Dual Growth Factor (rhTPO + G-CSF) and Chemotherapy Combination Regimen in Acute Myeloid Leukemia: Study Protocol for a Randomized Controlled Trial

Overview

Acute myeloid leukemia (AML) is a disease affecting older adults, although optimal strategies for treating such patients remain unclear. This prospective phase II, openlabel, multicenter study was designed to assess the efficacy and safety of two hematologic growth factors, recombinant human thrombopoietin (rhTPO) and granulocyte colonystimulating factor (G-CSF), in combination with decitabine, cytarabine, and aclarubicin (D-CTAG regimen) to treat older adults with newly diagnosed AML (Identifier: NCT04168138). The above agents were administered as follows: decitabine (15 mg/m2 daily, days 1-5); low-dose cytarabine (10 mg/m2 q12 h, days 3-9); rhTPO (15,000U daily, days 2, 4, 6, 8, 10-24 or until \>50×109/L platelets); aclarubicin (14 mg/m2 daily, days 3-6); and G-CSF (300 μg daily, days 2-9). We concurrently monitored historic controls treated with decitabine followed by cytarabine, aclarubicin, and G-CSF (D-CAG) only. After the first D-CTAG cycle, the overall response rate (ORR) was 84.2% (16/19), including 13 (73.7%) complete remissions (CRs) and three (15.8%) partial remissions. This CR rate surpassed that of the D-CAG treatment (p \< 0.05). Median overall survival (OS) time in the D-CTAG group was 20.2 months (range, 4-31 months), compared with 14 months in the D-CAG group, and 1-year OS was 78%. The proportion of those experiencing grade III-IV thrombocytopenia was significantly lower for D-CTAG (57.9%) than for D-CAG (88.4%; p \< 0.05). Ultimately, the curative effect of adding rhTPO was not inferior to that of D-CAG, and D-CTAG proved safer for elderly patients, especially in terms of hematologic toxicity. A prospective phase III randomized study is warranted to confirm these observations.

Acute myeloid leukemia (AML) is one of the most common hematologic malignancies and affects older adults. The median age at diagnosis is 67 years. As the elderly increasingly account for a greater population percentage, AML is becoming more problematic. During the past 30 years, outcomes have improved for younger patients, whereas the prospects for older adults (\> 60 years) have remained poor. The response rate in older adults given standard induction regimens is \< 50%, and median overall survival (OS) is \< 1 year. Older adults elderly are also inordinately burdened by unfavorable cytogenetic defects, medical comorbidities, and reduced tolerability to intensive chemotherapeutic protocols. These vulnerabilities predispose older adults to poorer outcomes than their younger counterparts, conferring lower response rates and shortened survival times (progression-free and overall survival \[OS\]). Safe and effective treatments for elderly patients with AML are thus urgently needed. In 2000, Saito et al introduced a regimen of granulocyte colony-stimulating factor (G-CSF) plus low-dose cytarabine (ara-C) and aclarubicin (ACR) for use in this setting (CAG regimen), in an attempt to incorporate a hematologic growth factor in AML induction therapy, rather than relying on supportive care. The addition of decitabine, a demethylation agent, further improved the prognosis, yielding a 10-month median OS. This successful use of G-CSF in an induction regimen for AML confirmed its utility, helping to increase efficacy and reduce side effects in elderly patients. Thrombopoietin (TPO) is a major factor in regulating megakaryocytic proliferation, maturation, and platelet formation. Recombinant human TPO (rhTPO) has been approved by China's State Food and Drug Administration to treat thrombocytopenia after chemotherapy. TPO and c-MPL receptors are also involved in various physiologic processes, such as mitigating myocardial injury, nerve repair, vascular regeneration, sex hormone secretion, and immune regulation. However, the role of rhTPO in an induction regimen for AML is unreported as yet. To determine if adding rhTPO to D-CAG (G-CSF) will increase the overall response rate (ORR) while decreasing the side effect of toxic agents, we designed a regimen of rhTPO and G-CSF in combination with decitabine, cytarabine, and aclarubicin (D-CTAG regimen). This trial aimed to determine the safety and efficacy of this D-CTAG regimen as a treatment for older adult patients with newly diagnosed AML.