BASEL, Switzerland (AP) – Shares in Roche Holding AG plummeted Wednesday after the Swiss drugmaker said its best-selling cancer medicine Avastin fails to stop early stage colon cancer.

The highly anticipated study results were a key sticking point in the back-and-forth negotiations between Roche and Genentech before Roche’s $46.8 billion acquisition of the California biotech company.

Roche said a first phase III trial combining Avastin – also known by its generic name bevacizumab – with chemotherapy to treat patients after surgery showed it was no more effective than chemotherapy alone.

Shares in Roche fell 10.4 percent to close at 137.4 Swiss francs ($118) on the Zurich exchange.

Roche said it remains committed to testing Avastin in combination with chemotherapy for other forms of cancer.

Avastin was one of the main reasons why Roche recently completed a $95-per-share deal to buy California biotech firm Genentech, which had developed the drug. It is already approved as a treatment for various forms of colon, breast and lung cancers.

Analysts were mixed on whether Genentech should wait for the results before making a deal, with some saying success could fetch a sale price of more than $100 per share.

Others, though, pushed for a sale before the results to reduce the risk that a failed study would depress the company’s value.

“We remain fully committed to the ongoing Avastin adjuvant programs in early stage colon, breast and lung cancers,” said Hal Barron, senior vice president of Genentech.

He added that findings for the effectiveness of Avastin in treating advanced-stage cancer were not affected.

Source: The Associated Press