Trastuzumab deruxtecan for human epidermal growth factor receptor 2-low advanced or metastatic breast cancer: recommendations from the Japanese Breast Cancer Society Clinical Practice Guidelines

The Japanese Breast Cancer Society Clinical Practice Guidelines are published as timely guidance on clinical issues in breast cancer treatment in Japan. In the recent edition of these guidelines, we addressed a new clinical question 34 (CQ 34, systemic treatment part) "Is trastuzumab deruxtecan recommended for patients with unresectable or metastatic HER2-low breast cancer?" and a new future research question 7 (FRQ 7, pathological diagnosis part) "How is HER2-low breast cancer diagnosed for the indication of trastuzumab deruxtecan?". These questions address use of trastuzumab deruxtecan in patients with unresectable or metastatic HER2-low breast cancer who have previously received chemotherapy for metastatic disease. The strengths of evidence and recommendation were determined through a quantitative and qualitative systematic review using multiple outcomes, including efficacy and safety. We conclude that trastuzumab deruxtecan is recommended for this patient population (strength of recommendation: 1; strength of evidence: moderate; CQ34) and that HER2-low expression for the indication of trastuzumab deruxtecan should be diagnosed using companion diagnostics based on appropriate criteria (FRQ7).

The Japanese Breast Cancer Society Clinical Practice Guidelines for systemic treatment of breast cancer, 2022 edition

The Japanese Breast Cancer Society (JBCS) Clinical Practice Guidelines for systemic treatment of breast cancer were updated to the 2022 edition through a process started in 2018. The updated guidelines consist of 12 background questions (BQs), 33 clinical questions (CQs), and 20 future research questions (FRQs). Multiple outcomes including efficacy and safety were selected in each CQ, and then quantitative and qualitative systematic reviews were conducted to determine the strength of evidence and strength of recommendation, which was finally determined through a voting process among designated committee members. Here, we describe eight selected CQs as important updates from the previous guidelines, including novel practice-changing updates, and recommendations based on evidence that has emerged specifically from Japanese clinical trials.

Successful Prevention of Tumour Lysis Syndrome in HER2-positive Breast Cancer: Case Report and Literature Review

BACKGROUND/AIM

Tumour lysis syndrome (TLS) is a life-threatening oncological emergency. TLS is rare and associated with a higher mortality rate in solid tumours than in haematological malignancies. Our case report and literature review aimed to identify the distinctive features and hazards of TLS in breast cancer.

CASE REPORT

A 41-year-old woman complained of vomiting and epigastric pain and was diagnosed with HER2-positive, hormone-receptor-positive breast cancer with multiple liver and bone metastases and lymphangitis carcinomatosis. She had several risk factors for TLS: high tumour volume, high sensitivity to antineoplastic treatment, multiple liver metastases, high lactate dehydrogenase levels, and hyperuricaemia. To prevent TLS, she was treated with hydration and febuxostat. One day after the first course of trastuzumab and pertuzumab, she was diagnosed with disseminated intravascular coagulation (DIC). After 3 further days of observation, she was relieved of DIC and administered a reduced dose of paclitaxel without life-threatening complications. The patient achieved a partial response after four cycles of anti-HER2 therapy and chemotherapy.

CONCLUSION

TLS in solid tumours is a lethal situation and can be complicated by DIC. Early recognition of patients who are at risk of TLS and initiation of therapy is essential to avoid fatal situations.

Abstract P3-07-09: The preoperative systemic inflammatory response as a strong prognostic factor in breast cancer patients

Background: Recent reports show that the preoperative systemic inflammatory response status correlate with the survival rate in cancer patients. The Prognostic Nutritional Index (PNI), Controlling Nutritional Status (CONUT), Neutrophil Lymphocyte Ratio (NLR) and Platelet Lymphocyte Ratio (PLR) score are used as screening tools for immunonutritional status and reported to be a predictor of postoperative recurrence in patients with various gastrointestinal cancers. However, the clinical importance of these scoring in breast cancer has not been fully elucidated. The aim of this study is to investigate the clinical impact of preoperative systemic inflammatory response on long-term survival of breast cancer patients. Patients and Methods: We retrospectively analyzed 653 consecutive stage I-III breast cancer patients who were treated from January 2002 to December 2013. The PNI score was calculated as 10 x serum albumin (g/dl) + 0.005 x total lymphocyte count (per mm3). The CONUT score is calculated from three parameters, serum albumin, cholesterol, and total lymphocytes count. The patients were divided into two groups according to each value. The uni- and multivariate Cox regression analyses were performed to evaluate the prognositic value of the systemic inflammatory response in breast cancer. Results: The malnutritional or high SIR status was observed in 170 (26%),131 (20%), 119 (18%) and 226 (35%) patients as low-PNI, high-CONUT, elevated NLR and PLR, respectively. The relapse-free survival (RFS) and overall survival (OS) rates were significantly lower in the low-PNI group (RFS: p<0.0001, OS: p<0.0001) and high-CONUT group (RFS: p=0.0009, OS: p=0.0018). No significant association was found between NLR, PLR and prognosis. In the multivariate analysis, low-PNI was the independent prognostic factors for OS (HR4.71, p=0.0023). In the subset analysis, the low-PNI group showed poor prognosis especially in the postmenopausal, hormone receptor negative patients. The low-PNI also had poorer prognosis in post-recurrence survival. Conclusions: The preoperative systemic inflammatory response, especially PNI, is a strong independent predictor of long-term survival among breast cancer patients.

Citation Format: Nami Yamashita, Sayuri Akiyoshi, Eiki Sano, Tomoko Shigechi, Yuichi Hisamatsu, Eriko Tokunaga, Eiji Oki, Masaki Mori. The preoperative systemic inflammatory response as a strong prognostic factor in breast cancer patients [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-07-09.

Abstract P5-07-07: The immune microenvironment of ductal carcinoma in situ of the breast

Background: The importance of tumor-infiltrating lymphocytes (TIL) in invasive breast carcinoma for tumor development and therapeutic response is widely accepted. However, the immune microenvironment of breast ductal carcinoma in situ (DCIS) has not been fully elucidated. Evasion of immune surveillance is a necessary step in tumor evolution. In DCIS, the tumor cells are relatively protected from the immune system due to an myoepithelial cell layer and basement membrane, and intraductal immune cells are rarely detected. In contrast, in invasive disease, cancer cells and immune cells are often intermingled. Thus, understanding the immune microenviroment of in situ to invasive carcinoma transition might be particularly important to identify novel targets for early stage of tumor invasion.

Aims: The aim of this study is to evaluate the clinical importance of TILs in DCIS.

Methods: TILs were assessed in 133 DCIS samples with or without microinvasive disease according to the proposed method from the International Immuno-Oncology Working Group on Breast Cancer. In addition, the relationship between TILs in DCIS and clinicopathological features was evaluated.

Results: TILs are present in most DCIS in varying levels. The median proportion of TILs in DCIS was 14%. Only a minority of DCIS showed >50% TILs, which represented only 12.8% of all cases. High TILs in DCIS was significantly associated with comedo necrosis (p<0.0001), high nuclear grade (p=0.0030), ER negativity (p<0.0001), PR negativity (p<0.0001), HER2 positivity (p=0.0030). Triple negative DCIS and HER2 positive DCIS had significantly higher level of TILs (p=0.0008). No correlation was demonstrated between TILs and recurrence risk.

Conclusions: High TILs in DCIS was significantly associated with adverse histopathologic features. Further characterization of immune environment of DCIS may be essential for immunotherapy and breast cancer prevention.

Citation Format: Yamashita N, Hisamatsu Y, Shigechi T, Tokunaga E, Saeki H, Oki E, Maehara Y. The immune microenvironment of ductal carcinoma in situ of the breast [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-07-07.

A novel interplay between the Fanconi anemia core complex and ATR-ATRIP kinase during DNA cross-link repair

When DNA replication is stalled at sites of DNA damage, a cascade of responses is activated in the cell to halt cell cycle progression and promote DNA repair. A pathway initiated by the kinase Ataxia teleangiectasia and Rad3 related (ATR) and its partner ATR interacting protein (ATRIP) plays an important role in this response. The Fanconi anemia (FA) pathway is also activated following genomic stress, and defects in this pathway cause a cancer-prone hematologic disorder in humans. Little is known about how these two pathways are coordinated. We report here that following cellular exposure to DNA cross-linking damage, the FA core complex enhances binding and localization of ATRIP within damaged chromatin. In cells lacking the core complex, ATR-mediated phosphorylation of two functional response targets, ATRIP and FANCI, is defective. We also provide evidence that the canonical ATR activation pathway involving RAD17 and TOPBP1 is largely dispensable for the FA pathway activation. Indeed DT40 mutant cells lacking both RAD17 and FANCD2 were synergistically more sensitive to cisplatin compared with either single mutant. Collectively, these data reveal new aspects of the interplay between regulation of ATR-ATRIP kinase and activation of the FA pathway.

Abstract P3-06-26: Serum anti-p53 antibody titers predict pathological response to preoperative chemotherapy in women with HER2 positive or triple negative breast cancer

Background: In SABCS 2009, we reported that the high level of serum anti-p53 antibody titers was associated with response to preoperative chemotherapy in cases with primary breast cancer (SABCS 2009). Prognostic meaning of pathological complete response (pCR) after preoperative chemotherapy differs among various subtype, and there is a close relationship between pCR and prognosis in cases with HER2 positive or triple negative disease. The aim of this study is to evaluate the association between the high level of serum anti-p53 antibody titers and pCR in patients with HER2-positive or triple negative breast cancer.

Patients and Methods: In this study, we analyzed 196 women with operable early stage breast cancer (T1-T3, N0-1) treated with preoperative chemotherapy and definitive curative surgery since 2002 to 2011. All of the patients received four cycles of FEC (fluorouracil 500 mg/m2, epirubicin 100 mg/m2, cyclophosphamide 500 mg/m2 q3w) followed by four cycles of docetaxel (75 mg/m2 q3w). The serum anti-p53 antibody titers were assessed by ELISA with the anti-p53 EIA Kit II (MESACUP anti-53 Test: MBL) in the pre-treatment serum samples. The test's cut-off value was determined to be 1.3 IU/ml based on reference distribution in healthy control individuals. The association between serum anti-p53 antibody titers and pCR was analyzed.

Results: The subtype of tumors of 196 patients were classified to 86 of ER+/HER2−, 24 of ER+/HER2+, 29 of ER−/HER2+ and 57 of ER−/HER2−. The pCR was achieved 49 of 196 patients (25%). The pCR rate were 7%(6/86), 33%(8/24), 48%(14/29) and 37%(21/57) in the subtype of ER+/HER2−, ER+/HER2+, ER−/HER2+ and ER−/HER2− respectively. The range of serum anti-p53 antibody titers in the serum samples of 196 patients was between 0.40 and 5610 (the median was 0.40 and the average was 85.2). Excluding 86 cases with ER+/HER2−, relationship between serum anti-p53 antibody titers and pCR was evaluated. According to serum anti-p53 antibody titers with the patients of pCR, cut-off value of serum anti-p53 antibody titers was set to be 6 IU/ml. The pCR was observed in nine of 12 cases (75%) with high serum anti-p53 antibody titers, which was significantly higher than those with low titers (35%: 34/98; p = 0.01). Multivariate analysis showed that the only high anti-p53 antibody titer was an independent predictive factor for pCR due to preoperative chemotherapy (p = 0.01).

Conclusion: p53 mutation analysis using serum anti-p53 antibody titers might be a useful predictive test for response to preoperative chemotherapy in patients especially with HER2 positive or triple negative breast cancer.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-06-26.

ATR-ATRIP kinase complex triggers activation of the Fanconi anemia DNA repair pathway

ATR kinase activates the S-phase checkpoint when replication forks stall at sites of DNA damage. This event also causes phosphorylation of the Fanconi anemia (FA) protein FANCI, triggering its monoubiquitination of the key DNA repair factor FANCD2 by the FA core E3 ligase complex, thereby promoting this central pathway of DNA repair which permits replication to be restarted. However, the interplay between ATR and the FA pathway has been unclear. In this study, we present evidence that their action is directly linked, gaining insights into this relationship in a DT40 mutant cell line that is conditionally deficient in the critical ATR-binding partner protein ATRIP. Using this system, we showed that ATRIP was crucial for DNA damage-induced FANCD2 monoubiquitination and FANCI phosphorylation. ATR kinase phosphorylated recombinant FANCI protein in vitro, which was facilitated by the presence of FANCD2. Mechanistic investigations revealed that the RPA region but not the TopBP1 region of ATRIP was required for FANCD2 monoubiquitination, whereas Chk1 phosphorylation relied upon both domains. Together, our findings identify ATR as the kinase responsible for activating the FA pathway of DNA repair.