Many patients respond well to these treatments, sometimes experiencing long-lasting remissions. But some cancers remain difficult to treat with immunotherapy, and expanding the impact of the approach is a high priority.
Researchers from Cambridge University and Cold Spring Harbour Laboratory (CSHL) in the US have completed a clinical trial of a drug that induces an integrated immune response in the tumours of patients with cancer types that do not usually respond to immunotherapy.
The results published in the Proceedings of the National Academy of Sciences mean that the researchers hope the potential treatment might make such tumours more responsive to the class of drugs known as immune checkpoint inhibitors.
Checkpoint inhibitors release natural brakes on the immune system, freeing it to find and destroy cancer cells. But they generally have not been effective against cancer cells with low levels of genetic mutation.
Tobias Janowitz, CSHL said: “Those tumours often do not seem to be visible to the immune system and do not seem to be unmasked by these therapies that are currently available.
“And we have reasons to believe that that is because they can engage an immune suppressive pathway that keeps most of the immune cells out of the cancer cell nest.”
In this clinical trial, the research team interrupted that immunosuppressive pathway with a drug called plerixafor. The drug was administered intravenously for one week to 24 patients with either pancreatic cancer or colorectal cancer with a low tumour mutational burden.
All patients had advanced disease, and biopsies were collected from metastatic tumours before and after treatment.
When the team analysed the patient samples, they found that critical immune cells had infiltrated the tumours during the time patients received plerixafor, including a cell type known to summon and organise key players in the anti-cancer response.
Lead author Daniele Biasci, who led the computational immunology analyses of the study, added: “This finding is encouraging, because the gene expression patterns induced by plerixafor in this study have also been observed in tumors from patients who respond to immune checkpoint inhibitors, a class of drugs increasingly used for cancer immunotherapy.”
Professor Duncan Jodrell, who led the planning and patient recruitment for the clinical study and co-leads our Pancreatic Cancer Programme, said: “I am delighted that the work of this multi-disciplinary team has translated important laboratory findings into patients, with the potential to make a difference in these hard-to-treat cancers.”
A clinical trial based on this study is about to start recruitment and will test the effects of combining plerixafor with an approved checkpoint inhibitor.
Biasci, D., et al., CXCR4 inhibition in human pancreatic and colorectal cancers induces an integrated immune response, PNAS October 30, 2020. DOI: 10.1073/pnas.2013644117