Ludovic Lacroix

Dendritic cell-derived exosomes (Dex) are small extracellular vesicles secreted by viable dendritic cells. In the two phase-I trials that we conducted using the first generation of Dex (IFN-γ-free) in end-stage cancer, we reported that Dex exerted natural killer (NK) cell effector functions in patients. A second generation of Dex (IFN-γ-Dex) was manufactured with the aim of boosting NK and T cell immune responses. We carried out a phase II clinical trial testing the clinical benefit of IFN-γ-Dex loaded with MHC class I- and class II-restricted cancer antigens as maintenance immunotherapy after induction chemotherapy in patients bearing inoperable non-small cell lung cancer (NSCLC) without tumor progression. The primary endpoint was to observe at least 50% of patients with progression-free survival (PFS) at 4 mo after chemotherapy cessation. Twenty-two patients received IFN-γ-Dex. One patient exhibited a grade three hepatotoxicity. The median time to progression was 2.2 mo and median overall survival (OS) was 15 mo. Seven patients (32%) experienced stabilization of >4 mo. The primary endpoint was not reached. An increase in NKp30-dependent NK cell functions were evidenced in a fraction of these NSCLC patients presenting with defective NKp30 expression. Importantly, MHC class II expression levels of the final IFN-γ-Dex product correlated with expression levels of the NKp30 ligand BAG6 on Dex, and with NKp30-dependent NK functions, the latter being associated with longer progression-free survival. This phase II trial confirmed the capacity of Dex to boost the NK cell arm of antitumor immunity in patients with advanced NSCLC.

Abstract High-throughput genomic analyses may improve outcomes in patients with advanced cancers. MOSCATO 01 is a prospective clinical trial evaluating the clinical benefit of this approach. Nucleic acids were extracted from fresh-frozen tumor biopsies and analyzed by array comparative genomic hybridization, next-generation sequencing, and RNA sequencing. The primary objective was to evaluate clinical benefit as measured by the percentage of patients presenting progression-free survival (PFS) on matched therapy (PFS2) 1.3-fold longer than the PFS on prior therapy (PFS1). A total of 1,035 adult patients were included, and a biopsy was performed in 948. An actionable molecular alteration was identified in 411 of 843 patients with a molecular portrait. A total of 199 patients were treated with a targeted therapy matched to a genomic alteration. The PFS2/PFS1 ratio was >1.3 in 33% of the patients (63/193). Objective responses were observed in 22 of 194 patients (11%; 95% CI, 7%–17%), and median overall survival was 11.9 months (95% CI, 9.5–14.3 months). Significance: This study suggests that high-throughput genomics could improve outcomes in a subset of patients with hard-to-treat cancers. Although these results are encouraging, only 7% of the successfully screened patients benefited from this approach. Randomized trials are needed to validate this hypothesis and to quantify the magnitude of benefit. Expanding drug access could increase the percentage of patients who benefit. Cancer Discov; 7(6); 586–95. ©2017 AACR. See related commentary by Schram and Hyman, p. 552. This article is highlighted in the In This Issue feature, p. 539

Diffuse intrinsic pontine glioma (DIPG) is the most severe paediatric solid tumour, with no significant therapeutic progress made in the past 50 years. Recent studies suggest that diffuse midline glioma, H3-K27M mutant, may comprise more than one biological entity. The aim of the study was to determine the clinical and biological variables that most impact their prognosis. Ninety-one patients with classically defined DIPG underwent a systematic stereotactic biopsy and were included in this observational retrospective study. Histone H3 genes mutations were assessed by immunochemistry and direct sequencing, whilst global gene expression profiling and chromosomal imbalances were determined by microarrays. A full description of the MRI findings at diagnosis and at relapse was integrated with the molecular profiling data and clinical outcome. All DIPG but one were found to harbour either a somatic H3-K27M mutation and/or loss of H3K27 trimethylation. We also discovered a novel K27M mutation in HIST2H3C, and a lysine-to-isoleucine substitution (K27I) in H3F3A, also creating a loss of trimethylation. Patients with tumours harbouring a K27M mutation in H3.3 (H3F3A) did not respond clinically to radiotherapy as well, relapsed significantly earlier and exhibited more metastatic recurrences than those in H3.1 (HIST1H3B/C). H3.3-K27M-mutated DIPG have a proneural/oligodendroglial phenotype and a pro-metastatic gene expression signature with PDGFRA activation, while H3.1-K27M-mutated tumours exhibit a mesenchymal/astrocytic phenotype and a pro-angiogenic/hypoxic signature supported by expression profiling and radiological findings. H3K27 alterations appear as the founding event in DIPG and the mutations in the two main histone H3 variants drive two distinct oncogenic programmes with potential specific therapeutic targets.

PURPOSE: To evaluate the efficacy and safety of cetuximab, a monoclonal antibody that inhibits the epidermal growth factor receptor (EGFR), as a first-line monotherapy in patients with unresectable squamous cell carcinoma of the skin (SCCS). PATIENTS AND METHODS: Thirty-six patients received cetuximab (initial dose of 400 mg/m(2) followed by subsequent weekly doses of 250 mg/m(2)) for at least 6 weeks with a 48-week follow-up. The primary end point was the disease control rate (DCR) at 6 weeks (according to Response Evaluation Criteria in Solid Tumors [RECIST] criteria). Secondary end points included best response rate, overall survival, progression-free survival (PFS), and toxicity assessment. Association of treatment efficacy with RAS mutations or FcγR genotypes was investigated. RESULTS: Median age of the study population was 79 years. DCR at 6 weeks was obtained in 25 of 36 patients (69%; 95% CI, 52% to 84%) of the intention-to-treat population. The best responses were eight partial responses and two complete responses. There were no cetuximab-related deaths. There were three related serious adverse events: two grade 4 infusion reactions and one grade 3 interstitial pneumopathy. Grade 1 to 2 acne-like rash occurred in 78% of patients and was associated with prolonged PFS. One HRAS mutation was identified. Combined FcγRIIa-131H/H and/or FcγRIIIa-158V/V polymorphisms were not associated with the clinical outcomes. CONCLUSION: As a first-line treatment in patients with unresectable SCCS, cetuximab achieved 69% DCR. A randomized phase III trial is warranted to confirm that cetuximab may be considered as a therapeutic option especially in elderly patients. The low frequency of RAS mutations in SCCS makes SCCS tumors attractive for EGFR inhibition.

Gut microbiota composition influences the clinical benefit of immune checkpoints in patients with advanced cancer but mechanisms underlying this relationship remain unclear. Molecular mechanism whereby gut microbiota influences immune responses is mainly assigned to gut microbial metabolites. Short-chain fatty acids (SCFA) are produced in large amounts in the colon through bacterial fermentation of dietary fiber. We evaluate in mice and in patients treated with anti-CTLA-4 blocking mAbs whether SCFA levels is related to clinical outcome. High blood butyrate and propionate levels are associated with resistance to CTLA-4 blockade and higher proportion of Treg cells. In mice, butyrate restrains anti-CTLA-4-induced up-regulation of CD80/CD86 on dendritic cells and ICOS on T cells, accumulation of tumor-specific T cells and memory T cells. In patients, high blood butyrate levels moderate ipilimumab-induced accumulation of memory and ICOS + CD4 + T cells and IL-2 impregnation. Altogether, these results suggest that SCFA limits anti-CTLA-4 activity.