441O - A phase I clinical trial on the intracranial administration of autologous CD1c(BDCA-1)+ /CD141(BDCA-3)+ myeloid dendritic cells (myDC) in combination with ipilimumab (IPI) and nivolumab (NIVO) in patients with recurrent high-grade glioma (rHGG)

Background

Intracranial admin of NIVO and IPI following the resection of rHGG is safe and has resulted in encouraging survival (J Duerinck et al. JITC 2021). myDC play a pivotal role in initiating an adaptive anti-tumor immune response and licensing of immune anti-tumor effector cells within the tumor microenvironment.

Methods

rHGG pts (after prior RT and TMZ, <8 mg methylprednisolone QD), underwent a leukapheresis followed by isolation/cryopreservation of myDC. NIVO (10 mg IV) was administered preoperatively. myDC (5-, 10-, or 20.10⁶ cells) were injected into the brain tissue lining the resection cavity (iCer) following a maximal safe resection (MSR) or intratumorally (iTum) following a stereotactic biopsy (STX). IPI (5 mg) plus NIVO (10 mg) were co-injected iCer or iTum with the myDC. Postoperative NIVO was administered intracavitary (iCav, 10 mg) and intravenously (IV, 10 mg) Q2w (max 11x).

Results

21 pts (13 M; med 49 y [range 20 -78]; IDHwt 17 pts, ECOG PS 0 or 1: 18-, 3 pts) underwent procurement of myDC; intraoperative administration of myDC was preceded by MSR in 19 pts, and STx in 2 pts. Respectively 6, 3, and 12 pts were treated at the 3 myDC dose levels. All pts received the peri-op iTum/iCer/IV-admin of IPI and NIVO as planned. The median postop iCav and IV NIVO-admin was 7 (range 0-11) and 8 (0-11). Study treatment was discontinued early for PD in 9- and AE in 3 pts. Most important TRAEs: bacterial colonization of the Ommaya reservoir (n=4), craniotomy wound dehiscence (n=2), and bacterial meningitis (n=1). At DBL (01MAY2024), 6 pts (29%) remain progression-free (incl. 3 pts with >2y PFS). PFS (med. 24w [95% CI 8- 39]) is superior when compared to the pts (n=70) with resectable rHGG treated in 4 other cohorts of the GlITIpNi trial (p=0.003). When including the durable benefit from bevacizumab at first PD in 3 pts, PFS compared favorably to a historical pooled cohort (n=469) of rHGG treated with VEGF(R)-inhibitors (p=0.007). The 1-year OS-rate was 50% [95% CI 24-76].

Conclusions

Intracranial administration of myDC combined with IPI/NIVO is feasible, safe and associated with encouraging survival, deserving further investigation.

Clinical trial identification

NCT03233152.

Editorial acknowledgement

Legal entity responsible for the study

UZ Brussel.

Funding

Kom-Op-Tegen-Kanker (KOTK), Belgium.

Disclosure

All authors have declared no conflicts of interest.