Efficacy of the combination of venetoclax and hypomethylating agents in the treatment of patients with primary, relapsed and/or refractory acute myeloid leukemia

Relevance and goals. Treatment of patients with acute myeloid leukemia has traditionally been highly intensive and includes induction therapy using cytarabine and anathracyclines. In addition to new opportunities in the treatment of acute myeloid leukemia, the problem of toxicity of high-intensity therapy in elderly and young somatically burdened patients is quite acute. International clinical trials of phases I-III demonstrated a combination of high efficacy and acceptable hematological toxicity of combinations of hypomethylating agents and venetoclax in the first line of therapy, as well as in the treatment of resistant forms and relapses of acute myeloid leukemia in the older age group, which contributed to the study of the effectiveness of combinations of hypomethylating agents and venetoclax in the treatment of similar groups of young comorbid patients. In this work, we evaluated the efficiency of a combination of hypomethylating agents and venetoclax and overall and disease-free survival in patients with acute myeloid leukemia in routine practice.

Methods. In the period from October 2017 to December 2021 on the basis of the Department of Hematology No. 11 and the Department of Bone Marrow and Hematopoietic Stem Cell Transplantation No. 56 of the Botkin Hospital (Moscow, Russia) 33 patients with acute myeloid leukemia received venetoclax therapy in combination with decitabine or azacitidine: 14 (42%) men and 19 (58%) women, median age was 60 years (23–83 years). In 42% (14 of 33) of cases, the regimen was prescribed for resistant course or relapse of acute myeloid leukemia and in 61% (20 of 33) as induction therapy. Three patients (15%) out of 19 from the group of newly diagnosed acute myeloid leukemia received this treatment regimen in the first line, taking into account the ECOG status 3-4. By August 2022, 13 (39%) patients are alive, 20 (61%) people have died. Overall survival, the rate of complete remission and complete remission with incomplete recovery, the rate of achieving negativity of minimal residual disease, the frequency of hematological toxicity and infectious complications were assessed. Statistical data processing used: frequency analysis using contingency tables (Fisher's exact test), survival analysis using the Kaplan-Meier method.

Results. Complete remission and complete remission with incomplete recovery were achieved in 72.72% (24 of 33) of patients. In the group of primary acute myeloid leukemia, remissions were observed in 80% (16 out of 20) of cases, in the group with resistant course or recurrence of acute myeloid leukemia in 67% (8 out of 12) (p = 0.3). Determination of minimal residual disease by flow cytometry after the 1st course was performed for 54.54% (18 of 33) patients, while negativity was stated in 84.2% (14 of 18 patients) cases. In both groups, the incidence of hematological toxicity and infectious complications are comparable to those according to the literature data. The median follow-up was 9.5 months (1–47). Median overall survival was 39 months, 2-year overall survival was 63%, and overall 4-year survival was 39%. The disease-free survival rate was 33%.

Conclusion. The combination of hypomethylating agents and venetoclax showed good efficacy and fairly high overall survival in patients of all age groups, both for primary acute myeloid leukemia and for relapses and resistant forms, regardless of previous therapy. Given the moderate hematological toxicity, as well as the relatively low rates of infectious complications during therapy, including the rather low mortality rates in case of COVID-19 infection in comparison with those on the background of high-intensity courses of therapy for acute myeloid leukemia, this scheme can be widely used not only in patients of the older age group, but also in young comorbid patients.

[The detection of minimal residual disease in patients with chronic B-cell lymphatic leukemia using patient-specified polymerase chain reaction]

The new effective protocols of treatment of chronic B-cell lymphatic leukemia, including purine analogs and monoclonal antibodies, provide robust remissions under this disease. Accordingly, the requirements to remission quality assessment are changed too. In particular the assessment of minimal residual disease is obligatory. To assess minimal residual disease in terms of quantity in case of chronic B-cell lymphatic leukemia the technique of polymerase chain reaction was applied in real time with patient-specific primers from the area of V-D-J combinations of genes of heavy chain of immunoglobulin. The study included samples from 60 patients suffering of chronic B-cell lymphatic leukemia. In 15 of them (25%), it was impossible to apply neither the sequence analysis of genes of heavy chain of immunoglobulin nor the fitting of patient-specific primer. The results of quantitative determination of minimal residual disease were obtained in 45 patients (55 tests). The minimal residual disease was detected in 30 of 55 samples (54.5%) and was not detected in 25 of 55 samples (45.5%). At the same time, the quantitative determination of minimal residual disease was implemented in regard to the initial level of neoplastic cells. The method sensitivity qualified by serial dilutions, consisted 10(-5) or 1 neoplastic cell to 100 000 normal cells. The comparative analysis was applied to the results of determination of minimal residual disease using two methods -polymerase chain reaction in real time using patient-specified primers and four-color flow cytofluometry. The determination of minimal residual disease with both methods was implemented in 37 patients (45 tests). The results of both methods matched in 93.3% (42 tests out of 45) with maximal disparity of one degree. Then Spearman factor consisted 0.87 (p < 0.0001). In 3 out of 45 tests (6.7%) neoplastic cells were detected with only one method. In the first case, it was the method of four-color flow cytofluometry and in other two cases it was polymerase chain reaction in real time. Therefore, the detection of minimal residual disease under chronic B-cell lymphatic leukemia using the method of polymerase chain reaction in real time is rather sensitive and specific and correlates with the results received with the method of four-color flow cytofluometry. The results are the same in the case of using anti-CD20 monoclonal antibodies under treatment.

[The characteristics of evaluation of expression of ZAP-70 in tumor cells under b-cell chronic lymphatic leukemia using the flow cytofluorometry technique]

The b-cell chronic lymphatic leukemia is the most common among all lymphatic proliferative diseases and is characterized by significant variability of its clinical course. The mutation status of genes of variable region of heavy chains of immunoglobulins (IgVH) is the most reliable prognostic factor forecasting time until beginning of treatment in case of b-cell chronic lymphatic leukemia. However its detection nowadays is inaccessible for routine diagnostics. Among surrogate markers of mutation status the indicator of expression of ZAP-70 by tumor cells estimated using flow cytofluorometry. However, in publications there are different guidelines concerning the technique of mentioned marker. To establish the optimal approach to evaluation of expression of ZAP-70 the peripheral blood samples of 5I patients with b-cell chronic lymphatic leukemia and 10 healthy persons were analyzed. The comparison with the results of detection of mutation status of IgVH-genes revealed the advantage of applying the technique of calculation of MFI ratio during interpretation of data of expression of ZAP-70 obtained with flow cytofluorometry. In this framework, the indicator of expression of ZAP-70 can be applied in assessing the course of disease and time until the beginning of treatment of b-cell chronic lymphatic leukemia.

[The prognostic value of evaluation of minimal residual disease using technique of flow cytofluorometry during application of therapy of chronic lymphatic leukemia]

The achievement of molecular remission is associated with increasing of survival of patients with chronic lymphatic leukemia. The important direction of research is seeking of parameters applicable to forecast of response to therapy. The purpose of the study was evaluating prognostic significance of indicator of minimal residual disease detected by technique of flow cytofluorometry of peripheral blood of patients with chronic lymphatic leukemia during therapy application. The sampling included 112 patients with chronic lymphatic leukemia aged from 43 to 82 years. All patients were given treatment consisted of 6 courses of immune chemotherapy combined with fludarabine with cyclophosphan and rituximab. The samples of peripheral blood were analyzed after 3 courses during therapy and after 6 courses after completion of treatment. The cells were analyzed using 5 and 6 color flow cytometry for the purpose of detection of immune phenotype associated with chronic lymphatic leukemia. The evaluation of minimal residual disease was implemented according international standardized protocol (Rawstron A.C. et al. 2007; 21 (5): 956-64). The minimal residual disease negative status was reached in 87 (78%) patients during evaluation of response after 6th course of treatment. The implementation of indicators of residual disease after 3 courses with fludarabine, cyclophosphan and rituximab permitted to sort out two groups of patients with chronic lymphatic leukemia i.e 67 patients with low (< 0.12%) level of minimal residual disease and 45 patients with high (> 0.12%) level of tumor cells. The rate of molecular remission after completion of treatment. in the given groups consisted 100% and 44% correspondingly. The study demonstrates possibilities of early immune phenotype evaluation of minimal residual disease to forecast differences in response to treatment in patients with chronic lymphatic leukemia that makes it possible to avoid undesirable toxicity of therapy or to choose method of consolidation.