Baseline data. A total of 35 patients with AML, including 15 women and 20 men, were involved in the analyses, with a median age of 56 years. Before accepting venetoclax, 3 patients were in a state of no remission after chemotherapy, 2 patients had relapsed after chemotherapy, 4 patients had accepted treatment after allogeneic hematopoietic stem cell transplantation because of different reasons (in 3 patients minimal residual disease reverted to positive; 1 patient progressed from myelodysplastic syndrome), 1 patient had relapsed before treatment, and the remaining 26 patients were newly diagnosed. Among them, 4 patients had favorable risk, 10 had intermediate risk and 21 had poor risk AML. The range and median of bone marrow blasts was 2.04–94.6 and 26.98%, respectively. Blast data from 4 patients were missing. Regarding genetic mutations, there were 11 patients with the WT1 mutation, 4 with the NPM1 mutation, 5 with the RUNX1 mutation, 4 with the ASXL1 mutation, 4 with the TET mutation, 3 with the TP53 mutation, 2 with the BCOR mutation, 4 with the AML-ETO1 mutation and 3 with the NRAS mutation. The albumin level in the 35 patients fluctuated between 29 and 56 g/l, with a median albumin concentration of 37.6 g/l (normal albumin level, 35–50 g/l). A total of 17 patients received 100 mg venetoclax once a day + 5 ml posaconazole three times a day, and 18 patients took only venetoclax daily. The venetoclax concentration varied greatly, with the minimum and maximum concentrations at 250 and 5,370 ng/ml, respectively, and the median venetoclax concentration was 1,420 ng/ml. By the end of the follow-up, 3 patients relapsed after taking venetoclax. In total, 6 patients died: 1 from severe pneumonia, 2 from septic shock and 3 from AML. Baseline data and the grouping of patients are shown in Figs. 1 and 2, and Table I.
Analyses of the potential influential factors on blood venetoclax concentration. The present study assessed patient sex, age, albumin level and whether treatment was combined with posaconazole or not to explore their effects on venetoclax concentration. It was observed that age (P = 0.689; Fig. 3A), albumin level (P = 0.945; Fig. 3B) and sex (P = 0.771; Fig. 3D) were not significantly associated with blood venetoclax concentration. However, patients who received venetoclax and posaconazole had higher blood venetoclax concentrations than those who used venetoclax only (P < 0.001; Fig. 3C). The ranges in the venetoclax monotherapy group and venetoclax plus posaconazole group were 256-2,430 and 969-5,370 ng/ml, respectively. Furthermore, in the venetoclax monotherapy group, half of the patients (9/18) achieved a low concentration while the rest of the patients achieved high concentrations. In the venetoclax plus posaconazole group, the proportion of patients that achieved low concentrations, standard concentrations and high concentrations were 6% (1/17), 35% (6/17) and 59% (10/17), respectively (Fig. 1).
Analyses of potential influential factors on BCL-2 expression. The present study revealed that BCL-2 expression in the 35 patients with AML at primary diagnosis was significantly correlated with bone marrow blast percentage (P < 0.001, r = 0.717; Fig. 3F). However, BCL-2 expression was not significantly correlated with age (P = 0.943; Fig. 3E), sex (P = 0.128; Fig. 3G) and cytogenetic risk (P = 0.170; Fig. 3H).
In all patients, a statistically significant difference was seen in BCL-2 expression between primary diagnosis and after using venetoclax within 28 days (P < 0.001; Fig. 3I). Statistically significant differences in BCL-2 expression before and after medication were also seen in the venetoclax monotherapy group (P < 0.001) and in the venetoclax plus posaconazole group (P < 0.001) (Fig. 3I). Notably, significant differences in BCL-2 expression before and after medication were also detected in the low concentration group (P = 0.002), the standard concentration group (P = 0.031) and the high concentration group (P < 0.001) (Fig. 3J).
Efficacy analyses. Out of the 35 patients, 18 patients were in the low BCL-2 expression group and 17 patients were in the high BCL-2 expression group. A significant difference was observed in the number of patients with overall response (OR) (P < 0.0001) and in the number of patients that achieved CR (P = 0.005) (Fig. 4A) The proportion of patients with OR and CR in the low-expression and high-expression BCL-2 groups was 100% (18/18) vs. 41% (7/17), and 61% (11/18) vs. 12% (2/17), respectively. (Fig. 4A) There was no significant difference in the number of patients who achieved CRi (P = 0.658) and the number of patients who achieved PR (P = 1) between the two different BCL-2 expression groups (Fig. 4A).
There was no significant difference in the number of patients who achieved CRi (P = 0.177), PR (P = 0.177) or OR(P = 0.711) between the venetoclax monotherapy group and the venetoclax plus posaconazole group (Fig. 4B). However, there was a significant difference in the number of patients who achieved CR (P = 0.002) between these two groups. In the venetoclax monotherapy group and venetoclax plus posaconazole group, 2 and 11 patients achieved CR, respectively (Fig. 4B).
In the low blood venetoclax concentration group, the numbers of patients with OR, and those that achieved CR, CRi and PR were 6, 1, 3 and 2 patients, respectively. In the standard concentration group, the number of patients were 5, 4, 1 and 0, respectively. Furthermore, in the high blood venetoclax concentration group the numbers were 14, 8, 2 and 4 patients, respectively. There was no significant difference in the number of patients in the three different venetoclax concentration groups (low venetoclax concentration vs. standard venetoclax concentration vs. high venetoclax concentration) that were OR(P = 0.680), achieved CR (P = 0.068), achieved CRi (P = 1) or achieved PR (P = 0.696) (Fig. 4C).
Safety analyses. Regarding adverse events, similar results were recorded between the venetoclax monotherapy group and the venetoclax plus posaconazole group, as follows:
Group 1 (without agranulocytosis or fever), P = 0.603; group 2 (fever with agranulocytosis), P = 0.489; group 3 (only agranulocytosis), P = 0.711 ; group 4 (only fever), P = 0.264; 0–2 grade leukopenia, P = 0.489; 3–4 grade leukopenia, P = 0.489; 0–2 grade anemia, P = 1; 3–4 grade anemia, P = 1; 0–2 grade thrombocytopenia, P = 1; 3–4 grade thrombocytopenia, P = 1; alanine aminotransferase (ALT) increase, P = 1 (Fig. 5A, C, E, G and S1).
No significant difference was observed in the number of adverse-exposure reactions between the patients within different venetoclax concentration groups (low concentration vs. standard concentration vs. high concentration), as follows: Group 1 (without agranulocytosis or fever), P = 0.472; group 2 (fever with agranulocytosis), P = 0.510; group 3 (only agranulocytosis), P = 0.886; group 4 (only fever), P = 0.071; 0–2 grade leukopenia, P = 0.343; 3–4 grade leukopenia, P = 0.343; 0–2 grade anemia, P = 0.260; 3–4 grade anemia, P = 0.260; 0–2 grade thrombocytopenia, P = 0.307; 3–4 grade thrombocytopenia, P = 0.307; ALT increase, P = 0.208 (Figs. 5B, D, F, H and S2). Throughout the study, no renal function impairments and tumor lysis syndrome were observed.
Effect of BCL-2 expression and venetoclax concentration on prognosis. OS of the patients was not significantly associated with initial BCL-2 expression (high expression vs. low expression, P = 0.11; Fig. 6A). In addition, no significant differences in OS were determined among the three venetoclax concentration groups (low concentration vs. standard venetoclax, P = 0.91; low concentration vs. high concentration, P = 0.32; standard venetoclax vs. high concentration, P = 0.40; Fig. 6B), or between the venetoclax monotherapy group and the venetoclax plus posaconazole group (P = 0.50; Fig. 6C).
Regarding PFS, patients with low initial BCL-2 expression had a better trend than those in the high BCL-2 expression group (P = 0.04; Fig. 6D). There were no obvious significant differences in PFS among the different venetoclax concentration groups and between the two treatments groups, respectively (low venetoclax concentration vs. standard concentration, P = 0.48; high concentration vs. standard concentration, P = 0.71; low concentration vs. high concentration, P = 0.06; venetoclax monotherapy vs. venetoclax plus posaconazole, P = 0.38). However, the PFS trend in the high concentration group was higher than that in the low concentration group, but this was not significant (Fig. 6E and F).
There were no significant differences in EFS between patients in the high and low initial BCL-2 expression groups (P = 0.79; Fig. 6G). Furthermore, the differences in EFS were not significant between the standard concentration and low concentration (P = 0.75), and standard concentration and high concentration (P = 0.10) groups. However, EFS was significantly different between the high concentration and low concentration groups (P = 0.01; Fig. 6H). There was no evident difference in EFS between patients treated with venetoclax and those treated with venetoclax plus posaconazole (P = 0.31; Fig. 6I).