Updated Standardized Definitions for Efficacy End Points (STEEP) in Adjuvant Breast Cancer Clinical Trials: STEEP Version 2.0.

Purpose: The Standardized Definitions for Efficacy End Points (STEEP) criteria, established in 2007, provide standardized definitions of adjuvant breast cancer clinical trial end points. Given the evolution of breast cancer clinical trials and improvements in outcomes, a panel of experts reviewed the STEEP criteria to determine whether modifications are needed.
Methods: We conducted systematic searches of ClinicalTrials.gov for adjuvant systemic and local-regional therapy trials for breast cancer to investigate if the primary end points reported met STEEP criteria. On the basis of common STEEP deviations, we performed a series of simulations to evaluate the effect of excluding non-breast cancer deaths and new nonbreast primary cancers from the invasive disease-free survival end point.
Results: Among 11 phase III breast cancer trials with primary efficacy end points, three had primary end points that followed STEEP criteria, four used STEEP definitions but not the corresponding end point names, and four used end points that were not included in the original STEEP manuscript. Simulation modeling demonstrated that inclusion of second nonbreast primary cancer can increase the probability of incorrect inferences, can decrease power to detect clinically relevant efficacy effects, and may mask differences in recurrence rates, especially when recurrence rates are low.
Conclusion: We recommend an additional end point, invasive breast cancer-free survival, which includes all invasive disease-free survival events except second nonbreast primary cancers. This end point should be considered for trials in which the toxicities of agents are well-known and where the risk of second primary cancer is small. Additionally, we provide end point recommendations for local therapy trials, low-risk populations, noninferiority trials, and trials incorporating patient-reported outcomes.
Competing Interests: Sara M. TolaneyConsulting or Advisory Role: Novartis, Pfizer, Merck, Lilly, Nektar, NanoString Technologies, AstraZeneca, Puma Biotechnology, Genentech, Eisai, Sanofi, Celldex, Bristol Myers Squibb, Paxman, Seattle Genetics, Odonate Therapeutics, AbbVie, Silverback Therapeutics, G1 Therapeutics, OncoPep, Kyowa Hakko Kirin, Samsung Bioepis, CytomX Therapeutics, Daiichi Sankyo, Athenex, Immunomedics/Gilead, Mersana, CertaraResearch Funding: Genentech/Roche, Merck, Exelixis, Pfizer, Lilly, Novartis, Bristol Myers Squibb, Eisai, AstraZeneca, NanoString Technologies, Cyclacel, Nektar, Immunomedics, Odonate Therapeutics, Sanofi, Seattle GeneticsTravel, Accommodations, Expenses: AstraZeneca, Lilly, Merck, Nektar, Novartis, Pfizer, Genentech/Roche, Immunomedics, Eisai, NanoString Technologies, Puma Biotechnology, Celldex Elizabeth Garrett-MayerConsulting or Advisory Role: Deciphera, Tyme Julia WhiteResearch Funding: Intraop Medical Judith M. BlissResearch Funding: AstraZeneca, Merck Sharp & Dohme, Puma Biotechnology, Pfizer, Roche, GlaxoSmithKline/Novartis, Lilly, Janssen-Cilag, Clovis OncologyTravel, Accommodations, Expenses: Pfizer Eileen RakovitchHonoraria: AstraZenecaResearch Funding: Genomic Health International Patricia A. SpearsConsulting or Advisory Role: Pfizer Elizabeth FrankHonoraria: AstraZenecaTravel, Accommodations, Expenses: Roche Nadine M. TungResearch Funding: AstraZeneca Anthony D. EliasStock and Other Ownership Interests: AbbVie, Merck, Gilead Sciences, Allergan, Pfizer, Abbott Laboratories, Amgen, Bristol Myers Squibb, United Health Group, Align Oncology, Illumina, Exact Sciences, Lilly, Agilent, Cigna, Alexion Pharmaceuticals, BiogenerixConsulting or Advisory Role: Ayala PharmaceuticalsResearch Funding: Medivation, Astellas Pharma, Genentech, Deciphera, Xencor, Infinity Pharmaceuticals, Karyopharm Therapeutics, TopAlliance BioSciences Inc, Fosun Orinove, BioAtlaUncompensated Relationships: Seiyax David CameronConsulting or Advisory Role: Lilly, Novartis, Research Triangle Institute Health Solutions, Daiichi Sankyo, Prima BioMed, Merck Sharp & Dohme, Zymeworks, Eisai, Puma Biotechnology, Pfizer, Oncolytics, Roche, Samsung Bioepis, Seattle Genetics, Synthon, Clarity PharmaceuticalsResearch Funding: Roche, Novartis, AstraZenecaTravel, Accommodations, Expenses: Novartis Neelima DenduluriEmployment: AstraZenecaResearch Funding: Amgen, Novartis, Genentech, Lilly, Pfizer, Daiichi Sankyo, ImmunomedicsTravel, Accommodations, Expenses: Seattle Genetics Angelo DiLeoHonoraria: Roche, Novartis, Pfizer, AstraZeneca, Eisai, Lilly, Celgene, AmgenConsulting or Advisory Role: Roche, Novartis, Pfizer, AstraZeneca, Lilly, Celgene, Puma Biotechnology, Ipsen, Genentech, Amgen, Seattle Genetics, Genomic Health, Athenex, Daiichi SankyoTravel, Accommodations, Expenses: Roche, Pfizer, Celgene, Novartis Eric P. WinerHonoraria: Genentech/Roche, Genomic HealthConsulting or Advisory Role: Leap Therapeutics, Seattle Genetics, Jounce Therapeutics, GlaxoSmithKline, Carrick Therapeutics, Lilly, G1 Therapeutics, Syros Pharmaceuticals, Genentech/Roche, Gilead Sciences, ZymeworksResearch Funding: Genentech, AstraZenecaOther Relationship: InfiniteMDNo other potential conflicts of interest were reported.