Abstract 327P
Background
Treatment pathways in HR+/HER2- locally advanced or metastatic breast cancer (aBC) have changed following the introduction of CDK4/6 inhibitors (CDK4/6i) in Europe in 2016. Several clinical trials are exploring treatment sequencing and related outcomes in aBC. However, data in real-world patient (pt) populations is limited. This study examined real-world clinical characteristics and treatment sequencing among a multinational sample of pts with HR+/HER2- aBC.
Methods
Oncologists in four European countries abstracted information from medical records of pts, aged ≥18, who were receiving second-line treatment for HR+/HER2- aBC between 10/2019 and 02/2020. Clinical characteristics, treatment characteristics, and first to second line (1L→2L) treatment sequences were assessed.
Results
The sample consisted of 740 pts currently receiving 2L therapy. The majority were female (99%) with a mean age of 63 years. Two-thirds of pts presented with de novo aBC, while 34% had recurrent disease. Among pts with recurrent disease, 51% received adjuvant chemotherapy (CT). In the 1L aBC setting, 28% of pts received a CDK4/6i in combination with AI or fulvestrant, 27% of pts received AI monotherapy, 17% received CT, and 23% received other regimens (e.g., other targeted therapies, combination CT and endocrine therapy). Disease progression (76%) was the most frequent reason for initiation of 2L therapy. The most common treatment sequences were AI monotherapy → CDK4/6i + fulvestrant; CDK4/6i + AI → CT; and CDK4/6i + AI → other (table). Table: 327P
Top 15 most common treatment sequences among patients with HR+/HER2- aBC receiving second-line therapy
| First Line | Second Line | n | % |
| AI monotherapy | CDK4/6i + fulvestrant | 96 | 13 |
| CDK4/6i + AI | CT | 63 | 9 |
| CDK4/6i + AI | Other | 57 | 8 |
| Other | Other | 56 | 8 |
| AI monotherapy | Fulvestrant monotherapy | 48 | 6 |
| CT | Other | 41 | 6 |
| Other | CT | 40 | 5 |
| CT | CT | 33 | 4 |
| CDK4/6i + AI | Fulvestrant monotherapy | 29 | 4 |
| Other | CDK4/6i + fulvestrant | 28 | 4 |
| Other | CDK4/6i + AI | 26 | 4 |
| CT | CDK4/6i + AI | 24 | 3 |
| AI monotherapy | CT | 23 | 3 |
| CDK4/6i + fulvestrant | Other | 21 | 3 |
| CDK4/6i + fulvestrant | CT | 20 | 3 |
Conclusions
Prior to approval of CDK4/6i, endocrine monotherapy was standard of care in HR+/HER2- aBC. This recent real-world analysis of treatment sequences demonstrates shifting treatment pathways after introduction of CDK4/6i in Europe. Further research is needed to understand clinical outcomes associated with common treatment sequences to enable optimal treatment strategies in diverse pt populations.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Pfizer Inc.
Funding
Pfizer Inc.
Disclosure
K. Lewis: Full/Part-time employment, Employee of Adelphi Real World, who were paid consultants to Pfizer in connection with the development of this abstract.: Adelphi Real World. S. Kurosky: Shareholder/Stockholder/Stock options, Full/Part-time employment: Pfizer Inc. M. Last: Full/Part-time employment, Employee of Adelphi Real World, who were paid consultants to Pfizer in connection with the development of this abstract.: Adelphi Real World. D. Mitra: Shareholder/Stockholder/Stock options, Full/Part-time employment: Pfizer Inc. A. Lambert: Full/Part-time employment, Employee of Adelphi Real World, who were paid consultants to Pfizer in connection with the development of this abstract.: Adelphi Real World. R. Mahtani: Advisory/Consultancy, Research grant/Funding (institution): Genentech; Advisory/Consultancy: Pfizer; Advisory/Consultancy: Eli Lilly; Advisory/Consultancy: Novartis; Advisory/Consultancy: Daiichi-Sankyo; Advisory/Consultancy: Seattle Genetics; Advisory/Consultancy: Eisai; Advisory/Consultancy: AstraZeneca; Advisory/Consultancy: Puma; Advisory/Consultancy: Amgen.