On July 31, 2017 Mateon Therapeutics, Inc. (OTCQX:MATN), a biopharmaceutical company developing vascular disrupting agents (VDAs) for the treatment of orphan oncology indications, reported preliminary data from the fifth dose cohort of OX1222, a phase 1b dose-ranging study of OXi4503 in combination with cytarabine in patients with relapsed/refractory acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) (Press release, Mateon Therapeutics, JUL 31, 2017, View Source [SID1234519942]). Schedule your 30 min Free 1stOncology Demo! Two of four patients had morphological complete remissions after one cycle of treatment with 9.76 mg/m2 of OXi4503. Both patients will receive a second cycle of treatment.
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To date, five of 21 study patients in OX1222 have achieved complete remission. At lower doses of OXi4503, the complete remissions occurred following two cycles of treatment, with AML blast reductions noted following one cycle of treatment. In addition to the complete remissions, three other patients in the study experienced meaningful AML blast reductions – two in the third cohort and one in the fourth cohort.
"Every dose of OXi4503 tested in this study has shown encouraging signs of efficacy and a favorable safety profile, with the highest doses showing the earliest and best activity," said William D. Schwieterman, M.D., President and Chief Executive Officer of Mateon. "We continue to be excited about the potential to bring a much needed new treatment option to these very ill patients."
There were no dose-limiting toxicities observed in the fifth cohort and OXi4503 continued to have a favorable safety profile. The most common adverse events (AEs) of any grade across all cohorts include neutropenia, fever, nausea, anemia and diarrhea. Grade 3 or above AEs which were related to treatment include decreased neutrophil count (28%), decreased platelet count (28%), febrile neutropenia (22%), anemia (17%), and decreased white blood cell count (11%).
Mateon is continuing pharmaceutical partnering discussions to secure a partner or additional capital prior to initiating additional clinical studies of OXi4503 in AML.
About Acute Myeloid Leukemia
A devastating form of cancer of the blood and bone marrow, AML is the most common type of acute leukemia in adults and accounts for the greatest number of leukemia deaths in the United States. There is no standard regimen of care for patients who relapse following front-line treatment or have refractory disease. According to the NIH’s National Cancer Institute Surveillance, Epidemiology and End Results (SEER) program, there are an estimated 21,380 new cases of AML and 10,590 deaths expected in 2017 in the United States. AML arises from a clonal hematopoietic stem cell and is characterized by accumulation of malignant myeloblasts in the bone marrow and resulting in ineffective hematopoiesis. AML often responds initially to front-line treatment of conventional cytotoxic chemotherapy, but it often relapses and long-term disease-free survival is low, posing a significant challenge to treat relapsed and/or refractory disease.
About OXi4503
OXi4503 has received Fast Track designation from the U.S. Food and Drug Administration for the treatment of AML. It is a VDA that disrupts tumor vasculature residing within bone marrow while simultaneously targeting malignant myeloid cells. Preclinical data show that OXi4503 disrupts bone marrow endothelial cells which normally protect AML cells from exposure to chemotherapeutic agents. In human xenograft animal models of AML, OXi4503 has demonstrated almost complete elimination of leukemic cells. In other animal models, the combination of OXi4503 and cytarabine has shown a much greater effect against AML than either agent alone.