: 76 Commercial activity to bring an IL-2 drug to market was intense in the 1980s and 90s. By 1983, Cetus Corporation had created a proprietary recombinant version of IL-2 (Aldesleukin, later branded as Proleukin), with the alanine removed from its N-terminal and residue 125 replaced with serine. : 76–77 : 201  Amgen later entered the field with its own proprietary, mutated, recombinant protein and Cetus and Amgen were soon competing scientifically and in the courts; Cetus won the legal battles and forced Amgen out of the field. : 151   By 1990 Cetus had gotten aldesleukin approved in nine European countries but in that year, the U.S. Food and Drug Administration (FDA) refused to approve Cetus application to market IL-2. The failure led to the collapse of Cetus, and in 1991 the company was sold to Chiron Corporation. Chiron continued the development of IL-2, which was finally approved by the FDA as Proleukin for metastatic renal carcinoma in 1992.By 1993 aldesleukin was the only approved version of IL-2, but Roche was also developing a proprietary, modified, recombinant IL-2 called teceleukin, with a methionine added at is N-terminal, and Glaxo was developing a version called bioleukin, with a methionine added at is N-terminal and residue 125 replaced with alanine. Dozens of clinical trials had been conducted of recombinant or purified IL-2, alone, in combination with other drugs, or using cell therapies, in which cells were taken from patients, activated with IL-2, then reinfused.
However, those who develop C-PTSD do so as a result of the intensity of the traumatic bond – in which someone becomes tightly biolo-chemically bound to someone who abuses them and the responses they learned to survive, navigate and deal with the abuse they suffered then become automatic responses, imbedded in their personality over the years of trauma – a normal reaction to an abnormal situation. Treatment
While standard evidence-based treatments may be effective for treating post traumatic stress disorder, treating complex PTSD often involves addressing interpersonal relational difficulties and a different set of symptoms which make it more challenging to treat. According to the United States Department of Veteran Affairs:

 
The current PTSD diagnosis often does not fully capture the severe psychological harm that occurs with prolonged, repeated trauma. People who experience chronic trauma often report additional symptoms alongside formal PTSD symptoms, such as changes in their self-concept and the way they adapt to stressful events. The utility of PTSD-derived psychotherapies for assisting children with C-PTSD is uncertain. This area of diagnosis and treatment calls for caution in use of the category C-PTSD. Dr. Julian Ford and Dr. Bessel van der Kolk have suggested that C-PTSD may not be as useful a category for diagnosis and treatment of children as a proposed category of developmental trauma disorder (DTD).