Study Title: SX-682 and Nivolumab for the Treatment of RAS-Mutated, MSS Unresectable or Metastatic Colorectal Cancer, the STOPTRAFFIC-1 Trial
This Phase Ib/II trial studies the side effects and best dose of SX-682 that can be given alone and in combination with nivolumab in treating patients with RAS-Mutated, microsatellite stable (MSS) colorectal cancer that has spread to other places in the body (metastatic) or cannot be removed by surgery (unresectable). SX-682 may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Immunotherapy with monoclonal antibodies, such as nivolumab, may help the body’s immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving SX-682 alone and together with nivolumab may kill more tumor cells.
Background: Refractory RAS mutated MSS mCRC represents a critical unmet need with minimal response to immune checkpoint blockade (ICB). Preclinical CRC models reveal that KRAS mutations activate the CXCR2 axis promoting an immunosuppressive tumor microenvironment (TME). This occurs via KRAS repression of interferon regulatory factor 2 (IRF2) resulting in upregulation of CXCL3 chemokines, which bind CXCR2 and recruit myeloid-derived suppressor cells (MDSC; Liao et al, Cancer Cell 2019; Grover et al, Cancer Discovery, 2022). SX-682 is a novel oral small-molecule inhibitor of the CXCR1/2 chemokine receptors involved in MDSC-recruitment to the TME. This proof-of-concept study investigates whether de novo immunotherapy resistance in MSS RAS mutated mCRC can be overcome by treatment with a small molecule CXCR1/2 antagonist in combination with anti-PD-1 therapy.
Methods: STOPTRAFFIC-1 (NCT04599140, enrolling) is a phase I/II, open-label, dose-escalation/dose expansion study of SX-682 in combination with nivolumab to evaluate safety and clinical activity for patients (pts) with refractory RAS (KRAS and NRAS) mutated MSS mCRC. Key eligibility criteria: patients (pts) with MSS mCRC with measurable disease, progression or intolerance to at least 2 prior lines of standard therapy, and ECOG 0 or 1. Pts will receive SX-682 (5 dose levels: 25 mg, 50 mg, 100mg, 200mg, or 400 mg by mouth twice daily) administered in an 8-week cycle with intravenous nivolumab (480 mg) on days 1 and 29 of each cycle. Adverse events are assessed according to CTCAE v5.0. Response assessments (per RECIST) occur every 8 weeks. In dose escalation, pts enter a 3-week monotherapy safety run-in of SX-682 followed by 3-week combination with nivolumab for a six-week dose-limiting toxicity (DLT) period. Cohorts 1-4 have been completed without DLT. Enrollment to cohort 5 began in January 2022. Following determination of maximum tolerated dose (MTD), dose expansion design is a Simon’s optimal two-stage design. Efficacy will be assessed in the first 15 pts with a requirement of at least 2 responses in order to enroll 14 additional pts (N=29) in the second stage. Pre- and on-treatment tissue biopsies will be collected in the expansion phase. The primary objectives are to determine the safety profile of SX-682 alone and in combination with nivolumab, including the MTD, recommended phase 2 dose, and the DLT. The secondary objectives include overall response rate, progression-free survival, overall survival, and pharmacokinetic profiles of SX-682. Translational analyses include correlations of clinical outcomes with genomic and immune biomarkers from paired tissue and plasma samples.
Treatment Regimens
OUTLINE: This is a phase I, dose-escalation study of CXCR1/2 Inhibitor SX-682, followed by a phase II study.
MONOTHERAPY STAGE: Patients receive SX-682 orally (PO) twice daily (BID) on days 1-21 in the absence of disease progression or unacceptable toxicity.
COMBINATION STAGE: Patients receive SX-682 PO BID on days 1-56 and nivolumab intravenously (IV) over 30 minutes on days 1 and 29. Treatment repeat every 56 days weeks for up to 12 cycles in the absence of disease progression or unacceptable toxicity.
After completion of study, patients with no have tumor response are followed up every 3 weeks for 90 days, and patients with tumor response every 3 months for up to 6 months.
SX-682 is an investigational CXCR1/2 inhibitor, which may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Immunotherapy with monoclonal antibodies, such as nivolumab, may help the body’s immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving SX-682 alone and together with nivolumab may kill more tumor cells.
Key Eligibility Criteria
Inclusion Criteria:
Patients must have confirmed adenocarcinoma of the colon or the rectum that is metastatic or unresectable.
Tumor must be determined to be RAS-mutated (KRAS or NRAS) and microsatellite stable/proficient in mismatch repair.
Patients must have received at least two prior regimens of therapy for unresectable or metastatic CRC including fluoropyrimidine-, oxaliplatin-, and irinotecan-based regimens. Patients who relapse within 6 months of adjuvant chemotherapy composed of oxaliplatin and a fluoropyrimidine will have their adjuvant therapy count as one prior regimen.
For the expansion cohort, pre-treatment primary tumor tissue (i.e., archived paraffin embedded) or from an unresectable metastatic site must be available for biomarker analyses. Biopsy should be excisional or core needle. Fine needle aspirates or other cytology samples are insufficient
Patients must have measurable disease with at least 1 unidimensional measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST) version (v)1.1
There are other standard eligibility criteria related to lab values and other chronic illnesses that would need to be reviewed.
For full Inclusion/Exclusion Criteria: http://clinicaltrials.gov/show/NCT04599140
NCT record is available here. This includes enrolling sites.