As expected, Gilead Sciences Inc. reported robust revenues for the fourth quarter of 2013, up 21 percent to $3.12 billion from $2.59 billion for the same period a year earlier. Total revenues for the full year were $11.2 billion, up 15 percent compared to $9.7 billion a year earlier, on record product sales of $10.8 billion – a 15 percent year-over-year increase.

It’s what the Foster City, Calif.-based company didn’t say – declining to provide sales guidance on chronic hepatitis C virus (HCV) product Sovaldi (sofosbuvir) – that left some investors chagrined.

The company also changed its tune around prescribing trends for the $1,000-a-day, once-daily nucleotide analog polymerase inhibitor, which gained FDA approval in December, indicating that 70 percent of patients taking the drug so far are genotype (GT) 1, not GT2, as the company suggested during its presentation last month at the 32nd Annual J.P. Morgan (JPM) Healthcare Conference in San Francisco. (See BioWorld Today, Dec. 9, 2013, and Jan. 15, 2014.)

Neither issue fazed ISI group analyst Mark Schoenebaum, chalking up Gilead’s “extraordinary conservative” business style to the lack of guidance and the company’s evolving view on Sovaldi usage to the receipt of additional data as prescription numbers grow. The drug was approved in January by the European Commission and was launched in the UK, Germany and France, chairman and CEO John Martin told investors and analysts on a call late Tuesday.

Still, “the Street is clearly worried” that the lack of guidance was a “signal” by management “that sell side numbers are getting out of hand,” Schoenebaum wrote in an email Wednesday morning. “Personally, I disagree.”

Company officials may have overreached at JPM, Schoenebaum added, when Gilead reported most patients treated in December were GT2. In defending Sovaldi’s hefty price tag of $84,000 per treatment period, Gilead stressed Sovaldi’s efficacy across all genotypes and reported that, for GT2 and GT3, its use was indicated only in combination with ribavirin, eliminating the need for side effect-plagued interferon.

Plus, in some GT2 patients, the treatment period was cut to 12 weeks, Gilead said last month.

The difference could be meaningful, if it meant Gilead was “working through the G1 patients faster than expected and that there is an increased risk of a sales slowdown over the summer ahead of the all-in-one-pill G1 launch,” Schoenebaum suggested, referring to the fixed-dose combination of sofosbuvir with Gilead’s ledipasvir, which in December reported top-line data from the phase III ION1, ION2 and ION3 studies. In GT1 affected cirrhotic and noncirrhotic, treatment-naïve and treatment-experienced patients, with and without ribavirin, response rates in the 8- and 12-week arms evaluating the once-daily combination ranged from 93.6 percent to 97.75 percent, according to Gilead.

On the call, Kevin Young, executive vice president of commercial operations, said, “It really is still incredibly early days” in Sovaldi, adding that much of the launch month included the holiday period. “I think it’s so difficult to say what’s going to happen in the transition period between Sovaldi and Sovaldi/ledipasvir,” he added.

In addition to Schoenebaum, other analysts accepted that explanation, predicting glowing sales for the HCV drug. In an earnings update, Cowen and Co. analyst Phil Nadeau increased his 2014 Sovaldi estimate from $3 billion to $4 billion, and said Gilead is expected to continue to outperform as consensus Sovaldi estimates increase.

“Management noted that it is ‘extremely pleased’ with Sovaldi’s early uptake, and that Sovaldi is being reimbursed nearly universally,” Nadeau wrote, adding that Gilead’s field work did not detect significant secondary warehousing in front of the Sovaldi/ledipasvir combo launch.

Credit Suisse analyst Ravi Mehotra telegraphed his optimism by leading his note with “HCV – How big is big?” Mehotra observed that Gilead beat analyst expectations both on the top and bottom line, driven by strong across-the-board product performance, including a solid start from Sovaldi. And RBC Capital Markets analyst Michael Yee wrote, “We think GILD continues to go higher based on very strong pending Sovaldi sales,” with the potential for 2014 global sales to exceed $5 billion, “which is well above consensus.”

Despite analyst optimism, Schoenebaum conceded that Gilead was “weak” on Wednesday, possibly due to investor blowback. The company’s shares (NASDAQ:GILD) were off as much as 7 percent early before regaining some ground to close at $78.15 for a loss of $3.87, or 4.7 percent, on the day. Twice the average volume of shares changed hands.

Gilead also reported that fourth quarter product sales increased 21 percent, to $3.04 billion, compared to $2.51 billion in the same period in 2012. Antiviral product sales increased 22 percent, to $2.64 billion in the fourth quarter, reflecting sales growth of 30 percent in the U.S. and 7 percent in Europe. For 2013, antiviral product sales increased 15 percent, to $9.34 billion, reflecting sales growth of 19 percent in the U.S. and 6 percent in Europe.

The company has a smaller footprint in cardiovascular products, where sales increased 24 percent in 2013, to $968.6 million, compared to 2012.

Gilead reported cash, equivalents and marketable securities of $2.57 billion as of Dec. 31, 2013, compared to $2.58 billion as of Dec. 31, 2012. Excluding Sovaldi, the company projected 2014 net product sales in a range of $11.3 billion to $11.5 billion and an effective tax rate of 28 percent to 29 percent in 2014, though Schoenebaum suggested the tax rate on global HCV product sales could be as low as approximately 15 percent, compared to approximately 28 percent for other products, based on his discussions with management.