Mateon Therapeutics Announces Updated Data from Fifth Cohort of Phase 1b Study of OXi4503 in Acute Myeloid Leukemia
New Data Continue to Show OXi4503 has Significant Potential as New Treatment for AML
OXi4503 Recently Prioritized as Lead Drug Development Program at Mateon
SOUTH SAN FRANCISCO, Calif. , Oct. 30, 2017 (GLOBE NEWSWIRE) -- Mateon Therapeutics, Inc . (OTCQX:MATN), a biopharmaceutical company developing investigational drugs for the treatment of orphan oncology indications, today announced updated 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 syndromes (MDS).
Mateon previously reported that two of four patients in this cohort of the study had morphological complete remissions following one cycle of treatment with OXi4503. A morphological complete remission occurs when an AML patient has fewer than 5% AML blasts in the bone marrow count following treatment and has no significant hematologic abnormalities or other evidence of disease.
One of the patients showing disease remission discontinued the study due to an unrelated adverse event. The other patient continued to receive treatment with an additional two cycles of OXi4503 and remains in complete remission with a cytogenetic complete response. A cytogenetic complete response occurs when testing shows eradication of chromosomal abnormalities following treatment.
"We continue to see encouraging signs of safety and efficacy for OXi4503 in Study OX1222, including complete remissions at very low doses and evidence of a dose-response as we progressively increase the dose of OXi4503 in the trial," said William D. Schwieterman, M.D., President and Chief Executive Officer of Mateon. "OXi4503 represents a completely new way to treat AML - by both killing tumor cells directly and by destroying their protective environment in the bone marrow. Based on the results seen to date, we are excited about the enormous potential for this compound in relapsed/refractory AML, especially in older patients unable to tolerate the high levels of chemotherapy typically needed to see a response. There is a huge unmet medical need in these patients and they specifically appear to benefit from treatment with OXi4503."
Summarized initial efficacy data generated to date from OX1222 in relapsed/refractory AML or MDS are as follows:
Cohort (Dose) n CR% PR% ORR%
Cohort 1 (3.75 mg/m2) 6 17% 0% 17%
Cohort 2 (4.68 mg/m2) 4 25% 0% 25%
Cohort 3 (6.25 mg/m2) 4 25% 25% 50%
Cohort 4 (7.81 mg/m2) 3 0% 33% 33%
Cohort 5 (9.76 mg/m2) 4 50% 0% 50%
n: number of patients
CR: complete remission
PR: partial remission
ORR: overall response rate (sum of partial and complete)
OXi4503 continues 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 anemia (32%), decreased platelet count (27%), decreased neutrophil count (23%) and decreased white blood cell count (18%).
Mateon is in the process of expanding the size of future, higher-dose cohorts to 10 patients to increase the utility of the data generated. The company is also continuing discussions to secure a partner or otherwise obtain additional capital prior to initiating treatment in the sixth cohort of Study OX1222.
