North America retains its position as the largest revenue contributor, capturing roughly 43% of global sales through high biologic uptake and favorable reimbursement, while Asia-Pacific is the fastest-growing region, propelled by expanding healthcare infrastructure, rising diagnosis rates, and cost-effective biosimilar adoption. Competitive dynamics are shifting as biosimilar erosion compresses biologic prices, payers tighten step-therapy rules, and real-world evidence requirements intensify for novel JAK inhibitors post-approval. Additionally, supply-chain resilience is under scrutiny after recent API shortages, prompting manufacturers to diversify sourcing and invest in continuous manufacturing technologies to safeguard product flow and margin stability.