Camu-Camu Prebiotic and Immune Checkpoint Inhibition in Patients With Non-small Cell Lung Cancer and Melanoma

Immune-checkpoint inhibitors (ICI) now represent the backbone therapy for patients with advanced or unresectable non-small cell lung cancer (NSCLC) and metastatic melanoma. However, only a minority of patients obtain durable complete responses. In patients with advanced NSCLC with a Programmed Death Ligand-1 (PD-L1) expression level below 50%, the standard-of-care is pembrolizumab plus platinum doublet chemotherapy, with overall survival (OS) at 2 years reaching 46%. In patients with advanced melanoma, combination of anti-CTLA-4 (ipilimumab) and anti-PD-1 (nivolumab) is a key standard-of-care option. In a study in patients with advanced melanoma evaluating the combination regimen of nivolumab plus ipilimumab group, OS at 5 years was 52% in the nivolumab plus ipilimumab group and 44% in the nivolumab group, as compared with 26% in the ipilimumab group. Despite these improvements in outcomes with ICI, these survival and response rates remain suboptimal, and therefore, developing strategies to safely increase ICI efficacy or reverse ICI resistance represents an unmet clinical need. Moreover, there are currently no available options for patients who progress on standard-of-care ICI. Recent pre-clinical studies have demonstrated the role of the gut microbiome in improving ICI efficacy, and therefore, efforts to modulate the gut microbiome is an active area of study. Indeed, two phase I clinical studies evaluating gut microbiome modulation with fecal microbial transplantation (FMT) demonstrated increase in objective response rate compared to historical controls. Moreover, studies in over 8,000 patients (including patients with NSCLC and melanoma) have confirmed the independent and negative role of antibiotics (ATB) in patients receiving ICI, further validating the important role of the gut microbiome. Therefore, it is clear that modulation of the gut microbiome represents a promising therapeutic strategy in improving ICI efficacy. Other than FMT, prebiotic substances (compounds which positively shift the gut microbiome) are a reliable and safe method of gut microbiome modulation. Data suggest that the berry Camu Camu (CC), also known as Myrciaria dubia has prebiotic potential to enrich Akkermansia muciniphila, a bacterium shown to alleviate metabolic disorders and improve ICI efficacy in preclinical models. Our preclinical work showed that CC oral supplementation significantly decreased tumor size and had an additive effect in combination with anti-PD-1 in two murine tumor models, MCA-205 (anti-PD-1 sensitive) and E0771 (anti-PD-1 resistant). Flow cytometry and RNA seq analysis of the tumor microenvironment (TME) and T cell depletion showed that CC's anti-tumor effect was dependent on CD8+ T cells. Moreover, CC supplementation was able to transform an anti-PD-1-resistant tumor into an anti-PD-1-sensitive tumor. ATB administration inhibited CC activity, proving that the activity of CC was dependent on the gut microbiome. The 16S rRNA profiling of murine fecal samples showed that CC increased bacterial diversity and enrichment of beneficial bacteria. CC is available over the counter as a natural prebiotic and has been approved for human clinical trials in obesity (NCT04130321) and HIV (NCT04058392).