Background: Ganglioside GD2 is a glycolipid highly expressed on neuro-ectodermal tumors including melanoma and neuroblastoma (NB). It is ranked on position 12 of the list of tumor associated antigens by the NCI. Anti-GD2 antibody (Ab) ch14.18/CHO targets this antigen and effectively orchestrates innate immune effector mechanisms against GD2 expressing malignancies. However, one on target effect of anti-GD2 Abs is the induction of neuropathic pain when applied as short term infusion (STI) requiring co-medication with intravenous morphine. Here we investigated whether long-term infusion (LTI) of anti-GD2 Ab ch14.18/CHO may have an improved pain toxicity profile and at the same time mediate an effective immune response in patients (pts) with high risk relapsed/refractory NB which translates to objective clinical responses and an improved survival.

Methods: 97 pts received 6x106 IU/m2 sc IL2 (d1-5; 8-12), LTI of 100 mg/m2 ch14.18/CHO (d8-17) and 160 mg/m2 oral 13-cis-RA (d19-32) in an ongoing SIOPEN Phase II study (APN311-202) (NCT01701479) (44 pts) and a closed single center program (53 pts) (APN311-303). Response assessments followed INRG criteria. Serum ch14.18/CHO concentration-time curves were determined by validated ELISA methods and pharmacokinetics parameter were analyzed using standard non-compartmental methods. Fcγ;-receptor polymorphisms FCGR2A (H131R), -3A (V158F) and -3B (NA1/NA2) and patient-specific antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and whole blood cytotoxicity (WBT) responses were determined.

Results: LTI was associated with low pain scores and a decreasing morphine usage compared to STI. Clinical overall responses were 30% (APN311-303) and 31% (APN311-202). The survival update of the APN311-303 cohort revealed a 1-y & 4-y OS of 94.2±3.2% & 60.9±9.0% (median FU 2.9y [0.7-5.2y]) and a 1-y & 4-y PFS of 54.4±6.9% & 32.3%±6.9% (median FU 2.8y [0.7 - 4.9y]). Median TTP was 571d (95% CI: 232.7d). The comparator is the reported historical gold standard for relapsed refractory NB patients with 1-y & 4-y PFS of 19±2% & 8±3% and OS of 56±3% & 14±4% and a median TTP of 63 d (95% CI: 56.8d). NB pts with high affinity FCGR alleles and an increase in ADCC (cut off 15%) are associated with longer PFS and OS rates (p<0.03; p<0.005), supporting NK-cell mediated ADCC as the mechanism of action.

Parameters of immune modulation (CDC, and WBT) and PK of ch14.18/CHO were comparable between APN311-202 and -303 cohorts. PK of ch14.18/CHO was analyzed in cycle 1: Cmax=12.2±0.4μg/ml, t½=8.4±1.1 d, AUC=145.3± 5.8 μg*d/ml, Vdss=9.3±0.5L/m2. A pro-inflammatory cytokine response (IL-2, IL-6, IL-8, IFNγ) translated into the expansion of effector NK- (3x) and T-cells (2x). We observed HACA in 17/97 pts (17.5%) of which only 9/97 (9.3%) were neutralizing with respect to the inhibition of CDC and WBT activity. In HACA negative patients, levels of ch14.18/CHO and functional parameters (CDC and WBT) analyzed before subsequent treatment cycles indicate persistent anti-NB activity for the entire treatment period.

Conclusion: LTI of ch14.18/CHO has an improved pain toxicity profile and at the same time is active and effective in high-risk relapsed/refractory NB.

Citation Format: Holger N. Lode, Dominique Valteau-Couanet, Alberto Garaventa, Juliet Gray, Victoria Castel, Isaac Yaniv, Nikolai Siebert, Christian Jensen, Stefanie Endres, Lena Pill, Christin Eger, Diana Seidel, Madlen Jüttner, Silke Kietz, Karoline Ehlert, Evelyne Janzek, Carla Manzitti, Ina Müller, Hans Loibner, Ruth Ladenstein. Immunotherapy with ch14.18/CHO in combination with IL2 is active and effective in high-risk relapsed/refractory neuroblastoma patients. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A032.