On April 17, 2026 Cardiff Oncology, Inc. (Nasdaq: CRDF), a clinical-stage biotechnology company leveraging PLK1 inhibition to develop novel therapies across a range of cancers, reported it will present new preclinical data in a poster at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2026, taking place April 17–22 in San Diego, California. These data highlight the potential of Cardiff’s highly specific oral PLK1 inhibitor, onvansertib, in combination with the HER2-targeted antibody-drug conjugate (ADC), trastuzumab deruxtecan (T-DXd), demonstrating robust antitumor activity and the ability to overcome resistance in HER2-low breast cancer models.
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"These preclinical findings highlight a potential new opportunity for onvansertib, demonstrating its ability to enhance the activity of ADCs, which are becoming mainstays in oncology across multiple indications," said Tod Smeal, Ph.D., Chief Scientific Officer of Cardiff Oncology. "By enhancing and prolonging DNA damage, this combination appears to drive greater apoptosis than either agent alone, offering a promising new approach for patients whose cancers have become resistant to standard-of-care treatments."
Poster Presentation Highlights:
Onvansertib + T-DXd synergistically inhibited the viability of HER2-low breast cancer cell lines, including fulvestrant- and CDK4/6i-resistant cells
In the resistant triple-negative breast cancer model and two hormone receptor-positive models, the combination drove tumor regression in nearly all mice, with complete response rates up to 62%
Increased tumor regression, improved tumor growth inhibition, and extended event-free survival across models
Combination showed favorable tolerability in vivo
Following the presentation on April 19, 2026 from 2:00–5:00 PM PT, the poster titled "PLK1 inhibitor onvansertib potentiates the antitumor efficacy of trastuzumab deruxtecan (T-DXd) and reverses its resistance in therapy-resistant HER2-low breast cancer models" will be available on the Scientific Publications page of the Company’s website.
About Onvansertib
Onvansertib is a highly specific, oral PLK1 inhibitor currently in mid-stage clinical development for RAS-mutated metastatic colorectal cancer. It 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).
(Press release, Cardiff Oncology, APR 17, 2026, View Source [SID1234664509])