Cancer-drug developer Medivation (MDVN) continued to demonstrate the steady progress of its late-stage prostate cancer treatment Xtandi with its first-quarter earnings release after the closing bell.

For the quarter, Medivation's collaborative partner Astellas Pharma (ALPMY 0.32%) reported robust sales growth for Xtandi of 65% in the U.S., to $124.5 million from $75.4 million in the year-ago period, while Ex.-U.S. sales surged to $47.8 million from a mere $0.3 million in the year-prior period. Collaboration revenue attributed to upfront and milestone payments also rose nicely, to $19.2 million. Added together, Medivation's collaboration revenue totaled $87.2 million for the quarter, up 89% from Q1 2013.

Partially offsetting this revenue surge was a 40% rise in operating expenses, to $95.7 million, primarily due to an 84% rise in research and development expenses tied to Medivation's maturing clinical programs.

The net effect, however, was a 50% reduction in its net loss, to $13.7 million, or $0.18 per share, from $27.2 million, or $0.36 per share in the year-ago quarter. Wall Street, on the other hand, had been counting on a smaller loss of $0.09 per share, and $98.4 million in collaborative revenue.

Medivation also announces a modest increase in cash and cash equivalents, to $241.5 million from $228.8 million in the sequential fourth quarter.

Looking ahead, Medivation projected U.S. net sales of Xtandi to be between $540 million and $575 million with total operating expenses of $400 million to $430 million. Of that, $45 million to $50 million will be non-cash stock-based compensation.