SAN DIEGO, Calif. — October 21, 2026
Cardiff Oncology, Inc. (NASDAQ: CRDF), a clinical-stage biotechnology company developing cancer therapies through polo-like kinase 1 (PLK1) inhibition, announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to onvansertib for the treatment of chronic myelomonocytic leukemia (CMML). The designation supports the development of onvansertib, an investigational oral PLK1 inhibitor, for this rare hematologic malignancy, which has limited treatment options and can lead to progressive bone marrow failure or transformation to acute myeloid leukemia (AML). Cardiff Oncology is evaluating onvansertib across several cancers, including CMML and RAS-mutated metastatic colorectal cancer. According to the company, the designation adds to the clinical development program for onvansertib and its investigation as a potential treatment for patients with significant unmet medical needs.
Clinical Study Reports Preliminary Activity in CMML
Onvansertib is being evaluated in company-sponsored and investigator-initiated clinical studies, including a Phase 1 investigator-initiated trial in relapsed or refractory CMML. Data presented at the 2025 American Society of Hematology (ASH) Annual Meeting indicated that onvansertib monotherapy was relatively well tolerated and demonstrated preliminary clinical activity in patients with myeloproliferative CMML. The company reported clinical benefits in approximately 40% of patients in the dose-ranging trial. Specifically, three patients, representing 38% of the reported group, experienced individual clinical benefits: one had a 100% platelet response, another achieved normalization of white blood cell counts from a baseline above 50 × 10⁹/L, and a third experienced a spleen response. Additionally, one patient, or 12.5%, achieved an optimal bone marrow response, with bone marrow blasts decreasing from 8% to 2%, enabling progression toward an allogeneic hematopoietic stem cell transplant. Three patients, representing 38%, experienced stable disease. These findings are preliminary and do not establish onvansertib’s efficacy for CMML; further clinical evaluation is needed to determine its safety and therapeutic benefit.
Orphan Drug Designation Offers Development Incentives
The FDA grants Orphan Drug Designation to support the development of drugs intended to treat rare diseases or conditions affecting fewer than 200,000 people in the United States. Potential benefits include tax credits for qualified clinical trials, exemptions from certain FDA user fees and up to seven years of market exclusivity following regulatory approval, subject to applicable requirements. The designation does not mean that a drug has been approved or that its safety and effectiveness have been established. Cardiff Oncology CEO Mani Mohindru said the designation highlights the potential of PLK1 inhibition in cancers with substantial unmet medical needs. The company noted that approximately 40%–50% of patients with myeloproliferative CMML-1 harbor RAS-pathway mutations, which are associated with more aggressive disease. Cardiff Oncology intends to continue investigating onvansertib as a monotherapy and across additional cancer indications.
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Onvansertib Development Extends Across Multiple Cancers
Beyond CMML, Cardiff Oncology is advancing onvansertib for RAS-mutated metastatic colorectal cancer (mCRC). In a randomized Phase 2 trial, onvansertib combined with FOLFIRI and bevacizumab demonstrated dose-dependent improvements in overall response rate and progression-free survival compared with standard-of-care treatment alone, according to the company. Building on findings from an earlier Phase 2 trial in second-line RAS-mutated mCRC, Cardiff Oncology selected a 30 mg dose of onvansertib in combination with FOLFIRI and bevacizumab for a planned registrational trial in first-line patients. Investigator-initiated studies are also evaluating the drug in metastatic pancreatic ductal adenocarcinoma, small cell lung cancer and triple-negative breast cancer. CMML is characterized by features of both myelodysplastic syndromes and myeloproliferative neoplasms and primarily affects older adults. The new FDA designation supports continued development of onvansertib for this rare disease, while its potential role in CMML and other cancers remains dependent on further clinical results and regulatory review.
Source:Cardiff Oncology,press release
