Subcutaneous Immunotherapy in Cancer: Where We Are Now, What It Changes, and What to Watch Next

Subcutaneous (SC) formulations of monoclonal antibodies are rapidly transforming the delivery of cancer immunotherapy. Designed to replace or complement intravenous (IV) administration, SC delivery reduces infusion chair time, improves convenience, and may enhance patient and provider satisfaction while preserving pharmacokinetics (PKs), efficacy, and safety. Recent phase III studies of immune checkpoint inhibitors and bispecific antibodies-including atezolizumab, nivolumab, pembrolizumab, and amivantamab-have consistently demonstrated PK noninferiority and comparable clinical outcomes with IV formulations. Safety profiles are largely unchanged, with immune-related adverse events occurring at similar rates, although mild injection site reactions are more common. Importantly, SC amivantamab has shown a marked reduction in infusion-related reactions relative to IV dosing. Operational studies confirm that SC administration shortens treatment delivery from 30 to 60 minutes to <10 minutes, reduces chair occupancy, and optimizes infusion center capacity. Patient preference studies indicate strong favorability toward SC treatment, with most patients citing convenience, reduced venipunctures, and shorter visits as major advantages. Regulatory approvals now include SC atezolizumab and nivolumab across broad indications, SC amivantamab in Europe, and SC pembrolizumab following positive phase III results. The integration of SC immunotherapy into routine practice may improve patient experience, alleviate pressure on oncology services, and reduce health system costs without compromising outcomes. Future research should focus on implementation, real-world cost-effectiveness, and the potential for SC combinations in multiagent regimens.