Real world patterns of use and value of pertuzumab in the treatment of HER2+ metastatic breast cancer in Singapore: The National Cancer Centre Singapore experience

Abstract

Background: There are currently few reports on the pattern of use and value of Pertuzumab in the real-world setting. Our study describes the clinical efficacy and treatment costs of Pertuzumab in HER2-positive metastatic breast cancer (MBC) treated in a tertiary cancer centre in Singapore. Method(s): A retrospective study of consecutive HER2-positive MBC patients seen from 1st January 2011 to 31st December 2017 at National Cancer Centre Singapore (NCCS) was conducted. Demographic and clinical data were extracted from medical records. Clinical characteristics of patients who received Pertuzumab were compared with those who did not. Billing data during the treatment period of all patients was also collected. Result(s): A total of 329 patients were included: Median age of diagnosis was 58 years where 196 (64.5%) were of Chinese ethnicity. Invasive Ductal Carcinoma (IDC) was diagnosed in 268 (88.2%) patients, and 168 (55.3%) had estrogen receptor (ER) and/or progesterone receptor (PR) positive disease. Bone was the most common site of metastasis which was observed in 167 (54.9%) of patients, while 225 (68.4%) patients had visceral metastases. Forty-nine (14.9%) patients received Pertuzumab, 30 of whom received it as first-line therapy. With an median duration of follow-up of 21 months, there was a statistically significant difference in the median overall survival (OS): 52 months (95% CI 32.7-71.3) versus 33 months (95% CI 28.5-37.5) (Log Rank p=0.013) for Pertuzumab versus non-Pertuzumab groups, respectively. Two (4.1%) patients in the Pertuzumab group experienced grade 3 (G3) cardiotoxicity. The median treatment cost of the Pertuzumab group was SGD$152,283 compared to SGD$63,130 for the non-Pertuzumab group. The median percentage of total chemotherapy costs per patient in the Pertuzumab group spent on Pertuzumab was 49.8%. Conclusion(s): This study shows that pertuzumab use in the treatment of metastatic breast cancer is associated with a significant improvement in survival and a low incidence of serious cardiotoxicities. However, the proportionate cost of Pertuzumab therapy remains high and further cost-effectiveness studies should be conducted.