PV-0518: Phase 1 study of Debio 1143 in combination with Concurrent Chemo-Radiotherapy in LA-SCCHN

Exploratory window-of-opportunity trial to investigate the tumor pharmacokinetcs/pharmacodynamics of the IAP antagonist Debio 1143 in patients with head and neck cancer

Inhibitor of apoptosis proteins (IAPs) regulate apoptosis and modulate NF-κB signalling thereby driving expression of genes involved in immune/inflammatory responses. The orally available IAP antagonist Debio 1143 has potential to enhance tumor response to chemoradiotherapy and/or immunotherapy. Patients with pre-operative squamous cell carcinomas of the head and neck (SCCHN) received: Debio 1143 monotherapy (200 mg/day D1-15 +/-2); Debio 1143 (200 mg/day D1-15 +/-2) plus cisplatin (40 mg/m² D-1 and 8); cisplatin alone (40 mg/m² D-1 and 8) (EudraCT: 2014-004655-31). Pharmacokinetic/pharmacodynamic effects were assessed in plasma and resected tumors. Primary endpoint; effect of Debio 1143 on cellular IAP-1 (cIAP-1). Levels of cIAP-1/-2, X-linked inhibitor of apoptosis protein (XIAP), tumor infiltrating lymphocytes (TILs) including CD8+ T cells, programmed cell death protein 1 (PD-1) and PD-ligand 1 (PD-L1) and gene expression were also analyzed. Twenty-three of 26 patients completed treatment. In the Debio 1143 monotherapy cohort (n=13), mean tumor concentrations of Debio 1143 were 18-fold (maximum 55.2-fold) greater than in plasma, exceeding the IC⁵⁰ for cIAPs and XIAP by 100 to 1000-fold, with significant engagement/degradation of cIAP-1 (p <0.05). Overall, levels of CD8+ TILs, PD-1 and PD-L1 positive immune cells increased significantly (p <0.05) following Debio 1143 treatment. Changes were observed in the expression of genes related to NF-κB signalling. Treatments were well tolerated. Debio 1143 penetrated SCCHN tumors, engaged cIAP-1 and induced immune inflammatory changes in the tumor microenvironment. Based on the mode of action demonstrated here and in previous studies, these data support future combinations of Debio 1143 with immune-checkpoint agents.

Debio 1143 and high-dose cisplatin chemoradiotherapy in high-risk locoregionally advanced squamous cell carcinoma of the head and neck: a double-blind, multicentre, randomised, phase 2 study

BACKGROUND

Debio 1143 is an orally available antagonist of inhibitor of apoptosis proteins with the potential to enhance the antitumour activity of cisplatin and radiotherapy. The radiosensitising effect of Debio 1143 is mediated through caspase activation and TNF, IFNγ, CD8 T cell-dependent pathways. We aimed to investigate the efficacy and safety of Debio 1143 in combination with standard chemoradiotherapy in patients with high-risk locally advanced squamous cell carcinoma of the head and neck.

METHODS

This double-blind, multicentre, randomised, phase 2 study by the French Head and Neck Radiotherapy Oncology Group (GORTEC) was run at 19 hospitals in France and Switzerland. Eligible patients were aged 18-75 years with locoregionally advanced, squamous cell carcinoma of the head and neck (characterised as non-metastatic, measurable stage III, IVa, or IVb [limited to T ≥2, N0-3, and M0] disease), Eastern Cooperative Oncology Group performance status of 0 or 1, a history of heavy tobacco smoking (>10 pack-years) with no previous or current treatment for invasive head and neck cancer, and no previous treatment with inhibitor of apoptosis protein antagonists. Patients were randomly assigned (1:1) to receive oral Debio 1143 (200 mg per day on days 1-14 of 21-day cycles, for three cycles) or oral placebo (20 mg/mL, administered at the same dosing schedule) using a stochastic minimisation technique according to node involvement and primary tumour site, and HPV-16 status in patients with an oropharyngeal primary tumour site. All patients received standard high-dose cisplatin chemoradiotherapy. The primary endpoint was the proportion of patients with locoregional control 18 months after chemoradiotherapy, analysed in the intention-to-treat population (primary analysis), and repeated in the per-protocol population. Responses were assessed according to Response Evaluation Criteria in Solid Tumors (version 1.1). This trial is registered with ClinicalTrials.gov, NCT02022098, and is still active but not recruiting.

FINDINGS

Between Jan 25, 2016, and April 24, 2017, 48 patients were randomly assigned to the Debio 1143 group and 48 to the placebo group (one patient in the placebo group did not receive the study drug and was not included in the safety analysis). Median duration of follow-up was 25·0 months (IQR 19·6-29·4) in the Debio 1143 group and 24·2 months (6·6-26·8) in the placebo group. Locoregional control 18 months after chemoradiotherapy was achieved in 26 (54%; 95% CI 39-69) of 48 patients in the Debio 1143 group versus 16 (33%; 20-48) of 48 patients in the placebo group (odds ratio 2·69 [95% CI 1·13-6·42], p=0·026). Grade 3 or worse adverse events were reported in 41 (85%) of 48 patients in the Debio 1143 group and in 41 (87%) of 47 patients in the placebo group. The most common grade 3-4 adverse events were dysphagia (in 24 [50%] patients in the Debio 1143 group vs ten [21%] in the placebo group), mucositis (in 15 [31%] vs ten [21%]), and anaemia (in 17 [35%] vs 11 [23%]). Serious treatment-emergent adverse events were recorded in 30 (63%) of 48 patients in the Debio 1143 group and 28 (60%) of 47 in the placebo group. In the placebo group, two (4%) deaths were due to adverse events (one multiple organ failure and one asphyxia; neither was considered to be related to treatment). No deaths due to adverse events occurred in the Debio 1143 group.

INTERPRETATION

To our knowledge, this is the first treatment regimen to achieve superior efficacy in this disease setting against a high-dose cisplatin chemoradiotherapy comparator in a randomised trial. These findings suggest that inhibition of inhibitor of apoptosis proteins is a novel and promising approach in this poor prognostic population and warrant confirmation in a phase 3 study with the aim of expanding the therapeutic options for these patients.

FUNDING

Debiopharm.

SMAC Mimetic Debio 1143 and Ablative Radiation Therapy Synergize to Enhance Antitumor Immunity against Lung Cancer

PURPOSE

Adaptive antitumor immunity following ablative radiotherapy (ART) is attenuated by host myeloid-derived suppressor cell (MDSC), tumor-associated macrophage (TAM), and regulatory T-cell (Treg) infiltrates. We hypothesized treatment with ART and a secondary mitochondrial-derived activators of caspase (SMAC) mimetic could reverse the immunosuppressive lung cancer microenvironment to favor adaptive immunity.

EXPERIMENTAL DESIGN

To evaluate for synergy between ART and the SMAC mimetic Debio 1143 and the dependence upon CD8⁺ T cells and TNFα, we used LLC-OVA syngeneic mouse model of lung cancer and treated them with Debio 1143 and/or ART (30 Gy) with or without anti-CD8, anti-TNFα, or anti-IFNγ antibodies. Tumor-infiltrating OVA-specific CD8⁺ T cells, Tc1 effector cells, MDSCs, TAMs, and Tregs, were quantified by flow cytometry. Tc1-promoting cytokines TNFα, IFNγ, and IL1β and the immunosuppressive IL10 and Arg-1 within LLC-OVA tumor tissue or mouse serum were measured by RT-PCR and ELISA.

RESULTS

ART delayed tumor growth, and the addition of Debio 1143 greatly enhanced its efficacy, which included several complete responses. These complete responders rejected an LLC-OVA tumor rechallenge. ART and Debio 1143 synergistically induced a tumor-specific, Tc1 cellular and cytokine response while eliminating immunosuppressive cells and cytokines from the tumor microenvironment. Depletion of CD8⁺ cells, TNFα, and IFNγ with blocking antibody abrogated synergy between ART and Debio 1143 and partially restored tumor-infiltrating MDSCs.

CONCLUSIONS

Debio 1143 augments the tumor-specific adaptive immunity induced by ART, while reversing host immunosuppressive cell infiltrates in the tumor microenvironment in a TNFα, IFNγ, and CD8⁺ T-cell-dependent manner. This provides a novel strategy to enhance the immunogenicity of ART.