A new multicenter Phase II clinical trial, led by researchers from several institutions including Jiangsu Cancer Hospital, is showing promising results in treating patients with advanced metastatic solid tumors. This innovative treatment regimen combines hypofractionated radiotherapy (HFRT) with a PD-1 inhibitor, granulocyte macrophage-colony stimulating factor (GM-CSF), and thymosin-α1. The combination aims to enhance the immune response and potentially overcome the limited therapeutic options for metastatic cancers that have relapsed after standard treatments.
The trial enrolled 37 patients between September 2022 and May 2024, assessing the efficacy and safety of this combined approach. According to the study’s results, which were presented in June 2024, the treatment demonstrated a median progression-free survival (PFS) of 3.5 months, a promising objective response rate (ORR) of 23.08%, and a disease control rate (DCR) of 65.38%. Notably, 23% of the patients experienced the abscopal effect, a phenomenon where radiation therapy causes tumor regression in non-irradiated areas, suggesting the treatment may trigger a broader immune response.
The inclusion of GM-CSF and thymosin-α1 aims to enhance the immune system’s ability to fight cancer. GM-CSF boosts the activity of dendritic cells, which are key to activating T-cells that fight tumors, while thymosin-α1 regulates inflammation and enhances the effect of immunotherapy. Together with the PD-1 inhibitor camrelizumab, which blocks a pathway that cancer cells use to evade the immune system, the combination therapy appears to help reawaken the body’s immune defenses against cancer.
The treatment protocol also highlighted that the lower the baseline neutrophil-lymphocyte ratio (NLR), a marker of inflammation, the better the overall prognosis. Patients with lower NLRs had significantly reduced risks of distant metastasis and death, further confirming the link between inflammation and immune response efficacy in cancer treatment.
While the treatment was generally well-tolerated, with some side effects such as hypothyroidism and skin reactions, no grade 5 adverse events were reported, indicating a manageable safety profile.
This study represents a step forward in the fight against hard-to-treat metastatic cancers and sets the stage for future research to refine and expand these findings. The results have paved the way for additional trials, with larger sample sizes and further exploration of the mechanisms behind the abscopal effect, which could revolutionize how cancers are treated in the future.
The findings from this promising study provide new hope for patients with metastatic solid tumors, offering a potential combination therapy that could enhance current cancer treatments.
