It was ugly.

Everyone expected Gilead Sciences (NASDAQ:GILD) to report yet another decline in hepatitis C virus (HCV) franchise sales when the biotech reported its first-quarter results on Tuesday. But many didn't expect the magnitude of the decline. And many also didn't anticipate that Gilead's HIV drugs, which typically perform very well, would only see anemic year-over-year growth in Q1.

But as dismal as Gilead's first quarter was, there remain reasons for optimism. Here are five reasons you shouldn't worry about the company's ugly Q1 results. 

Worry written on chalkboard with eraser nearby.

Image source: Getty Images.

1. It's a trough year that's still on track

Gilead CFO Robin Washington was asked by an analyst during the biotech's Q1 earnings conference call if the company was "in an earnings trough this year." Washington replied, "We do believe that 2018 is a trough year for us on which we can grow." 

Despite the tough quarter, Gilead still thinks 2018 will turn out like it has projected. The company reaffirmed its full-year guidance provided in February of revenue between $20 billion and $21 billion. Washington said, "We'll have seasonality fluctuations from quarter to quarter, but we're very confident, hence we reiterated our overall guidance for the year and expect to be able to grow off of our 2018 base going forward." 

2. Biktarvy is just getting started

Biktarvy only contributed $35 million in sales in the first quarter. But the new HIV drug was only on the market for six weeks during the period. Biktarvy's total prescription volume is tracking only slightly behind that of Genvoya so far -- and Genvoya enjoyed the most successful launch of any HIV drug ever. 

Analysts project that Biktarvy will ultimately generate peak annual sales of more than $6 billion. But how much of that could be at the expense of Gilead's other HIV drugs? The biotech expects around 80% of patients will switch from other therapies to Biktarvy, with 20% of those switches coming from patients on GlaxoSmithKline's Tivicay and Triumeq. That translates to somewhere in the ballpark of 60% of Biktarvy sales that might be cannibalized from Gilead's other HIV drugs -- but it also means Biktarvy should be a significant growth driver for the company.

3. HCV should still stabilize

AbbVie appears to be taking a sizable chunk of market share away from Gilead's HCV products with its new drug Mavyret. Gilead expected this, though, and doesn't appear to be overly concerned.

Robin Washington stated that prices for HCV drugs have largely stabilized. Gilead also continues to think that its market share will stabilize mid-year. Perhaps most important, Washington said that "patient starts have become more predictable, and we expect a slow and steady decline moving forward." Add all of this up, and you have an HCV franchise that generates lower revenue than in the past but one that doesn't keep weighing on growth.

4. Yescarta is gaining momentum

Yescarta didn't even merit its own line item in Gilead's Q4 earnings release. That changed in the first quarter, though. The CAR-T therapy showed up in the list of Gilead's "other products" with Q1 sales of $40 million -- an amount that Washington called "very robust."

Look for Yescarta to gain even more momentum in the coming months. Gilead CEO John Milligan stated that the biotech has completed the authorization of 40 cancer centers and is "on track to have enough centers certified to treat 80% of Yescarta-eligible patients in the United States by the middle of the year." He also expects potential European approval for the CAR-T therapy in the third quarter of 2018.

5. The pipeline has a lot of potential

Gilead highlighted its pipeline in the Q1 conference call before there was any detailed discussion of the first-quarter results. This sequence of topics symbolically underscored that the biotech believes its future prospects are brighter than its present. That belief could be right on the money.

Several important pipeline milestones are on the way over the next year and a half for Gilead's promising non-alcoholic steatohepatitis (NASH) candidates and inflammatory drug filgotinib. NASH is a huge opportunity for the biotech, with the annual market size for all treatments projected to eventually be between $20 billion and $35 billion. Analysts think that filgotinib could achieve peak annual sales of close to $3 billion. 

Think long-term

There's no sugar-coating that will make Gilead's Q1 results look good. However, if you closely examine those results and management's comments in the conference call, the opportunities for Gilead to rebound later this year and in 2019 are apparent.

Gilead's trouble spots of today shouldn't be as problematic in the not-too-distant future. And its newer products like Biktarvy and Yescarta, along with its strong pipeline candidates, should step up. I think it's important to think long-term when it comes to Gilead Sciences. Investors with a long-term perspective don't have to worry about quarterly results. 

Keith Speights owns shares of AbbVie and Gilead Sciences. The Motley Fool owns shares of and recommends Gilead Sciences. The Motley Fool has the following options: short May 2018 $85 calls on Gilead Sciences. The Motley Fool has a disclosure policy.