DUBLIN – For many chasing the newest new thing in biotech, the tricarboxylic acid (TCA) cycle was something learned during an undergraduate biochemistry module and then promptly forgotten about. But startup firm Sitryx Therapeutics Ltd. is among an emerging minicluster of ventures that is going back over that well-trodden ground and exploring its links with immunology, in an effort to find a new generation of immune-acting drugs for cancer and inflammation.