On October 21, 2026 Cardiff Oncology, Inc. (Nasdaq: CRDF), a clinical-stage biotechnology company leveraging PLK1 inhibition to develop novel cancer therapies, reported that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to onvansertib for the treatment of patients with chronic myelomonocytic leukemia (CMML).
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"CMML remains a difficult-to-treat hematologic malignancy with limited treatment options for patients, and 40-50% of myeloproliferative CMML1 patients harbor RAS-pathway mutations, which are associated with more aggressive disease," said Mani Mohindru, PhD, President and Chief Executive Officer of Cardiff Oncology. "Receiving Orphan Drug Designation for onvansertib in CMML further validates the therapeutic potential of PLK1 inhibition in cancers with significant unmet need and adds to the growing body of evidence supporting this mechanism across both solid tumors and hematologic malignancies. We believe this designation highlights the broader clinical opportunity for onvansertib as a monotherapy as we continue advancing therapies for patients across cancers where new therapeutic approaches are urgently needed."
Onvansertib is being evaluated in both company-sponsored and investigator-initiated clinical studies, including a Phase 1 investigator-initiated study in relapsed/refractory CMML. As presented at the 2025 American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting, onvansertib was relatively well-tolerated as a monotherapy and demonstrated preliminary efficacy in approximately 40% of myeloproliferative CMML patients in the dose ranging trial. The responses included three patients experiencing clinical benefits (38%), with one each of the following: a 100% platelet response, normalization of White Blood Cells, WBC (baseline WBC count > 50 x 109/L), and spleen response. Additionally, one patient (12.5%) had optimal marrow response with bone marrow blast reduction from 8% to 2% facilitating for allogeneic hematopoietic stem transplant and 3 patients experienced stable disease (38%).
Orphan Drug Designation is granted by the FDA to support the development of therapies intended to treat rare diseases or conditions affecting fewer than 200,000 people in the United States. Benefits of the designation may include tax credits for qualified clinical trials, exemption from certain FDA user fees, and up to seven years of market exclusivity upon regulatory approval. Orphan Drug Designation does not alter the standard regulatory requirements or approval process.
About Onvansertib
Onvansertib is a highly specific, oral PLK1 inhibitor advancing toward a registrational trial in first-line RAS-mutated metastatic colorectal cancer (mCRC). In a randomized Phase 2 trial, onvansertib in combination with FOLFIRI/bevacizumab (first-line standard-of-care) demonstrated dose-dependent improvements in overall response rate and progression-free survival compared to standard-of-care alone, building on findings from a prior Phase 2 trial in second-line RAS-mutated mCRC. Based on these results, the Company has selected the 30 mg dose of onvansertib in combination with FOLFIRI/bevacizumab as the regimen to advance into the planned registrational trial in first-line patients with RAS-mutated mCRC.
Onvansertib is also being evaluated in multiple other cancers through investigator-initiated studies, including metastatic pancreatic ductal adenocarcinoma (mPDAC), small cell lung cancer (SCLC), triple-negative breast cancer (TNBC), and chronic myelomonocytic leukemia (CMML).
About Chronic Myelomonocytic Leukemia
Chronic myelomonocytic leukemia (CMML) is a rare and aggressive hematologic malignancy characterized by features of both myelodysplastic syndromes and myeloproliferative neoplasms. CMML primarily affects older adults and is associated with poor clinical outcomes, including progressive bone marrow failure and risk of transformation to acute myeloid leukemia (AML). Current treatment options remain limited, highlighting the need for novel targeted therapies that can improve outcomes for patients with this disease.
(Press release, Cardiff Oncology, OCT 21, 2026, View Source [SID1234673658])