Germany’s Merck KGaA says that second-quarter net income more than doubled to 211.2 million euros, boosted by strong sales of the cancer drug Erbitux.

Operating profit was up 15.5% to 320.5 million euros and group turnover climbed 6.1% to 1.90 billion euros. The Darmstadt-based group’s Merck Serono unit contributed 1.24 billion euros, an increase of 8.3%, helped by sales of the multiple sclerosis drug Rebif (interferon beta-1a) which rose 2.8% to 320 million, boosted by 15% growth from the USA.

However the most eye-catching performance came from Erbitux (cetuximab), which jumped 24% to 145 million euros, helped by strong growth in France, Spain and China. As for Merck’s other products, the beta blocker Cardicor/Concor (bisoprolol) was up 11% to 115 million euros, while its Glucophage (metformin) diabetes products increased 18% to 78 million euros. The fertility treatment Gonal F (follitropin) was up 6.3% to 122 million euros, while the thyroid treatment Euthyrox (levothyroxine) contributed 39 million euros, up 12%. Sales of Raptiva (efalizumab), for the treatment of moderate-to-severe psoriasis, rose 16% to 23 million euros.

The results came in a little short of analyst forecasts, which was due in part to the effects that the weak dollar is having on Merck’s liquid crystals unit.