Trader Guy Adami was also cautious on the sector, saying he would not buy any of its stocks until the biotech ETF cracks $285 per share. It closed at about $268 on Friday.
On Gilead specifically, Nathan noted that its sales have sagged.
Traders also looked to Amgen, which posted earnings Thursday that beat expectations. Still, its shares fell 1.4 percent on Friday.
Trader Tim Seymour said the results were "not extraordinary." Adami, though, called Amgen a "great company," saying its shares had a "cheap valuation."
Guy Adami is long CELG, EXAS, GDX, INTC, Guy Adami's wife, Linda Snow, works at Merck.
Steve is Long AAPL, BA, BAC, CC, DD, DIS, DECK, EVGN, KBH, MJNA, MU, OLN, PFE, PHM, T, TWTR, GDX firm is long CVX, NE, OXY, RIG kids own EFA, EFG, EWJ, IJR, SPY
Dan is long XLF may/ sept put spread. long PFE, long TWTR, long GE May 28 puts, long HYG June puts, long IWM May and September puts, long XHB June put spread, long XLE April/June put spread, FXI Long Aug Puts, SMH Long Aug puts, XLK long Sept put spread. TWTR long Sept risk reversal
Tim Seymour is long AAPL, AVP, BAC, BBRY, CLF, DO, EDC, EWZ, F, FCX, FXI, GM, GOOGL, GRMN, GE, GLNCY, INTC, LQD, MCD, MPEL, NKE, RACE, RAI, RL, SINA, T, TWTR, UA, VALE, VZ, XOM. Tim's firm is long BABA, BIDU, CLF, EWZ, F, HD, KO, MCD, MPEL, NKE, PEP, PF, SAVE, SBUX, SINA, VALE, VIAB, WMT, WEN, YHOO, short HYG, IWM, WYNN