Purple Biotech Ltd. reported additional positive interim data from its randomized, controlled, open label, multicenter Phase 2 study (NCT 04731467) of CM24, in combination with Bristol Myers Squibb's immune checkpoint inhibitor nivolumab and standard of care (SoC) chemotherapy, in second-line metastatic pancreatic ductal adenocarcinoma (PDAC). These results suggest that serum MPO may be a predictive biomarker for survival in the CM24+Nivolumab + Nal-IRI/5FU/LV arm. The company also announced that it will host a virtual KOL event on July 11, 2024 at 10:30 AM ET to discuss the results in detail.

Interim results that were presented on June 1, 2024 during a late-breaking abstract poster presentation at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting demonstrated a 26% reduction in risk of death (HR=0.74) and a 28% risk reduction in progression or death (HR=0.72) in previously-treated patients treated with CM24+nivolumab+Nal-IRI/5FU/LV vs. Nal-IRI/5FU/LV chemotherapy alone (i.e., SoC). Median OS was prolonged by 2.1 months and median PFS was extended by 1.9 months in the CM24+nivolumab+Nal-IRI/5FU/LV regimen vs.

SoC. The prolongation of both OS and PFS by the CM-24-nivolumab therapy is further supported by a higher ORR (25% vs 7%), DCR (63% vs 40%), and decrease in CA19-9 level (61% decrease vs. 34% increase).

New Interim Exploratory Biomarker Data: This interim biomarker analysis comparing the experimental and control arms suggests measured baseline serum MPO as a potential clinical outcome biomarker for CM24-nivolumab therapy. Enhanced MPO levels were measured in >90% of the patients with mean MPO over 6-fold higher than healthy donors. The mean MPO is used as a threshold for evaluating MPO as a potential biomarker.

The effect of the CM24-nivolumab therapy in combination with Nal-IRI/5FU/LV is most pronounced among patients with serum MPO levels below the mean MPO and is associated with OS improvement of 3.6 months in median OS of 8.1 months vs. 4.5 months (HR 0.34 (95% CI: 0.099-1.149)). While in a small sample size, these findings suggest that serum MPO may be a predictive biomarker for the treatment effect of CM24+Nivo+ Nal-IRI/5FU/LV on OS.

While in a small sample size, these findings suggest that serum MPO may be a predictive biomarker for the treatment effect of CM24+Nivo+ Nal-IRI/5FU/LV on OS. The experimental arms of the randomized Phase 2 study administered patients with CM24 plus nivolumab and a choice of one of two SoC chemotherapies used in second-line PDAC, and dependent on prior first line therapy regimen; either gemcitabine/nab-paclitaxel or liposomal irinotecan (Nal-IRI)/5-fluorouracil (5-FU) and leucovorin (LV) (Nal-IRI/5FU/LV), while the control arms administered either respective SoC chemotherapy alone. Interim results are provided for the Nal-IRI/5FU/LV sub study.

An analysis of the gemcitabine/nab-paclitaxel sub study will be performed later when the data sufficiently matured. CM24 is a humanized monoclonal antibody that blocks CEACAM1, an immune checkpoint protein responsible for tumor immune evasion and poor tumor response and/or resistance to immune checkpoint inhibitors. Neutrophil extracellular traps (NETs) which are involved in immune evasion and metastasis known to affect disease progression and patient survival.

CM24, a CEACAM1 antibody, was reported to also bind to NET structures and significantly suppresses the NET-induced migration of various cancer cells, as an additional Mechanism of Action. In an earlier part of this study, CM24+nivolumab treatment significantly reduced the level of the NET marker, as represented by measurable MPO in patient serum.