Citius Pharmaceuticals Inc.’s retooled version of withdrawn cancer drug Ontak (denileukin diftitox) is not quite ready for prime time, according to the U.S. FDA, which issued a complete response letter (CRL) for the interleukin-2-diphtheria toxin fusion protein known as Lymphir. The agency is asking for Citius to incorporate enhanced product testing and additional controls but did not raise any concerns regarding safety and efficacy, the company said.