A four-drug regimen combining the CXCR4 antagonist motixafortide (APHEXDA) with cemiplimab and chemotherapy produced responses in seven of 11 treatment-naïve patients with metastatic pancreatic ductal adenocarcinoma (PDAC), according to Phase II pilot data published August 21 in Nature Communications. The study pairs the early clinical signal with single-cell evidence that CXCR4 blockade may help reshape the immune-resistant PDAC tumor microenvironment.
The study enrolled 11 treatment-naïve patients with metastatic PDAC and treated them with the four-agent combination — referred to as MCGN — comprising motixafortide, cemiplimab, gemcitabine, and nab-paclitaxel. Corresponding authors Kenneth P. Olive, Benjamin Izar, and Gulam A. Manji led the work through Columbia University Irving Medical Center's Herbert Irving Comprehensive Cancer Center, with collaborators at Brown University's Legorreta Cancer Center, Memorial Sloan Kettering Cancer Center, the Huntsman Cancer Institute at the University of Utah, the University of North Carolina, and the Case Comprehensive Cancer Center.
Clinical findings
In the 11-patient pilot cohort, the regimen produced an objective response rate (ORR) of 64%, a confirmed partial response rate of 55%, and a disease control rate (DCR) of 91%, according to the paper. Four of the 11 patients remained progression-free after more than one year. Median progression-free survival and overall survival figures from the pilot phase have been reported at scientific meetings, though these are from a small, single-arm cohort without a contemporaneous comparator.
Motixafortide is FDA-approved under the brand name APHEXDA — in combination with filgrastim — for hematopoietic stem cell mobilization in multiple myeloma, marketed by BioLineRx. In the metastatic PDAC context it remains investigational.
Mechanism and single-cell correlatives
Cancer-associated fibroblasts in the PDAC tumor microenvironment (TME) secrete CXCL12, which signals through CXCR4 on immune cells to physically exclude cytotoxic T cells from the tumor — a principal reason checkpoint inhibitors have failed in this disease. Motixafortide blocks CXCR4, with the goal of disrupting this exclusion barrier and permitting T-cell infiltration that cemiplimab can then sustain.
Single-nucleus RNA sequencing (snRNA-seq) of serial biopsies in responding patients revealed decreased tumor heterogeneity and reduced epithelial-to-mesenchymal transition states compared with resistant patients. Responders showed enrichment of CXCL12-expressing cancer-associated fibroblasts, the paper reported, consistent with the proposed mechanism and potentially identifying a TME-based biomarker of response.