Alnylam Pharmaceuticals Inc. said Monday it took a smaller loss in the first quarter as its expenses decreased.

The RNAi drugmaker said its general and administrative spending decreased, mostly because costs related to legal activity were down. It also reported less in revenue because payments from its drug development partners decreased.

Alnylam lost $9 million, or 15 cents per share, in the latest quarter. A year ago the company took a loss of $11.4 million, or 25 cents per share. Its revenue fell to $18.6 million from $20.6 million.

Analysts were expecting a loss of 29 cents per share and $16.6 million in revenue, according to FactSet.

Alnylam’s drugs use RNA interference, or RNAi, technology. RNAi therapies work by turning off or silencing disease-causing genes. The company received about half its revenue from a partnership with Cubist Pharmaceuticals Inc. Alnylam and Cubist were studying a treatment for respiratory syncytial virus, an infection in adult lung transplant patients. Alnylam said in February that the companies had decided to end the partnership, and its first-quarter results include all the revenue that remained under the collaboration.

Other revenue came from Alnylam’s alliances with Takeda Pharmaceuticals of Japan, Monsanto Co., and Medicines Co. A year ago the company received $14 million from Swiss drugmaker Roche.

In June Alnylam expects to report mid-stage clinical trial results from a key drug candidate called ALN-TTR02. The drug is designed to treat transthyretin familial amyloid polyneuropathy, a rare condition that is normally treated with a liver transplant.

Shares of Alnylam rose 11 cents to $23.70 on Monday. The stock has risen 29.9 percent in 2013. In after-hours trading the stock picked up 3 cents to $23.73.