Triple negative breast cancer carries a poor prognosis. Cytotoxic chemotherapy (chemo) is the standard of care. Recent data demonstrate that immunotherapy and anti-body drug conjugate based therapy can improve outcomes. Nevertheless survival remains poor. This SLR and MA was performed to assess the efficacy of current treatments for 2 nd line (2L) mTNBC.
EMBASE, MEDLINE, Cochrane databases were systematically searched from database inception to December 2018 for relevant studies of mTNBC with any systemic therapies in metastatic disease. Relevant congresses proceedings since 2016 and ClinicalTrials.gov were also searched. This SLR followed PRISMA guidelines with scope defined in terms of PICOS criteria (Population, Intervention, Comparators, Outcomes and Study design). Weighted averages (WA) for outcomes by treatment arm and line of therapy (LOT) were calculated. In addition, MA of overall response rate (ORR) among patients receiving single agent chemo (single chemo) as 2L and first line or later (1L+) was carried out using random-effects modeling for ORR.
44 original studies were selected: 22 with 1L+, 7 with 2L, 15 with 2L or later (2L+). WAs of outcomes are presented in the Table. WAs of ORR for single chemo were less than ORR for combination chemo or chemo & biologics. No treatment showed consistently better survival over other treatments across all 3 groupings. MA of ORR in patients receiving single chemo as 2L and 1L+ were 11.9% (95% CI: 4.6, 20.8) and 15.6% (95% CI: 8.8-32.9), respectively. Table. Weighted Averages of Clinical Outcomes by Treatment and Line of Therapy. 360P Single agent chemotherapy Combination chemotherapy Chemotherapy & BiologicsTreatment Line of Therapy Overall Response Rate (%) Progression Free Survival (median months) Overall Survival (median months) 1L+ 14.6 2.3 10.8 2L 14.3 2.4 12.6 2L+ - 3.1 12.3 1L+ 29.7 4.4 10.5 2L 31.0 4.1 10.0 2L+ - 2.9 8.1 1L+ 22.6 2.9 10.6 2L 35.8 5.6 17.9 2L+ 21.2 3.5 10.7
There is no clear standard of care in 2L TNBC. Response rates are low for single chemo and although response rates improve with combination therapies, no treatment regimen has demonstrated definitive improvement in outcomes. These results reinforce the need for new treatment strategies for mTNBC after 1L.
Purple Squirrel Economics.
Seattle Genetics, Inc.
P.A. Kaufman: Full / Part-time employment: Seattle Genetics, Inc. J. Feliciano: Full / Part-time employment: Seattle Genetics, Inc. P. Garfin: Full / Part-time employment: Seattle Genetics, Inc. L. Brown: Full / Part-time employment: Seattle Genetics, Inc. All other authors have declared no conflicts of interest.