterium (A) or probiotic Bifidobacterium and TM (B) groups. Endocrine therapy, Abemaciclib and probiotic Bifidobacterium three times a day for 28 days, was administered to both arms. Arm B was treated with TM upon the onset of diarrhea. The primary endpoint was the percentage of patients who experienced grade ≥2 diarrhea. The secondary endpoints were safety, frequency, and duration of all-grade diarrhea; frequency of emesis and constipation; usage of loperamide; and health-related QOL/patient-reported outcome during the study. We evaluated whether the primary endpoint of each arm exceeded the predetermined threshold.

RESULTS

Fifty-one patients completed treatment. Grade 2 diarrhea occurred in 52% and 50% of patients in Arm A and Arm B, respectively. One patient experienced grade 3 diarrhea in each arm. The median duration of grade2 diarrhea was 2 and 2.5day, and only one patient required dose reduction. Grade ≥2 constipation was observed in 4% of Arm A and 3.6% of Arm B.

CONCLUSIONS

Probiotic Bifidobacterium or the combination of probiotic Bifidobacterium with TM did not decrease the incidence of grade 2 or greater diarrhea compared with historical control, although the grade 3 or greater diarrhea was reduced.

CLINICAL TRIAL REGISTRATION

jRCT (Japan registry of clinical trials). jRCTs031190154.

Ataxia Telangiectasia in a Patient with Breast Cancer: A Case Report

Ataxia telangiectasia (AT) is a rare autosomal recessive disorder caused by the pathological variants of the ATM gene. Owing to i ts r arity a nd n ature, complications of AT, such a s malignant tumors, a re often difficult to manage with standard imaging studies and treatments, and there are no established management strategies. We report the case of a woman who had AT in childhood and developed breast cancer in her 20s; the disease was successfully managed by the decision-making of multidisciplinary physicians professionals with ethics support. She was immunocompromised, ataxic, and mentally impaired. The patient's mother noticed a tumor in her right breast and subsequently brought her to our department. Although preoperative testing and surgical procedures were limited as AT is extremely radiosensitive, the patient was diagnosed with cT2N0M0 breast cancer and underwent right mastectomy and axillary lymph node sampling. The final diagnosis was pT2N0M0 pStage IIA mucinous carcinoma, and immunohistochemistry of the tumor specimen was estrogen receptor-positive, progesterone receptor-positive, and HER2-negative. Tamoxifen was administered as postoperative adjuvant therapy, and the patient has survived to date without recurrence. Here, we report our experience with breast cancer treatment for AT, along with a review of the literature.

Retrospective study to estimate the prevalence and describe the clinicopathological characteristics, treatments received, and outcomes of HER2-low breast cancer

BACKGROUND

Approximately 80% of all breast cancers (BCs) are currently categorized as human epidermal growth factor receptor 2 (HER2)-negative [immunohistochemistry (IHC) 0, 1+, or 2+/in situ hybridization (ISH) negative]; approximately 60% of BCs traditionally categorized as HER2-negative express low levels of HER2. HER2-low (IHC 1+ or IHC 2+/ISH-) status became clinically actionable with approval of trastuzumab deruxtecan to treat unresectable/metastatic HER2-low BC. Greater understanding of patients with HER2-low disease is urgently needed.

PATIENTS AND METHODS

This global, multicenter, retrospective study (NCT04807595) included tissue samples from patients with confirmed HER2-negative unresectable/metastatic BC [any hormone receptor (HR) status] diagnosed from 2014 to 2017. Pathologists rescored HER2 IHC-stained slides as HER2-low (IHC 1+ or IHC 2+/ISH-) or HER2 IHC 0 after training on low-end expression scoring using Ventana 4B5 and other assays at local laboratories (13 sites; 10 countries) blinded to historical scores. HER2-low prevalence and concordance between historical scores and rescores were assessed. Demographics, clinicopathological characteristics, treatments, and outcomes were examined.

RESULTS

In rescored samples from 789 patients with HER2-negative unresectable/metastatic BC, the overall HER2-low prevalence was 67.2% (HR positive, 71.1%; HR negative, 52.8%). Concordance was moderate between historical and rescored HER2 statuses (81.3%; κ = 0.583); positive agreement was numerically higher for HER2-low (87.5%) than HER2 IHC 0 (69.9%). More than 30% of historical IHC 0 cases were rescored as HER2-low overall (all assays) and using Ventana 4B5. There were no notable differences between HER2-low and HER2 IHC 0 in patient characteristics, treatments received, or clinical outcomes.

CONCLUSIONS

Approximately two-thirds of patients with historically HER2-negative unresectable/metastatic BC may benefit from HER2-low-directed treatments. Our data suggest that HER2 reassessment in patients with historical IHC 0 scores may be considered to help optimize selection of patients for treatment. Further, accurate identification of patients with HER2-low BC may be achieved with standardized pathologist training.

Assessment of the Impact of Alternative Fixatives on HER2 Detection in Breast Cancer and Gastric Cancer Tumor Specimens

The type of fixative used for preserving tumor specimens can significantly impact the performance of the immunohistochemistry and in situ hybridization assays used for assessing human epidermal growth factor receptor 2 (HER2) status. This study reports the prevalence of the use of alternative fixatives other than the guideline-recommended 10% neutral buffered formalin (NBF) during HER2 testing in a real-world setting. The effects of alternative fixatives [20% NBF and 10% unbuffered formalin (UBF) fixatives] on HER2 testing of breast cancer (BC) and gastric cancer (GC) cell lines and tissues are also assessed. Overall, 117,636 tumor samples received at a central laboratory from >8000 clinical trial sites across 60 countries were reviewed to determine the prevalence of alternative fixative usage. To investigate the impact of alternative fixatives, 27 cell lines (21 BC and 6 GC) and 76 tumor tissue samples (50 BC and 26 GC) were fixed in 10% NBF, 20% NBF, or 10% UBF, and evaluated for HER2 status by immunohistochemistry and in situ hybridization. Real-world data showed that 9195 (7.8%) tumor samples were preserved using an alternative fixative. In cell lines, overall percentage agreement, negative percentage agreement, and positive percentage agreement among the 3 fixatives were 100%. In tumor tissues, the agreement among 10% NBF, 20% NBF, and 10% UBF ranged between 94.7% and 96.6% for negative percentage agreement and 90.9% for overall percentage agreement compared with a range of 58.3% to 66.7% for positive percentage agreement. These results suggest that alternative fixatives may have the potential to convert HER2 status in tissues from positive to negative.

Fulvestrant plus palbociclib in advanced or metastatic hormone receptor-positive/human epidermal growth factor receptor 2-negative breast cancer after fulvestrant monotherapy: Japan Breast Cancer Research Group-M07 (FUTURE trial)

PURPOSE

The combination of cyclin-dependent kinase 4/6 inhibitors and endocrine therapy is a standard treatment for hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC); however, their toxicities and financial burden are major issues, especially for prolonged treatment. We investigated fulvestrant plus palbociclib in patients with HR-positive MBC resistant to fulvestrant monotherapy.

METHODS

Patients who initially received fulvestrant as their first- or second-line endocrine therapy were assigned to group A. Patients with disease progression during fulvestrant monotherapy who subsequently received fulvestrant plus palbociclib were assigned to group B. The primary endpoint was progression-free survival (PFS1) in group B. We set the threshold median PFS of 5 months (null hypothesis).

RESULTS

Between January 2018 and February 2020 we enrolled 167 patients in group A (January 2018-February 2020) from 55 institutions, of whom 72 subsequently received fulvestrant plus palbociclib and were enrolled in group B. The median follow-up was 23.8 and 8.9 months in groups A and B, respectively. The median PFS in group B (combination therapy) was 9.4 (90% confidence interval [CI]: 6.9-11.2) months (p < 0.001). This was 25.7 (90% CI: 21.2-30.3) months in group A (fulvestrant monotherapy). The TTF in group B was 7.2 (90% CI: 5.5-10.4) months. In the post-hoc analysis, the median PFS1 in group B among patients with longer-duration fulvestrant monotherapy (> 1 year) was longer than that of patients with shorter-duration monotherapy (≤ 1 year) (11.3 vs. 7.6 months). No new toxicities were observed.

CONCLUSION

Our findings suggest that palbociclib plus fulvestrant after disease progression despite fulvestrant monotherapy is potentially safe and effective in patients with HR-positive/HER2-negative advanced MBC.

Abstract HER2-15: HER2-15 Retrospective Study to Estimate the Prevalence and Describe the Clinicopathological Characteristics, Treatment Patterns, and Outcomes of HER2-Low Breast Cancer

Background: About 60% of breast cancers (BCs) traditionally categorized as HER2 negative (HER2-neg; immunohistochemistry [IHC] 0, IHC 1+ or IHC 2+/in situ hybridization [ISH]–) express low levels of HER2 (HER2-low; IHC 1+ or IHC 2+/ISH–; Schettini, NPJ Breast Cancer 2021). In the phase 3 DESTINY-Breast04 trial (NCT03734029), trastuzumab deruxtecan (T-DXd) showed significantly longer progression-free survival and overall survival (OS) vs physician’s choice of chemotherapy in patients (pts) with HER2-low metastatic BC (mBC) who previously received chemotherapy (Modi, NEJM 2022). As HER2-low becomes a clinically relevant HER2 status among pts with BC, greater understanding of pts with HER2-low disease is needed, including identification of these pts using conventional IHC assays. Our objectives were to assess the prevalence of HER2-low among HER2-neg mBC based on rescored HER2 IHC slides, to describe characteristics of pts with HER2-low mBC, and to characterize concordance between historical HER2 scores and rescores. Methods: This global, multicenter, retrospective study (NCT04807595) included pts with confirmed HER2-neg (HER2 IHC 0, 1+, or 2+/ISH−) unresectable/mBC diagnosed from 2014 through 2017. HER2 IHC-stained slides were rescored after training on low-end expression scoring using Ventana 4B5 and other assays by local laboratories at 13 sites in 10 countries blinded to historical HER2 scores. BCs were categorized as HER2-low (IHC 1+ or IHC 2+/ISH−) or HER2 IHC 0 (IHC 0 or &gt;0&lt; 1+). Prevalence of HER2-low and concordance between historical HER2 scores and rescores were assessed. Demographics, clinicopathological characteristics, treatment patterns, and outcomes were examined via data from medical charts/health records. Results: HER2 rescores were obtained for 781 pts with HER2-neg mBC. HER2-low prevalence was 67.1% overall; 71.1% in hormone receptor (HR)–positive (HR+) and 52.5% in HR–negative (HR−) subgroups. There were no notable differences in characteristics (Table) or treatment patterns between pts with HER2-low and HER2 IHC 0. The most frequent therapies used in the first treatment in the metastatic setting were endocrine therapy (64.1%) for pts with HR+ mBC and chemotherapy (94.4%) for pts with HR− mBC. Among pts with HR+ mBC, 10.2% received cyclin-dependent kinase 4/6 inhibitors as part of their first treatment. There were no statistically significant differences in clinical outcomes between the HER2-low and HER2 IHC 0 groups within each HR subgroup. For pts with HR+ mBC, median time to first subsequent treatment was 10 and 8 months for the HER2-low and HER2 IHC 0 groups, respectively. Overall, concordance was 81.2% (kappa=0.582). Concordance between historical HER2 scores and rescores was 87.3% for HER2-low and 70.1% for HER2 IHC 0 samples. Conclusions: The prevalence of HER2-low (67.1%) among pts previously categorized as HER2-neg mBC in this study was similar to that of an earlier study (≈60%). No obvious differences in patient characteristics or clinical presentation were seen between pts with HER2-low and HER2 IHC 0 mBC. Overall percentage agreement between rescored and historical HER2 scores was 81.2%; agreement was numerically greater for HER2-low than HER2 IHC 0. As HER2-targeted therapies such as T-DXd for the treatment of pts with HER2-low BC are emerging, a greater understanding of pts with HER2-low expression who may benefit from these therapies is important.

Citation Format: Giuseppe Viale, Mark Basik, Naoki Niikura, Eriko Tokunaga, Sara Brucker, Frédérique Penault-Llorca, Naoki Hayashi, Joo Hyuk Sohn, Rita Teixeira de Sousa, Adam M. Brufsky, Ciara S. O’Brien, Fernando Schmitt, Gavin Higgins, Della Varghese, Gareth D. James, Akira Moh, Andrew Livingston, Victoria de Giorgio-Miller. HER2-15 Retrospective Study to Estimate the Prevalence and Describe the Clinicopathological Characteristics, Treatment Patterns, and Outcomes of HER2-Low Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr HER2-15.

Abstract OT2-16-02: Open-label, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with advanced/metastatic human epidermal growth factor receptor 2–positive breast cancer: DESTINY-Breast12

Background: Patients (pts) with human epidermal growth factor receptor 2–positive breast cancer (HER2+ BC) have a high incidence (up to 50%) of brain metastasis (BM) despite advances in treatment (Zimmer AS et al. Cancer Rep (Hoboken). 2020;e1274; Hurvitz SA et al. Clin Cancer Res. 2019;25:2433-2441). Although several agents have been studied in pts with HER2+ BC with BM, an unmet medical need remains. In DESTINY-Breast01, T-DXd demonstrated efficacy in the overall population and preliminary efficacy in a pt subgroup with stable BM (n=24), with a confirmed objective response rate (ORR) of 61.4%, an extracranial confirmed ORR by independent central review (ICR) of 58.3%, respectively, and median progression-free survival (PFS) of 19.4 and 18.1 months, respectively (Modi S et al. Cancer Res. 2021. Abst PD3-06; Jerusalem G et al. Ann Oncol. 2020. Abst 138O). T-DXd also demonstrated preliminary efficacy in a subgroup of pts with BM in the DESTINY-Breast03 trial, with an extracranial ORR of 67.4%, intracranial ORR of 63.9%, and median PFS of 15.0 months (Hurvitz S et al. SABCS 2021. Abst GS3-01). However, both trials excluded pts with active/progressive BM. Here we describe a trial evaluating T-DXd in a real-world setting in pts with stable or active BM and pts without BM with previously treated advanced/metastatic HER2+ BC. The data generated by this study will complement previous and ongoing studies, providing a more robust understanding of T-DXd treatment in patients with and without BM. Trial design: DESTINY-Breast12 (NCT04739761) is an open-label, multicenter, international (91 sites in the US, Europe, Australia, Canada, and Japan), phase 3b/4 study assessing the efficacy and safety of T-DXd 5.4 mg/kg every 3 weeks in pts with HER2+ BC ± BM. As part of prescreening, all pts will provide informed consent for tumor tissue samples (archival tumor tissue or fresh biopsy) to be collected and tested for HER2 status. Pts will be enrolled in 1 of 2 cohorts (250 pts each): cohort 1 (no BM at baseline) and cohort 2 (BM at baseline). Pts must have previously treated HER2-positive BC that has progressed on or after ≥1 prior anti-HER2–based regimen (including disease progression ≤6 months after adjuvant treatment with HER2-targeted therapies) and received ≤2 lines of therapy in the metastatic setting (excluding pts with prior tucatinib). Cohort 1 will be limited to include ≤25% third-line pts. Pts with BM must have untreated BM not needing immediate local therapy or previously treated stable or progressing BM. Primary endpoints are ORR in cohort 1 and PFS in cohort 2 (both by Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1 per ICR). Secondary endpoints in both cohorts are overall survival, DOR, time to progression, duration of subsequent therapy, PFS2, safety, and changes in symptoms, functioning, and quality of life. Incidence of new symptomatic central nervous system (CNS) metastasis is a secondary endpoint in cohort 1, and ORR and CNS ORR by RECIST 1.1 per ICR, CNS PFS and DOR, and time to new CNS metastasis are secondary endpoints in cohort 2.

Citation Format: Nancy U. Lin, Eva Ciruelos, Guy Jerusalem, Volkmar Müller, Naoki Niikura, Giuseppe Viale, Emma Oscroft, Shawn Anand, Manoj Prahladan, Nadia Harbeck. Open-label, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with advanced/metastatic human epidermal growth factor receptor 2–positive breast cancer: DESTINY-Breast12 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-16-02.

Abstract PD7-01: Trastuzumab deruxtecan for the treatment of patients with HER2-positive breast cancer with brain and/or leptomeningeal metastases: A multicenter retrospective study (ROSET-BM study)

Background: Brain metastases (BM) occur in 20%-50% of patients (pts) with HER2-positive (HER2+) metastatic breast cancer (MBC), and their presence is a poor prognostic factor. Leptomeningeal carcinomatosis (LMC) occurs in 12%–43% of pts with MBC. Therapeutic options for BC pts with BM and/or LMC are limited. Results of the DESTINY-Breast01 and DESTINY-Breast03 studies have shown the clinical benefit of trastuzumab deruxtecan (T-DXd) in HER2+ MBC pts with stable BM; however, the study populations were small and did not include pts with active BM (untreated or progressive) and/or LMC. This data gap is addressed in the present study. Methods: ROSET-BM (UMIN000044995) is a multicenter, retrospective chart review study of pts who received T-DXd for HER2+ MBC with BM and LMC between May 25, 2020, and April 30, 2021, in a standard-of-care setting. Overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) were evaluated. Additionally, in the pts with brain imaging data, intracranial (IC)-ORR and IC-PFS were evaluated by independent radiologists to provide central review according to RECIST v1.1. Active BM were determined by independent central review (ICR). Pts whose baseline and pre-baseline brain imaging data were compared and confirmed increased tumor size, or pts with new lesions were classified as active BM. LMC was determined by ICR using brain imaging. Results: In the study period, 62 sites participated, enrolling 113 pts with HER2+ MBC and BM were treated with T-DXd. After exclusion of data from 9 who did not meet the criteria for inclusion, 104 pts were included in the analysis. In the 104 pts, 70.2% (n=73) were active BM, 16.3% (n=17) were active BM with LMC, 5.8% (n=6) were stable BM, 1.9% (n=2) were only LMC, and 5.8% (n=6) were not classified. Symptomatic BM were observed in 30.8% (n=32). Median number of prior lines of therapy was 4 (range, 1–15). Median duration of follow up from first T-DXd treatment was 11.2 months. ORR assessed by investigator was 55.7% (complete response [CR], 5.2%) in all pts, 51.7% (CR, 6.9%) in symptomatic BM pts (n=29), and 57.4% (CR, 4.4%) in asymptomatic BM pts (n=68). Among all pts, median PFS was 16.1 months (95%CI, 12.0–n/a), and median OS was not reached (OS at 1 year was 74.9%). In the 19 pts with LMC, 1-year PFS and OS were 60.7% (95%CI, 34.5–79.1) and 87.1% (95%CI, 57.3–96.6), respectively (neither reached the median). Of the 89 pts with brain lesion imaging data (at both baseline and follow-up), IC-ORR was 62.7% (CR, 0.0%). IC-PD was observed in 5.9% (n=3) of pts. Median IC-PFS was 16.1 months (95%CI, 12.2–n/a). In all pts, the most common event and adverse event leading to discontinuation of T-DXd were PD (27 pts, 26.0%) and interstitial lung disease (19 pts,18.3%), respectively. Conclusion: The results of this retrospective chart review show that T-DXd has promising efficacy in HER2+ MBC pts with active BM and LMC. This study was funded by Daiichi Sankyo Co., Ltd.

Citation Format: Takashi Yamanaka, Naoki Niikura, Hironori Nomura, Hiroki Kusama, Mitsugu Yamamoto, Kazuo Matsuura, Kenichi Inoue, Sachiko Takahara, Shosuke Kita, Miki Yamaguchi, Tomoyuki Aruga, Nobuhiro Shibata, Akihiko Shimomura, Yuri Ozaki, Kazuhiro Shiraishi, Shuji Sakai, Yoko Kiga, Tadahiro Izutani, Kazuhito Shiosakai, Junji Tsurutani. Trastuzumab deruxtecan for the treatment of patients with HER2-positive breast cancer with brain and/or leptomeningeal metastases: A multicenter retrospective study (ROSET-BM study) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD7-01.

Abstract P1-11-01: Trastuzumab deruxtecan vs treatment of physician’s choice in patients with HER2-low unresectable and/or metastatic breast cancer: Subgroup analyses from DESTINY-Breast04

Background: DESTINY-Breast04 demonstrated that the HER2 targeting antibody–drug conjugate trastuzumab deruxtecan (T-DXd) significantly prolonged progression-free survival (PFS) and overall survival (OS) vs treatment of physician’s choice (TPC) in patients (pts) with HER2-low (immunohistochemistry [IHC] 1+ or IHC 2+/in situ hybridization negative) metastatic breast cancer (mBC) in pts in the hormone receptor−positive (HR+) cohort and all pts (HR+ and HR-; median PFS, 9.9 vs 5.1 months [mo], hazard ratio: 0.50; median OS, 23.4 vs 16.8 mo, hazard ratio: 0.64; both P &lt; 0.0001; Modi et al. N Engl J Med 2022). Objective response rate (ORR) with T-DXd was ≥50% across cohorts. These subgroup analyses examine pt history and disease characteristics that may correlate with response to therapy.

Methods: N = 557 pts with centrally confirmed HER2-low mBC were randomized 2:1 to T-DXd or TPC. Randomization was stratified by HER2 status (IHC 1+ vs 2+), 1 vs 2 prior lines of chemotherapy, and HR+ (with vs without prior treatment with cyclin-dependent kinase 4/6 inhibitor [CDK4/6i]) vs HR−. With the exception of the PFS and OS analyses by prior CDK4/6i use, all other described efficacy analyses were assessed post-hoc.

Results: Benefit of T-DXd vs TPC was consistent in pts with or without prior CDK4/6i use (Table 1). Pts with high disease burden (ie, ≥3 metastatic sites) also benefited from T-DXd vs TPC (Table 2). There was a small subgroup (n = 22) among all pts (HR+ [n = 18] and HR− disease [n = 4]) with rapid progression prior to enrollment (disease progression within 6 mo of concluding a prior course of chemotherapy in early breast cancer). T-DXd showed responses in 7/14 (50%) pts in this subgroup vs 0/8 with TPC; this subgroup also had prolonged median PFS with T-DXd vs TPC (Table 3). Efficacy data for HER2 IHC 1+ vs 2+ and prior chemotherapy subgroups will be presented. Median OS was not reached for many subgroups (insufficient events in each group [data not shown]); however, subgroups in general showed OS benefit consistent with the primary analysis. With T-DXd, rates of interstitial lung disease/pneumonitis were similar in pts with/without prior CDK4/6i use.

Conclusions: T-DXd treatment for HER2-low mBC in the phase 3 study DESTINY-Breast04 showed consistent efficacy independent of disease burden, prior CDK4/6i treatment, or rapid progression status. ILD is an important identified risk and requires proactive monitoring and management. These data continue to support the use of T-DXd as the new standard of care across subgroups of pts with HER2-low mBC.

Editorial Acknowledgment

Under guidance of the authors, assistance in medical writing and editorial support was provided by Eileen McIver, PhD, and Soniya Patel, PhD, of ApotheCom, and was funded by Daiichi Sankyo.

Funding

This study was funded by Daiichi Sankyo and AstraZeneca.

Table 1. Efficacy by Prior CDK4/6i Treatment in Pts With HER2-Low Breast Cancer, HR+ Cohort.

Table 2. Efficacy by Disease Burdena in Pts With HER2-Low Breast Cancer, ITT.

Table 3. Efficacy by Rapid Progressor Statusa in Pts With HER2-Low Breast Cancer, ITT.

Citation Format: Nadia Harbeck, Shanu Modi, William Jacot, Toshinari Yamashita, Joo Hyuk Sohn, Maria Vidal, Junji Tsurutani, Naoto T. Ueno, Aleix Prat, Naoki Niikura, Binghe Xu, Hope Rugo, Konstantinos Papazisis, Javier Cortés, Ian Krop, Dhiraj Gambhire, Lotus Yung, Yibin Wang, Jasmeet Singh, David Cameron. Trastuzumab deruxtecan vs treatment of physician’s choice in patients with HER2-low unresectable and/or metastatic breast cancer: Subgroup analyses from DESTINY-Breast04 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-11-01.

Abstract P2-20-16: Hormone receptor expression is associated with specific immunological profiles in the breast cancer microenvironment

Purpose: Elucidating the unique immunomodulatory mechanisms in breast cancer microenvironment should provide useful insights to aid the development of new therapeutic strategies for this disease. Some studies suggested the immune regulatory function of hormone receptor such as estrogen receptor-α (ER) and androgen receptor (AR), but their mechanism has not been fully understood because of the complexity of immune milieu in breast cancer microenvironment. In this study, we systematically analyzed the relationships between ER, progesterone receptor (PgR), and AR expression and the immunological profile in breast cancer tissue. Methods: Gene set enrichment analysis (GSEA) was used to screen the biological processes associated with the expression of human sex hormone receptor genes (ESR1, PGR, and AR), using a gene expression profile dataset of the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC). Then, using METABRIC and a gene expression profile dataset of The Sweden Cancerome Analysis Network - Breast (SCAN-B), the correlation between the immune cell composition in breast cancer tissue (estimated with the CIBERSORTx) and hormone receptor expression was analyzed. In our previous study of 45 breast cancer tissues, we evaluated the level of human tumor infiltrating lymphocytes (hTILs), expression of human programmed death-ligand 1 (hPD-L1), and infiltration of 11 types of immune cells, using hematoxylin–eosin staining, immunohistochemistry (IHC), and multicolor flow cytometry, respectively. In this study, the levels of ER, PgR, and AR expression were further evaluated using IHC, and their relationship with the immunological profile of breast cancer tissues was analyzed. Results: GSEA showed that the expression levels of the ESR1, PGR, and AR genes were negatively correlated with multiple immunological processes, including “INFLAMMATORY RESPONSE.” Analysis of the correlations between the immune cell composition and hormone receptor gene expression showed that ESR1 expression was inversely correlated with Macrophage M1, CD4 memory activated T cells, Macrophage M0, CD8 T cells, and CD4 memory resting T cells; PGR expression was inversely correlated with Macrophage M1, CD4 memory activated T cells, and Macrophage M0; and AR expression was inversely correlated with Macrophage M0 and Macrophage M1. Immunohistochemical evaluation of ER and AR expression revealed both receptors to be inversely associated with hTIL, hPD-L1 expression, and leukocyte infiltration in breast cancer tissue. Analysis of the immune cell composition in these tissues revealed that ER expression was associated with the decreased infiltration of total T cells, CD4+ T cells, monocytes/macrophages, myeloid-derived suppressor cells, dendritic cells, and myeloid dendritic cells; PgR expression was associated with the decreased infiltration of dendritic cells; and AR expression was associated with the decreased infiltration of CD4+ T cells, monocytes/macrophages, nonclassical monocytes, myeloid-derived suppressor cells, dendritic cells, myeloid dendritic cells, and minor natural killer cells. Conclusion: The correlation of hormone receptor expression with specific immunological profiles in the breast cancer microenvironment both at the genetic and protein levels strongly suggests that hormonal signals may preferentially affect certain subsets of immune cells.

Citation Format: Toru Hanamura, Shigehisa Kitano, Hiroshi Kagamu, Makiko Yamashita, Mayako Terao, Takuho Okamura, Nobue Kumaki, Katsuto Hozumi, Takayuki Iwamoto, Chikako Honda, Sasagu Kurozumi, Naoki Niikura. Hormone receptor expression is associated with specific immunological profiles in the breast cancer microenvironment [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-20-16.

Expression of hormone receptors is associated with specific immunological profiles of the breast cancer microenvironment

BACKGROUND

Elucidating the unique immunoregulatory mechanisms in breast cancer microenvironment may help develop new therapeutic strategies. Some studies have suggested that hormone receptors also have immune regulatory functions, but their mechanisms are not fully understood. In this study, we have comprehensively analyzed the relationship between the expressions of estrogen (ER), progesterone (PgR), and androgen receptors (AR), and the immunological profile in breast cancer.

METHODS

Using publicly available gene expression profile datasets, METABRIC and SCAN-B, the associations between the expressions of hormone receptors and the immune cell compositions in breast cancer tissue, estimated by CIBERSORTx algorithm, were analyzed. We histologically evaluated tumor-infiltrating lymphocytes (hTIL), PD-L1 (hPD-L1) expression, and the infiltration of 11 types of immune cells by flow cytometry (FCM) for 45 breast cancer tissue samples. The relationships between them and the expressions of ER, PgR, and AR of tumor tissues, evaluated immunohistochemically, were analyzed.

RESULTS

Expressions of ESR1, PGR, and AR were negatively correlated with overall immune composition. Expressions of ER and AR, but not that of PgR, were inversely associated with hTIL and hPD-L1 expression. FCM analysis showed that the expressions of ER and AR, but not that of PgR, were associated with decreased total leukocyte infiltration. Both CIBERSORTx and FCM analysis showed that ER expression was associated with reduced infiltration of macrophages and CD4+ T cells and that of AR with reduced macrophage infiltration.

CONCLUSION

Hormone receptor expression correlates with specific immunological profiles in the breast cancer microenvironment both at the gene and protein expression levels.

Characteristics of female breast cancer in japan: annual report of the National Clinical Database in 2018

Information regarding patients who were treated for breast cancer in 2018 was extracted from the National Clinical Database (NCD), which is run by Japanese physicians. This database continues from 1975, created by the Japanese Breast Cancer Society (JBCS). A total of 95,620 breast cancer cases were registered. The demographics, clinical characteristics, pathology, surgical treatment, adjuvant chemotherapy, adjuvant endocrine therapy, and radiation therapy of Japanese breast cancer patients were summarized. We made comparisons with other reports to reveal the characteristics of our database. We also described some features in Japanese breast cancer that changed over time. The unique characteristics of breast cancer patients in Japan may provide guidance for future research and improvement in healthcare services.

Physicians' perception about the impact of breast reconstruction on patient prognosis: a survey in Japan

BACKGROUND

One barrier to the widespread use of breast reconstruction (BR) is physicians' perception that BR adversely affects breast cancer prognosis. However, there is limited information regarding physicians' understanding of the impact of BR on patient prognosis and which physicians have misunderstandings about BR.

METHODS

We conducted an e-mail survey regarding the impact of BR on the prognosis of patients with breast cancer among members of the Japanese Breast Cancer Society.

RESULTS

Of 369 respondents, 99 (27%) said that they believe BR affects patient prognosis. Female respondents and those who treat fewer new breast cancer patients per year were more likely to state that they believe BR affects patient prognosis (P = 0.006 and 0.007). Respondents who believed that BR affects patient prognosis underestimated 5-year overall survival rates in patients who receive BR and subsequently have local or regional recurrence in different sites.

CONCLUSION

Our survey demonstrated that a quarter of respondents believe that BR affects patient prognosis and underestimate survival rates in patients who receive BR and have subsequent local or regional recurrence. Because of the lack of evidence regarding the impact of BR on patient prognosis, educating physicians by providing accurate knowledge regarding BR and patient prognosis is highly recommended.

Quantitative Values from Synthetic MRI Correlate with Breast Cancer Subtypes

The purpose of this study is to correlate quantitative T1, T2, and proton density (PD) values with breast cancer subtypes. Twenty-eight breast cancer patients underwent MRI of the breast including synthetic MRI. T1, T2, and PD values were correlated with Ki-67 and were compared between ER-positive and ER-negative cancers, and between Luminal A and Luminal B cancers. The effectiveness of T1, T2, and PD in differentiating the ER-negative from the ER-positive group and Luminal A from Luminal B cancers was evaluated using receiver operating characteristic analysis. Mean T2 relaxation of ER-negative cancers was significantly higher than that of ER-positive cancers (p < 0.05). The T1, T2, and PD values exhibited a strong positive correlation with Ki-67 (Pearson’s r = 0.75, 0.69, and 0.60 respectively; p < 0.001). Among ER-positive cancers, T1, T2, and PD values of Luminal A cancers were significantly lower than those of Luminal B cancers (p < 0.05). The area under the curve (AUC) of T2 for discriminating ER-negative from ER-positive cancers was 0.87 (95% CI: 0.69−0.97). The AUC of T1 for discriminating Luminal A from Luminal B cancers was 0.83 (95% CI: 0.61−0.95). In conclusion, quantitative values derived from synthetic MRI show potential for subtyping of invasive breast cancers.

Trastuzumab Deruxtecan in Previously Treated HER2-Low Advanced Breast Cancer

BACKGROUND

Among breast cancers without human epidermal growth factor receptor 2 (HER2) amplification, overexpression, or both, a large proportion express low levels of HER2 that may be targetable. Currently available HER2-directed therapies have been ineffective in patients with these "HER2-low" cancers.

METHODS

We conducted a phase 3 trial involving patients with HER2-low metastatic breast cancer who had received one or two previous lines of chemotherapy. (Low expression of HER2 was defined as a score of 1+ on immunohistochemical [IHC] analysis or as an IHC score of 2+ and negative results on in situ hybridization.) Patients were randomly assigned in a 2:1 ratio to receive trastuzumab deruxtecan or the physician's choice of chemotherapy. The primary end point was progression-free survival in the hormone receptor-positive cohort. The key secondary end points were progression-free survival among all patients and overall survival in the hormone receptor-positive cohort and among all patients.

RESULTS

Of 557 patients who underwent randomization, 494 (88.7%) had hormone receptor-positive disease and 63 (11.3%) had hormone receptor-negative disease. In the hormone receptor-positive cohort, the median progression-free survival was 10.1 months in the trastuzumab deruxtecan group and 5.4 months in the physician's choice group (hazard ratio for disease progression or death, 0.51; P<0.001), and overall survival was 23.9 months and 17.5 months, respectively (hazard ratio for death, 0.64; P = 0.003). Among all patients, the median progression-free survival was 9.9 months in the trastuzumab deruxtecan group and 5.1 months in the physician's choice group (hazard ratio for disease progression or death, 0.50; P<0.001), and overall survival was 23.4 months and 16.8 months, respectively (hazard ratio for death, 0.64; P = 0.001). Adverse events of grade 3 or higher occurred in 52.6% of the patients who received trastuzumab deruxtecan and 67.4% of those who received the physician's choice of chemotherapy. Adjudicated, drug-related interstitial lung disease or pneumonitis occurred in 12.1% of the patients who received trastuzumab deruxtecan; 0.8% had grade 5 events.

CONCLUSIONS

In this trial involving patients with HER2-low metastatic breast cancer, trastuzumab deruxtecan resulted in significantly longer progression-free and overall survival than the physician's choice of chemotherapy. (Funded by Daiichi Sankyo and AstraZeneca; DESTINY-Breast04 ClinicalTrials.gov number, NCT03734029.).

Atezolizumab With Neoadjuvant Anti-Human Epidermal Growth Factor Receptor 2 Therapy and Chemotherapy in Human Epidermal Growth Factor Receptor 2-Positive Early Breast Cancer: Primary Results of the Randomized Phase III IMpassion050 Trial

Combining standard of care (pertuzumab-trastuzumab [PH], chemotherapy) with cancer immunotherapy may potentiate antitumor immunity, cytotoxic activity, and patient outcomes in high-risk, human epidermal growth factor receptor 2 (HER2)–positive early breast cancer. We report the phase III IMpassion050 primary analysis of neoadjuvant atezolizumab, PH, and chemotherapy in these patients.

Pertuzumab retreatment for HER2-positive advanced breast cancer: a randomized, open-label phase III study (PRECIOUS)

No standard options existed for human epidermal growth factor receptor 2 (HER2)‐positive advanced breast cancer that progresses after second‐line trastuzumab emtansine therapy before 2020. The purpose of this study was to examine the efficacy of pertuzumab retreatment after disease progression following pertuzumab‐containing therapy for HER2‐positive locally advanced or metastatic breast cancer for the first time. This randomized, open‐label, multicenter phase III trial was undertaken in 93 sites in Japan. Eligible patients with HER2‐positive breast cancer who had received pertuzumab, trastuzumab, and chemotherapy as first‐ and/or second‐line therapy were randomly assigned (1:1) to: (i) pertuzumab, trastuzumab, and physician's choice chemotherapy (PTC), or (ii) trastuzumab and physician's choice chemotherapy (TC). The primary end‐point was investigator‐assessed progression‐free survival (PFS). Between August 1, 2015 and December 31, 2018, 219 patients were randomized to PTC (n = 110) or TC (n = 109). Median follow‐up was 14.2 months (interquartile range, 9.0–22.2), and median PFS was 5.3 months (95% confidence interval [CI], 4.0–6.6) with PTC and 4.2 months (95% CI, 3.2–4.8) with TC (stratified hazard ratio 0.76 [95% CI upper limit 0.967]; p = 0.022). Progression‐free survival was improved by adding pertuzumab in all prespecified subgroups. The PTC arm showed a trend towards better overall survival and duration of response, but similar objective response and health‐related quality of life. The incidence of treatment‐related adverse events was similar between groups except for diarrhea. Pertuzumab retreatment contributes to disease control for HER2‐positive locally advanced or metastatic breast cancer previously treated with pertuzumab‐containing regimens.

Subgroup analysis of Japanese patients in a phase III randomized, controlled study of neoadjuvant atezolizumab or placebo, combined with nab-paclitaxel and anthracycline-based chemotherapy in early triple-negative breast cancer (IMpassion031)

Background

In the global phase III IMpassion031 study, neoadjuvant atezolizumab plus nab-paclitaxel/anthracycline-based chemotherapy improved pathological complete response in patients with early stage triple-negative breast cancer. Here, we report primary analysis results from a subgroup of Japanese patients.

Methods

Patients with histologically documented, previously untreated, stage cT2–cT4, cN0–cN3, cM0 triple-negative breast cancer were randomized 1:1 to receive intravenous atezolizumab 840 mg or placebo every 2 weeks in combination with chemotherapy consisting of nab-paclitaxel intravenous 125 mg/m² once a week, followed by doxorubicin intravenous 60 mg/m² and cyclophosphamide intravenous 600 mg/m² every 2 weeks. Patients then underwent surgery. Pathological complete response (ypT0/is ypN0) in the intention-to-treat and PD-L1-positive (≥1% PD-L1-expressing tumor-infiltrating immune cells) populations were co-primary endpoints.

Results

This subanalysis (data cutoff: 3 April 2020) included 36 patients from Japan (intention-to-treat; atezolizumab arm, n = 17; placebo arm, n = 19). Pathological complete response occurred in 41% (n = 7; 95% confidence interval, 18–67) of patients in the atezolizumab arm and 37% (n = 7; 95% confidence interval, 16–62) in the placebo arm. In the PD-L1-positive population, pathological complete response occurred in 50% (n = 5; 95% confidence interval, 19–81) of patients in the atezolizumab arm and 45% (n = 5; 95% confidence interval, 17–77) in the placebo arm. Treatment-related grade 3–4 adverse events occurred in 71% and 68% of patients in the respective arms.

Conclusion

Atezolizumab added to neoadjuvant chemotherapy numerically improved pathological complete response versus placebo in this small exploratory analysis of Japanese patients with early stage triple-negative breast cancer, a trend directionally consistent with the global study results. No new safety signals were identified.

Prognostic impact of postoperative radiotherapy in patients with breast cancer and with pT1-2 and 1-3 lymph node metastases: A retrospective cohort study based on the Japanese Breast Cancer Registry

AIM

Postmastectomy radiotherapy (PMRT) is the standard treatment for locally advanced breast cancer. However, the effectiveness of PMRT in patients with pT1-2 and N1 tumours remains controversial. Therefore, this study aimed to determine the prognostic impact of PMRT in patients with breast cancer and with pT1-2 and 1-3 lymph node metastases.

METHODS

Using data from the Japanese National Clinical Database from 2004 to 2012, we evaluated the association of PMRT with locoregional recurrence (LRR), any recurrence, and mortality. We enrolled patients who had undergone mastectomy and axillary node dissection and were diagnosed with pT1-2 and N1. We compared clinicopathological factors and prognosis between patients who received (PMRT group) and those who did not receive (No-PMRT group) PMRT.

RESULTS

Among 8914 patients enrolled, 492 patients belonged to the PMRT group and 8422 to the No-PMRT group. The median observation time was 6.3 years. There was no significant difference in the incidences of LRR (4.0% versus 5.0%, P = 0.61), recurrence (13.8% versus 11.8%, P = 0.23) and breast cancer death (6.0% versus 4.3%, P = 0.08) at 5 years between the groups. Multivariable analysis revealed that LRR was significantly associated with tumour size, number of node metastases and triple-negative subtype but not with PMRT.

CONCLUSIONS

The LRR rate in the No-PMRT group was 5.0% at 5 years among patients with T1-2 and N1. PMRT did not significantly influence LRR in patients with T1-2 and N1. However, PMRT administration should be tailored considering the individual risks of tumour size, 3 node metastases and triple-negative subtype.

Trastuzumab deruxtecan (T-DXd) versus treatment of physician’s choice (TPC) in patients (pts) with HER2-low unresectable and/or metastatic breast cancer (mBC): Results of DESTINY-Breast04, a randomized, phase 3 study

LBA3

Background: About 55% of mBC typically categorized as HER2 negative, express low levels of HER2 (IHC 1+ or IHC 2+/ISH− by ASCO/CAP 2018 guidelines) with poor outcomes in later lines (Tarantino 2020). T-DXd has shown promising efficacy in HER2-low mBC in a phase 1 study (NCT02564900; Modi 2020). This is the primary report from DESTINY-Breast04 (NCT03734029), the first randomized, multicenter, open-label, phase 3 study comparing efficacy and safety of T-DXd vs TPC in pts with HER2-low mBC treated with 1-2 prior lines of chemotherapy in the metastatic setting. Methods: 557 pts with centrally confirmed HER2-low mBC were randomly assigned 2:1 to T-DXd 5.4 mg/kg or TPC (capecitabine, eribulin, gemcitabine, paclitaxel, or nab-paclitaxel). The primary endpoint was progression-free survival (PFS) determined by blinded independent central review (BICR) in pts with hormone receptor–positive (HR+) mBC. Key secondary endpoints (hierarchically tested after the primary endpoint) include PFS by BICR in the full analysis set (FAS; HR+/−) and overall survival (OS) in pts with HR+ mBC and in FAS. Other endpoints were objective response rate, duration of response, safety, and an exploratory analysis of pts with HR− mBC. Results: As of Jan 11, 2022, 373 and 184 pts (88.7% and 88.6% HR+ mBC) were assigned to T-DXd and TPC, respectively. Median follow-up was 18.4 months (mo; 95% CI, 17.9-19.1). Median treatment duration was 8.2 mo (range, 0.2-33.3) with T-DXd and 3.5 mo (range, 0.3-17.6) with TPC. Efficacy results are in the Table. 52.6% of pts with T-DXd vs. 67.4% of pts with TPC had grade (G) ≥ 3 treatment-emergent adverse events (TEAEs). With T-DXd, 45 pts (12.1%; 10.0% G1/2, 1.3% G3/4, 0.8% G5) had independently adjudicated drug-related interstitial lung disease [ILD]/pneumonitis vs. 1 pt (0.6% G1) with TPC. Conclusions: DESTINY-Breast04 is the first phase 3 trial of a HER2-directed therapy in pts with HER2-low mBC to show a statistically significant and clinically meaningful benefit in PFS and OS compared to standard-of-care treatment, regardless of HR status, with a generally manageable safety profile. Funding: Daiichi Sankyo, Inc., and AstraZeneca. Clinical trial information: NCT03734029. [Table: see text]

Retrospective study to estimate the prevalence of HER2-low breast cancer (BC) and describe its clinicopathological characteristics

1087

Background: Approximately 50% of BCs traditionally categorized as HER2 negative (HER2-neg) express low levels of HER2 (IHC 1+ or IHC 2+/ISH-; Miglietta, NPJ Breast Cancer 2021). HER2-targeted therapies for HER2-low metastatic BC (mBC) are under investigation (eg, T-DXd in the phase 3 DESTINY-Breast04 study; NCT03734029), but HER2 assays currently used to select patients (pts) for approved anti-HER2 therapies are optimized for high HER2 expression and are not validated for HER2-low detection. A recent study found relatively poor agreement (<70% interrater agreement) in evaluation of IHC scores of 0 and 1+ using current HER2 assays (Fernandez, JAMA Oncol 2022). Our objectives were to assess the prevalence of HER2-low among HER2-neg based on rescored HER2 IHC slides after training on low-end expression scoring and to describe pt characteristics of HER2-low vs HER2 IHC 0 mBC. Preliminary results are reported for 233 of 1000 planned pts. Methods: This multicenter, retrospective study (NCT04807595) included pts with confirmed HER2-neg unresectable/mBC diagnosed between 2015 and 2017. Local laboratories, blinded to historical HER2 scores, rescored HER2 IHC-stained slides. HER2 was assessed using Ventana 4B5 and other assays. BCs were categorized as HER2-low or HER2 IHC 0. The prevalence of HER2-low BC among pts originally scored as HER2-neg was measured. Demographics (eg, age, country, race) and clinicopathological characteristics were examined via medical charts/electronic health records. Concordance between historical HER2 scores and rescores was assessed. Results: HER2 rescores were obtained for 233 pts (mean age, 54 y). HER2-low prevalence was 63.2% overall and numerically greater in hormone receptor (HR)–positive vs HR-negative subgroups (66.1% vs 54.8%; Table). No notable differences in prevalence were seen among different HER2 assays or in demographic/baseline disease characteristics between the HER2-low and HER2 IHC 0 groups. Concordance rate between historical and rescored slides for HER2-status classification was 82.3%. The presentation will include an expanded data set (≈400 pts) with additional results. Conclusions: Data on HER2-low prevalence in BC is limited. Preliminary data from this study of mBC samples suggest a somewhat higher prevalence estimate (≈63%) than a previous study of primary BC samples (≈50%). Concordance was 82%; ongoing analyses with updated data will clarify the concordance between rescored and historical HER2 slides. These data can support development of best practices for identifying pts with HER2-low expression who may benefit from HER2-targeted therapies. Clinical trial information: NCT04807595. [Table: see text]

Surgical treatment trends and identification of primary breast tumors after surgery in occult breast cancer: a study based on the Japanese National Clinical Database-Breast Cancer Registry

BACKGROUND

Occult breast cancer (OBC) is classified as carcinoma of an unknown primary site, and the adequate therapy for OBC remains controversial. This retrospective study aimed to reveal the transition in breast cancer therapy and the frequency of primary breast tumors after resection in clinical OBC (cT0N+) patients using the Japanese Breast Cancer Registry database.

METHODS

We enrolled OBC patients with cT0N+ from the registry between 2010 and 2018. On the basis of the period of diagnosis, OBC patients were divided into the following two groups: 2010-2014 and 2015-2018. We described the transition in treatments and tumor characteristics. After breast resection, the frequency of pathological identification of primary tumors and tumor sizes was assessed.

RESULTS

Of the 687,468 patients registered, we identified 148 cT0N+ patients with a median age of 61 years. Of these patients, 64.2% (n = 95) received breast surgery (2010-2014: 79.1%, 2015-2018: 50.0%). Axillary lymph node dissection was performed in 92.6% (n = 137, 2010-2014: 91.6%, 2015-2018: 93.4%). The breast tumor size in the resected breast was 0-7.0 cm (median: 0 cm, 2010-2014: 0-7.0 cm [median: 0 cm], 2015-2018: 0-6.2 cm [median: 0 cm]). The pathological identification rate of the primary tumor was 41.1% (n = 39, 2010-2014: 40.4%, 2015-2018: 42.1%).

CONCLUSIONS

Breast surgery for cT0N+ decreased between 2010 and 2018. Despite the high identification rate of primary tumors, most tumors were small, and there was no significant change in the identification rate or invasive diameter of the identified tumors after 2010.

Abstract P4-04-09: Systematic analysis of immune cell composition revealed immunological profile of breast cancer microenvironment represented by histologically assessed tumor-infiltrating lymphocyte and PD-L1 expression

Purpose. The clinical use of immune checkpoint inhibitors for multiple cancers has attracted attention in tumor immunology. Emerging evidence suggests that a better understanding of tumor immunology will lead to the development of new treatment strategies or the effective use of existing therapies. Histologically assessed tumor-infiltrating lymphocytes (hTIL) and programmed cell death 1 ligand 1 (hPD-L1) have been established as prognostic or predictive biomarkers in certain subsets of breast cancer. In addition, researchers have shifted their focus to the various immune cell subsets that make up TILs. However, the complexity of multiple types of immune cells in TIL or PD-L1 expressing cells is not fully understood. In this analysis, the immune cell fraction in breast cancer tissue and blood was evaluated by multicolor flow cytometry (FCM) to analyze the association between them and hTIL and hPD-L1. Methods. Forty-five tumor and 18 blood samples were collected from breast cancer patients. The leukocyte count, proportion of 11 types of immune cell fraction, and PD-L1 expression of each fraction were evaluated by FCM for both tumor and blood samples. The immune cell fractions are classified into the following categories based on the expression of cell surface markers: leukocyte, total T cell (total T), CD4+ T cell (CD4+ T), CD8+ T cell (CD8+T), B cell (B), monocyte/macrophage (Mo/Mϕ), nonclassical monocyte (CD16+Mo), myeloid-derived suppressor cells (MDSC), dendritic cells (DC), myeloid dendritic cells (mDC), natural killer cells (NK), minor NK, and natural killer T cells (NKT). hTIL, and hPD-L1 were evaluated by H-E staining and immunohistochemistry, respectively. Results. The mean density and interquartile range of tumor-infiltrating leukocytes were similar to those in previous report. For the immune cell fraction in the leukocytes of tumor tissue, the main population consisted of CD8+T and CD4+T, which showed a similar trend to that of blood. The proportions of DC, mDC, NK, and minor NK in tumor tissues were positively correlated with those of blood. When the percentage of each immune cell fraction of tumor tissue and that of blood were compared, the proportions of DC, mDC, and minor NK were significantly higher in tumor tissues than those in blood samples, and the proportions of CD4+T and NK were significantly lower in tumor tissue than in blood. No significant association was found between blood immune cell composition and hTIL or hPD-L1. High hTIL levels were associated with high leukocyte infiltration, high proportions of CD4+ T and CD8+ T, and a low proportion of NK and NKT in the tumor tissue. When PD-L1 positive cell percentage of each immune cell fraction was compared between the tumor tissue and blood, PD-L1 positive ratios were significantly higher in tumor tissue than in blood for all lineages except for lymphoid fractions. For tumor tissues, PD-L1 expression was high in Mo/Mϕ, CD16+Mo, MDSC, DC, and mDC. hPD-L1 positivity was associated with PD-L1 expression in Mo/Mϕ, CD16+Mo, DC, and mDC. Conclusion. Comprehensive analysis of the immune cell fractions revealed the immunological profile of breast cancer tissue represented by hTIL or hPD-L1. Our data indicate that hTIL not only reflects the amount of immune cell infiltration but also reflects a state in which acquired immunity is activated relative to innate immunity. Non-B cell antigen-presenting cell fractions such as Mo/Mϕ, CD16+ Mo, MDSC, DC, and mDC were primarily involved in the PD-L1 pathway in breast cancer microenvironments. In addition, hPD-L1 reflects PD-L1 expression in these immune cell fractions. Our data provide a basic understanding of the immune response in the breast cancer microenvironment and contribute to further development of tumor immunology.

Citation Format: Toru Hanamura, Shigehisa Kitano, Hiroshi Kagamu, Makiko Yamashita, Mayako Terao, Banri Tsuda, Takuho Okamura, Nobue Kumaki, Katsuto Hozumi, Naoki Harada, Takaiki Iwamoto, Chikako Honda, Sasagu Kurozumi, Naoki Niikura. Systematic analysis of immune cell composition revealed immunological profile of breast cancer microenvironment represented by histologically assessed tumor-infiltrating lymphocyte and PD-L1 expression [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-04-09.

Abstract OT1-02-03: Trastuzumab deruxtecan (T-DXd; DS-8201) vs trastuzumab emtansine (T-DM1) in high-risk patients with HER2-positive, residual invasive early breast cancer after neoadjuvant therapy: A randomized, phase 3 trial (DESTINY-Breast05)

Background Preoperative chemotherapy in combination with trastuzumab and pertuzumab is a preferred regimen for treating patients (pts) with HER2-positive, invasive, early breast cancer (BC). Pts who have received such treatment but still have residual invasive disease in the breast or lymph nodes at surgery are at greater risk for disease recurrence or death than those with a pathological complete response. The antibody-drug conjugate (ADC) T-DM1 is approved as a postneoadjuvant treatment for pts with residual invasive disease (in the breast and/or axillary nodes) after optimal neoadjuvant chemotherapy and trastuzumab (or trastuzumab with pertuzumab). T-DXd is a potent HER2-targeted ADC with a humanized HER2 antibody attached to a membrane-permeable topoisomerase I inhibitor payload by a cleavable tetrapeptide-based linker and a drug-to-antibody ratio of ≈8. T-DXd is approved globally for the treatment of adult pts with HER2-positive, unresectable or metastatic BC who have received ≥2 prior anti-HER2-based regimens in the metastatic setting or had prior chemotherapy and are refractory to or intolerant of standard treatments. These approvals have been supported by results from DESTINY-Breast01, an open-label, international, multicenter, phase 2 study of T-DXd in patients with HER2-positive metastatic BC. In an updated data cutoff (June 8, 2020), T-DXd demonstrated an objective response rate (ORR) of 61.4% (113/184 pts) and a duration of response of 20.8 months in pts with HER2-positive (IHC 3+ or ISH+), unresectable or metastatic BC previously treated with T-DM1 (Modi et al. Cancer Res. 2021;81[4 suppl]:PD3-06). Yet, further unmet need exists in patients who do not achieve pathologic complete response to neoadjuvant treatment, as these patients have increased risk of recurrence. Here, we describe a randomized phase 3 trial evaluating T-DXd vs T-DM1 as postneoadjuvant treatment for high-risk pts with HER2-positive primary BC who have residual invasive disease following neoadjuvant therapy. Study Description DESTINY-Breast05 is a multicenter, open-label, randomized, phase 3 trial comparing the efficacy and safety of T-DXd with those of T-DM1 in pts with HER2-positive (IHC 3+ or ISH+, centrally confirmed on pretreatment biopsy), invasive BC with pathologic evidence of residual invasive disease in the breast or axillary lymph nodes after neoadjuvant therapy. Additionally, pts must have a higher residual risk for recurrence, following standard T-DM1, defined as either presenting with inoperable disease (clinical stages T4, N0-3, M0 or T1-3, N2-3, M0) or operable BC at presentation (clinical stages T1-3, N0-1, M0) with axillary node-positive disease after neoadjuvant chemotherapy and anti-HER2 treatment. Approximately 1600 pts will be randomly assigned (1:1) to T-DXd or T-DM1 from ≈ 400 sites globally. Randomization is stratified by operative status at presentation, hormone receptor status, pathologic nodal status following neoadjuvant therapy, and type of HER2-targeted neoadjuvant therapy (single vs dual). T-DXd 5.4 mg/kg or T-DM1 3.6 mg/kg will be administered intravenously once every 3 weeks for 14 cycles. Invasive disease-free survival based on investigator assessment is the primary efficacy endpoint. Secondary endpoints are overall survival, disease-free survival, distant recurrence-free interval, and brain metastasis-free interval. The pharmacokinetics of T-DXd, biomarkers, and health-related quality of life will also be evaluated (NCT04622319).

Citation Format: Charles E Geyer, Jr, Michael Untch, Aleix Prat, Priya Rastogi, Naoki Niikura, Elton Mathias, Lee Anne McLean, Yibin Wang, Sibylle Loibl. Trastuzumab deruxtecan (T-DXd; DS-8201) vs trastuzumab emtansine (T-DM1) in high-risk patients with HER2-positive, residual invasive early breast cancer after neoadjuvant therapy: A randomized, phase 3 trial (DESTINY-Breast05) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-02-03.

Abstract P5-16-11: Ipatasertib (ipat) in combination with palbociclib (palbo) and fulvestrant (fulv) in patients (pts) with hormone receptor-positive (HR+) HER2-negative advanced breast cancer (aBC)

Background: Ipat is a potent oral AKT inhibitor that has been studied in multiple clinical trials, primarily in breast and prostate cancers. Combining fulv and AKT inhibition demonstrated efficacy in pts with HR+ aBC regardless of PI3K/AKT pathway alterations [Jones, Lancet Oncol 2020]. IPATunity150 (NCT04060862) was designed as a phase III trial with an open-label phase Ib portion adding ipat to palbo plus fulv in biomarker-unselected HR+ HER2-negative aBC. The biological rationale was to prevent or delay resistance to CDK4/6 inhibition plus endocrine therapy (ET). AKT1 alterations and PTEN loss have been implicated in resistance to CDK4/6 inhibitors [Wander, Cancer Discov 2020; Costa, Cancer Discov 2020]. We report results from the open-label phase Ib portion. Patients and Methods: The primary objective was to assess safety and pharmacokinetics (PK) of ipat in combination with palbo and fulv; several efficacy parameters were also analyzed. Pts with measurable disease who had not previously received a CDK4/6 inhibitor and had experienced relapse during adjuvant ET were treated with ipat at a dose of 300 mg/d, d1-21 q28d, plus standard-of-care doses of palbo (125 mg/d, d1-21 q28d) plus fulv (500 mg q28d with a loading dose in cycle 1). The selected ipat dose was lower than the 400 mg typically used in other studies because of the anticipated drug-drug interaction (DDI) when combining ipat (a sensitive CYP3A4 substrate and mild-to-moderate CYP3A inhibitor) with palbo (a weak time-dependent CYP3A4 inhibitor and CYP3A substrate). Results: Of the 20 pts treated, 20% were Asian, 65% had primary endocrine resistance (relapse ≤2 years after starting adjuvant ET), 80% had received prior (neo)adjuvant chemotherapy, and 60% had liver and/or lung metastases. At the data cutoff (19 Mar 2021; median follow-up 6.1 months), median treatment duration was 5.1, 5.9, and 5.3 months for ipat, palbo, and fulv, respectively. Treatment was ongoing in 13 pts. Grade 3/4 adverse events (AEs) occurred in 80% of pts (no grade 5). The most common AEs were diarrhea (80% any grade, 10% grade 3, no grade 4) and neutropenia (75% any grade, 45% grade 3, 20% grade 4). Other notable grade ≥3 AEs were grade 3 liver function test elevations in 10%. There were no cases of febrile neutropenia and only 1 case of pneumonitis (grade 1). AEs led to at least one dose reduction of ipat in 6 pts (30%; diarrhea n=3 [with vomiting in 1 pt], neutropenia n=3 [with fatigue in 1 pt]) and of palbo in 9 pts (45%; all for neutropenia). One pt (5%) discontinued ipat and palbo permanently due to ongoing neutropenia after protocol-defined dose reductions. As expected, a DDI led to increased ipat exposure (AUC0-24,ss ~60% and Cmax ~40%) when ipat and palbo were combined. Based on population PK analysis, palbo AUC0-24,ss was ~30% higher than reported from the PALOMA 1 and 2 trials, which was expected and consistent with previously reported physiologically based PK modeling of palbo exposure when administered with moderate CYP3A inhibitors [Yu, J Clin Pharmacol 2017]. All 20 pts had at least one post-baseline tumor assessment. Best overall response rate was 45% (95% CI: 23-68%), including confirmed responses in 7 pts (35%; 5% complete response, 30% partial response) at the clinical cutoff date. Median duration of response was 9.6 months (95% CI: 7.1-not estimable). An additional 10 pts (50%) had stable disease. Progression-free survival results were immature (events in 7 pts). There was no obvious association between efficacy and mutations in PIK3CA/AKT1 as tested in ctDNA. Conclusion: The triplet combination of ipat, fulv, and palbo had an acceptable safety profile generally consistent with that of the individual study drugs; ipat exposure was increased through a predicted DDI. Updated results will be presented.

Citation Format: Mafalda Oliveira, Aditya Bardia, Sung-Bae Kim, Naoki Niikura, Cristina Hernando, Gustavo Werutsky, Yoland Antill, Pedro Liedke, Catherine Oakman, Eriko Tokunaga, Seth Wander, Vanessa Krause, Toshinari Yamashita, Frauke Schimmoller, Jacob Rotmensch, Heidi Savage, Rucha Sane, Nicholas Turner. Ipatasertib (ipat) in combination with palbociclib (palbo) and fulvestrant (fulv) in patients (pts) with hormone receptor-positive (HR+) HER2-negative advanced breast cancer (aBC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-16-11.

Abstract OT2-26-01: Open-label, multinational, multicenter, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with previously treated advanced/metastatic human epidermal growth factor receptor 2-positive breast cancer (HER2+ BC): DESTINY-Breast12

Background: HER2+ BC is associated with a high incidence (up to 50%) of brain metastasis (BM) despite advances in treatment (Zimmer AS et al. Cancer Rep (Hoboken). 2020;e1274; Hurvitz SA et al. Clin Cancer Res. 2019;25:2433-2441). Although several agents have been studied in patients (pts) with HER2+ BC with BM, an unmet medical need remains due to the poor prognosis in this pt population. In DESTINY-Breast01, T-DXd demonstrated efficacy in the overall population and preliminary efficacy in a pt subgroup with stable BM, with a confirmed objective response rate (ORR) of 61.4% and an extracranial confirmed ORR by independent central review (ICR) of 58.3%, respectively, median progression-free survival (PFS) of 19.4 and 18.1 mo, respectively, and median duration of response (DOR) of 20.8 and 16.9 mo, respectively (Modi S et al. Cancer Res. 2021. Abst PD3-06; Jerusalem G et al. Ann Oncol. 2020. Abst 138O). Here we describe a trial evaluating T-DXd in pts ± BM with previously treated advanced/metastatic HER2+ BC. Trial design: DESTINY-Breast12 (NCT04739761) is an open-label, multicenter, international (86 sites in the US, Europe, Australia, and Japan), phase 3b/4 study assessing the efficacy and safety of T-DXd 5.4 mg/kg q3w in pts with HER2+ BC ± BM. Pts will be enrolled in 1 of 2 cohorts (250 pts each): cohort 1 (−BM at baseline) and cohort 2 (+BM at baseline). Pts must have previously treated advanced/metastatic HER2+ BC that has progressed with ≥1 prior anti-HER2-based regimen and received ≤2 lines of therapy in the metastatic setting (excludes pts with prior tucatinib). Pts with BM must have untreated BM not needing immediate local therapy or previously treated stable or progressing BM. Primary endpoints are ORR in cohort 1 and PFS in cohort 2 (both by RECIST version 1.1 per ICR). Secondary endpoints in both cohorts are OS, DOR, time to progression, duration of subsequent therapy, PFS2, safety, and changes in symptoms, functioning, and QOL. Incidence of new symptomatic CNS metastasis (CNSM) is a secondary endpoint in cohort 1, and ORR and CNS ORR by RECIST 1.1 per ICR, CNS PFS and DOR, and time to new CNSM are secondary endpoints in cohort 2.

Citation Format: Nancy U Lin, Eva Ciruelos, Guy Jerusalem, Volkmar Müller, Naoki Niikura, Giuseppe Viale, Emma Oscroft, Shawn Anand, Graham Walker, Nadia Harbeck. Open-label, multinational, multicenter, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with previously treated advanced/metastatic human epidermal growth factor receptor 2-positive breast cancer (HER2+ BC): DESTINY-Breast12 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-26-01.

Trends in adjuvant therapy after breast-conserving surgery for ductal carcinoma in situ of breast: a retrospective cohort study using the National Breast Cancer Registry of Japan

PURPOSE

Radiotherapy (RT) and endocrine therapy (ET) are standard treatment options after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS). We investigated the national patterns of adjuvant therapy use after BCS for DCIS in Japan.

METHODS

We obtained relevant data of patients diagnosed with DCIS undergoing surgery and treated with BCS between 2014 and 2016 from the Japanese Breast Cancer Registry database. The relationship between the clinicopathologic, institutional, and regional factors, and adjuvant treatment was examined using multivariable analyses.

RESULTS

We identified 9516 patients who underwent BCS for DCIS. Overall, 23% received no adjuvant treatment, 71% received RT, 32% received ET, and 26% received combination therapy. The percentages of patients who received ET and combination therapy in 2016 were significantly lower [odds ratio (OR): 0.71, 0.77, respectively] than in 2014. The proportion of RT was low among young or elderly patients (OR: 0.75, 0.44, respectively) and in non-certified facilities (OR: 0.56). The proportion of ET was high in non-certified facilities (OR: 1.58) and among patients with positive margins (OR: 1.62). Combination therapy was higher among patients with positive margins (OR: 1.53).

CONCLUSIONS

Our study found a distinct adjuvant treatment pattern after BCS for DCIS depending on clinicopathologic factors, year, age, which indicate that physicians provide individualized treatment according to the background of the patients and the biology of DCIS. The facilities and regions remain significant factors of influencing adjuvant treatment pattern.

CLRM-14. OPEN-LABEL, MULTINATIONAL, MULTICENTER, PHASE 3B/4 STUDY OF TRASTUZUMAB DERUXTECAN (T-DXD) IN PATIENTS WITH OR WITHOUT BASELINE BRAIN METASTASIS (BM) WITH PREVIOUSLY TREATED ADVANCED/METASTATIC HUMAN EPIDERMAL GROWTH FACTOR RECEPTOR 2–POSITIVE BREAST CANCER (HER2+ BC): DESTINY-BREAST12

BACKGROUND

Despite treatment advances, up to 50% of patients with advanced HER2+ BC develop BM (Zimmer. Cancer Rep. 2020). Patients with HER2+ BC with BM have a worse prognosis than patients without BM. In DESTINY-Breast01, T-DXd demonstrated efficacy in the overall population and preliminary efficacy in a subgroup with stable BM, with a confirmed objective response rate (ORR) of 61.4% and an extracranial confirmed ORR by independent central review (ICR) of 58.3%, median progression-free survival (PFS) of 19.4 and 18.1 mo, and median duration of response (DOR) of 20.8 and 16.9 mo (Modi. Cancer Res. 2021; Jerusalem. Ann Oncol. 2020). Here we describe a trial evaluating T-DXd in patients with previously treated advanced/metastatic HER2+ BC ±BM.

DESIGN

DESTINY-Breast12 (NCT04739761) is an open-label, multicenter, international (86 sites in the US, Europe, Australia, and Japan), phase 3b/4 study assessing T-DXd 5.4 mg/kg q3w efficacy and safety in patients with previously treated advanced/metastatic HER2+ BC ±BM that progressed with ≥1 prior anti-HER2–based regimen and received ≤2 lines of therapy in the metastatic setting (excluding patients with prior tucatinib). Patients (n=250/cohort) will be enrolled in cohort 1 (−BM at baseline) or 2 (+BM at baseline). BM must be untreated and not needing immediate local therapy or previously treated and stable or progressing. Primary endpoints are ORR (cohort 1) and PFS (cohort 2) (both by RECIST version 1.1 per ICR). Secondary endpoints are OS, DOR, time to progression, duration of subsequent therapy, PFS2, safety, and changes in symptoms, functioning, and QOL in both cohorts; incidence of new symptomatic CNS metastasis (CNSM) in cohort 1; and ORR and CNS ORR by RECIST 1.1 per ICR, CNS PFS and DOR, and time to new CNSM in cohort 2. This is an encore; the original presentation will be at The European Society for Medical Oncology 2021.

persevERA Breast Cancer (BC): Phase III study evaluating the efficacy and safety of giredestrant (GDC-9545) + palbociclib versus letrozole + palbociclib in patients (pts) with estrogen-receptor-positive, HER2-negative locally advanced or metastatic BC (ER+/HER2– LA/mBC)

TPS1103

Background: Modulating estrogen synthesis and/or ER activity is the mainstay of treatment for pts with ER+ BC. Despite substantial progress, many pts experience relapse during/after adjuvant endocrine therapy. However, even though resistant to aromatase inhibitors (AIs) or tamoxifen, growth and survival of the majority of tumors are thought to remain dependent on ER signaling. Therefore, pts with ER+ BC can still respond to second- or third-line endocrine treatment after progression on prior therapy (Di Leo 2010; Baselga 2012). Therapeutic resistance can arise from mutations in ESR1, which can drive estrogen-independent transcription and proliferation. The highly potent, non-steroidal oral selective ER degrader giredestrant achieves robust ER occupancy and is active regardless of ESR1 mutation status. Phase I data indicate that giredestrant is well tolerated, with encouraging activity as a single agent and in combination with the CDK4/6 inhibitor palbociclib (Lim 2020). Single-agent activity was observed after prior treatment with fulvestrant and/or a CDK4/6 inhibitor (Jhaveri 2019). Methods: persevERA BC (NCT04546009) is a double-blind, placebo-controlled, randomized, multicenter phase III study designed to evaluate the efficacy and safety of first-line giredestrant + palbociclib in pts with ER+/HER2– LA/mBC. Randomization: 1:1 to either giredestrant (30 mg PO) plus letrozole placebo QD or letrozole (2.5 mg PO) plus giredestrant placebo QD on Days 1–28 of each 28-day cycle, with palbociclib (125 mg PO QD) on Days 1–21 of each 28-day cycle. Men and premenopausal women will receive an LHRH agonist. Eligibility: females or males ≥18 years old with measurable disease or evaluable bone disease and no prior treatment for advanced disease. Pts who received prior fulvestrant or who have relapsed within 12 months of completion of (neo)adjuvant therapy with an AI and/or prior therapy with CDK4/6 inhibitor are not eligible; relapse during tamoxifen therapy but > 24 months after the start of tamoxifen therapy is allowed. Stratification: site of disease, disease-free interval since the end of (neo)adjuvant therapy, menopausal status, and geographic region. Primary efficacy endpoint: progression-free survival (determined locally by the investigator per RECIST v1.1). Secondary endpoints include overall survival, objective response rate, duration of response, clinical benefit rate, QoL, and safety. Enrollment is open (first patient in: Oct 9, 2020); target recruitment is 978 pts across all sites in a global enrollment phase. After completion of the global enrollment, additional pts may be enrolled in China. Clinical trial information: NCT04546009 .

Oral care and oral assessment guide in breast cancer patients receiving everolimus and exemestane: subanalysis of a randomized controlled trial (Oral Care-BC)

Background

Oral mucositis is a clinically significant adverse event linked to cancer therapy; it reduces the quality of life of patients and may result in the discontinuation of treatment and a poorer prognosis. Based on level 3 evidence, the Mucositis Study Group of Multinational Association for Supportive Care in Cancer and the International Society of Oral Oncology recommend oral care for all patients receiving cancer chemotherapy and radiotherapy, although no data from large-scaled randomized controlled trials support the efficacy of oral care in preventing oral mucositis. Therefore, this randomized, controlled, multicenter, open-label, phase III study sought to determine whether professional oral care reduces oral mucositis in everolimus and exemestane-treated estrogen receptor-positive metastatic breast cancer patients.

Methods

Altogether, 169 patients were randomized into the professional oral care (n=82) and control (n=87) groups. The professional oral care group received oral health instruction, professional mechanical tooth and tongue cleaning, gargling with a benzethonium chloride mouthwash, and dexamethasone ointment when grade 1 mucositis manifested. The control group received oral health instruction and gargling. Eight weeks after the everolimus and exemestane administration, the oral status (Oral Assessment Guide criteria) and oral mucositis status (Common Terminology Criteria for Adverse Events functional and clinical examinations) were evaluated.

Results

The incidence of oral mucositis of any grade and grade 2 severe mucositis was significantly lower in the professional oral care group, based on the Common Terminology Criteria for Adverse Events functional and clinical examinations. The total Oral Assessment Guide score, total Oral Assessment Guide grade, and Oral Assessment Guide score of teeth/dentures and mucous membranes were significantly different between the two groups. The Oral Assessment Guide grade for swallow, lip, teeth/dentures, mucous membrane, tongue, and saliva significantly correlated to oral mucositis severity.

Conclusions

Professional oral care may prevent oral mucositis and improve teeth/denture conditions in patients receiving everolimus and exemestane.

Abstract OT-03-01: Trastuzumab deruxtecan (T-DXd; DS-8201) vs trastuzumab emtansine (T-DM1) in high-risk patients with HER2-positive, residual invasive early breast cancer after neoadjuvant therapy: A randomized, phase 3 trial (DESTINY-Breast05)

Background

Preoperative chemotherapy in combination with trastuzumab and pertuzumab is a preferred regimen for treating patients (pts) with HER2-positive, invasive, early breast cancer (BC). Pts who have received such treatment but still have residual invasive disease in the breast or lymph nodes at surgery are at greater risk for disease recurrence or death than those with a pathological complete response. The antibody-drug conjugate (ADC) T-DM1 was recently approved as a postneoadjuvant treatment for pts with residual invasive disease (in the breast and/or axillary nodes) after optimal neoadjuvant chemotherapy and trastuzumab (or trastuzumab with pertuzumab). T-DXd is a potent HER2-targeted ADC with a humanized HER2 antibody attached to a membrane-permeable topoisomerase I inhibitor payload by a cleavable tetrapeptide-based linker and a drug-to-antibody ratio of ≈ 8. Recently, T-DXd was approved for the treatment of adult pts with HER2-positive, unresectable or metastatic BC who have received ≥ 2 prior anti-HER2─based regimens in the metastatic setting (US) or had prior chemotherapy and are refractory to or intolerant of standard treatments (Japan). These approvals were based on a phase 2 study in which T-DXd demonstrated an objective response rate (ORR) of 60.9% (112/184 pts) and duration of response of 14.8 months in pts with HER2-positive (IHC 3+ or ISH+), unresectable or metastatic BC previously treated with T-DM1 (Modi et al. N Engl J Med. 2020;382:610-621). Here, we describe a randomized phase 3 trial evaluating T-DXd vs T-DM1 as postneoadjuvant treatment for high-risk pts with HER2-positive primary BC who have residual invasive disease following neoadjuvant therapy.

Study Description

DESTINY-Breast05 is a multicenter, open-label, randomized, phase 3 trial comparing the efficacy and safety of T-DXd with those of T-DM1 in pts with HER2-positive (IHC 3+ or ISH+, centrally confirmed on pretreatment biopsy), invasive BC with pathological evidence of residual invasive disease in the breast or axillary lymph nodes after neoadjuvant therapy. Additionally, pts must be at higher risk for recurrence, having either inoperable (clinical stages T4, N0-3, M0 or T1-3, N2-3, M0) or operable BC at presentation (clinical stages T1-3, N0-1, M0) with axillary node-positive disease after optimal neoadjuvant chemotherapy and anti-HER2 treatment. The trial is recruiting pts from ≈ 400 sites globally. Approximately 1600 pts will be randomized (1:1) to T-DXd or T-DM1. Randomization is stratified by operative status, hormone receptor status, pathological nodal status following neoadjuvant therapy, and type of HER2-targeted neoadjuvant therapy (single vs dual). T-DXd 5.4 mg/kg or T-DM1 3.6 mg/kg will be administered intravenously once every 3 weeks for 14 cycles. Invasive disease-free survival based on investigator assessment is the primary efficacy endpoint; disease-free survival is the key secondary efficacy endpoint. Other secondary endpoints are overall survival, distant recurrence-free interval, and brain metastasis-free interval. Safety assessments include serious and treatment-emergent adverse events, physical examinations, vital signs, on-study chest imaging (to screen for pneumonitis), and clinical laboratory parameters. The pharmacokinetics of T-DXd, biomarkers, and health-related quality of life will also be evaluated. Long-term follow-up will continue after the primary analysis every 6 months until death, withdrawal of consent, loss to follow-up, or trial closure.

Citation Format: Charles E Geyer, Jr, Michael Untch, Aleix Prat, Priya Rastogi, Naoki Niikura, Elton Mathias, Lee Anne McLean, Yibin Wang, Sibylle Loibl. Trastuzumab deruxtecan (T-DXd; DS-8201) vs trastuzumab emtansine (T-DM1) in high-risk patients with HER2-positive, residual invasive early breast cancer after neoadjuvant therapy: A randomized, phase 3 trial (DESTINY-Breast05) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr OT-03-01.

Secondary endpoints analysis in patients with estrogen receptor-positive metastatic breast cancer treated with everolimus and exemestane enrolled in Oral Care-BC

BACKGROUND

The Oral Care BC-trial reported that professional oral care (POC) reduces the incidence and severity of oral mucositis in patients receiving everolimus (EVE) and exemestane (EXE). However, the effect of POC on clinical response among patients receiving EVE and EXE was not established. We compared outcomes for estrogen receptor-positive metastatic breast cancer patients who received POC to those who had not, and evaluated clinical prognostic factors. All patients simultaneously received EVE and EXE.

METHODS

Between May 2015 and Dec 2017, 174 eligible patients were enrolled in the Oral Care-BC trial. The primary endpoint was the comparative incidence of grade 1 or worse oral mucositis, as evaluated for both the groups over 8 weeks by an oncologist. The secondary endpoints were progression-free survival (PFS) and overall survival (OS). Data were collected after a follow-up period of 13.9 months.

RESULTS

There were no significant differences in PFS between the POC and Control Groups (P = 0.801). A BMI <  25 mg/m2 and non-visceral metastasis were associated with longer PFS (P = 0.018 and P = 0.003, respectively) and the use of bone modifying agents (BMA) was associated with shorter PFS (P = 0.028). The PFS and OS between the POC and control groups were not significantly different in the Oral-Care BC trial.

CONCLUSIONS

POC did not influence the prognosis of estrogen receptor-positive metastatic breast cancer patients. Patients with non-visceral metastasis, a BMI <  25 mg/m2, and who did not receive BMA while receiving EVE and EXE may have better prognoses.

TRIAL REGISTRATION

The study protocol was registered online at the University Hospital Medical Information Network (UMIN), Japan (protocol ID 000016109), on January 5, 2015 and at ClinicalTrials.gov ( NCT02376985 ).

Current Status of Advance Care Planning and End-of-life Communication for Patients with Advanced and Metastatic Breast Cancer

BACKGROUND

Advance care planning (ACP) is a process that supports adults in understanding and sharing their personal values, life goals, and preferences regarding future medical care. We examined the current status of ACP and end-of-life (EOL) communication between oncologists and patients with metastatic breast cancer.

MATERIALS AND METHODS

We conducted a survey among 41 institutions that specialize in oncology by using an online tool in October 2019. Participants (118 physicians) from 38 institutions completed a 39-item questionnaire that measured facility type and function; physicians' background and clinical approach, education about EOL communication, and understanding about ACP; and the current situation of ACP and EOL discussions.

RESULTS

Ninety-eight responses concerning physicians' engagement in ACP with patients were obtained. Seventy-one (72%) answered that they had engaged in ACP. Among these, 23 (33%) physicians used a structured format to facilitate the conversation in their institutions, and only 6 (8%) settled triggers or sentinel events for the initiation of ACP. In the multivariable analysis, only the opportunity to learn communication skills was associated with physicians' engagement with ACP (odds ratio: 2.8, 95% confidence interval: 1.1-7.0). The frequency and timing of communication about ACP and EOL care with patients substantially varied among the oncologists. Communication about patients' life expectancy was less frequent compared with other topics.

CONCLUSION

The opportunity to improve EOL communication skills promoted physicians' engagement with ACP among patients with metastatic/advanced breast cancer. However, there were still substantial variabilities in the method, frequency, and timing of ACP and EOL communication among the oncologists.

IMPLICATIONS FOR PRACTICE

This study found that the opportunity to improve end-of-life (EOL) communication skills promoted physicians' engagement in advance care planning (ACP) among patients with metastatic/advanced breast cancer. All oncologists who treat said patients are encouraged to participate in effective education programs concerning EOL communication skills. In clinical practice, there are substantial variabilities in the method, frequency, and timing of ACP and EOL communication among oncologists. As recommended in several clinical guidelines, the authors suggest a system that identifies patients who require conversations about their care goals, a structured format to facilitate the conversations, and continuous measurement for improving EOL care and treatment.

Stability of HER2 Status by Dual-color in Situ Hybridization Before and After Neoadjuvant Chemotherapy in Breast Cancer

OBJECTIVE

Trastuzumab may convert human epidermal growth factor receptor-2 (HER2)-positive primary breast tumors to HER2-negative tumors after chemotherapy. This study determined whether trastuzumab increases the number of patients with conversion to HER2-negative status and assessed the effect of neoadjuvant chemotherapy.

METHODS

We retrospectively reviewed 46 patients diagnosed with HER2-overexpression in primary breast cancers at Tokai University Hospital, receiving neoadjuvant chemotherapy by immunohistochemistry and fluorescence in situ hybridization (FISH). Surgical specimens of patients achieving less than pathological complete response (pCR) were verified for sufficient residual tissue to evaluate post-treatment HER2 status by dual-color in situ hybridization (DISH).

RESULTS

pCR was achieved in 8 of the 46 (17.4%) patients. The residual tumor was sufficient for a ssessing post-treatment HER2 status in 25 patients. DISH of pretreatment specimens confirmed HER2 amplification prior to therapy. Of the 25 HER2-positive patients, DISH revealed 3 were HER2 negative in pretreatment specimens. No post-treatment tumors were HER2-negative according to DISH in HER2-positive pre-treatment tumors. Among HER2-negative pretreatment tumors, 1 post-treatment tumor was HER2 positive and 2 had stable HER2 status.

CONCLUSION

HER2 status determined by DISH was stable between pretreatment breast tumors and residual tumors. However, a small discrepancy regarding HER2 status determined by immunohistochemistry and DISH existed.

Prediction of pathological complete response after neoadjuvant chemotherapy in breast cancer by combining magnetic resonance imaging and core needle biopsy

BACKGROUND

Pathological complete response (pCR) is often achieved by neoadjuvant chemotherapy (NAC), particularly in hormone receptor-negative breast cancer. Contrast-enhanced magnetic resonance imaging (cMRI) is the most reliable imaging modality to evaluate the pathological effect of NAC. Ultrasonography is indispensable to collect representative specimens from the target lesion by core needle biopsy (CNB). This study aimed to evaluate the accuracy of predicting pCR by adding CNB after NAC, in cases with complete clinical response (cCR) diagnosed by cMRI.

METHODS

In this prospective multicentre study, we evaluated patients diagnosed with cCR by cMRI after NAC. Ultrasound-guided CNB (uCNB) using a 14G needle was performed without clip markers under general anaesthesia as planned surgery. Specimens collected by uCNB were compared to those resected surgically and were categorized as (i) no carcinoma (ypT0), (ii) no invasive carcinoma and only residual carcinoma in situ (ypTis) and (iii) residual invasive carcinoma. The concordance of pathological results between the uCNB and surgical specimens was evaluated.

RESULTS

Of the 83 patients evaluated, 41 (49.4%) and 17 (20.5%) of them had ypT0 and ypTis, respectively. The false negative rates (FNR), sensitivity and specificity for predicting ypT0 by uCNB were 50.0%, 50.0%, 100%, respectively, and those for predicting ypT0+ypTis were 28.0%, 72.0% and 98.3%, respectively. The concordance rates were 74.7% (62/83) for ypT0 and 90.4% (75/83) for ypT0+ypTis.

CONCLUSION

In cCR cases diagnosed by cMRI, uCNB was not accurate enough to predict pCR. Additional modalities like clip placements and/or thicker core needles may be required for better prediction.