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Nov 13, 2021 07:24PM
Nov 13, 2021 07:27PM
Here are some interesting results from a phase 2 trial looking at Keytruda in combination with Imprime PGG (an activator of the innate immune system that reprograms the suppressive immune environment around the tumor). Consistent with earlier findings that those individuals whose cancer subtype switched from ER-positive to ER-negative are more sensitive to immunotherapy, this trial came to the same conclusion:
"Researchers observed a particularly pronounced clinical benefit in a subgroup of patients who initially were diagnosed with ER-positive/PR-positive disease but progressed on endocrine therapy and, prior to treatment, had biopsies that confirmed conversion to triple-negative breast cancer..."
The IMPRIME1 trial included 44 patients, 27% had liver mets. Overall, they found that 27% responded (ie, tumor shrinkage or stable disease) for at least six months.
"Investigators observed pronounced clinical benefit with the combination among a subgroup of 12 patients originally diagnosed with ER-positive/PR-positive disease who underwent prior treatment with endocrine therapy and later converted to triple-negative disease."
In this group, six (50%) achieved response (tumor shrinkage) to the combination, four (33%) achieved stable disease, and six (50%) achieved disease control for 6 months.
In a subsequent publication, they reported: Ten IMPRIME 1 patients were originally ER/PR+, received hormonal Tx and progressed to TNBC. Of these, 5 are confirmed PR (tumor shrinkage), 4 SD (stable disease, 3 are still on treatment), and one had progressive disease. https://ascopubs.org/doi/abs/10.1200/JCO.2019.37.1...
Adding Imprime IGG almost doubled the overall survival compared to Keytruda alone. This trial ended in March, and in January the company announced they had developed an assay for an immune biomarker that is necessary for patients to respond to the Imprime IGG treatment.