Updated from July 7

Genentech ( DNA) shares rose early Thursday after the company kicked off the biotech earnings season with a bang Wednesday evening, announcing strong sales of its cancer-treatment Avastin, while boosting earnings guidance going forward.

On a non-GAAP basis, Genentech announced second-quarter net income of $201.8 million, or 19 cents a share, matching rising Wall Street estimates and rising 23% from the $163.5 million, or 16 cents a share, it had a year ago. On a GAAP basis, the company said it earned $170.8 million, or 16 cents a share, up from $132.3 million, or 13 cents a share, a year ago.

Genentech's quarterly operating revenue came in at $1.1 billion, up 41% from last year and topping the Wall Street estimate of $1.060 billion. Product sales came in at $913.4 million, up 42% year over year, driven by strong sales of the company's cancer fighter, Avastin, which booked $133 million in its first full quarter on the market.

Shares gained $1.40, or 2.6%, to $55.30 in premarket trading.

"Genentech topped $1 billion in quarterly revenues for the first time in our history, and we are exiting the first half of the year with revenues of more than $2 billion," said Arthur D. Levinson, Genentech's chairman and CEO. "Our unrelenting focus on science has led us to launch three successful products, Avastin, Xolair and Raptiva, in a recent nine-month period.

Indeed, Avastin successfully outperformed Wall Street expectations. Heading into the earnings release, analysts had been tweaking sales estimates on the drug, with the average sales estimate coming in around $85 million. Earlier in the week, even Genentech's bulls were growing more skittish on Avastin's prospects, with Merrill Lynch quietly snipping its estimate to $115 million from $130 million.

And sales of the drug could continue to outperform. On a conference call, the company said wholesalers did not increase stocking levels in the quarter, which would imply that the $133 million in Avastin sales could be the tip of the iceberg. The company also said 80% of those who took shipments of Avastin reordered the drug vs. about 50% during the brief span the drug was on sale in the previous quarter.

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