Context: Lean development has been often proposed as an adaptation to agile for scaling-up to larger contexts. Goals: we wanted to better understand the “agile-to-lean” transformation, in terms of: i) reported benefits, ii) challenges faced, iii) metrics used. Method: we performed a Systematic Literature Review (SLR) about “agile-to-lean” transformations. Results: reduced lead time, improved flow, continuous improvement, and improved defect fix rate were the main reported benefits. Adaptation to lean thinking, teaching the lean mindset, identification of the concept of waste, and scaling flexibility were the main challenges. Lead time was the most reported metric.