US biotechnology giant Amgen has posted a strong set of results for the first quarter of 2007 which show healthy sales and earnings growth despite a major jump in the firm's R&D spend.

Revenues rose 15% to $3.69 billion in the quarter, with net income climbing 11% to $1.11 billion, while R&D expenditure was up 29% to $803 million, Amgen noted, used to “support the increased number and expense of mega-trials to advance our late-stage pipeline”.

Sales growth was once again driven by anaemia drug Aranesp (darbepoetin alfa) which increased 14% to just over $1.11 billion, while Epogen (epoetin alfa) - whose growth has been pegged back by conversion of patients to Aranesp treatment - managed a 3% increase to $625 million. International sales of Aranesp increased 23% which made up for “slowing growth rate in the USA was driven by initial customer reaction to label changes”.

In January Amgen reported that cancer patients not receiving chemotherapy or radiation had a higher risk of dying if treated with Aranesp and full results from that study released last week showed that one in four cancer patients given the drug died after 19 weeks. A higher incidence of death in patients taking Aranesp was also reported in a Danish study of head and neck cancer patients undergoing radiation and the FDA issued a black-box warning for Aranesp and other erythropoieses-stimulating agents, which put pressure on the firm’s stock price but Amgen has moved to back the drug this week with data from a Phase III study of 600 patients with advanced small cell lung cancer receiving chemotherapy, which showed no statistically significant difference in risk of death.

As for its other drugs, Neupogen (filgrastim) and Neulasta (pegfilgrastim), used to boost white blood cells in patients on chemotherapy, saw combined sales rise 14% to $1.02 billion, while turnover from rheumatology and psoriasis treatment Enbrel (etanercept) was up 11% to $730 million, despite slowing growth in the USA in the face of increased competition. Colorectal cancer Vectibix (panitumumab), which was approved in September, had sales of $51 million, while Sensipar (cinacalcet), for the treatment of secondary hyperparathyroidism in dialysis patients, climbed 72% to $105 million.

The results matched analysts’ expectations for earnings per share, but Amgen said it expects its EPS for the year to be on the low end of $4.30-$4.50 per share as it works to cut operating expenses.