HLX15-SC

Participants who meet all inclusion criteria and none of the exclusion criteria will receive either the HLX15-SC-Rd regimen or the D-Rd regimen for 4 cycles (one cycle = 4 weeks). After 4 cycles of treatment, based on clinical benefit and participant preference, participants may continue to receive the locally marketed daratumumab subcutaneous formulation (Dara-SC) in combination with Rd according to clinical practice, up to 32 weeks or until loss of clinical benefit, death, unacceptable toxicity, withdrawal of informed consent, or any other protocol-specified reason, whichever occurs first. After 32 weeks of dosing, participants will continue to receive appropriate standard of care according to local guidelines (including marketed Dara-SC).