Supplementary Material for: Durable and Drastic Response to the Trastuzumab, Letrozole, Abemaciclib, and Goserelin Combination as First-line Therapy in HER2-positive and Hormone Receptor-Positive Metastatic Breast Cancer: A Case Report

Introduction: Chemotherapy combined with anti-HER2 targeted therapy is currently a standard treatment for advanced HER2/HR-positive breast cancer (BC), although evidences showed that HR expression compromised effectiveness of the treatment. While cyclin dependent kinase (CDK) 4/6 inhibitors combined with endocrine therapy is a key therapy for the BC with HR expression, data on the effectiveness and safety of cyclin-dependent kinase 4/6 inhibitors combined with Trastuzumab and endocrine therapy as a first-line treatment for HER2-positive and HR-positive metastatic BC are limited. Case presentation: Here we report a case of a 46-year-old premenopausal woman diagnosed with stage 4 HER2/HR-positive invasive ductal carcinoma from both right and left breast with hypermetabolic activities in multiple lymph nodes, adrenal, bone, and skin. Interventions: because of patient refusal to use chemotherapy, she was started on Goserelin + Abemaciclib + Letrozole + Trastuzumab. Outcomes: the patient’s symptoms were relieved with near resolutions at the primary breast mass and nearly all of the metastatic sites and metabolic resolution was observed in bone lesions. The disease was under control for 57 weeks. During the treatment, neutropenia (Grade 3) and thrombocytopenia (Grade 2) occurred during treatment, but improved after symptomatic treatment. Conclusion: We believe that Trastuzumab, hormone suppression, and Palbociclib is a practicable and effective treatment for HER2-positive and HR-positive metastatic BC in premenopausal patients who cannot tolerate first-line chemotherapy.

引言：化疗联合抗HER2靶向治疗目前是晚期HER2/HR阳性乳腺癌（BC）的标准治疗方案，尽管有证据表明HR表达会降低该治疗的疗效。细胞周期蛋白依赖性激酶（CDK）4/6抑制剂联合内分泌治疗是HR表达阳性乳腺癌的关键治疗手段，但关于细胞周期蛋白依赖性激酶4/6抑制剂联合曲妥珠单抗（Trastuzumab）及内分泌治疗作为HER2阳性/HR阳性转移性乳腺癌一线治疗的有效性与安全性数据仍较为有限。
病例报告：本文报告1例46岁绝经前女性患者，诊断为双侧乳腺4期HER2/HR阳性浸润性导管癌，伴多发淋巴结、肾上腺、骨及皮肤高代谢活性。
干预措施：因患者拒绝接受化疗，遂给予戈舍瑞林（Goserelin）+阿贝西利（Abemaciclib）+来曲唑（Letrozole）+曲妥珠单抗治疗。
治疗结局：患者症状缓解，原发乳腺肿块及几乎所有转移灶接近消退，骨病变出现代谢缓解。疾病控制达57周。治疗期间出现3级中性粒细胞减少症（neutropenia）及2级血小板减少症（thrombocytopenia），经对症治疗后好转。
结论：我们认为，曲妥珠单抗、激素抑制治疗联合哌柏西利（Palbociclib），对于无法耐受一线化疗的绝经前HER2阳性/HR阳性转移性乳腺癌患者而言，是一种可行且有效的治疗方案。