Intoduction
Optimal nutritional care is pivotal in the treatment of cachexia and is recommended as a cornerstone of multimodal therapy. Here, we investigated the therapeutic effect of a multitargeted intervention diet with a specific combination of high protein, leucine, fish oil, vitamin D, galacto-oligosaccharides and fructo-oligosaccharides on the development of cachexia in an orthotopic lung cancer (OLCC) mouse model.

Methods
Immune competent, 11 weeks old, male 129S2/Sv mice, were randomly allocated to either sham operated or tumor-bearing (TB) groups. In this syngeneic OLCC mouse model, lung epithelium-derived adenocarcinoma cells (K-rasG12D; p53R172HΔG) were inoculated intrapulmonary, and TB mice were allocated to either control diet (TB-CD) or isocaloric and isonitrogenous intervention diet (TB-ID) starting 7 days post tumor inoculation. Body weight and food intake were measured daily. At baseline and weekly after surgery, grip strength was measured and tumor growth and muscle mass were assessed using µCT imaging. Skeletal muscles of the lower hind limbs and other tissues (epididymal fat, blood) were collected at 5 days of consecutive body weight loss (cachexia) as predefined study endpoint.

Results
TB mice developed cachexia evidenced by significant loss of body weight and muscle strength, and reduced muscle and epididymal fat mass compared to sham control mice. Compared to the TB-CD group, the onset of cachexia was significantly delayed in the TB-ID group, resulting in prolonged time to reaching the cachexia-related study endpoint. The extent and progression of body weight loss during the last 5 days of the experiment was also significantly decreased in the TB-CD group compared to the TB-ID group. Moreover, muscle function and muscle mass were better preserved in the TB-ID compared to TB-CD group. Additionally, alterations in molecular markers for proteolysis (Atrogin-1, MuRF-1, LC3b and Bnip3) and protein synthesis (ribosomal S6 and 4E-BP1), indicative for muscle atrophy signaling in TB-CD, were normalized in the skeletal muscle of the TB-ID group.

Conclusion
Targeted dietary intervention results in sparing of muscle function, delays the onset, and attenuates the progression of cachexia in an orthotopic lung cancer mouse model.