203P Real-world treatment patterns in patients with HER2+ unresectable (u) or metastatic (m) breast cancer (BC): HER2 real study final analysis in Asia-Pacific (APAC) and Brazil

The HER2 REAL (NCT04857619) retrospective study explored treatment practices and survival outcomes in HER2+ u/mBC patients (pts) in routine clinical care in APAC and Brazil. Pts diagnosed since wider access to trastuzumab emtansine (T-DM1) or 01/01/2017, whichever was earlier with ≥12 months (mo) of follow-up data from the index date (u/mBC diagnosis) and treated with ≥1 (line of treatment) LOT were enrolled based on medical chart review from 6 countries. We present treatment patterns and final survival outcomes. Of the 763 pts screened, 684 were analyzed (AU: 62, BR: 120, HK: 92, KR: 157, SG: 105, TW: 148) with median (range) age of 55 (20–91) yrs. Overall, 363 (53.1%) pts were hormone receptor-positive; 156 (22.8%) had visceral only, 126 (18.4%) non-visceral only, and 31 (4.5%) had CNS only metastases. The top regimen overall in LOT1 was trastuzumab (TRA) + pertuzumab (PTZ) + chemotherapy (CT; 321/670 47.9%) and in LOT2 was T-DM1 (254/596 42.6%). CT alone was the most common regimen in LOT3 (132/381 34.6%) and LOT4 (106/217 48.8%; Table). For TRA+PTZ+CT in LOT1, OS ranged from 36 to 49 mo for all countries with a median (95% CI) follow-up time of 30.1 (1–167) mo. Median PFS ranged from 8.8 (7.3–14.6) to 15.5 (12.5–22.3) mo for TRA+PTZ+CT in LOT1 and from 6.0 (4.6–8.2) to 7.1 (4.4–28.3) mo for T-DM1 in LOT2 for all 6 countries. Treatment discontinuation was mostly due to disease progression.Table: 203PLOT n (%)Median duration of LOT (range), moReal-world treatment patterns, n (%)Attrition rate n (%)TRA+PTZ+CTT-DM1TRA+ CTTRA+PTZ+CT+HTCT-aloneHT-aloneAnti-HER2+ HTAnti-HER2+ HT+CT*LOT1, 670 (98.0)8.3 (4.4, 15.5)321 (47.9)44 (6.6)103 (15.4)66 (9.9)60 (9.0)22 (3.3)25 (3.7)30 (4.5)65 (9.7)LOT2, 596 (87.1)5.1 (2.6, 10.5)44 (7.4)254 (42.6)54 (9.1)-84 (14.1)24 (4.0)55 (9.2)21 (3.5)110 (18.5)LOT3, 381 (55.7)3.5 (1.6, 7.0)22 (5.8)42 (11.0)64 (16.8)-132 (34.6)24 (6.3)24 (6.3)10 (2.6)81 (21.3)LOT4, 217 (31.7)2.8 (1.4, 4.9)12 (5.5)18 (8.3)36 (16.6)-106 (48.8)15 (6.9)5 (2.3)11 (5.1)52 (24.0)*excluding TRA+PTZ+CT+HT; HT, hormone therapy. Open table in a new tab *excluding TRA+PTZ+CT+HT; HT, hormone therapy. In this retrospective series of HER2+ u/mBC pts from APAC and Brazil, <50% received guideline-recommended therapies. The unexpected short PFS and OS outcomes indicate substandard treatment sequencing practices. Poor outcomes and high attrition rates in later lines highlight the need for better treatment alternatives in earlier lines of therapy. Optimization of standard of care practices in these regions is urgently needed to improve survival outcomes in this pt population.