Despite reporting positive efficacy results for its Nana-val combination therapy in treating EBV+ PTCL, Viracta Therapeutics saw a significant drop in its stock price. This decline could be attributed to market reactions to the overall response and complete response rates, or possibly concerns over the safety profile and treatment-related adverse events reported. The market's reaction suggests that while the clinical results are promising, investors may have had higher expectations or there could be concerns about the commercial viability or regulatory path forward.