ZURICH: Roche's off-patent cancer medicines Rituxan, Avastin and Herceptin will likely see sales erosion of 4.6 billion Swiss francs ($5.11 billion) in 2021, Chief Executive Severin Schwan said on Thursday, as rivals' cheaper copies make further inroads.

That is slightly down from more than 5 billion franc hit from so-called biosimilars in 2020, and Roche still expects overall sales to grow at a low- to mid-single-digit rate this year as declining revenue from the older medicines is more than offset by newer drugs, Schwan said.