Retrospective single-center outcome analysis of neoadjuvant and palliative treatment with dual trastuzumab and pertuzumab in HER2-positive breast cancer.

Abstract

e12114 Background: Her2-positive (Her2pos) breast cancer (BCa) is the second most lethal subtype of BCa. The treatment of Her2-positive BCa was revolutionized due to the dual use of trastuzumab and pertuzumab (T+P) in recent years both in the neoadjuvant and the palliative setting. Although several years have passed after initial approval of these drugs, single-center outcome data as reported by clinicians is sparse. In this retrospective study, we set to assess outcomes measures at our institution, Austria’s largest academic hospital, for the use of T+P in early and metastasized BCa. Methods: We acquired records on combined pertuzumab and trastuzumab orders from our intramural drug order software (CATO, Cato Research, Durham, NC, USA) for the time period of May 2013 to March 2018. Further, using electronic patient histories, we described both the neoadjuvant and palliative patient groups by assessment of body weight/size, tumor stage, histology including immunohistochemistry (IHC), lines of oncological therapies received, ejection fraction (EF) drops>10%, deaths and most importantly the outcomes measures pathological complete response (pCR, neoadjuvant cohort) rate and progression-free survival (PFS, palliative cohort). Results: 120 breast cancer patients were given dual therapy with T+P. The neoadjuvant cohort contained 63 patients, while the palliative cohort included 57 patients. All patients included were female. Full histology including IHC data was available for 47 of 63 patients in the neoadjuvant cohort and 30 of 57 patients in the palliative cohort. BMI was 25.6 and 23.3, respectively, on average. The mean age was 54 years in the neoadjuvant and 56 years in the palliative cohort. 73.6% (39/53) and 65.9% (29/44) of tumors were ER positive as determined by IHC. While neoadjuvant patients obtained an average of 6.5 cycles, patients within the palliative cohort received a mean of 17.3 cycles of T+P. 0 and 17 deaths were observed in the respective cohorts. Data on pCR and PFS was available for 95.2% and 91.2% of patients, respectively. The pCR rate within the neoadjuvant cohort was 46.7% (28/60), and mean PFS across all treatment lines of the palliative cohort was 10.2 months. Conclusions: We report retrospective single-center outcome data for the combined use of trastuzumab and pertuzumab in both early and metastatic Her2pos BCa in line with previously published data.