Dr. Blank on the OpACIN, OpACIN-neo Trials in Stage III Macroscopic Melanoma

Christian U. Blank, MD, PhD, a medical oncologist in the Division of Immunology at the Netherlands Cancer Institute, discusses the OpACIN and OPACIN-neo trials examining ipilimumab (Yervoy) plus nivolumab (Opdivo) in stage III macroscopic melanoma. 

In the phase 1b OpACIN trial, neoadjuvant ipilimumab plus nivolumab was compared with adjuvant ipilimumab plus nivolumab, while the subsequent OpACIN-neo trial evaluated 3 different dosing schedules of neoadjuvant ipilimumab plus nivolumab.

As the OpACIN study looked at a very small patient population, the OpACIN-neo study was conducted, says Blank. In the OpACIN study, patients were treated using the stage IV schema with 3 mg/kg of ipilimumab and 1 mg/kg of nivolumab; this was a toxic regimen. Therefore, different dosing schemes were evaluated in the OpACIN-neo study.

One scheme was sequential and 1 gave only 2 courses instead of the 4 courses of therapy that were given in the OpACIN study. Additionally, the dosing of ipilimumab was lowered to 1 mg/kg and the dosing of and nivolumab was increased to 3 mg/kg. By doing this, the rate of grade 3/4 toxicities was reduced to 20% while preserving the pathologic complete response rate of 77% compared with the 80% observed with the previous dosing; this regimen was found to be equally effective, according to Blank.

Only 1.4% of responders relapsed while 65.2% of non-responders relapsed, adds Blank. As such, at week 6, patients can live their lives freely. Unfortunately, patients who do not respond should undergo have strict follow-up because they have a higher chance of relapse, concludes Blank.