A 72.2% confirmed objective response rate in first-line RAS-mutated metastatic colorectal cancer is not a number the field has seen from a chemotherapy-backbone combination — historical benchmarks for FOLFIRI/bevacizumab alone sit closer to 47%, and the CRDF-004 control arm’s 42.1% ORR lands right in that range. That 30-percentage-point gap, reported Monday at the 2026 ASCO Annual Meeting, is the headline Cardiff Oncology needed to credibly pursue a registration strategy in one of oncology’s most treatment-resistant molecular subgroups.
The CRDF-004 Phase 2 trial randomized patients with KRAS- or NRAS-mutated mCRC across multiple dose and chemotherapy-backbone arms. The signal that matters came from one arm: 30 mg onvansertib added to FOLFIRI/bevacizumab. Median PFS has not been reached in that arm — nor in the 20 mg combination arm — while both SoC control arms have crossed their medians. Four patients have now been on onvansertib beyond 15 months, two beyond 20 months. The PFS hazard ratio of 0.55 by blinded independent central review carries a wide confidence interval given the small numbers (18 patients in the selected arm), but the directionality is consistent and the durability argument is real. Critically, no new or overlapping toxicities emerged; neutropenia was the most common Grade 3-plus event and appeared across both onvansertib and SoC arms equally.
The strategic setup here is specific. RAS mutations — predominantly KRAS and NRAS variants other than G12C — represent the majority of RAS-mutated colorectal cancers, and approved targeted options for this population remain extremely limited. The KRAS G12C niche now has a designated therapy following FDA’s January 2025 approval of sotorasib plus panitumumab, but that mutation accounts for less than 4% of all colorectal cancers. Onvansertib’s PLK1 mechanism is mutation-agnostic within the RAS-mutated class, which is precisely why the FOLFOX arms were also tested — though no efficacy signal emerged there, narrowing the registrational path cleanly to FOLFIRI/bevacizumab. Cardiff has already completed an End-of-Phase 2 meeting with FDA and aligned on a Phase 3 design comparing onvansertib 30 mg plus FOLFIRI/bevacizumab against FOLFIRI/bevacizumab alone in first-line RAS-mutated mCRC.
The number to watch now is enrollment pace for the Phase 3, not the Phase 2 ORR. Cardiff’s Phase 2 was designed for 110 patients across six arms — lean by design for dose selection, not powered for survival. A registrational trial in a molecularly defined subpopulation will require both geographic reach and biomarker-prescreening infrastructure Cardiff has not yet demonstrated at scale. Whether the company partners, raises capital, or runs it independently will determine whether this ASCO data point becomes a pivotal trial readout or a partnering asset.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
