Belonging to the CD28 family, PD-1 (CD279) is one of the T-cell co-inhibitory receptors, expressing on various immune cells, such as activated T cells, regulatory T cells (Tregs, CD4+ Foxp3+), natural killer cells (NK cells), activated B cells, and macrophages. PD-1 has two known ligands—PD-L1(B7-H1/CD274) and programmed cell death ligand 2 (PD-L2/CD273)—from which PD-L1 is mainly expressed on T cells, B cells, dendritic cells (DCs), and macrophages.
Nevertheless, many patients still do not respond to the PD-1/PD-L1 checkpoint inhibitor treatment, indicating innate, adapted, or quickly acquired resistance to the immunotherapy.
Anti-programmed cell death protein 1 (PD-1) agents have become the standard of care for platinum-refractory recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) and are currently being evaluated in various disease settings. However, despite the gain in overall survival seen in some of the clinical trials, the majority of patients display primary resistance and do not benefit from these agents.
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For those able to receive treatment for metastatic spread, treatment again consists mainly of systemic therapies: cytotoxic chemotherapy, cytotoxic chemotherapy combined with cetuximab, or immunotherapy.
For those who have a significant burden of symptoms but are still able to receive systemic therapy, single-agent rather than combination therapy is recommended. For those with a minimal burden of symptoms and a good ability to participate in the daily activities of life, multi-agent systemic therapy is the treatment of choice after clinical trial enrolment and can consist of the agents in the local/regional recurrence.
Usually, if cancer becomes resistant to the current regimen, the patient is switched to new regimens until the patient is unable to tolerate further therapy or cancer grows beyond the control of any therapy. At that time, palliative care services are essential for symptom control, end-of-life planning, and psychological counseling.
Original Source:- PD-1 resistant head and neck cancer Market Report