* U.S. regulators allow clinical trial to resume
* Trial evaluates Avastin with chemotherapy in breast cancer
* Also reports positive mid-stage Herceptin data
* Stock in line with European sector
* Roche shares near flat
(Adds details on Avastin, Herceptin results, stock)
ZURICH, Dec 14 (Reuters) - The U.S. Food and Drug Administration is allowing Roche Holding AG (ROG.VX) to resume enrolment to a late-stage trial of Avastin in early-stage HER2-negative breast cancer, the Swiss drugmaker said on Monday.
Enrolment in the trial had been temporarily suspended on Sept. 25, because six cases of clinical congestive heart failure (CHF) were reported during a pre-planned cardio-toxicity analysis of the first 200 patients.
Roche, the world's largest maker of cancer drugs, said the study's data safety monitoring board had concluded that the risk-benefit assessment of Avastin in combination with anthracycline, cyclophosphamide and paclitaxel chemotherapy in this trial remained unchanged.
Avastin, which works by starving tumours of blood supply and is made by Roche's recently acquired Genentech unit, is also used to treat lung and colon cancers, and had annual global sales of 5.2 billion Swiss francs ($5.1 billion) in 2008.
The Phase III trial (E5103) began enrolment in November 2007 and 3,487 of the planned 4,950 patients have been enrolled to date, Roche said.
Roche also reported positive results from a mid-stage trial of another of its drugs, trastuzumab-DM1, against advanced HER2 positive breast cancer. The medicine is a combination of Roche's Herceptin and a cancer cell killing agaent from U.S. group Immunogen (IMGN.O).
The data are encouraging but the treatment is sufficiently far away from market that it revenues are not yet included in models for Roche, analysts said. Roche stock was down 0.5 percent by 1044 GMT at 167.70 Swiss francs, while the DJ Stoxx European healthcare index .SXDP was down 0.3 percent. (Editing by David Holmes and Mike Nesbit) ($1=1.030 Swiss Franc)