Daratumumab in combination with lenalidomide-dexamethasone (D-Rd) recently received FDA approval for the treatment of transplant-ineligible patients with newly diagnosed multiple myeloma (NDMM). The present PEGASUS study compared progression-free survival (PFS) in patients treated with D-Rd in the MAIA trial and patients treated with common standard-of-care regimens from the Flatiron Health electronic health record-derived deidentified database, which has data from patients treated primarily at community-based oncology practices in the United States. Individual-level patient data from both data sources were used to perform an anchored indirect treatment comparison (ITC) of D-Rd to bortezomib-lenalidomide-dexamethasone (VRd) and bortezomib-dexamethasone (Vd); lenalidomide-dexamethasone (Rd) was the common anchor for the ITC. Hazard ratios (HRs) reflecting direct comparisons of PFS within MAIA (D-Rd vs Rd) and Flatiron Health (VRd vs Rd; Vd vs Rd) were used to make ITCs for D-Rd vs VRd and Vd, respectively. After application of MAIA inclusion/exclusion criteria and propensity-score weighting, the Flatiron Health patients resembled the MAIA trial population on measured baseline characteristics. Based on the direct comparison within MAIA, treatment with D-Rd was associated with a significantly lower risk of progression or death compared to Rd (HR 0.54; 95% CI 0.42, 0.71). Based on the ITCs, D-Rd was associated with a significantly lower risk of progression or death compared to VRd (HR 0.68; 95% CI 0.48, 0.98) and Vd (HR 0.48; 95% CI 0.33, 0.69). In the absence of head-to-head trials comparing D-Rd to VRd or Vd, the present ITC may help inform treatment selection in transplant-ineligible patients with NDMM.