A series of substituted fused tricyclic imidazo pyrazine derivatives and analoges thereof, represented by formula (I), being potent modulators of human TNFa activity, are accordingly of benefit in the treatment and/or prevention of various human ailments, including autoimmune and inflammatory disorders; neurological and neurodegenerative disorders; pain and nociceptive disorders; cardiovascular disorders; metabolic disorders; ocular disorders; and oncological disorders.