Chronic lymphocytic leukemia

Currently, several novel drugs are available for chronic lymphocytic leukemia (CLL) in Western countries. Of these drugs, those that inhibit the B-cell receptor (BCR) signaling pathway are the most promising. Ibrutinib inhibits BTK in the BCR pathway and can be administered orally. The results of several clinical trials suggest that ibrutinib is highly effective against relapsed/resistant (RR) and treatment-naive CLL. Furthermore, ibrutinib shows equivalent efficacy on CLL with the 17p deletion. Idelalisib, which also blocks the BCR pathway, inhibits PIK3delta and induces CLL cell death. Clinical trials have shown outstanding efficacy of idelalisib against RR-CLL, especially when administered with antiCD20 antibodies. This drug is also effective against CLL with the 17p deletion. ABT-199 is another novel drug; it inhibits BCL2 signaling, not the BCR pathway, and can be administered orally. The efficacy of ABT-199 against RR-CLL has been demonstrated in a number of clinical trials. These drugs have only mild toxicity and can be used for patients in poor general condition. Unfortunately, none of these drugs have yet been approved in Japan. Rapid resolution of the 'drug lag' problem is necessary.