Divergent Time Courses of Poly-L-Lactic Acid and Hyaluronic Acid Fillers for Nasolabial Fold Correction: A Multicenter Randomized Trial With 120-Week Follow-Up

INTRODUCTION: Nasolabial fold (NLF) correction is commonly evaluated at 6 to 12 months, yet the clinical distinction between immediate volumizing fillers and delayed biostimulatory fillers is best understood as a time-course problem rather than a single-visit comparison. This study compared the long-term efficacy trajectory and late safety profile of a poly-L-lactic acid (PLLA) dermal filler with a hyaluronic acid (HA) filler for correction of moderate-to-severe NLFs through 120 weeks after the final injection. METHODS: This multicenter randomized, evaluator-blinded, parallel-group parent trial with an observational extension enrolled adults aged 18 to younger than 65 years with bilateral Wrinkle Severity Rating Scale (WSRS) grade 3 or 4 NLFs at 6 centers in China. The parent trial followed participants for 52 weeks after the final injection; extension participants were then followed for an additional 68 weeks, giving a total follow-up of 120 weeks after the final injection. The parent trial randomized 208 participants to PLLA (n=106) or HA (n=102). The 120-week analysis included 135 participants: 63 in the PLLA group and 72 in the HA group. RESULTS: In the parent-trial full analysis set, WSRS effective correction rates were similar between PLLA and HA at 4 weeks (89.80% versus 92.78%; P=0.461) and 12 weeks (90.00% versus 88.12%; P=0.670). The treatment curves separated later, favoring PLLA at 24, 36, and 52 weeks. At 120 weeks, the WSRS effective correction rate was 55.56% (35/63) with PLLA and 25.00% (18/72) with HA (P<0.001). Participant-rated GAIS improvement was numerically greater with PLLA (73.02% versus 56.94%; P=0.108), whereas investigator-rated GAIS improvement significantly favored PLLA (80.95% versus 63.89%; P=0.024). No late device-related safety event was observed. CONCLUSION: PLLA and HA showed similar short-term efficacy through 12 weeks, whereas PLLA provided superior long-term performance through 120 weeks. These findings support PLLA as a durable biostimulatory option when sustained correction is prioritized, while also underscoring that long-term extension data should be interpreted in light of attrition and observational follow-up.