PD-1 blockade augments anti-neuroblastoma immune response induced by anti-GD₂ antibody ch14.18/CHO

Abstract

Immunotherapy with anti-GD antibody (Ab) ch14.18/CHO is effective for treatment of high-risk neuroblastoma (NB) patients and is mainly based on GD-specific Ab-dependent cellular cytotoxicity (ADCC). Strategies to further enhance the efficacy are important and currently explored in prospective clinical trials randomizing ch14.18/CHO ± IL-2. Recently, expression of programmed death 1 (PD-1) inhibitory receptor by effector cells and its ligand (PD-L1) by tumor cells has been shown. Here, we report for the first time effects of PD-1 blockade on ch14.18/CHO-based immunotherapy and mechanisms involved. Expression of PD-1 and PD-L1 on NB and effector cells was analyzed by RT-PCR and flow cytometry in the presence of ch14.18/CHO and/or IL-2. The effect of PD-1 blockade on ch14.18/CHO-mediated anti-NB immune response was evaluated using anti-PD-1 Ab both in vitro (Nivolumab) and in a syngeneic PD-L1/GD NB mouse model (anti-mouse PD-1). Culture of NB cells LA-N-1 (low PD-L1 baseline expression) with leukocytes and subtherapeutic ch14.18/CHO concentrations for 24 h induced strong upregulation of PD-L1, which was further increased by IL-2 resulting in complete inhibition of ch14.18/CHO-mediated ADCC. Importantly, blockade with Nivolumab reversed the PD-L1-dependent inhibition of ADCC. Similarly, co-incubation with anti-CD11b Ab abrogated the PD-L1 upregulation and restored ADCC. Mice treated with ch14.18/CHO in combination with PD-1 blockade showed a strong reduction of tumor growth, prolonged survival and the highest cytotoxicity against NB cells. In conclusion, ch14.18/CHO-mediated effects upregulate the inhibitory immune checkpoint PD-1/PD-L1, and combination of ch14.18/CHO with PD-1 blockade results in synergistic treatment effects in mice representing a new effective treatment strategy against GD-positive cancers.

Monitoring Immune Responses in Neuroblastoma Patients during Therapy

“…Nevertheless, the potency of CPis to induce a more potent anti-tumor immune response, and therefore potential induction of anti-tumor immunological memory, makes checkpoint inhibition a very interesting candidate as an adjuvant therapy in curative treatment settings. The utilization of CPis as a monotherapy in NBL has been investigated in multiple pre-clinical studies [42,[111][112][113]. These studies show no effect of CPi treatment on systemic NBL progression in vivo.…”

“…Next to these observations, especially studies investigating CPi-including combination therapies revealed some insights in mechanisms explaining NBL resistance to CPi monotherapy [42,[111][112][113]. Rigo and colleagues showed that combining CPi with temporary CD4 depletion by anti-CD4 monoclonal antibody (mAb) treatment caused a very potent CD8 T cell dependent response causing significantly longer tumor-free survival, complete tumor regression, and durable anti-NBL immunity in vivo [111].…”

“…Other combination strategies which seem promising based on preclinical studies include combinations of CPis with whole tumor cell vaccination [113], high intensity ultrasound [117], and anti-GD2 treatment [112]. All mentioned preclinical evidence of effective NBL targeting treatment combinations provides a clear rationale for clinical assessment of CPi therapy as an adjuvant therapy against NBL.…”

Co-expression of IL-15 enhances anti-neuroblastoma effectivity of a tyrosine hydroxylase-directed DNA vaccination in mice

“…Prior to injection into mice, NXS2-HGW tumor cells were analyzed for NB-specific characteristics[ 31 ]. Gene-specific RT-PCR analysis revealed a strong mRNA expression of the TAA TH (175 bp; Fig 3A ), underlining the applicability of this model to investigate the TH-directed immunotherapy.…”

Novel Immunotherapeutic Approaches for Neuroblastoma and Malignant Melanoma

“…Syngenic PD-L1 + /GD2 + NB-bearing mice treated with ch14.18/CHO combined with anti-PD-1 mAb showed a strong reduction of tumor growth, prolonged survival, and the highest cytotoxicity against NB cells. These data suggested that the combination of ch14.18/CHO with PD-1 blockade may represent a new effective treatment strategy against GD2-positive cancers [ 51 ].…”