OBJECTIVE To investigate the cognition， attitudes， and current practices of Chinese physicians regarding biosimilars and their clinical switching， so as to provide a basis for the rational clinical application of biosimilars in China and the improvement of related policies.METHODS A national cross-sectional online questionnaire survey was conducted in 2025. Quota sampling was adopted， with quotas based on physicians’ sex， city tier， and specialty. Questionnaire invitations were distributed to licensed physicians， and physicians who had prescribed monoclonal antibody biosimilars were included for analysis. The questionnaire covered their familiarity with biosimilars， attitudes， clinical switching practices， and reasons. Data were processed using reliability and validity tests， dispersion analysis， and cross-tabulation analysis.RESULTS The questionnaire scale showed good reliability and validity， with Cronbach’s α coefficient ＞0.7 and KMO value ＞0.6. A total of 2 071 survey invitations were distributed， and 300 valid questionnaires were returned， with an effective response rate of 14.5%. Among the respondents， 75.3% had prescribed 3-5 types of monoclonal antibody biosimilars； only 35.3% were aware that China currently has no clear regulatory provisions on biosimilar switching； 46.3% and 47.3% of respondents believed that there was no difference in safety and efficacy， respectively， between biosimilars and originator products； 63.0% of respondents were concerned about the immunogenicity risk of long-term switching between originator drugs and biosimilars. A total of 92.3% of respondents had experience with biosimilar switching， 87.7% of which involved switching from originator products to biosimilars， and 28.2% of respondents had completed three or more switches in the same patient. Among the primary reasons for switching， non-medical factors accounted for 57.4%， higher than medical factors at 42.6%； “lower treatment cost after switching” was the most important reason for switching； 95.3% of respondents believed that informed consent should be obtained from patients before switching.CONCLUSIONS The surveyed physicians had basic knowledge of biosimilars， but their understanding of the relevant regulations of the national drug regulatory authority was insufficient. Although most physicians were concerned about the risks of non-medical switching， clinical switching was mostly driven by non-medical factors. It is recommended to strengthen policy education for medical professionals and standardize clinical switching behavior. The National Medical Products Administration should also promptly improve the interchangeability review standards and post-marketing surveillance system for biosimilars, so as to promote the rational use of biosimilars.

Cardiac fibrosis is characterized by an elevated amount of extracellular matrix (ECM) within the heart. However, the persistence of cardiac fibrosis ultimately diminishes contractility and precipitates cardiac dysfunction. Circular RNAs (circRNAs) are emerging as important regulators of cardiac fibrosis. Here, we elucidate the functional role of a specific circular RNA CELF1 in cardiac fibrosis and delineate a novel feedback loop mechanism. Functionally, circ-CELF1 was involved in enhancing fibrosis-related markers' expression and promoting the proliferation of cardiac fibroblasts (CFs), thereby exacerbating cardiac fibrosis. Mechanistically, circ-CELF1 reduced the ubiquitination-degradation rate of BRPF3, leading to an elevation of BRPF3 protein levels. Additionally, BRPF3 acted as a modular scaffold for the recruitment of histone acetyltransferase KAT7 to facilitate the induction of H3K14 acetylation within the promoters of the Celf1 gene. Thus, the transcription of Celf1 was dramatically activated, thereby inhibiting the subsequent response of their downstream target gene Smad7 expression to promote cardiac fibrosis. Moreover, Celf1 further promoted Celf1 pre-mRNA transcription and back-splicing, thereby establishing a feedback loop for circ-CELF1 production. Consequently, a novel feedback loop involving CELF1/circ-CELF1/BRPF3/KAT7 was established, suggesting that circ-CELF1 may serve as a potential novel therapeutic target for cardiac fibrosis.