The effectiveness and safety of eribulin therapy in HR-positive HER2-negative metastatic breast cancer post-CDK4/6 inhibitor therapy in Russian clinical practice.

person Larisa Bolotina National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation, Moscow, Russian Federation info_outline Larisa Bolotina, Lyudmila Zhukova, Liubov Yu Vladimirova, Alexander Sultanbaev, Elena Karabina, Inna Ganshina, Elena Ovchinnikova, Irina Vladimirovna Kolyadina, Galina Antonova, Mikhail Volkonsky, James Kolokolov, Elena Zueva, I Akopyan, Natalia Fadeeva, Irina Evstigneeva, Svetlana Orlova, Anna Vasilevskaya, Oxana Shalaeva, Oxana Shirokova

Authors person Larisa Bolotina National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation, Moscow, Russian Federation info_outline Larisa Bolotina, Lyudmila Zhukova, Liubov Yu Vladimirova, Alexander Sultanbaev, Elena Karabina, Inna Ganshina, Elena Ovchinnikova, Irina Vladimirovna Kolyadina, Galina Antonova, Mikhail Volkonsky, James Kolokolov, Elena Zueva, I Akopyan, Natalia Fadeeva, Irina Evstigneeva, Svetlana Orlova, Anna Vasilevskaya, Oxana Shalaeva, Oxana Shirokova Organizations National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation, Moscow, Russian Federation, N. N. Blokhin Cancer Research Center, Moscow, Russian Federation, National Medical Research Centre for Oncology, Rostov-on-Don, Russian Federation, Republic Clinical Oncology Dispensary of Bashkortostan Republic, Ufa, Russian Federation, Tula Regional Oncology Dispensary, Tula, Russian Federation, Federal State Budgetary Institution “N.N. Blokhin National Medical Research Center of Oncology”оf the Ministry of Health of the Russian Federation, Moscow, Russian Federation, Nizhegorodskiy Regional Clinical Oncology Dispensary, Nizhniy Novgorod, Russian Federation, National Medical Oncology Center named after N.N. Petrov, Saint-Petersburg, Russian Federation, Moscow City Clinical Hospital #40, Moscow, Russian Federation, Moscow City Oncology Hospital #62, Moscow, Russian Federation, Moscow Department of Oncology, Moscow, Russian Federation, Moscow City Clinical Oncology Hospital #1, Moscow, Russian Federation, Moscow City Clinical Hospital named after Bakrusheny, Moscow, Russian Federation, Chelyabinsk Regional Center of Oncology and Nuclear Medicine, Chelyabinsk, Russian Federation, Tver Oncilogy Center, Tver, Russian Federation, Republic Clinical Oncology Dispensary of Chuvash Republic, Cheboksary, Russian Federation, Moscow Regional Oncology Dispensary, Moscow, Russian Federation, Perm Regional Oncology Dispensary, Perm, Russian Federation, Ekaterinburg Regional Oncology Dispensary, Ekaterinburg, Russian Federation Abstract Disclosures Research Funding No funding received None Background: EMPOWER trial demonstrated the benefit of eribulin administrated post CD4/6i in patients (pts) with HR+ HER2-negative (HR+HER2-) metastatic breast cancer (MBC). There are several important limitations to this trial: > 60% of pts were stage IV at the time of treatment initiation, eribulin used in late lines (2L only in 30% pts) and follow-up data were immature. Current study aimed to provide additional data on the real-world effectiveness and safety of eribulin monotherapy in this setting. Methods: Observation study of eribulin monotherapy in standard regimen enrolled 54 pts (median age 56; range 29-79 years) with HR+ HER2- MBC received at least one dose of eribulin post CDK 4/6i in metastatic settings; 24% pts had de novo metastatic BC, 76% - recurrent BC; 77% received palbociclib, 21% ribociclib, 2% both drugs; 49% pts received CDK4/6i with fulvestrant and 51% with AI. CDK4/6i was used: 49% pts in 1L, 36% in 2L, 16% in 3L. Median DOR of CDK4/6i treatment was 9.07 months (range 2-38). 94% pts received anthracyclines and taxanes, eribulin was used in 2L in 60%, 30% in 3L, 8% in 4L, 2% in 5L. The most common sites of metastases (Mts) were bones (78%), liver (73%), lung (56%) and brain (8%); visceral Mts were seen in 90% pts. Median follow-up – 11,5 months (range 3-36). Results: Median cycles of eribulin therapy was 10,5 (range 1-44); objective response rate was seen in 24%, stabilization - 67%, progression - in 9%. Median PFS was 10.0 months, there were no significant differences in the different subgroups (visceral/no visceral; recurrent/de novo BC; age; CDK4/6i as 1L vs 2L, fulvestrant vs AI), p > 0,05. Median PFS was higher in pts with lung Mts vs non-lung (24 vs 9,1 months, p = 0.056). Most common AEs all grades were neutropenia (26%), anemia (9%), asthenia (9%), polyneuropathy (11.1%). AE did not affect the effectiveness of eribulin (p = 0.648). Dose reduction was in 19% pts and did not affect the effectiveness of eribulin (p = 0.612). At median follow-up of 11.5 months, 92.5% of patients still alive. Conclusions: As post-CDK4/6i therapy, eribulin in HR+HER2- MBC pts was effective and well tolerated, regardless of age, line of CDK4/6, CDK 4/6i combination partner. Patients with metastasis to the lung have better mPFS. Results in this real-world population of pts with HR+HER2- MBC were consistent with the EMPOWER study, and support administration of eribulin in 2-3 lines as an effective option for post-CD4/6i pts.