Abstract PS10-20: Neoadjuvant (neoadj) and adjuvant (adj) treatment patterns in HER2-positive early breast cancer (EBC): Analysis of US real-world oncology data
Authors: Dhillon Preet K. , Flores Carlos , Sanglier Thibaut , Antao Vincent , Tesarowski David , Fung Anita , Incerti Devin , Restuccia Eleonora , Luhn Patricia 
Published: February 2021

Abstract
OBJECTIVES
Over the last decade, new treatment options have transformed the standard of care for patients (pts) with HER2-positive EBC and the treatment landscape continues to evolve. The primary objectives of our study were (1) to describe and compare the demographic and clinical characteristics of pts with HER2-positive EBC who received neoadj or adj treatment, (2) to describe the common neoadj and adj regimens according to hormone receptor (HR) status, and (3) to describe trends in neoadj treatment use from 2011 to 2019 in a US real-world setting.
METHODS
Unstructured and structured electronic health record-derived data were analyzed from the US Flatiron Health de-identified database (2011-2020), a longitudinal database of &gt;2.4 million pts with cancer in &gt;280 clinics, largely from community-based practices. Eligible pts had HER2-positive EBC (diagnosis: Jan 1, 2011-Jul 31, 2019; follow-up: until Feb 29, 2020). Systemic or oral anti-neoplastic treatments with initiation either prior to (neoadj) or within 6 months (adj) of the first primary surgery date were included. Adj treatment also required at least 6 months of follow-up and was captured for up to 1 year after initiation of adj therapy.
RESULTS
Pts with HER2-positive EBC treated in the neoadj setting, versus those in the adj setting alone, were more likely to be younger, pre-menopausal, have HR-negative disease, clinical stage II or III stage disease (refer to footnote in Table 1), have received treatment at an academic center, and were ~2 times as likely to have bilateral mastectomies (Table 1). Conversely, race/ethnicity as well as tumor grade, histology and laterality did not differ by neoadj versus adj treatment. The most common therapies are presented in Table 1. There was an upward trend in the annual percentage of pts diagnosed with HER2-positive EBC who initiated neoadj treatment starting in 2011 (&lt;20% of pts) and peaking in 2017 (~50% of pts). Most pts (78%) who received neoadj therapy were treated with a taxane-based chemotherapy regimen and a dual blockade of HER2 with trastuzumab plus pertuzumab (HP). A minority of neoadj pts (11%) received an anthracycline-based regimen plus HER2-targeted therapy. As expected, most pts received HER2-targeted therapy alone with HP post-surgery. The most common chemotherapy for adj-only pts included a taxane-based regimen combined with H (+/- P). Hormonal therapy was mostly administered post-surgery (adj-continuation: 61%; adj-only: 78%) with low use in the neoadj setting (9%). When evaluating pts by HR status, pts with HR-positive EBC more commonly received hormonal and ‘other’ therapy; adj-only pts with HR-negative disease more commonly received HER2-targeted therapies with taxanes (83% v 54%), irrespective of the additional use of platinum-based chemotherapy (64% v 38%) or anthracyclines (15% v 8%).
CONCLUSIONS
Neoadj therapy use has increased, which is in line with changes in the standard anti-HER2 therapies that have occurred since 2013. Despite considerable variation, neoadj pts are mostly treated with dual HER2 blockade and chemotherapy, with a preference for taxane-based regimens.
Table 1. Summary of key demographics and clinical characteristicsCharacteristic*Neoadj (n = 394)Adj (n = 696)Age at diagnosis, mean (IQR)55 (46, 64)61 (51, 69)Race / ethnicity- Non-Hispanic white237 (60)433 (62)- Other134 (34)218 (31)- Unknown23 (6)45 (7)Menopausal status- Postmenopausal219 (56)495 (71)ECOG PS- 0203 (52)277 (40)- 152 (13)86 (12)- 2+7 (2)13 (2)- Unknown132 (34)320 (46)Combined clinical stage†- Clinical stage I30 (8)364 (52)- Clinical stage II167 (42)216 (31)- Clinical stage III104 (26)57 (8)- Unknown93 (24)59 (9)Type of surgery- Lumpectomy155 (41)435 (63)- Mastectomy225 (59)261 (37)- Unknown14 (4)0Year of Diagnosis- 2011-1245 (11)180 (26)- 2013-14109 (28)209 (30)- 2015-1698 (25)170 (24)- 2017-19142 (36)137 (20)Practice type (EHR format)- Community348 (88)659 (95)- Academic46 (12)37 (5)ER-positive and/or PR-positive280 (71)557 (80)Most common treatment regimens, n (%)‡Pts with HER2-positive EBC, with available treatment dataNeoadjn = 280- TCH / TCHP43 (15) / 176 (63)- ACT + H/HP§14 (5) / 18 (6)- Any hormonal therapy25 (9)Adj continuationn = 266- H / HP only171 (64) / 38 (14)- Any hormonal therapy163 (61)- T (H / HP) + other¶35 (13)Adj-onlyn = 642- Any hormonal therapy500 (78)- TCH / TCHP223 (35) / 43 (7)- T (H / HP) + other¶106 (17)*P &lt;0.05 (t-test) when comparing pts in the neoadj and adj treatment groups for the clinical characteristics listed (with the exception of race / ethnicity where no major differences were noted). †Clinical stage prior to the start of systemic treatment, which is close to the time of diagnosis for neoadj pts and after the time of surgery for adj pts. ‡‘Other’ therapies accounted for 5% of regimens. §The majority of anthracycline use was a TCH / HP regimen. ¶‘Other’ treatments include CD20 monoclonal antibody, CDK 4/6 inhibitors, antimetabolites (e.g., gemcitabine) and clinical trial study drugs (not specifically listed/known). A, anthracycline; adj, adjuvant; C, a platinum-based compound; ECOG PS, Eastern Cooperative Oncology Group Performance Status; EHR, electronic health record; ER, estrogen receptor; H, trastuzumab; IQR, interquartile range; neoadj, neoadjuvant; P, pertuzumab; PR, progesterone receptor; pts, patients, T, taxane.
Citation Format: Preet K. Dhillon, Carlos Flores, Thibaut Sanglier, Vincent Antao, David Tesarowski, Anita Fung, Devin Incerti, Eleonora Restuccia, Patricia Luhn. Neoadjuvant (neoadj) and adjuvant (adj) treatment patterns in HER2-positive early breast cancer (EBC): Analysis of US real-world oncology data [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS10-20.