Cardiff Oncology, Inc. (NASDAQ: CRDF) announced that the U.S. Food and Drug Administration has granted Orphan Drug Designation to onvansertib for the treatment of chronic myelomonocytic leukemia (CMML), a rare hematologic malignancy.

The FDA grants Orphan Drug Designation to therapies intended to treat rare diseases affecting fewer than 200,000 people in the United States. The designation may provide benefits including tax credits for qualified clinical trials, exemption from certain FDA user fees, and up to seven years of market exclusivity upon regulatory approval. The designation does not alter standard regulatory requirements or the approval process.

Onvansertib is currently being evaluated in a Phase 1 investigator-initiated study in relapsed/refractory CMML. Data presented at the 2025 American Society of Hematology Annual Meeting showed the drug was relatively well-tolerated as a monotherapy and demonstrated preliminary efficacy in approximately 40% of myeloproliferative CMML patients in a dose-ranging trial. Among respondents, three patients experienced clinical benefit, including a 100% platelet response, normalization of white blood cell count, and a spleen response. One additional patient had an optimal marrow response with bone marrow blast reduction from 8% to 2%, facilitating an allogeneic hematopoietic stem cell transplant, and three patients experienced stable disease.

Mani Mohindru, PhD, President and Chief Executive Officer of Cardiff Oncology, said the designation "further validates the therapeutic potential of PLK1 inhibition in cancers with significant unmet need."

Onvansertib is also being evaluated in other cancer types through investigator-initiated studies, including metastatic pancreatic ductal adenocarcinoma, small cell lung cancer, and triple-negative breast cancer. The company's primary development focus for onvansertib remains a planned registrational trial in first-line RAS-mutated metastatic colorectal cancer, based on results from a randomized Phase 2 trial.