Cohort 1 Combination Therapy Arm Shows 36% Remission Rate Among Response-evaluable Patients Treated to Date
Cohort 3 Monotherapy Patient Achieved Bone Marrow Complete Remission
Company Also Reports Myelodysplastic Syndrome Patient Enrolled in Dose Escalation Trial Remains Stable and on APVO436 After 18 Months of Treatment
SEATTLE, WA / ACCESSWIRE / June 9, 2022 / Aptevo Therapeutics Inc. ("Aptevo" or the "Company") (NASDAQ:APVO), a clinical-stage biotechnology company focused on developing novel immuno-oncology therapeutics based on its proprietary ADAPTIR™ and ADAPTIR-FLEX™ platform technologies, today announced new remission data on four additional patients. The new data includes one patient who achieved a complete remission (CR), one patient who achieved a complete remission with incomplete hematologic recovery (CRi) and two patients who achieved bone marrow complete remissions, or morphological leukemia-free state (MLFS), in the Company's on-going multi-cohort, multi-center Phase 1b expansion trial evaluating APVO436 for the treatment of acute myeloid leukemia (AML). The Company also provided an update on a myelodysplastic syndrome (MDS) patient from the dose escalation part of the trial.
Cohort 1 currently has the highest enrollment rate in the trial and preliminary data show that a total of four out of 11 response-evaluable patients (36%) reported on to date, have experienced remission while on therapy. Of the three new cohort 1 patients announced today, one is a CR, one is a CRi, and one is a bone marrow complete remission (MLFS). Cohort 1 is a combination arm of the trial that includes relapsed patients and those with primary refractory AML that failed to respond to frontline standard induction chemotherapy. Cohort 1 patients receive standard chemotherapy drug cytarabine or the standard chemotherapy triple drug combination MEC (mitoxantrone, etoposide, cytarabine) plus APVO436.
The fourth new patient reported on today participated in cohort 3, a monotherapy arm of the trial, and achieved a bone marrow complete remission (MLFS).
The table below summarizes the positive outcomes we have previously reported and those we are reporting today:
Summary of Reported Data (As of June 9, 2022) | Cohort 1 | Cohort 3 | Total |
| Previously Reported | |||
| 1 | 1 | |
| 1 | 1 | |
| Newly Reported - June 9, 2022 | |||
| 1 | 1 | |
| 1 | 1 | |
| 1 | 1 | 2 |
| Total | 4 | 2 | 6 |
"We are enthusiastic about sharing this remission data for four new patients, including three cohort 1 participants who are receiving APVO436 in combination with standard of care, after experiencing relapsed/refractory disease, meaning they did not respond or stopped responding to prior therapy, narrowing their options for further treatment," said Dirk Huebner, Chief Medical Officer at Aptevo Therapeutics. "The observed data are very encouraging and show a positive trend in the trial, potentially establishing a path for APVO436 in combination therapy."
The Company also announced today that a patient with high-risk myelodysplastic syndrome (MDS) enrolled in the dose escalation trial remains stable and continues treatment with APVO436 now exceeding 18 months. Prior to joining the trial, this patient received and failed treatment with a hypomethylating agent, a situation that is commonly expected to be a poor prognostic event associated with short survival probability of approximately four to six months.
In this study, a "complete remission (CR)" is defined as a patient with no evidence of leukemia after treatment. This means the bone marrow contains < 5% leukemic blasts and hematologic (blood) recovery that includes normal white blood cell and platelet counts and other markers of healthy blood.
A "CRi" is defined as a complete remission except for residual thrombocytopenia or neutropenia. A "bone marrow complete remission (MLFS)" is defined as bone marrow blasts consistent with complete remission,