In-depth characterization of NK cell markers from CML patients who discontinued tyrosine kinase inhibitor therapy

Introduction

Treatment-free remission (TFR) in patients with chronic myeloid leukemia in chronic phase is considered a safe option if suitable molecular monitoring is available. However, the question arises as to which factors can contribute to the maintenance of TFR, and immunologic surveillance of the remaining leukemic cells is believed to be one of them. Argentina Stop Trial is an open-label, single-arm, multicenter trial assessing TFR after tyrosine kinase inhibitors interruption, that after more than 4 years showed a successful TFR rate of 63%.

Methods

In this context, we set up an immunological study by flow cytometry in order to analyze specific NK cell subsets from peripheral blood patient samples both at the time of discontinuation as well as during the subsequent months.

Results

At the time of discontinuation, patients show a mature NK cell phenotype, probably associated to TKI treatment. However, 3 months after discontinuation, significant changes in several NK cell receptors occurred. Patients with a higher proportion of CD56dim NK and PD-1+ NK cells showed better chances of survival. More interestingly, non-relapsing patients also presented a subpopulation of NK cells with features associated with the expansion after cytomegalovirus infection (expression of CD57+NKG2C+), and higher proportion of NKp30 and NKp46 natural cytotoxicity receptors, which resulted in greater degranulation and associated with better survival (p<0.0001).

Discussion

This NK cell subset could have a protective role in patients who do not relapse, thus further characterization could be useful for patients in sustained deep molecular response.

Elevated plasma levels of IL-6 and MCP-1 selectively identify CML patients who better sustain molecular remission after TKI withdrawal

Treatment-free remission (TFR) in chronic myeloid leukemia (CML) is safe under adequate molecular monitoring, but questions remain regarding which factors may be considered predictive for TFR. Argentina Stop Trial (AST) is a multicenter TFR trial showing that 65% of patients sustain molecular remission, and the prior time in deep molecular response (DMR) was associated with successful TFR. Luminex technology was used to characterize cytokines in plasma samples. Using machine learning algorithms, MCP-1 and IL-6 were identified as novel biomarkers and MCP-1^low/IL-6^low patients showed eightfold higher risk of relapse. These findings support the feasibility of TFR for patients in DMR and MCP-1/IL-6 plasma levels are strong predictive biomarkers.

Is assessment of surface CD38 expression worthwhile as a prognostic factor in chronic lymphocytic leukemia patients?

We studied the clinical impact of CD38 expression in 226 chronic lymphocytic leukemia patients (CLL) at disease presentation and during follow up to determine its prognostic significance, progression free survival (PFS) and overall survival (OS), and to verify whether this parameter changed over time. Various patients' characteristics were studied including gender, Rai and Binet stages, immunoglobulin light chain expression, lymphocyte doubling time and CD38 expression. After a median follow up of 53 months (range 6-282), 62% CD38 positive(+) patients required therapy. PFS and OS at 84 months were significantly lower for CD38(+) patients: 20 and 71% respectively, compared to CD38 negative(-): 70 and 96%. At multivariate analysis CD38(+) showed to be the best factor for predicting progression: HR 3.3, 95%CI 2.10-5.14, p = 0.000. Its expression did not change in 98% re-evaluated patients. We confirm that CD38(+) is a stable parameter for the identification of CLL patients with a more aggressive disease course.

[Eight years of experience in a single institution in hematopoietic stem cell autologous transplantation in malignant hematological diseases and in solid tumors]

Between August 1991 and December 1998, 400 patients (lymphomas: 197; acute leukemia: 86; multiple myeloma: 70 and solid tumors: 47) were admitted for autologous transplantation. All patients were mobilized with chemotherapy plus G-CSF. The hematological recovery was similar in all disease groups. Patients with acute leukemias and multiple myeloma had a slower platelet recovery. Treatment-related death was 4.5%. The status of the disease at diagnosis was the most significant prognostic factor. With a median follow-up of 23 months the probability of event-free survival at 60 months was 46% for low grade lymphoma, 44% for intermediate and high grade lymphoma, 58% for Hodgkin's disease, 45% for acute myeloblastic leukemia, 38% for solid tumors and 15% for multiple myeloma. The probability of survival at 60 months was 67% for low grade lymphoma, 47% for intermediate and high grade lymphoma, 75% for Hodgkin's disease, 52% for acute myeloblastic leukemia, 54% for solid tumors and 25% for multiple myeloma. It can be concluded that autologous progenitor cell transplantation induces a complete and faster hematological recovery in all groups of patients without any late graft failure. Results are similar to those published in the literature. The treatment-related death was low and acceptable.

Autologous peripheral blood progenitor cell transplantation mobilized with high-dose cytarabine in acute myeloid leukemia in first complete remission

BACKGROUND

The aim of this study was to increase disease-free survival (DFS) in AML in CR1 using a high-dose cytarabine consolidation plus G-CSF as in vivo purging and mobilization of CD34+ cells before ablative therapy and peripheral blood autograft.

PATIENTS AND METHODS

Fifty-six consecutive AML patients (pts) (including 11 children < 15 years), with a median age of 32 years, were analyzed. After achievement of CR with cytarabine-mitoxantrone (7 + 3) in adults and a BFM-like protocol in children, pts were intensified with cytarabine 2 g/m2 x six doses plus mitoxantrone for adults, or, 3 g/m2 x six doses plus etoposide for children, followed by G-CSF 5 micrograms/kg SC daily. The ablative regimens used were busulfan and cyclophosphamide (Bu/Cy) in standard-risk pts plus etoposide (2400 mg/m2) for high-risk pts.

RESULTS

For the 54 pts who underwent autologous transplant, the median time to reach > 1.0 x 10(9)/l neutrophils was 13 days (8-48), and to reach platelets > 25 x 10(9)/l 32 days (8-364), and the median numbers of red blood cell and platelet units transfused were 3 and 5, respectively. Six pts had treatment-related deaths (11%). The disease-free survival and overall survival at 30 months (mos) for the 56 eligible pts were 61% and 62%, respectively. Only two relapses were observed after 21 mos, while there were 12 relapses within 12 mos.

CONCLUSIONS

The above treatment results in a similar DFS rate as does rescue with bone marrow cells, with faster neutrophil and platelet recovery.