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. 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 percent to 138 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 $46.8 billion takeover of California biotech firm Genentech, which had developed the drug. "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 advance stage cancer were not affected.