What happened Shares of the clinical-stage biotech Adaptimmune Therapeutics (NASDAQ: ADAP) fell by as much as 11% immediately out of the gate Monday morning. The drugmaker's stock kicked off the week off on a sour note thanks to a fairly large public offering consisting of 12.5 million of its American depositary shares. However, Adaptimmune has sharply rebounded as today's trading session has unfolded: As of 11:44 a.m. EDT, the biotech's stock is currently up by 19%. Image source: Getty Images. So what Last Friday, Adaptimmune's shares rocketed higher on the heels of a positive clinical update for its experimental T-cell therapy platform, which was presented at the American Society for Clinical Oncology (ASCO) Annual Meeting. Most importantly, the company noted that its lead asset, ADP-A2M4, produced a 50% response rate in an early stage trial in patients with synovial sarcoma. So with its shares heating up in a big way last week, it's not exactly surprising to see the company pull the trigger on a public offering to raise capital. Adaptimmune, after all, is still over a year away from potentially launching its first product. Now what Is Adaptimmune's stock still a strong buy? At present, its market cap stands at roughly $1.56 billion. That's not exactly an outlandish valuation for a company that may have multiple anticancer cell therapies on the market by the middle of the decade. So if you're on the hunt for a top-notch growth opportunity and don't mind the risk that comes with a speculative biotech stock, Adaptimmune may indeed be worth adding to your portfolio. 10 stocks we like better than Adaptimmune 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 Adaptimmune 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 April 16, 2020 George Budwell 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