The signing of a confidentiality agreement suggests that Roche may have moved a step closer to success in its hostile takeover bid for Ventana Medical Systems though the US firm remains unconvinced about the Switzerland-headquartered firm’s offer.

A fortnight ago Ventana rejected, for the fourth time, an extension of Roche’s $75.00 per share cash offer which values the firm at $3 billion. That bid led the board at the world’s leading tissue-based cancer diagnostics to criticise Roche’s “futile and costly tactics”. However their stance seems to have softened, but only slightly.

Announcing the confidentiality agreement, Ventana said it allow Roche to commence due diligence and have appropriate access to non-public information “to better understand the company's business prospects and the inherent value in companion diagnostics”. This process “will allow Roche to recognise the significant additional value inherent in Ventana's business," the Tucson, Arizona-based company said.

Ventana added that it has not commenced negotiations with Roche and reiterated that Roche's offer “is grossly inadequate and not an appropriate starting point for negotiations as reflected by that fact that Ventana's share price has consistently traded well above Roche's offer and our stockholders have overwhelmingly rejected that offer four times”. The board concluded by saying that the Swiss firm’s bid “does not appropriately compensate Ventana's stockholders for the inherent value of the company or its synergistic value to Roche”.

The Basel-based group merely stated that it is about to commence due diligence and there is no assurance that any deal would be concluded. Indeed, the stumbling block of price is a big one and Roche’s chief executive Franz Humer has repeatedly said that his firm is not going to up its offer. However analysts feel that Roche has to raise its bid, possibly by up to $100 per share, given that Ventana’s diagnostics would help with detection and profiling of cancer, an area where Roche is number one.

Ventana’s shares have shot up since Roche’s initial offer in the summer and they closed at $84.18 last night.