Alnylam Pharmaceuticals' (ALNY) Amvuttra saw about $150 million in first full-quarter sales to treat ATTR cardiomyopathy, which was above market expectations by a "sizable margin," Oppenheimer said in a note to clients Monday.

Alnylam obtained payer agreements much faster than expected, the investment firm said.

Total sales of Amvuttra at $492 million were also "well ahead" of Oppenheimer's estimate of $345 million, and beat consensus forecasts for $351 million, the note said.

Oppenheimer said it it expects "further outperformance" as Amvuttra's commercialization for ATTR cardiomyopathy "continues to impress and Street estimates are revised upward."

The investment firm also said it sees "current-year sales outlook as way too conservative."

Consensus total sales estimates for Alnylam are now at $2.54 billion, including $1.82 billion for Amvuttra, Oppenheimer said, adding that "these figures imply Amvuttra growth slows through 2H vs. 2Q" which the investment firm sees as "unlikely."

Oppenheimer expects the company to post $2.4 billion and $3.1 billion, respectively, in Amvuttra and total net product sales in 2025.

The investment firm upgraded Alnylam to outperform from market perform and assigned it a $490 price target.

Price: 415.83, Change: +14.03, Percent Change: +3.49