A 24-year old female patient, without any medical history, not taking any medication or anticonception (as she and her partner desire to have a child), 78kg, 165cm, BMI 28.7 kg/m², presented with fatigue and malaise. Baseline ALT was 882 U/L but liver function was normal, including normal bilirubin levels. Liver ultrasound showed steatosis, also confirmed on the biopsy. The biopsy showed quite frank lobular and interface hepatitis (likely AIH). Fibrosis was staged as mild by the pathologist. IgG levels were 28 g/L (i.e., 2800 mg/dL).

What treatment would you preferably start in this patient?