Reply to letter to the editor in response to A real-world study of ART in France (REOLA) comparing a biosimilar rFSH against the originator according to rFSH starting dose' by Montenegro S et al. (JOGOH-D-23-00756)

Background Since the first launch of a biosimilar recombinant follicle stimulating hormone (rFSH), Bemfola®, in Europe in 2014, it has been possible to study in routine clinical care throughout France the effectiveness of a biosimilar rFSH including according to different rFSH starting doses. Methods REOLA was a non-interventional, retrospective, real world study using anonymized data from 17 Assisted Reproductive Technology (ART) centres’ data management systems across France including 2,319 ART ovarian stimulation cycles with Bemfola® and 4,287 ART ovarian stimulation cycles with Gonal-f®. For both products, four populations were studied according to starting dose of rFSH: < 150 IU, 150 - 224 IU, 225 - 299 IU and ≥ 300 IU. The primary endpoint was the cumulative live birth rate (cLBR) per commenced ART ovarian stimulation cycle including all subsequent fresh and frozen-thawed embryo transfers starting during a follow up period of at least 1 year following oocyte retrieval. Results A direct relationship of increasing rFSH starting dose with increasing age, increasing basal FSH, decreasing AMH and increasing body mass index was noted. No clinically relevant differences were seen in all outcomes reported, including the cLBR, between Bemfola® and Gonal-f®, but for both drugs, an association was seen with increasing rFSH starting dose and decreasing cLBR. Conclusions The REOLA study demonstrates that the cLBR with Bemfola® is very similar to Gonal-f® across all patient subpopulations. The cLBR is inversely related to the rFSH starting dose irrespective of the drug used, and the REOLA study provides reassurance of the clinical effectiveness of a biosimilar rFSH used in a real world setting.