Introduction:
Liposomal daunorubicin and cytarabine (CPX-351) was approved based on data which showed improved overall survival (9.56 v 5.95 months; p = .003) and remission rates (47.7% v 33.3%; p = .016) compared to conventional cytarabine and daunorubicin (7+3) chemotherapy in older patients with newly diagnosed secondary acute myeloid leukemia (sAML). Patients receiving CPX-351 had prolonged time to neutrophil and platelet count recovery compared to 7+3, which was not associated with adverse outcomes (Lancet et al, JCO 2018). Based on these data, our center adopted CPX-351 as a first-line agent in this patient population. Considering the significant cost differences and delays in count recovery, we conducted a comparison of outcomes in patients who received CPX-351 versus 7+3 at our center.
Methods:
The objective of this study was to compare efficacy and safety of CPX-351 versus 7+3 in patients with sAML. Primary outcome was response rate as defined by CR or CRi. Secondary outcomes included duration of neutropenia, incidence of invasive fungal infections (IFIs), and number of patients proceeding to allogeneic hematopoietic cell transplant (HCT). Patients with sAML receiving induction with 7+3 (daunorubicin dosed at 60 or 90 mg/m2 per treating physician's discretion) or CPX-351 from July 2014 to April 2020 were reviewed. Secondary AML was defined as: AML with a history of myelodysplastic syndrome (MDS) or chronic myelomonocytic leukemia (CMML), AML with myelodysplasia-related changes, or therapy-related AML. Patients with prior myeloproliferative neoplasms, myelofibrosis, or FLT3 mutations were excluded. Patient characteristics were summarized using descriptive statistics (TABLE 1) including mean for continuous measures and proportions and frequencies for categorical measures. The association between continuous variables and patient groups were assessed using ANOVA or Student's t-test. The associations between categorical variables and patient groups were evaluated using Chi-square test.
Results:
Over the study period, 65 patients with sAML received induction therapy with either CPX-351 (n = 31) or 7+3 (n = 34). Of these, 61 patients had an evaluable bone marrow biopsy at count recovery. The data is summarized in Table 2. The response rates (CR or CRi) were no different (36% 7+3 vs 36% CPX-351, p = 0.958) among the study population. Longer duration of neutropenia was observed with CPX-351 (33 days 7+3 vs 47 days CPX-351, p = 0.026). More patients in the 7+3 arm proceeded to allogeneic HCT; however, this was not statistically significant (59% 7+3 vs 39% CPX-351, p = 0.105). In an efficacy subgroup analysis of patients with TP53 mutation, there was no difference in response rates (33% 7+3 vs 11% CPX-351, p = 0.224).
There was no difference in IFI between the groups (38% 7+3 vs 42% CPX-351, p = 0.761). Upon further analysis of IFI characteristics, there was no difference in choice of mold-active vs non mold-active prophylaxis (ppx) and the incidence of IFIs (40% mold ppx vs 39% non-mold ppx, p = 0.91). Patients with baseline neutropenia prior to induction did not have increased risk of IFIs (65% 7+3 vs 74% CPX-351, p = 0.626). Additionally, there were no between group differences in incidence of IFIs in patients who were neutropenic prior to induction.
Conclusions:
In the evaluable dataset of patients receiving 7+3 or CPX-351, there was no difference in CR/CRi rate between the two subgroups. There was a longer duration of neutropenia in the CPX-351 group without increased incidence of IFI. However, we report a higher incidence of IFI compared to the study population in Lancet et al (18% Lancet vs 40% Miami) despite appropriate anti-fungal prophylaxis, which may be due to patient selection on the clinical trial, demographic differences (e.g., age, ethnicity), or locoregional environmental factors. In our population, a greater percentage of patients who received 7+3 proceeded to allogeneic HCT. While this study was not powered to detect a significant difference between the two regimens and these findings require validation in larger cohorts, they do not support superior outcomes in patients who receive CPX-351. Data on differences in hospital costs will also be presented. Future directions include a larger multi-center real-world analysis to evaluate patient outcomes, safety, and the financial implications of these two regimens.
Watts:Genentech: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Rafael Pharma: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Aptevo Therapeutics: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees.
