Soak the clams in plenty of cold water for a few hours, so as to allow them to loose the sand. Blanch the tomatoes in boiling water, peel them, deseed them and remove the cooking water and slice them finely.Clean the anchovies; remove head and insides, bone them and rinse them in cold water, once drained, dry them in a clean towel and chop them coarsely. Rinse the capers under running water, removing the salt and dry them.Put the drained clams in a saucepan, add some peeled garlic, a tbsp of oil, cover with a lid and place the pan over a heat until they open, tossing the pan from time to time to move the clams around.Remove the pan from the fire an set aside; discard the clams that have not opened. In another pan heat the leftover oil with the chilli, add the anchovies, season with a pinch of salt and brown them for about 2 minutes; drain them and set them aside.In the same pan add the tomatoes with the capers and simmer for 10 more minutes over a medium heat, stirring from time to time. Add the anchovies, left aside, with the clams sprinkled with a pinch of oregano.In the meanwhile bring to the boil plenty of salted water and toss the pasta in it; drain it al dente and season with the clam sauce. Serve warm.