Spero Therapeutics (SPRO) Stock Forecast & Price Target

Spero Therapeutics is attractive fundamentally because its strategy has shifted toward SP001, a Phase 2-ready Fc-silent anti-CD40L antibody aimed at IgG4-RD, where the disease biology strongly supports upstream modulation of B- and T-cell activation and fibrosis. The investment case is strengthened by encouraging Phase 1b signals in Sjögren’s disease, a differentiated safety design intended to avoid legacy CD40L thromboembolic risk, and a sizeable commercial opportunity that the analysis says could support more than $1B in peak sales at 30% market penetration. Financially, the company also gained non-dilutive support from a $35M upfront license payment and a $105M royalty financing, while the valuation work cites about $367M to $400M in total NPV and risk-mitigated upside if SP001 advances as planned.

Spero Therapeutics is facing a weak fundamental outlook because its 2024 interim analysis showed SPR720 failed to meet its primary endpoint, undermining confidence in one of its key wholly owned programs and forcing significant restructuring to extend cash runway into mid-2026. The company remains exposed to high clinical and regulatory risk, where even modest safety signals can derail development, and its pipeline assets still face uncertainty in proving statistically and clinically meaningful efficacy. With future commercialization dependent on new partnerships or financings and competitive pressure rising in IgG4-RD, its path to durable value creation looks increasingly constrained.