Personal Genome Diagnostics (PGDx) has won a contract to develop a liquid assay for identifying patients who are likely to respond to checkpoint inhibitors such as Merck’s Keytruda. The assay could expand the use of checkpoint inhibitors to new indications by identifying subpopulations of likely responders, and ensure more effective, targeted use of the drugs across the board.
Fueled by a contract from the National Cancer Institute (NCI), PGDx is aiming to complete initial development of the assay this year. The contract covers the development of the assay and its early evaluation in clinical samples.
Studies suggest that patients whose tumors have a lot of mutations are more likely to respond to PD-1 and PD-L1 drugs such as Keytruda. Lung, melanoma and bladder cancers, the early areas of focus for checkpoint inhibitors, are all characterized by above-average mutational loads, but counts vary from patient to patient. Equally, some patients with tumors typically associated with low mutational loads, such as colorectal cancers, have high levels of mutation. Studies suggest these patients respond better to checkpoint inhibitors than the broader population.
PGDx won the contract on the strength of its research into the link between patient tumor mutational load and responsiveness to checkpoint inhibitors.
“We have collaborated with pharmaceutical partners to evaluate the effects of mutational load by retrospectively applying whole exome sequencing and our ImmunoSelect analyses to clinical samples,” PGDx VP Mark Sausen said in a statement. “This contract now gives us the opportunity to work with these partners to develop the MutatorDETECT assay to identify patients prospectively for clinical trial enrollment.”
Currently, a tissue biopsy is needed to measure tumor mutational load. This limits the number of patients that are assessable and prevents continual monitoring of mutational load.
PGDx thinks it can create a blood test that delivers a readout on mutational load, freeing patients from the need to provide a tissue sample and opening the door to continual monitoring of their likely responsiveness to checkpoint inhibitors.
If all goes according to plan, PGDx will emerge with an assay that enables drug developers and physicians to identify the patients most likely to respond to checkpoint inhibitors, potentially increasing the hit rate in cancers such as melanoma and creating opportunities to use the drugs in new indications.