* Amgen to buy Onyx Pharma for about $10.4 billion, Onyx shares rise
* Berlusconi's party threatens to take down Italian government
* Pritzker family to buy TMS International
* Futures off: Dow 25 pts, S&P 1 pt, Nasdaq 2 pts
NEW YORK, Aug 26 U.S. stock index futures edged lower in thin volume on Monday ahead of data expected to show a drop in orders for long-lasting manufactured goods last month.
* Amgen Inc struck a deal to buy cancer drug maker Onyx Pharmaceuticals Inc for about $10.4 billion on Sunday, sweetening its original offer made in June. Onyx shares rose 6 percent in premarket trading.
* The Pritzker Organization said it will acquire scrap metal broker TMS International Corp for $17.50 a share, a premium of about 12 percent to TMS's Friday close of $15.57.
* The Commerce Department releases durable goods orders for July at 8:30 a.m. (1230 GMT). Economists in a Reuters survey expect a 4.0 percent drop in orders compared with a 3.9 percent increase in June.
* S&P 500 futures fell 1 point and were slightly below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures fell 25 points, and Nasdaq 100 futures lost 2 points.
* Italian stocks led euro zone shares lower as mounting concerns about a government crisis in the country fueled a selloff in shares exposed to Rome's government debt. Members of Silvio Berlusconi's center-right party warned they would bring down the government if the former premier is expelled from parliament.
* Friday's gains helped the S&P 500 and Nasdaq Composite end a two-week losing streak, but the Dow posted its third consecutive weekly decline. Last week the Dow fell 0.5 percent, the S&P gained 0.5 percent and the Nasdaq added 1.5 percent.