Trial evaluating safety and efficacy of intratumorally administered inflammatory allogeneic dendritic cells (ilixadencel) in
advanced gastrointestinal stromal tumors

Tumour shrinking with DCT

Tumour shrinking with DCT

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Summary

Patients with advanced gastrointestinal stromal tumor (GIST) develop resistance to imatinib, and subsequent treatments have limited efficacy. Ilixadencel (allogeneic inflammatory dendritic cells) is a cell-based immune primer injected intratumorally that previously has been clinically investigated in metastatic renal cell carcinoma and hepatocellular carcinoma. As a result the Ilixadencel treatment presented an acceptable safety profile among advanced GIST patients with encouraging radiological tumor responses.

Introduction

The study involved 6 patients, men and women, age 46 years old to 82 years old with the median age of 47 years old, with a diagnosis of unresectable or metastatic GIST that had progressed despite second-, third-, or fourth-line treatment with a TKI were enrolled in this trial.

Adequate bone marrow, liver and renal function and with no viral disease like Hepa B, C and HIV.

Methodology

Ilixadencel was prepared from healthy blood donors. Cells in the leukapheresis and thereafter fractionated by elutriation in a close system, ELUTRA®. The elutriation results in a cell product in fraction 5 that contains > 90% CD14+ monocytes. These cells are used for differentiation (using the well-established differentiation cocktail GM-CSF plus IL-4) and activation (R848.poly-IC and IFN-gamma) into proinflammatory DCs.

The final drug product is cryopreserved cells formulated in human plasma and 10% DMSO. Immediately before administration to the patient, the frozen vials were thawed, and the cells were washed and resuspended in 0.15 M saline with 2% human serum albumin before administration. These cells were used as a direct-injectable product after thawing without any additional preparation steps prior to the intratumorally administration.

Treatment

DC vaccine doses of 5 × 106 (low dose), 10 × 106 (medium dose), and 20 × 106 (high dose) were used and administered intratumorally (IT). All patients received a dose of 10×106.

Results

During the trial, five out of six patients experienced a total of 19 AEs. Grade 1 was the most common with 10 AE reported in 4 patients (66.7% of total); 8 grade 2 in 2 patients (33.3%), and 1 patient with grade 3 (16.7%). The adverse events related to ilixadencel, as defined by probable or possibly causative of ilixadencel, were 6 AEs. The AEs related to ilixadencel treatment was fever and chills (50%), abdominal pain (33%), and discomfort at injection site (17%). The grade 3 AE was related to general health deterioration and not related to ilixadencel treatment. No clinically relevant abnormalities were noted post-treatment with regard to hematology, biochemistry, coagulation, or serology.

Tumor response:
3 patients showed tumor progression at 3 months per RECIST. 1 patient showed clinical deterioration and CT scan was per- formed after 2 months, which showed progressive disease. One patient (on third line regorafenib) had stable disease for 9 months and another patient (on second line sunitinib) had stable disease at end of study (12 months) as per RECIST 1,1. These two patients developed a partial response as per Choi criteria with a duration of 3 and 6 months, respectively. The median PFS for the trial cohort was 4.0 months (95%; CI 3.2–4.8); the median OS was 19.0 months (95% CI 11.8–26.2).

Conclusion

Ilixadencel treatment presented an acceptable safety profile among advanced GIST patients who developed resistance to TKI. Encouraging radiological tumor responses were detected in 33% of treated patients.

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Scientific article publishing date : 28/5/2020

Immucura identifier : BSC21_023EN

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