Abstract
Abstract BACKGROUND: At SABCS 2018 and simultaneous publication in the NEJM, results of the phase 3 KATHERINE clinical trial comparing TDM1 vs trastuzumab as adjuvant therapy in patients with HER2-positive early-stage breast cancer with residual invasive disease after receiving neoadjuvant chemotherapy and trastuzumab, showed that TDM1 reduced the risk of invasive recurrence or death by 50%. We sought to determine the effect of the release of this data on clinical practice of general medical oncologists in the US by comparing the requests for treatment authorization for TDM1 in the quarters preceding and following SABCS 2018. METHODS: data from a pre-authorization platform used by multiple commercial insurance companies in the US (Eviti) was analyzed. Analysis for request for use of TDM1 was limited to 2nd and 3rd line of therapy in patients with a diagnosis of HER2+ breast cancer in stage <4 patients. Between 1/1/2018 and 6/30/2019, 29,525 breast cancer treatment plans were identified, of which 7,969 were identified as HER2-NEU+ (27%), either IHC3+ or FISH+. TDM1 was prescribed at any line of therapy in 886 patients (11%). RESULTS: Before April 5th 2019, when the adjuvant TDM1 regimen was published, users who entered the drug would have to pick one of the other 2 TDM1 regimens (1st line or 2nd line+). They could change the line of therapy to adjuvant if appropriate. TDM1 authorizations are shown in TABLE 1, indicating an immediate increase in TDM1 use in the quarter following SABCS and based on the quarter 2, 2019 data showing a 42% adjuvant-use rate, we model that 99 cases would have received adjuvant TDM1 in Q1 2019 after 0 in Q4 2018. Q 1, 2018Q 2, 2018Q 3, 2018Q 4, 2018Q 1, 2019Q 2, 2019TDM1 Adjuvant097TDM1 First Line11178195925TDM1 Second Line+104939276177108 CONCLUSIONS: Clinical uptake of practice changing data presented at SABCS 2018 regarding TDM1 was relatively rapid. SABCS and rapid simultaneous publication serves as an important and effective mechanism to communicate practice changing clinical data to practicing oncologists in the US. Citation Format: Neil Margolis, Vlad Kozlovsky, William Flood, Sandeep Reddy. Real world data on treatment patterns before and after reporting of the KATHERINE trial: A phase 3 study of adjuvant Ado-trastuzumab emtansine (TDM1) versus trastuzumab in early stage HER+ breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-15-08.
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