What happened Shares of Global Blood Therapeutics (NASDAQ: GBT) were sinking 8% as of 11:14 a.m. EDT on Thursday. The decline came after the company announced its first-quarter results following the market close on Wednesday. So what Global Blood Therapeutics reported net sales of $39 million in the first quarter, all of which stemmed from sickle-cell disease drug Oxbryta. This result fell well below the average analyst estimate of $47.3 million. The large revenue miss sparked today's sell-off of the biotech stock. Image source: Getty Images. The company blamed the disappointing performance for Oxbryta on COVID-19. It said there were fewer interactions with healthcare providers and patients in the first quarter due to the increased number of cases of COVID-19 in the U.S. As a result, new prescriptions for Oxbryta weren't as high as anticipated. However, the company thinks this is only a short-term problem. It expects that new prescription volume will increase and even top pre-COVID-19 levels in the future. Now what Global Blood Therapeutics said that it's on track to kick off two pivotal late-stage studies of another sickle-cell disease drug, inclacumab, by mid-2021. It also expects to soon submit for U.S. approval of an expansion of the label for Oxbryta to include treating kids ages 4 to 11 who have sickle-cell disease. 10 stocks we like better than Global Blood TherapeuticsWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Global Blood Therapeutics wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of February 24, 2021 Keith Speights has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source