Real-world treatment patterns in patients with HER2+unresectable or metastatic breast cancer: Interim results from HER2 REAL Asia cohort

1047 Background: HER2 REAL (NCT04857619) is the first multi-country, retrospective study exploring the treatment practices and outcomes in patients (pts) with HER2+ locally advanced, unresectable (u)/metastatic (m) breast cancer (BC) from routine clinical care in the APAC and LATAM. Methods: Adult HER2+ u/mBC pts diagnosed since reimbursement or wider access of trastuzumab emtansine (T-DM1) or 01 Jan 2017, whichever was earlier with ≥12 months (mo) of follow-up data from index date (u/mBC diagnosis) and treated with ≥1-line of therapy (LOT) were enrolled per medical chart review from 6 countries. Here we present interim descriptive analyses (cut-off 30 June 2022) on demographics, clinical characteristics, and treatment patterns. Results: Of the 763 enrolled pts, 370 with median (range) age of 55 (20–81) yrs from Hong Kong, Korea, Singapore, and Taiwan were eligible for interim analyses; 368 (99.5%) were female with 210 (57.1%) postmenopausal. A total of 210 (57.1%) pts with reported data had a median time of 2 (0–18) yrs from initial BC diagnosis to u/mBC relapse. At index date, majority had ductal carcinoma (227/254 [89.4%]), visceral (255/355 [71.8%]), and non-visceral (258/355 [72.3%]) metastases; 80/355 (22.5%) had CNS metastases. Family history of BC was reported by 45/370 (12.2%) pts completing the questionnaire; 209/370 (56.5%) had hormone receptor-positive BC. Treatments reported in the first to fifth line were quite variable. HER2-directed therapy was received by 323/367 (88.0%) in LOT1 (mainly trastuzumab [TRA] and pertuzumab [PTZ]-based) and 298/343 (86.9%) in LOT2 (mainly T-DM1). Median duration of LOT1 and LOT2 were 7.8 (0–130) and 5.0 (0–100) mo, respectively, that decreased to 2.3 (0–30) mo in LOT5. The prime reason for treatment discontinuation was disease progression (LOT1: 294 [80.1%]; LOT2: 273 [79.6%]; LOT3: 187 [68.5%]). Serious adverse effects from treatments were rare (LOT1: 7 [1.9%]; LOT2: 10 [2.9%]; LOT3: 5 [1.8%]). Conclusions: The interim analyses show heterogeneous treatment patterns in real-world among pts with HER2+ u/mBC progressing on HER2-directed therapies possibly due to access disparity in these 4 Asian countries. Clinical trial information: NCT04857619 . [Table: see text]