On August 12, 2026 Leap Therapeutics, Inc., the biotechnology subsidiary of Cypherpunk Technologies Inc. (Nasdaq: CYPH), reported the publication of results from the randomized Phase 2 DeFianCe study of sirexatamab (DKN-01), an anti-DKK1 monoclonal antibody, in Clinical Cancer Research.
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The publication, "Sirexatamab in Combination with Bevacizumab and Chemotherapy as Second-Line Therapy for Advanced Colorectal Adenocarcinoma: the Phase II DeFianCe Trial," reports the complete efficacy, safety and biomarker analyses from the study and details the statistical basis for the DKK1 biomarker finding. It is available online at View Source
The peer-reviewed analyses establish that the benefit of sirexatamab increases as a patient’s baseline plasma DKK1 level rises — a relationship confirmed by independent statistical approaches and reinforced by the observation that high DKK1 predicts poorer outcomes on standard of care alone. Together, these findings define DKK1-high mCRC as a biologically distinct population with high unmet need and provide the scientific foundation for a biomarker-selected Phase 3 trial. Additional information regarding the Company’s regulatory plans and strategic process for sirexatamab is included in the second quarter 2026 financial results announcement issued today by Cypherpunk Technologies Inc.
"In second-line colorectal cancer, we urgently need novel biomarkers that inform patients’ treatment options. The final data from the DeFianCe study show that baseline plasma DKK1 identifies patients with more aggressive disease, and it identifies the patients who benefit most from adding sirexatamab. Patients with high DKK1 do worse on standard of care, and they are the patients who gained the most in response and survival when sirexatamab was added," said Zev Wainberg, MD, Professor of Medicine at UCLA and co-director of the UCLA GI Oncology Program.
"Microsatellite-stable colorectal cancer remains one of the most difficult settings in gastrointestinal oncology, as patients whose disease progresses after first-line therapy have quite limited options. We need new liquid biopsy biomarkers that tell us effectively which patients will benefit from which therapy. These data support the utility of baseline plasma DKK1 as a liquid biomarker for improving response rates and survival with sirexatamab, making a compelling case for a biomarker-selected Phase 3 registrational trial," said Markus Moehler, MD, PhD, Head of GI Oncology, Senior Physician Gastroenterology & Endosonography Head at the Mainz University Clinic.
Key Findings from the Publication
DeFianCe (NCT05480306) was a two-part, randomized, open-label, multicenter Phase 2 study. Part B randomized 188 patients 1:1 to sirexatamab plus FOLFIRI or mFOLFOX6 and bevacizumab (Sirexatamab Arm) or to chemotherapy and bevacizumab alone (Control Arm). The primary endpoint was investigator-assessed progression-free survival (PFS); secondary endpoints included objective response rate (ORR) and overall survival (OS). Baseline plasma DKK1 was a prespecified candidate biomarker.
Sirexatamab benefit increased as baseline plasma DKK1 rose
Three independent analyses — a continuous treatment-by-DKK1 interaction model, a permutation-tested Biomarker Adaptive Threshold (BAT) analysis, and median- and upper-quartile subgroup analyses — converged on the same conclusion: benefit rises with baseline plasma DKK1.
The treatment-by-DKK1 interaction was statistically significant for both PFS (p=0.0129) and OS (p=0.0027), with DKK1 modeled as a continuous variable.
The BAT analysis with permutation testing reached the same conclusion (PFS p=0.018; OS p<0.001), and the data-driven cut points aligned with the median and upper quartile of baseline plasma DKK1.
DKK1-high patients above the median (n=88)
ORR was 38.0% in the Sirexatamab Arm compared with 23.7% in the Control Arm.
Median PFS was 9.0 months versus 7.1 months; HR 0.61 (95% CI, 0.37–1.00); p=0.0255.
Median OS was not reached versus 14.4 months; HR 0.42 (95% CI, 0.19–0.91); p=0.0118.
DKK1-high patients in the upper quartile (n=44)
ORR was 44.0% in the Sirexatamab Arm compared with 15.8% in the Control Arm; p=0.0149.
Median PFS was 9.4 months versus 5.9 months; HR 0.46 (95% CI, 0.22–0.96); p=0.0168.
Median OS was not reached versus 9.5 months; HR 0.17 (95% CI, 0.05–0.53); p<0.001.
Higher baseline DKK1 was also prognostic of poor outcome
In the Control Arm, median OS declined as DKK1 rose — not reached in the overall population, 14.4 months above the median, and 9.5 months in the upper quartile — consistent with published evidence linking elevated DKK1 to more aggressive disease.
DKK1-high patients therefore represent a population with both poor prognosis on standard therapy and the greatest observed benefit from sirexatamab.
Plasma DKK1 is a practical, blood-based biomarker
Baseline plasma DKK1 was detectable in 100% of patients across an approximately eight-fold dynamic range.
Levels were concordant across two orthogonal platforms — an aptamer-based SomaScan assay and an antibody-based Meso Scale Discovery (MSD) assay (Spearman r=0.77).
Tumoral DKK1 mRNA expression was low in most tissue samples, reinforcing that plasma — not tissue — reflects the systemic DKK1 burden relevant to colorectal cancer biology, and supporting a blood-based patient-selection test.
Results in the overall intent-to-treat (ITT) population
The prespecified primary endpoint of PFS in the ITT population was not met. Median PFS was 9.2 months in the Sirexatamab Arm versus 8.3 months in the Control Arm; HR 0.84 (95% CI, 0.58–1.21). ORR was 35.1% versus 26.6%, and median OS was not reached in either arm; HR 0.83 (95% CI, 0.46–1.48).
The final analysis included 119 investigator-assessed PFS events against the 145 events planned, leaving the ITT analysis underpowered in a biologically heterogeneous population.
Safety
Sirexatamab in combination with chemotherapy and bevacizumab was generally well tolerated. Grade 3 or higher treatment-emergent adverse events (TEAEs) occurred in 59.3% of patients in the Sirexatamab Arm compared with 67.0% in the Control Arm, and serious TEAEs were comparable between arms (19.8% versus 19.3%).
TEAEs leading to discontinuation of sirexatamab occurred in 4.4% of patients, indicating that adding sirexatamab did not meaningfully change the tolerability of standard of care.
About Sirexatamab (DKN-01)
Sirexatamab (DKN-01) is a humanized monoclonal antibody that binds and neutralizes Dickkopf-related protein 1 (DKK1), a secreted modulator of Wnt signaling associated with more aggressive disease, immune suppression, angiogenesis and poorer outcomes in colorectal and other cancers. In May 2026, the FDA granted Fast Track designation to sirexatamab in combination with fluoropyrimidine plus oxaliplatin- or irinotecan-based chemotherapy and bevacizumab for the treatment of patients with DKK1-high metastatic colorectal cancer whose disease has progressed following one prior systemic therapy.
(Press release, Leap Therapeutics, AUG 12, 2026, View Source [SID1234670021])