Biothera Pharmaceuticals has begun treating patients in a Phase 2 clinical trial evaluating its Imprime PGG in combination with Merck’s Keytruda (pembrolizumab) for patients with advanced squamous cell carcinoma of the head and neck (SCCHN).
The study (NCT03246685) will evaluate the combination as a second or third line treatment who either failed to respond or achieved stable disease after treatment with Keytruda alone.
Imprime PGG is an investigational pathogen-associated molecular pattern (PAMP) that acts as an immunological “ignition switch” that triggers a cascade of events throughout the innate immune system, culminating in T-cell activation and cancer cell elimination.
Keytruda is an immune checkpoint inhibitor that works to boost the anti-tumor functions of cytotoxic T-cells.
The study has been designed to determine if the two immunotherapies could be combined to improve immune responses and shrink tumors. It follows preclinical studies in which Imprime PGG was shown to enhance the effectiveness of anti-PD-1 and anti-PD-L1 immune checkpoint inhibitors in mice.
Researchers are now recruiting up to 87 participants with advanced SCCHN to enter one of two groups. One group will recruit patients with progressive SCCHN who already have undergone a first round of treatment with an immune checkpoint inhibitor. The second group will recruit patients who achieved stable disease after receiving Keytruda alone for three months or more.
Primary goals of the study are to evaluate safety and the proportion of patients responding to the combination. A secondary goal include sprogression-free survival and overall survival. Markers of immune activation and T-cell infiltration also will be assessed.
The trial is recruiting participants now. Eligible participants will be identified using select biomarkers for Imprime PGG.
This is the second time Biothera has collaborated with Merck (known as MSD outside the U.S. and Canada). The combination of Imprime PGG and Keytruda also is being studied in a Big Ten Cancer Research Consortium Phase 1b/2 trial (NCT03003468) in patients with non-small cell lung cancer.
In September 2017, a study including Keytruda in the treatment of head and neck cancer suggested that the medicine may be more beneficial than standard therapy after the cancer has spread or returned after a first round of chemotherapy. In a population that lives only seven to eight months on average, Keytruda lengthened survival by 1.3 months.