Peripheral blood mononuclear cells (PBMC) were obtained by leukapheresis procedures. For the single arm trial, PBMC were isolated by Ficoll–PaqueTM density gradient separation of the leukapheresis product and subsequent plastic adherence/wash steps. During the randomized trial, the Elutra Cell Separation System closed cell selection system was used to enrich for monocytes. After isolation of monocytes, immature DC was generated in a 6-day culture in AIM5 serum-free media to which the cytokines IL-4 (250 IU/ml) and GM–CSF (1000 IU/ml) were added. During this time, CD14-positive monocytes were converted into DC.
All treatment doses for each patient were manufactured a single batch in which the DC and cryopreserved irradiated tumor cells were coincubated for 12–18 hours at a ratio of about 3:1 in T25 flasks. For each treatment dose, cells were divided into ten fractions containing 1–33 million DC that had been coincubated with about 10 million irradiated tumor cells. These were cryopreserved in individual vials containing AIM 5 serum-free medium and 8% DMSO.
Just prior to administration, DCV was rapidly thawed in a 37◦C water bath. The thawed cell suspension was then rinsed in 10 ml of sterile AIM-V (antibiotic-free) medium in a 50 ml conical tube. The cell pellet was then suspended in 1 ml saline and 500 μg of GM–CSF in a 1.5 ml vial, and finally drawn into a 3.0 ml syringe for injection with a 25-gauge needle within 5 h of thawing.
In both trials, each vaccine dose was injected subcutaneously (SC) in an extremity once a week for 3 weeks, and then once a month for 5 months at weeks 8, 12, 16, 20 and 24. The same extremity was not used for consecutive injections. Concurrent anticancer therapy was not allowed, but patients could interrupt vaccine therapy for specific interventions, then resume vaccine treatment.
Overall survival by trial
The median survival for all 72 patients was 49.4 months (95% CI: 38.6–60 months). The 3-year survival rate was around 60% overall and in each trial. In the single arm open-label trial, median survival was greater than 60.0 months (95% CI lower limit 36.3 months) and the 5-year survival 50%, while the 18 patients treated with DCV in the randomized trial had a median survival of 43.4 months (95% CI: 18.6–60 months) and 5-year survival was 33%.
Overall survival by most advanced stage
The 5-year OS for the 18 patients whose most advanced stage was recurrent stage 3 was 72%. For the 54 patients whose most advanced stage was stage 4, the median OS was 42.5 months with 1-, 2-, 3-, 4- and 5-year survival rates of 83, 67, 57, 43 and 37%, respectively. However, this included patients who had measurable or non-measurable disease at the time of treatment. Median OS was greater than 60 months for recurrent stage 3 (95% CI lower limit: 38.7 months; n = 18) and for non-measurable stage 4 (n = 30), compared with 18.5 months (95% CI: 12.6–42.7 months) for patients with measurable stage 4 disease (n = 24). The 3-year survival rates were 83, 73 and 38%, respectively. Progression-free survival by most advanced stage
For all 72 patients, the median PFS was 5.4 months. Median PFS was 32 months for recurrent stage 3, 7.4 months for non-measurable stage 4, and 3.4 months for measurable stage 4. The 3- year PFS rates were 44, 23 and 4%, respectively.
Treatment with these patient-specific vaccines was well tolerated and consistent with the adverse event profile for a single injection of 500 μg of GM–CSF. There were no grade 4 adverse events (AE), and only five patients experienced a grade 3 AE; three reported a grade 3 headache and two reported a grade 3 skin rash. In contrast to what has been reported for monoclonal antibody checkpoint inhibitors, there were no immune-related adverse events resulting from autoimmune organ inflammation.
Patient-specific DCV therapeutic vaccines were well tolerated and associated with encouraging survival results in patients with metastatic melanoma, including those with resected recurrent stage 3 disease, stage 4 patients both with and without measurable disease at the time of treatment.
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Scientific article publishing date : 5/31/2019
Immucura identifier :BSC21_157EN