GMMG‐HD2.

Methods	Randomisation of patients with at least stable disease after induction Multicentre (N=66) RCT comparing TASCT with SASCT without reporting of aim (superiority/non‐inferiority) Optional additional randomisation of induction regimen (VID vs VAD)
Participants	TASCT N= 180; SASCT N=178 (evaluated patients; actual number of patients depending unclear and different in different conference presentations (N=358‐485) age 18 ‐ 66 years previously untreated (or max 6 cycles of conventional chemotherapy) patients with MM Salmon‐Durie stage II and III (Baseline characteristics Table 2)
Interventions	2 x 200 mg/m² melphalan TASCT vs 1 x 200 mg/m² melphalan SASCT (Treatment plan Table 3)
Outcomes	OS, EFS (primary endpoint), so‐called TRM (ITT and PP analyses) (Definitions of endpoints Table 4; Table 5)
Period and Location	Nov (96?) 98 – Feb 02 in Germany
Sample size calculation	NR
ITT analysis (n of drop‐outs)	Yes (unclear); per protocol analyses available
Notes	Conference presentation with some inconsistencies Unclear, how the two randomisations were analysed (separately?, interaction test?) Very low compliance (52% of evaluable population) with 2nd ASCT (null bias for OS, EFS); Potential confounding by salvage treatment (OS) Numerically inferior OS for TASCT group in PP analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	NR
Allocation concealment (selection bias)	Unclear risk	NR
Blinding (performance bias and detection bias) All outcomes	High risk	Unavoidable in view of obvious difference in treatment plan
Other bias	High risk	See Table 6 and Figure 2