Abstract P1-15-17: Liposomal-encapsulated doxorubicin (Myocet)as part of primary systemic therapy in HER2-positive operable breast cancer: Efficacy data, cardiotoxicity and long-term follow-up in 81 patients diagnosed from 2005-2016 at a single institution

Abstract

Abstract Objectives To evaluate the efficacy, cardiotoxicity profile and long-term benefits of liposomal doxorubicin (Myocet) as part of neoadjuvant therapy in HER2-positive operable breast cancer patients. Methods The treatment consisted of a sequential regimen of paclitaxel and liposomal doxorubicin (Myocet) plus trastuzumab. Clinical and pathologic response were evaluated and correlated with clinical and biological factors. Cardiotoxicity profile and long-term benefits were analyzed. Results Median age was 48 years and 4%, 69%, and 27% were stage I, II, and III, respectively, while 12% had inflammatory breast cancer at diagnosis. Hormone receptor (HR) status was negative in 43% and 70% were grade III. Patients Characteristics Total number (%)Age, years Median (Range)48 (30-79)Tumor (cT)* Tx1 (1)T14 (5)T253 (66)T313 (16)T410 (12)Nodal Status N024 (30)N1-257 (70)Stage I3 (4)II56 (69)III22 (27)Hormone Receptor Status HR+35 (43)HR-46 (57)HER2 IHC 3+74 (91)IHC 2+7 (9)FISH/SISH21 (26)Grade I1(1)II22 (27)III57 (71)Unknown1 (1)Ki-67 <20%6 (7)20-35%32 (40)>35%43 (53)Surgical Indication at Diagnosis Mastectomy58 (72)Tumorectomy22 (27)Any surgery in breast*1 (1)* One patient had an occult carcinoma. pCR by SubgroupsPathologic ResponsepCRNo pCR(n=81)n (%)n (%)Tumor Size (MRI) </=5 cm26 (49)27 (51)> 5 cm10 (67)5 (33)Nodes Positive26 (46)31 (54)Negative18 (75)6 (25)Histological Subtype Ductal43 (56)34 (44)Lobular0 (0)2 (100)Other1 (50)1 (50)Hormone Receptor Negative23 (66)12 (34)Positive21 (46)25 (54)Ki-67 <204 (67)2 (33)20-3512 (38)20 (62)>3528 (65)15 (35)Grade I0 (0)1 (100)II12 (55)10 (45)III31 (54)26 (46) The clinical complete response rate by ultrasound and MRI were 47% and 65%, respectively, and allowed a high rate of conservative surgery (72%). The pathologic complete response (pCR) rate in breast and axilla was 54%, higher in HR-negative (66%) than in HR-positive (46%),in ki-67>35% (65%) than ki-67 between 20-35% (38%) and similar in grade III (54%) and grade II (55%). Patients who achieved pCR had longer DFS and a trend to improve OS. Four percent of patients showed a decrease in the left ventricular ejection fraction below 50% during treatment. All except one of them recovered after discontinuation of trastuzumab. Conclusion: A sequential regimen of taxanes and liposomal doxorubicin (Myocet) plus trastuzumab was active with high pCR rates and long-term benefit with a very good cardiotoxicity profile. Citation Format: Antolin S, Calvo L, Prato J, Molina A, Reboredo C, Mosquera J. Liposomal-encapsulated doxorubicin (Myocet)as part of primary systemic therapy in HER2-positive operable breast cancer: Efficacy data, cardiotoxicity and long-term follow-up in 81 patients diagnosed from 2005-2016 at a single institution [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 P1-15-17.