Abstract 83P
Background
There are currently no established biomarkers that predict long-term treatment benefit from REG in pts with mCRC. Comprehensive studies on long-term responders to REG are lacking; in this context, we present an updated analysis of characteristics of pts treated in RW clinical practice using duration of treatment (DOT) as a surrogate for treatment response.
Methods
This retrospective cohort study used the de-identified US Flatiron Health electronic health record-derived database and included pts age ≥18 years with mCRC who initiated REG monotherapy (index date) from July 1, 2013, to June 30, 2023. Groups were defined by DOT of ≥4 months (m; LTR4), ≥5 m (LTR5), or ≥6 m (LTR6).
Results
Of 2444 eligible pts who initiated REG during the study period, 544 (22%) had LTR4, 367 (15%) had LTR5, and 250 (10%) had LTR6. Most LTR pts were treated in community practice (88%) and 60% initiated REG between 2019 and 2022. Median age in each LTR group was 66 yrs and pts most often initiated REG in the third line (30–33%). Median follow-up from index date was 10.7 m for LTR4, 13.0 m for LTR5, and 14.6 m for LTR6. Median time to REG discontinuation was 6.0 m for LTR4, 7.4 m for LTR5, and 9.3 m for LTR6. LTR6 pts had a longer median time from initial CRC diagnosis to index date and a smaller proportion had mCRC (stage IV) at initial diagnosis (Table). Of pts who initiated REG before 2019 (n=1061), 21% had LTR4, 14% had LTR5, and 9% had LTR6. Of pts who initiated REG from 2019 onwards (n=1383), 23% had LTR4, 16% had LTR5, and 11% had LTR6. The slightly higher proportion of LTR pts initiating REG after 2019 coincided with the phase 2 ReDOS study completion (Bekaii-Saab et al. Lancet Oncol 2019;20:1070).
Conclusions
In this updated analysis of a large-scale RW study, 10% had LTR6, deriving the longest benefit from REG treatment. Most of these pts had favorable ECOG PS at REG initiation, left-sided tumors, and received prior bevacizumab (BEV). Table: 83P
| Characteristic | LTR4 (n=544) | LTR5 (n=367) | LTR6 (n=250) |
| Male sex, n (%) | 309 (57) | 207 (56) | 141 (56) |
| ECOG PS 0‒1, n (%) ∗ | 366 (67) | 251 (68) | 170 (68) |
| Prior BEV, n (%) | 367 (67) | 231 (63) | 149 (60) |
| Median CEA (IQR), ng/mL ∗ | 36 (8, 152) | 32 (8, 139) | 29 (7, 108) |
| KRAS mutation, n (%) ∗ | 134/241 (56) | 89/169 (53) | 55/118 (47) |
| BRAF mutation, n (%) ∗ | 20/355 (6) | 13/236 (6) | 10/156 (6) |
| Stage IV at initial CRC diagnosis, n (%) | 261 (48) | 170 (46) | 104 (42) |
| Median time from initial CRC diagnosis to index date (IQR), m | 38.8 (24.3, 62.6) | 39.2 (24.8, 64.1) | 41.9 (27.9, 70.9) |
| Left-sided primary tumor, n (%) ∗ | 356 (65) | 249 (68) | 176 (70) |
| Site of metastasis, n (%) † | |||
| Liver | 333 (61) | 212 (58) | 138 (55) |
| Non-liver | 209 (38) | 153 (42) | 110 (44) |
∗At index
†Any time before or at index
Clinical trial identification
NCT06029010.
Editorial acknowledgement
Medical writing support was provided by Sam Coates of Luna, OPEN Health Communications, and funded by Bayer HealthCare.
Legal entity responsible for the study
Bayer Healthcare Pharmaceuticals.
Funding
Bayer Healthcare Pharmaceuticals.
Disclosure
R.D. Kim: Financial Interests, Personal, Other, Personal fees: Pfizer Ltd., AstraZeneca Ltd., Incyte Ltd., Roche Pharmaceuticals, Eisai Pharmaceuticals, GSK, USA, Taiho Pharmaceutical Group, Inc. X. Pan, Y. Zhang, O. Lunacsek, F. Pisa, H. Ostojic: Financial Interests, Personal, Full or part-time Employment: Bayer. All other authors have declared no conflicts of interest.