Discontinuation of alpha-interferon treatment in patients with chronic myeloid leukemia in long-lasting complete molecular response

What’s New in the Classification, Diagnosis and Therapy of Myeloid Leukemias

Myeloid leukemias are a broad group of hematological disorders, characterized by heterogeneous clinical and biological features. In recent years, unprecedented genetic discoveries and clinical–biological correlations have revolutionized the field of myeloid leukemias. The most relevant changes have specifically occurred in acute myeloid leukemia (AML), chronic myelomonocytic leukemia (CMML), chronic myeloid leukemia (CML) and myeloid neoplasms (MNs) with eosinophilia. The recently published International Consensus Classification (ICC) of myeloid neoplasms has addressed these changes, providing an updated framework and revised diagnostic criteria for such entities. This is also the aim of the 5th edition of the WHO classification of hematopoietic tumors, whose preliminary version was published in 2022. Parallel to this, new therapeutic options and novel molecular targets have changed the management of many myeloid entities, including AML and CML. This review aims to address the most relevant updates in the classification and diagnosis of AML, CMML, CML and MNs with eosinophilia. The state of the art of treatment and future therapeutic options for such disorders are also discussed.

Interferon-α as maintenance therapy can significantly reduce relapse in patients with favorable-risk acute myeloid leukemia

To evaluate the efficacy of interferon-α (IFN-α) as maintenance therapy in patients with favorable-risk acute myeloid leukemia (AML), this retrospective study enrolled 84 patients with favorable-risk AML: 42 patients who received IFN-α maintenance therapy and 42 patients who did not (control). The median follow-up time and duration of IFN-α treatment was 26 (6-54) months and 18 (2-24) months, respectively. The 4-year estimated relapse-free survival (RFS) after the last consolidation chemotherapy was 86.8% (95% confidence interval (CI), 75.8-97.8%) in the IFN-α group and 55.7% (95% CI, 37.2-74.3%) in the control group (p=.007). The 4-year estimated overall survival was 94.4% (95% CI, 86.8-102%) and 76.4% (95% CI, 61.9-90.9%) in IFN-α and control groups, respectively (p=.040). The Cox regression analysis showed that IFN-α treatment was the only independent factor affecting RFS (p=.004). Maintenance therapy with IFN-α may prevent relapse in favorable-risk AML after consolidation chemotherapy.

Interferons: role in cancer therapy

Interferons (IFNs) are a group of signaling cytokines, secreted by host cells to induce protection against various disorders. IFNs can directly impact on tumor cells or indirectly induce the immune system to protect host cells. The expression levels of IFNs and its functions of are excellently modulated in a way to protect host cells from probable toxicities caused by extreme responses. The efficacy of anticancer therapies is correlated to IFNs signaling. Although IFN signaling is involved in induction of antitumor responses, chronic stimulation of the IFN signaling pathway can induce resistance to various antineoplasm therapies. Hence, IFNs are expressed by both cancer and immune cells, and modulate their biological function. Understanding this mechanism of action might be a key target of combination therapies.

Type I Interferons and Cancer: An Evolving Story Demanding Novel Clinical Applications

The first report on the antitumor effects of interferon α/β (IFN-I) in mice was published 50 years ago. IFN-α were the first immunotherapeutic drugs approved by the FDA for clinical use in cancer. However, their clinical use occurred at a time when most of their mechanisms of action were still unknown. These cytokines were being used as either conventional cytostatic drugs or non-specific biological response modifiers. Specific biological activities subsequently ascribed to IFN-I were poorly considered for their clinical use. Notably, a lot of the data in humans and mice underlines the importance of endogenous IFN-I, produced by both immune and tumor cells, in the control of tumor growth and in the response to antitumor therapies. While many oncologists consider IFN-I as “dead drugs”, recent studies reveal new mechanisms of action with potential implications in cancer control and immunotherapy response or resistance, suggesting novel rationales for their usage in target and personalized anti-cancer treatments. In this Perspectives Article, we focus on the following aspects: (1) the added value of IFN-I for enhancing the antitumor impact of standard anticancer treatments (chemotherapy and radiotherapy) and new therapeutic approaches, such as check point inhibitors and epigenetic drugs; (2) the role of IFN-I in the control of cancer stem cells growth and its possible implications for the development of novel antitumor therapies; and (3) the role of IFN-I in the development of cancer vaccines and the intriguing therapeutic possibilities offered by in situ delivery of ex vivo IFN-stimulated dendritic cells.

Plasticity of Type I Interferon-Mediated Responses in Cancer Therapy: From Anti-tumor Immunity to Resistance

The efficacy of several therapeutic strategies against cancer, including cytotoxic drugs, radiotherapy, targeted immunotherapies and oncolytic viruses, depend on intact type I interferon (IFN) signaling for the promotion of both direct (tumor cell inhibition) and indirect (anti-tumor immune responses) effects. Malfunctions of this pathway in tumor cells or in immune cells may be responsible for the lack of response or resistance. Although type I IFN signaling is required to trigger anti-tumor immunity, emerging evidence indicates that chronic activation of type I IFN pathway may be involved in mediating resistance to different cancer treatments. The plastic and dynamic features of type I IFN responses should be carefully considered to fully exploit the therapeutic potential of strategies targeting IFN signaling. Here, we review available evidence supporting the involvement of type I IFN signaling in mediating resistance to various cancer therapies and highlight the most promising modalities that are being tested to overcome resistance.

How I manage relapse of chronic myeloid leukaemia after stopping tyrosine kinase inhibitor therapy

During the last 10 years, clinical trials formally demonstrated that about 50% of patients with chronic phase (CP) chronic myeloid leukaemia (CML) who achieve and maintain deep molecular responses for a prolonged period of time during treatment with imatinib or new generation tyrosine kinase inhibitors (TKIs) may successfully stop their anti-leukaemic therapy. Based on the accumulated knowledge from abundant clinical trial experience, TKI discontinuation is becoming an important goal to achieve and is about to enter clinical practice. This review focuses on relapse definition, laboratory tests to identify relapse and relapse management after TKI discontinuation.

Treatment-free remission in patients with chronic myeloid leukemia

Clinical trials have formally demonstrated that in chronic myeloid leukemia (CML), patients treated with tyrosine kinase inhibitors (TKI) who achieved and maintained deep molecular responses could discontinue their treatment after several years without facing overt signs of disease relapse in approximately 50% of the cases. In patients with a molecular relapse, prompt re-introduction of TKI therapy was able to rapidly restore deep molecular responses. The concept of a lifelong therapy with TKI has thus been challenged and treatment-free remission (TFR) strategies will soon integrate clinical practice, providing that safe recommendations will be established. In this article, we give an update on TKI discontinuation studies in CML and we also provide an overview of upcoming TFR clinical and biological challenges.

Discontinuation of dasatinib or nilotinib in chronic myeloid leukemia: interim analysis of the STOP 2G-TKI study

STOP second generation (2G)-tyrosine kinase inhibitor (TKI) is a multicenter observational study designed to evaluate 2G-TKI discontinuation in chronic myeloid leukemia (CML). Patients receiving first-line or subsequent dasatinib or nilotinib who stopped therapy after at least 3 years of TKI treatment and in molecular response 4.5 (MR4.5) with undetectable BCR-ABL1 transcripts for the 2 preceding years at least were eligible for inclusion. This interim analysis reports outcomes of 60 patients with a minimum follow-up of 12 months (median 47, range: 12-65). Twenty-six patients (43.3%) experienced a molecular relapse defined as the loss of a major molecular response (MMR). Relapses occurred after a median time of 4 months (range: 1-38). Cumulative incidences of molecular relapse by 12 and 48 months were 35% (95% confidence interval [CI], 24.79% to 49.41%) and 44.76% (95% CI, 33.35% to 59.91%), respectively. Treatment-free remission (TFR) rates at 12 and 48 months were 63.33% (95% CI, 51.14% to 75.53%) and 53.57% (95% CI, 40.49% to 66.65%), respectively. In univariate analysis, prior suboptimal response or TKI resistance was the only baseline factor associated with significantly worse outcome. A landmark analysis demonstrated that loss of MR4.5 3 months after stopping TKI was predictive of failure to maintain MMR later on. During the treatment-free phase, no progression toward advanced phase CML occurred, and all relapsing patients regained MMR and MR4.5 after restarting therapy. In conclusion, discontinuation of first-line or subsequent 2G-TKI yields promising TFR rates without safety concerns. Further research is encouraged to better define conditions that will offer patients the highest chance to remain free from 2G-TKI therapy.

Can chronic myeloid leukaemia in children and adolescents be successfully treated without haematopoietic stem cell transplant? A single centre experience

We analysed the long-term outcome of 35 children and adolescents (<20 years at diagnosis) with chronic myeloid leukaemia (CML) in chronic phase: 20 patients had received interferon-alpha and/or tyrosine kinase inhibitors (TKIs), and 15 underwent a haematopoietic stem cell transplant. The 10-year survival probabilities were similar in transplanted and non-transplanted patients (73·3% vs. 72·1%, respectively), whereas the survival probability was significantly lower in patients diagnosed before 1999 compared to those diagnosed afterwards (62·1% vs. 100%, P = 0·0384). The availability of TKIs and the standardized molecular monitoring have significantly improved treatment, management and outcome in children and adolescents with CML.

Effects of a Particular Heptapeptide on the IFN-α-Sensitive CML Cells

Using the phage display biopanning technique, we have previously identified a heptapeptide KLWVIPQ which specifically binds to the surface of the IFN-α-sensitive but not the IFN-α-resistant CML cells. The effects of this heptapeptide on the IFN-α-sensitive CML cells were investigated in the present study. IFN-α-sensitive KT-1/A3 and IFN-α-resistant KT-1/A3R CML cells were transfected by pEGFP-KLWVIPQ expression vector and/or induced by IFN-α. WST-1 cell proliferation assay, flow cytometry, and western blotting were performed to determine the effects of this heptapeptide and/or IFN-α on CML cells. The viability of the KT-1/A3 cells was inhibited and apoptosis was induced by either expression of the heptapeptide KLWVIPQ or IFN-α treatment with concurrent upregulation of P53 and downregulation of P210^bcr/abl. However, these effects were not observed in the IFN-α-resistant KT-1/A3R cells. These results suggest that the heptapeptide KLWVIPQ shares a similar mechanism with IFN-α in the regulation of CML cell growth and apoptosis, implying that the heptapeptide KLWVIPQ could be a novel target to go further into mechanisms of IFN-α sensitivity and/or resistance in CML.