Piper Jaffray analyst Edward Tenthoff says that, according to Exelixis, 300 doctors have prescribed its Cabometyx in renal cell carcinoma, or RCC, which increases the company's confidence that the launch of the new drug is off to a "good start." The analyst forecasts U.S. Cabometyx sales of $50M in 2016 and $102M in 2017. However, Tenthoff notes that Exelixis' Cotellic for BRAF-mutant melanoma sold only $2M in Q1, leaving the company with a $7.3M loss and causing Exelixis to file a formal complaint against its partner Genentech. The analyst reiterates a Neutral rating on Exelixis' stock and lowered his price target on the shares to $5 from $6.