Several major biotech stocks rallied on Friday after Biogen BIIB reported positive results from a Phase 2 study of its Ban2401 therapy, which seeks to reduce toxic amyloid proteins associated with cognitive decline and Alzheimer’s disease.

Shares of Biogen were up more than 17% through afternoon trading hours Thursday. Japan’s Eisai Co. ESALY, a partner in the Ban2401 development, saw gains of nearly 20%. This momentum was enough to lift the rest of the biotech space, evidenced by the iShares Nasdaq Biotechnology Index Fund IBB adding about 3.2%.

Biotech giants like Biogen, Celgene CELG, Amgen AMGN, and Gilead GILD have all underperformed the broader Nasdaq index over the past year, and the industry likely needed positive news to spark some optimistic trading.

Speaking to The Street’s “Real Money” column, Atlantic Equities analyst Steve Chesney said that investors might finally be noticing the value of R&D efforts from these companies.

“This is all about believing innovation and when a company like Biogen comes and reports positive clinical results for a disease like Alzehimer's the implied probability for success for the rest of the industry's pipeline moves a little bit higher,” Chesney told The Street.

Celgene shares added about 2.3% to touch an intraday and one-month high of $82.34. Meanwhile, Amgen moved about 2% higher, and Gilead gained more than 3.3%.

Biogen’s latest test included 856 patients with early Alzheimer’s disease. The company shared positive results from this group over a period of 18 months. Nevertheless, the trial is still only in Phase 2, and the challenges of Phase 3 and its additional regulatory hurdles are still looming.

Still, Biogen will hope that it can commercialize Ban2401 in a timely manner. A new product would likely inspire positive analyst sentiment and lift growth prospects for the coming years.

Within the past two months, the Zacks Consensus Estimate for Biogen’s 2018 earnings has dropped from $23.90 per share to $23.85 per share. This would mark year-over-year growth of 9.4%.

Early estimates for 2019 have the company’s earnings pegged at $26.19 per share, which would represent a 9.8% increase from this year’s projected totals.

BIIB is currently sporting a Zacks Rank #3 (Hold). Its “Medical – Biomedical and Genetics” industry is sitting in the bottom 38% of the Zacks Industry Rank.