This study will be conducted in adult participants diagnosed with any form of an advanced or progressive MSS CRC for which 1st and 2nd line standard therapy (at least one of which contained fluorouracil) is no longer effective or is intolerable. This is a phase 1b, multi-center, open label study designed to assess safety and tolerability of grapiprant in combination with pembrolizumab, to determine the recommended phase 2 dose (RP2D) with pembrolizumab, and to evaluate and characterize the PK of grapiprant alone and in combination with pembrolizumab. Disease response, pharmacodynamics, and response biomarkers will also be assessed.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
54
Cohort 1 will be treated for 1 week with oral grapiprant as a single agent, followed by 21-day combination treatment cycles of oral grapiprant in combination with IV pembrolizumab.
Cohort 2 will be administered 21-day combination treatment cycles of oral grapiprant in combination with IV pembrolizumab.
Mayo Clinic Cancer Center - Scottsdale
Phoenix, Arizona, United States
University of Colorado Denver-Anschutz Medical Campus
Aurora, Colorado, United States
Sarah Cannon Research Institute, LLC (SCRI)
Nashville, Tennessee, United States
New Experimental Therapeutics of San Antonio-NEXT Oncology
San Antonio, Texas, United States
Safety and tolerability of grapiprant alone and in combination with pembrolizumab
Number of incidence, severity, and duration of treatment emergent adverse events using CTCAE v5.0
Time frame: Up to 90 days after the end of treatment (average of 7 months)
Define the recommended phase 2 dose (RP2D) of grapiprant combined with pembrolizumab
Number, incidence and severity of treatment related adverse events as assessed by CTCAE 5.0
Time frame: Through Cycle 1 (21 days)
Overall Response Rate (ORR)
Proportion of participants who achieved PR or better during the study per RECIST 1.1
Time frame: 7 months
Duration of Response (DOR)
Time when criteria for response are met, to the first documentation of relapse or progression
Time frame: 7 months
Progression -free survival (PFS)
Participants who discontinue treatment without disease progression
Time frame: Up to 12 months
Disease control rate (DCR)
Percentage of participants who achieved a CR, PR and stable disease
Time frame: 7 months
Overall survival (OS)
Date of study drug to date of death due to any cause. If no documentation of death at time of the analysis will be censored as of the date last known to be alive, or the data cutoff date, whichever is earlier.
Time frame: Up to 2 years from start of study drug.
Duration of treatment (DOT)
Time of duration on treatment
Time frame: 7 months
Serum tumor marker changes
Assess changes in serum tumor markers including but not limited to carcinoembryonic antigen (CEA), when appropriate (eg. CA-19.9, CA125, and lactate dehyrogenase (LDH)) with disease response.
Time frame: 7 months
Pharmacodynamic immune effects in paired tumor biopsies
Assess changes in tumor infiltrating helper T cells, cytotoxic T cells and regulatory monocyte/macrophages with study drug treatment
Time frame: predose through cycle 3 (each cycle is 21 days)
PGEM as a pharmacodynamic and predictive biomarker
Evaluate disease response in all evaluable participants and in those with a positive initial assessment of Urine prostaglandin E2 metabolite (PGEM)
Time frame: PreScreening through 7 months
PK of grapiprant: Tmax
First time to reach maximum \[peak\] observed plasma concentration
Time frame: Safety Run-in (7 days); Days 1 and 2 of first 2 cycles (every 21 days), followed by Day 1 of every even cycle beginning with cycle 4 (every 42 days) through end of treatment (average of 4 months)
PK of grapiprant: AUC0 last
Area under the plasma concentration time curve from time 0 to the end of the dosing interval (AUC0 last)
Time frame: Safety Run-in (7 days); Days 1 and 2 of first 2 cycles (every 21 days), followed by Day 1 of every even cycle beginning with cycle 4 (every 42 days) through end of treatment (average of 4 months).
Plasma decay half-life (t1/2)
Measurement of half-life of grapiprant after dosing
Time frame: Safety Run-in (7 days); Days 1 and 2 of first 2 cycles (every 21 days), followed by Day 1 of every even cycle beginning with cycle 4 (every 42 days) through end of treatment (average of 4 months)
Apparent oral clearance (CL/F)
Rate of elimination of the drug from plasma after oral administration
Time frame: Safety Run-in (7 days); Days 1 and 2 of first 2 cycles (every 21 days), followed by Day 1 of every even cycle beginning with cycle 4 (every 42 days) through end of treatment (average of 4 months)
Peak to trough ratio
Measure how drug effect is sustained over dose interval
Time frame: Safety Run-in (7 days); Days 1 and 2 of first 2 cycles (every 21 days), followed by Day 1 of every even cycle beginning with cycle 4 (every 42 days) through end of treatment (average of 4 months)
Observed accumulation ratio
Relationship between the dosing interval and the rate of elimination for the drug.
Time frame: Safety Run-in (7 days); Days 1 and 2 of first 2 cycles (every 21 days), followed by Day 1 of every even cycle beginning with cycle 4 (every 42 days) through end of treatment (average of 4 months)
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