Shares of

Ventana Medical

(VMSI)

were soaring nearly 50% early Tuesday after Swiss pharmaceutical giant

Roche

said it wanted to buy the company for $75 a share.

Roche plans an all-cash tender offer worth about $3 billion. Ventana closed Monday at $51.74 but was lately jumping $25.13 to $76.87. Roche said the acquisition of Ventana allows it to take the important step of entering the tissue-based diagnostics market.

The company said it made "multiple efforts to engage in meaningful discussions" with Ventana's chairman and board concerning a negotiated transaction, but Ventana has declined to discuss a deal.

"Roche remains willing to discuss a negotiated transaction agreed to by both parties, as this continues to be Roche's preferred option," the company said.

Ventana's board recommended that its shareholders take no action at this time. The board, in consultation with its independent financial and legal advisers, said it will review the proposal and make a recommendation to investors within 10 business days.