Low-Dose Dasatinib (50 mg Daily) Frontline Therapy in Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia: 5-Year Follow-Up Results

Treatment-Free Remission in Chronic Myeloid Leukemia

With the discovery of tyrosine kinase inhibitors (TKIs), overall survival in patients with chronic myeloid leukemia (CML) now approaches that of the general population. While these TKIs have proven to be lifesaving, remaining on them lifelong creates both physical and financial burdens for patients. Recently, multiple trials have begun looking into the efficacy of trialing patients off these TKIs to see if they can sustain treatment-free remission (TFR). TFR eligibility is currently limited to a small population of patients with both robust and sustained responses to TKIs. Currently, for those who attempt a trial of TFR, the average success rates are promising, with anywhere from 38 to 54% of patients experiencing sustained TFR. For those who fail to maintain sustained TFR, safety results to date are reassuring, with almost all patients successfully responding to the re-initiation of TKIs, with death and disease progression being very rare complications. Moving forward, research is being conducted to more accurately risk stratify patients at diagnosis and pair them with optimized upfront treatment regimens aimed at increasing candidacy for the trial of TFR.

Challenges in management of older patients with chronic myeloid leukemia

Tyrosine kinase inhibitors (TKIs) have significantly improved the survival of patients with chronic myeloid leukemia (CML), however, older patients are often underrepresented in pivotal trials. Approximately 20% of older adults never start treatment and face significant barriers to accomplish favorable outcomes. The treatment goal is to improve survival, prevent progression, and preserve quality of life. This is achieved through optimizing TKI doses and employing discontinuation strategies to attain treatment-free remission (TFR), a goal increasingly pursued by older patients. Imatinib may be favored as the front-line option for older individuals due to its side effect profile and cost. Bosutinib's favorable cardiovascular tolerability makes it a suitable second-line agent, but lower-dose dasatinib may likewise be an attractive option. The prevalence of comorbidities can preclude the use of second generation TKIs in some older patients. Optimal care for older patients with CML centers on personalized treatment, close monitoring, and proactive support.

Combination of dasatinib and venetoclax in newly diagnosed chronic phase chronic myeloid leukemia

BACKGROUND

The dual inhibition of the BCR::ABL1 tyrosine kinase and BCL-2 could potentially deepen the response rates of chronic myeloid leukemia in chronic phase (CML-CP). This study evaluated the safety and efficacy of the combination of dasatinib and venetoclax.

METHODS

In this phase 2 trial, patients with CML-CP or accelerated phase (clonal evolution) received dasatinib 50 mg/day for three courses; venetoclax was added in course 4 for 3 years. The initial venetoclax dose was 200 mg/day continuously but reduced later to 200 mg/day for 14 days, and to 100 mg/day for 7 days per course once a molecular response (MR)4.5 was achieved. After 3 years of combination, patients were maintained on single-agent dasatinib. The primary end point was the rate of major molecular response (MMR) by 12 months of combination.

RESULTS

Sixty-five patients were treated. Their median age was 46 years (range, 23-73). By 12 months of combination, the MMR, MR4, and MR4.5 rates were 86%, 53%, and 45%, respectively. After a median follow-up of 42 months, the 4-year event-free and overall survival rates were 96% and 100%, respectively. Outcomes with the combination were comparable to historical outcomes with single-agent dasatinib (cumulative 12-months MMR rate of 79% with both strategies). The incidence of grade 3-4 neutropenia was 22% with the combination and 11% with single-agent dasatinib (p < .001).

CONCLUSIONS

Treatment with dasatinib and venetoclax was safe and effective in CML-CP. The cumulative response rates with the combination were similar to those with single-agent dasatinib. Further follow-up is needed to evaluate the rates of durable deep molecular response and treatment-free remission.

Real-World Effectiveness of Dasatinib Versus Imatinib in Newly Diagnosed Patients With Chronic Myeloid Leukemia

INTRODUCTION

Limited data exist comparing dasatinib with imatinib in clinical practice. This study assessed real-world outcomes associated with first-line (1L) dasatinib or imatinib treatment of chronic myeloid leukemia (CML).

PATIENTS AND METHODS

This retrospective, observational, United States multisite cohort study analyzed electronic medical record data from adults with Philadelphia chromosome-positive (Ph+) CML in the chronic phase (CML-CP) after 1L dasatinib or imatinib between January 2014 and September 2018. Rates of and times to major molecular response (MMR) and deep molecular response (DMR) were assessed overall and in subgroups (low vs. intermediate/high risk, aged <65 vs. ≥65 years, low/normal vs. high body mass index [BMI]).

RESULTS

The dasatinib cohort (n = 309) experienced higher rates of MMR (n = 304, 79% vs. 65%, P < .001) and DMR (44% vs. 25%, P < .001) vs. the imatinib cohort with shorter median times to MMR (11.9 vs. 14.7 months, P < .001) and DMR (30.3 vs. 66.1 months, P < .001). Patients with intermediate-/high-risk disease and those aged <65 years had higher MMR and DMR rates and achieved response earlier with dasatinib (P < .01). Patients with low-risk disease treated with dasatinib had higher rates of DMR (60% vs. 32%, P = .01). Across BMI strata, rates of MMR and DMR were higher with dasatinib (P < .05).

CONCLUSIONS

Patients with CML-CP treated with 1L dasatinib achieved higher rates of, with shorter times to, MMR and DMR versus 1L imatinib. These clinically meaningful improvements were observed across subgroups.

Long-term follow-up of efficacy and safety in elderly patients with chronic myeloid leukemia treated with intermittent low dose dasatinib therapy

Intermittent low dose dasatinib therapy brought about a beneficial effect in elderly patients with chronic-phase chronic myeloid leukemia (CML-CP) without inducing severe adverse events (AEs). An 85-year-old male patient, who received twice-weekly, thrice-weekly, or four-times-weekly administration of 20 mg/day dasatinib after once-weekly administration, achieved a major molecular response two years after the start of dasatinib treatment and later sometimes achieved a deep molecular response, maintaining the efficacy for 11 years. The mean daily dose ranged from 5.7 mg to 11.4 mg. Furthermore, a 79-year-old male patient, who received thrice-weekly or every other day administration of 20 mg/day dasatinib after once-weekly administration, achieved a deep molecular response at four and half years after the start of dasatinib treatment. The mean daily dose is 8.6 mg. Intermittent low dose dasatinib therapy appears to be feasible in elderly patients with CML-CP. The goal of treatment in elderly patients with CML-CP appears to be different from that in younger patients, since they often suffer from serious AEs in the case of standard dose tyrosine kinase inhibitor therapy, followed by the dose reduction or cessation of treatment.

How to improve treatment-free remission eligibility in chronic myeloid leukaemia?

The achievement of treatment-free remission (TFR) has become a significant clinical end-point in the management of patients with chronic myeloid leukaemia (CML), providing an opportunity to discontinue therapy with tyrosine kinase inhibitors (TKIs) while maintaining deep molecular response (DMR). Early studies, such as the French STIM trial, have demonstrated that a portion of patients can maintain DMR after treatment cessation, with rates ranging from 40% to 50%, and most relapses occurring within the first 6 months. Key prognostic factors for successful TFR, including treatment duration, duration of DMR, risk scores, and transcript type, have been identified. Optimal patient selection for TFR remains a challenge, but recent research provides insights into potential strategies to increase TFR eligibility. Evidence suggests that early intervention switching to achieve optimal response, treatment combinations, proactive switch in the case of absence of DMR, dose-optimization and induction-maintenance approach can improve molecular responses and, consequently, enhance TFR eligibility. In this review, we report and discuss all the potential therapeutic strategies that may enhance eligibility for a first attempt at TFR, with a particular emphasis on potential future approaches.