Biotech earnings were mixed midweek, but sector indices held up despite a few sagging stocks. Onyx ( ONXX) shares closed down $1.48, or 3.7%, at $38.36 on Wednesday. The company reported its quarterly results Tuedsay after the close, beating on EPS by a penny and surpassing revenue expectations. However, Wall Street viewed the company's new Nexavar sales guidance as underwhelming. The company guided to sales of $660 million to $675 million, up from $600 million to $650 million. Wall Street analysts had expected anywhere from between $650 and $700 million. Meanwhile, BioMarin ( BMRN) gave up $1.60, or 5.0%, to $30.10 and analysts dropped their price targets for the stock a day after it presented second quarter results. BioMarin's phenylketonuria (PKU) drug Kuvan registered $12 million in second-quarter sales, falling short of the $14.8 million consensus. And BioMarin scaled back the top end of its guidance for Kuva revenue by $5 million to $65 million. On the postive side, sales of its Naglazyme rose 68% to $35.1 million, surpassing expectations for $29.7 million, and the company boosted overall revenue expectations for 2008. Another stock in the red on midweek, Medarex ( MEDX) reported a widened quarterly loss and revenue below targets. The company reported a loss of $53.1 million, or 42 cents a share, vs. a loss of 32 cents a share a year prior. Factoring out one time charges, the company said it lost 34 cents a share for the quarter. Analysts polled by Thomson Financial expected a loss of 35 cents per share on revenue of $12.5 million. Its shares gave up 92 cents a share, or 9.3%, to $9.02 on Wednesday.