On November 15, 2021 Aadi Bioscience, Inc. ("Aadi") (Nasdaq: AADI), a clinical-stage biopharmaceutical company focusing on precision therapies for genetically-defined cancers with alterations in mTOR pathway genes, reported two oral presentations that were made related to its lead candidate, FYARRO (ABI-009 or nab-sirolimus) at the Connective Tissue Oncology Society (CTOS) 2021 Annual Meeting, held virtually from November 10-13, 2021 (Press release, Aadi Bioscience, NOV 15, 2021, View Source [SID1234595594]). CTOS is a multi-disciplinary group of specialized physicians, medical professionals and scientists from around the world who connect and share their knowledge, experiences and research for the advancement of treatment of sarcomas. Both studies, sponsored by Aadi, provided data in patients with advanced malignant PEComa, which is the clinical indication currently under review by the Food and Drug Administration (FDA) with a November 26, 2021 target Prescription Drug User Fee Act (PDUFA) date.
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Abstract (ID: 1080984), lead-authored by Mark A. Dickson, M.D., medical oncologist at Memorial Sloan Kettering Cancer Center is entitled, "nab-Sirolimus in Patients with Malignant PEComa Previously Treated With mTOR Inhibitors: Emerging Experience from an Expanded Access Program". Sixteen patients with Advanced Malignant Perivascular Epithelioid Cell Tumors (PEComa) were treated in an Expanded Access Program (NCT03817515) with nab-sirolimus, dosed intravenously at 100 mg/m2 given on day one and day eight of a 21-day cycle. The investigators concluded that nab-sirolimus showed encouraging clinical benefit including partial responses (PR) in 25% of patients previously progressing on other mTOR inhibitors and, in some cases, other targeted therapies. Disease control rate (DCR) as defined by complete or partial response + stable disease for ≥3 months, was 63%. In this study, the safety profile of nab-sirolimus was acceptable and allowed ongoing treatment for almost one year or more in several patients. In addition, consistent with results of the AMPECT trial, TSC1 or TSC2 alterations were associated with a higher response rate of 44% of patients, despite prior progression on other mTOR inhibitors and/or multiple lines of prior therapy. These results provide further rationale for investigation of nab-sirolimus in a tumor-agnostic study in patients with pathogenic inactivating TSC1 or TSC2 alterations.
A second abstract (ID: 1080747), lead-authored by Andrew J. Wagner, M.D., Ph.D., a senior oncologist at Dana-Farber Cancer Institute, is entitled, "Final Analysis from AMPECT, an Open-Label Phase 2 Registration Trial of nab-Sirolimus for Patients with Advanced Malignant Perivascular Epithelioid Cell Tumors (PEComa)". This abstract provided a final analysis of the AMPECT study with a data cut of June 30, 2021, updating the recent publication in the Journal of Clinical Oncology which was based on a data cut of November 23, 2020. nab-Sirolimus demonstrated rapid and durable responses in mTOR-naïve patients with locally advanced unresectable or metastatic PEComa. Specifically, of 31 treated and evaluable patients, the independently assessed confirmed overall response rate (ORR) was 39% (12/31, 95% confidence interval: 22, 58); of which 7% (2/31) of patients had a complete response (CR) and 32% (10/31) had a PR. Disease control was achieved in 71% of patients. The patient responses demonstrated long-term durability with a duration of response (DOR) of 92% at 6 months and 66% at 36 months amongst the 12 patients with a response. At the final analysis, the median DOR has not been reached, 50% of patients had a DOR of over 36 months (range 5.6, 55.5+ months). By the final analysis, two patients converted from a PR to CR after 11 months and 34 months of treatment, respectively. Finally, nab-sirolimus demonstrated an acceptable safety profile with no grade 4 or 5 treatment-related adverse events (TRAE) and no unexpected adverse events or new safety signals. Some of the most common TRAEs were stomatitis, rash, fatigue, anemia, nausea, diarrhea and hyperglycemia.
Dr. Dickson commented, "I am encouraged by the activity of nab-sirolimus not only in the AMPECT study, but in advanced PEComa patients previously progressing on other mTOR inhibitors, as well as in other solid tumor histologies with TSC1 or TSC2 inactivating alterations that has been previously presented. There is a strong rationale for conducting a broader investigation of nab-sirolimus in a tumor-agnostic setting."
About Malignant PEComa
Perivascular epithelioid-cell tumors (PEComa), defined by the World Health Organization as ‘mesenchymal tumors composed of distinctive cells that show a focal association with blood-vessel walls and usually express both melanocytic and smooth muscle markers,’ are a rare subset of soft-tissue sarcomas, with an undefined cell of origin. While there is no formal epidemiology for malignant PEComa, it is estimated that there are about 100-300 new patients per year in the United States. Malignant PEComas may arise in almost any body site (typically the uterus, retroperitoneum, lung, kidney, liver, genitourinary, and gastrointestinal tract with a female predominance) and can have an aggressive clinical course including distant metastases and ultimate death. The estimated survival based on retrospective reports is 12-16 months. Cytotoxic chemotherapies typically used for sarcoma show minimal benefit and there are currently no drugs approved for this disease. Malignant PEComas have been shown to frequently harbor mutations in the TSC1 and/or TSC2 genes that result in the activation of mTOR pathway making it a rational therapeutic target for this disease.