This is a Multi-center, Open-label Study on the Efficacy and Safety of Multiple Treatments with Recombinant Botulinum Toxin Type A for Injection in the Treatment of Moderate to Severe Glabellar Lines. The study has been designed to evaluate the long-term safety, tolerability, efficacy , maintain time and immunogenicity of multiple treatments with Recombinant Botulinum Toxin Type A for Injection (YY001) in the treatment of moderate to severe glabellar lines.

Inclusion Criteria:

1. Male or female 18 to 65 years (inclusive) at the time of signing the informed consent form.
2. At screening or baseline, participants who complete all visits of the REFINE study without major protocol deviations and SAEs
3. Agree to participate in the study and sign the informed consent form.
4. At the discretion of the investigator, the participants can comply with the protocol requirements.
5. Females and/or males of childbearing potential and their partners: those who should be using effective contraception and have no plans for childbearing, egg donation (females), or sperm donation (males) from the signing of the informed consent form to 3 months after the last administration. female participants of childbearing potential must have had a negative blood pregnancy test (human chorionic gonadotropin) within 7 days prior to the first administration of study drug or a Urine pregnancy test examination must be negative 3 days prior to the first administration of study drug.

Note:

1. Women of childbearing potential are those who have experienced menarche, have not undergone sterilization (hysterectomy or bilateral salpingo-oophorectomy or bilateral tubal ligation), and are not in a state of post-menopausal (defined as absence of menstrual bleeding for 12 months prior to screening, without any other medical reason).
2. Effective contraceptives include: vasectomy, abstinence, intrauterine devices, hormones [oral, patch, ring, injections, implants], barrier methods [diaphragm, cervical cap, sponge, condom].

Exclusion Criteria:

1. Use of medications or treatments prohibited by the REFINE study protocol.
2. Any condition that required permanent discontinuation of study treatment during the REFINE study.
3. Use of nonsteroidal anti-inflammatory drugs including aspirin or anticoagulants within 1 week prior to baseline.
4. Abnormal laboratory tests that, in the assessment of the investigator, are not appropriate for participation in this study: including, but not limited to: alanine aminotransferase (ALT)/aspartate aminotransferase (AST) ≥ 2.5 times the upper limit of the normal range (×ULN), creatinine ≥ 2 ×ULN, urea/urea nitrogen ≥ 2 ×ULN.
5. Female who is pregnant or breast feeding.

Open-label