Final report of TKI discontinuation trial with dasatinib for the second attempt of treatment-free remission after failing the first attempt with imatinib: Treatment-free Remission Accomplished by Dasatinib (TRAD) study.

Multiple studies have reported a significant treatment-free remission (TFR) rate of 50%-60% in patients with chronic myeloid leukaemia (CML) who discontinue tyrosine kinase inhibitor (TKI) therapy. However, the remaining half of these patients still require re-initiation of TKI therapy for leukaemia control. It remains unclear if TKI drugs should be switched for re-therapy in patients who failed the first TFR (TFR1) attempt. Our study attempted to determine whether dasatinib therapy after TFR1 failure post-imatinib discontinuation could improve the likelihood of TFR2. Of 59 patients who lost molecular response after imatinib discontinuation for TFR1, 55 patients (93.2%) were treated with dasatinib, of whom 49 (89.1%) regained MR4.5 or deeper response, with a median time of 1.85 months to achieve MR4.5. Dasatinib was discontinued in 35 patients for TFR2 attempt, of whom 26 patients (74.28%) lost MMR and 6 (17.14%) MR4. Risk factor analysis for the TFR2 after dasatinib discontinuation suggested three significant factors: (1) doubling time of BCR::ABL1 transcript following TFR1 attempt, (2) rapid regaining of molecular response following dasatinib therapy and (3) undetectable BCR::ABL1 transcript prior to TFR2 attempt. The present study showed that dasatinib does not increase the TFR2 rate in general, but a selected group of patients could benefit from this approach.

Efficacy and safety of nilotinib in chronic myeloid leukaemia patients who failed to achieve a treatment-free remission period after imatinib discontinuation: Results of the French Nilo post-STIM study.

Molecular recurrence (MRec) occurs in about half of all patients with chronic myeloid leukaemia (CML) who discontinue tyrosine kinase inhibitors (TKI) in sustained deep molecular response. A second TKI discontinuation has been attempted in some patients who regain the discontinuation criteria after resuming treatment. Nilotinib treatment affords faster and deeper molecular responses than imatinib as first-line therapy. We prospectively evaluated the efficacy and safety of nilotinib (300 mg twice daily) in chronic-phase CML patients who experienced MRec, after imatinib discontinuation and analysed the probability of TFR after a new attempt in patients treated for 2 years with sustained MR4.5 for at least 1 year. A total of 31 patients were included in the study between 2013 and 2018. Seven (23%) patients experienced serious adverse events after a median of 2 months of nilotinib treatment leading to discontinuation of treatment. One patient was excluded from the study for convenience. Among the 23 patients treated for 2 years with nilotinib, 22 maintained their molecular response for at least 1 year (median: 22 months) and stopped nilotinib. The TFR rates at 24 and 48 months after nilotinib discontinuation were 59.1% (95% confidence interval [CI]: 41.7%-83.7%) and 42.1% (95% CI: 25%-71%) respectively (NCT #01774630).

Psychological Factors Affecting the Willingness to Accept a Possible Tyrosine Kinase Inhibitor (TKI) Discontinuation in Chronic Myeloid Leukaemia (CML) Patients.

Purpose: Patients with chronic myeloid leukemia (CML) who present a sustained deep molecular response (DMR) for a stable period of time might benefit from discontinuing tyrosine kinase inhibitors (TKIs). A significant number of patients seem able to reach this stage due to the availability of TKIs. However, many patients remain reluctant about TKI discontinuation and may refuse treatment interruption. The purpose of this study was to explore the clinical and psycho-cognitive factors that may influence the decision to discontinue TKI therapy, thereby gaining a better understanding of patients' viewpoints on TKI discontinuation. Patients and Methods: One hundred and nineteen patients diagnosed with CML aged between 34 and 69 were enrolled (67 males and 52 females). Different clinical information and psycho-cognitive aspects such as attitude toward risk behaviours, risk preferences, need for cognitive closure, and tendency to resist to changes were assessed through the administration of a battery of questionnaires. Results: A higher tendency toward risk behaviours and the tendency to focus on possible gain in the short term rather than on losses might represent important predictors for the willingness to accept TKI discontinuation. Possible relapses following interruption of the therapy are the most common reason for concern. Furthermore, lower levels of resistance to change and having previously experienced the desire to interrupt the therapy might lead patients to accept a higher probability of relapse risk when facing such a decision. Conclusion: TKI discontinuation appears appealing and challenging at the same time for many CML patients, and different factors may influence this decision. Psychology plays a crucial role in assisting physician-patient communication and informed decision-making.

BCR-ABL1 transcript doubling time as a predictor for treatment-free remission failure after imatinib discontinuation in chronic myeloid leukaemia in chronic phase.

The doubling time (DT) of the BCR-ABL1 quantitative polymerase chain reaction (qPCR) transcript level reflects the re-growing fraction of leukaemic cells after discontinuation of tyrosine kinase inhibitor (TKI). The present study analyzed monthly DT within six months after imatinib discontinuation in 131 patients. Monthly DT was calculated as x = ln(2)/K, where x is the DT and K is the fold BCR-ABL1 change from the previous value divided by the number of days between each measurement. The optimal DT value was determined as 12·75 days at two months using a recursive partitioning method. The patients were stratified into three groups: the high-risk group (DT<12·75 days but >0, with rapidly proliferating chronic myeloid leukaemia (CML) cells; n = 26) showed the lowest molecular relapse-free survival (mRFS) of 7·7% at 12 months, compared to 53·6% in the intermediate-risk group (DT≥12·75 days, with slowly proliferating CML cells; n = 16) or 90·0% in the low-risk group (DT≤0, i.e., without proliferating CML cells; n = 71; P < 0·001). Monthly assessment of DT helps identify high-risk patients for treatment-free remission failure with an imminent risk of molecular recurrence, and to define low-risk patients who can be spared the frequent monitoring of monthly molecular tests.

A randomized, phase II trial of adjuvant immunotherapy with durable TKI-free survival in patients with chronic phase CML.

PURPOSE: Chronic myeloid leukemia (CP-CML) patients can achieve undetectable minimal residual disease (UMRD) and discontinue tyrosine kinase inhibitors (TKIs). Cellular immunity plays an important role in CML disease control. We conducted a randomized, non-blinded phase II trial of adjuvant immunotherapy with TKIs to facilitate TKI discontinuation. METHODS: TKI-treated patients with CP-CML were randomized to receive the K562/GM-CSF vaccine (vaccine) OR Interferon-α + Sargramostim (IFN). If UMRD was achieved, then all treatment was stopped. Patients who did not achieve UMRD within one year, had a molecular relapse, or discontinued therapy for toxicity could crossover. RESULTS: Thirty-four patients were randomized to IFN (n = 18) or vaccine (n = 16), and 21 patients crossed over (IFN⟶vaccine: n = 9, vaccine⟶IFN, n = 12). TKIs at enrollment included imatinib (n = 31), nilotinib (n = 2), and dasatinib (n = 1). No patients discontinued vaccine due to side effects, while 33 % of IFN-treated patients discontinued treatment. More patients randomized to IFN (47.4 %, 95 % CI: 16.7-66.7 %) versus vaccine (25.0 %, 95 % CI: 0.5-43.5 %) achieved UMRD within one year. Seven patients randomized to IFN discontinued treatment with 28.6 % (95 % CI: 8.9-92.2 %) sustaining treatment-free remission (TFR) at 1 year, while three patients randomized to vaccine discontinued treatment with none sustaining TFR. Including crossover, there was a cumulative discontinuation success rate of 36.4 % (95 % CI: 16.6 %-79.5 %) after adjuvant IFN. Patients who sustained TFR received a median of 29 months of imatinib prior to discontinuation. CONCLUSION: Adjuvant IFN led to durable TFRs with limited prior TKI exposure with comparable success to prior discontinuation trials, but many patients stopped IFN early.

When to Stop TKIs in Patients with Chronic Myeloid Leukemia and How to Follow Them Subsequently.

OPINION STATEMENT: ABL1 tyrosine kinase inhibitors (TKI) have dramatically improved the outcome for CML (chronic myeloid leukemia) patients. When TKI therapy is addressed appropriately, it can lead to an optimal molecular response in the majority of CML patients and a life expectancy that approaches that of the general population. However, lifelong TKI therapy may have consequences, including chronic, mostly low-grade, adverse events that can substantially impact patients' quality of life, adherence to therapy and, consequently, success of treatment. In the last few years, several groups have demonstrated that approximately 50% of chronic phase CML patients (CP-CML) who have achieved a stable deep molecular response (DMR) can stop therapy without suffering molecular relapse. Nowadays, treatment-free remission (TFR) has a significant role in the management of CML and should be considered in selected motivated patients that fulfill well-defined requirements to maximize the probability of successful discontinuation of TKI therapy.

Surrogate Markers for Treatment-Free Remission in Patients With Chronic Myeloid Leukemia.

BCR-ABL1 tyrosine kinase inhibitors (TKIs) improve long-term survival of patients with chronic-phase (CP) chronic myeloid leukemia (CML). Recently, the treatment goal for patients with CML-CP became safe discontinuation of TKIs. Several clinical trials have shown that approximately half of patients who experience a durable deep molecular response during TKI treatment maintain molecular remission after discontinuation of TKIs. However, the factors responsible for successful treatment-free remission (TFR) remain unclear. This study reviews very recent TKI discontinuation studies, focusing on factors responsible for TFR in patients with CML-CP. Longer TKI treatment duration, time of deep molecular response, presence of withdrawal syndrome, deeper molecular response, lower Sokal score, interferon α treatment before TKI administration, and favorable natural killer or T-cell profiles may be associated with TFR. However, different study designs have generated inconsistent data. Further investigations are needed to identify factors that consistently favor achievement of TFR.

Withdrawal Syndrome After Tyrosine Kinase Inhibitor Discontinuation in Patients With Chronic Myeloid Leukemia in the Russian Prospective Study RU-SKI.

We aimed to characterize withdrawal syndrome (WS) and evaluate factors associated with its development in the prospective clinical study RU-SKI in patients with chronic myeloid leukemia with deep molecular response who discontinued tyrosine kinase inhibitor (TKI) therapy. In total, 98 adult patients with chronic myeloid leukemia chronic phase, TKI therapy ≥ 3 years, and deep molecular response (BCR-ABL ≤ 0.01%) ≥ 2 years were enrolled and observed without treatment. WS was defined as newly observed or worsening musculoskeletal pain after TKI cessation. WS symptoms were found in 41 (42%) of 98 patients with a median time of observation of 25 months (range, 12-42 months). WS grades 1 to 2 and grade 3 were observed in 39 (95%) and in 2 (5%) patients, respectively. The median duration of WS was 5 months (range, 1-25 months). WS was resolved in 37 (90%) patients. Anti-inflammatory therapy was used in 21 (51%) patients. Older age (P = .039) and longer TKI therapy (P = .001) were associated with WS. The 2-month landmark analysis found no association of WS development and the rate of molecular relapses. In total, 42% of the patients experienced WS after TKI therapy discontinuation in the RU-SKI study. Physicians should be warned about the possibility of WS development, and patients of older age and with longer TKI treatment need special attention.

What are the considerations for tyrosine kinase inhibitor discontinuation in chronic-phase chronic myeloid leukemia?

Introduction: The outlook for patients with chronic myeloid leukemia (CML) has changed dramatically with the development of tyrosine kinase inhibitors (TKIs) with the current treatment goal for many patients being to obtain a durable deep molecular remission, discontinue TKI therapy, and remain treatment free.Areas covered: In this article, the authors review the data from the major TKI discontinuation studies, explore potential predictors of discontinuation outcome and look at possible mechanisms to explain the variable outcomes following TKI discontinuation including immune surveillance and leukemic stem cell (LSC) depletion following TKI treatment. Data from relevant articles published on the Pubmed database between January 2007 and January 2020 have been included.Expert opinion: The results from the majority of TKI discontinuation studies show a consistent picture with approximately half of eligible patients achieving treatment free remission (TFR). However, reliable clinical predictors or biomarkers for the outcome of TKI discontinuation remain elusive and the mechanisms to explain the diversity of discontinuation success are not completely understood. Future studies will need to focus on attempts to increase the number of patients eligible for treatment discontinuation and will likely involve drug combinations including novel agents aimed at targeting the residual LSC population and enhancement of immune surveillance mechanisms.

Digital PCR improves the quantitation of DMR and the selection of CML candidates to TKIs discontinuation.

Treatment-free remission (TFR) by tyrosine kinase inhibitors (TKI) discontinuation in patients with deep molecular response (DMR) is a paramount goal in the current chronic myeloid leukemia (CML) therapeutic strategy. The best DMR level by real-time quantitative PCR (RT-qPCR) for TKI discontinuation is still a matter of debate. To compare the accuracy of digital PCR (dPCR) and RT-qPCR for BCR-ABL1 transcript levels detection, 142 CML patients were monitored for a median time of 24 months. Digital PCR detected BCR-ABL1 transcripts in the RT-qPCR undetectable cases. The dPCR analysis of the samples, grouped by the MR classes, revealed a significant difference between MR4.0 and MR4.5 (P = 0.0104) or MR5.0 (P = 0.0032). The clinical and hematological characteristics of the patients grouped according to DMR classes (MR4.0 vs MR4.5-5.0 ) were superimposable. Conversely, patients with dPCR values <0.468 BCR-ABL1 copies/µL (as we previously described) showed a longer DMR duration (P = 0.0220) and mainly belonged to MR4.5-5.0 (P = 0.0442) classes compared to patients with higher dPCR values. Among the 142 patients, 111 (78%) discontinued the TKI treatment; among the 111 patients, 24 (22%) lost the MR3.0 or MR4.0 . RT-qPCR was not able to discriminate patients with higher risk of MR loss after discontinuation (P = 0.8100). On the contrary, according to dPCR, 12/25 (48%) patients with BCR-ABL1 values ≥0.468 and 12/86 (14%) patients with BCR-ABL1 values <0.468 lost DMR in this cohort, respectively (P = 0.0003). Treatment-free remission of patients who discontinued TKI with a dPCR <0.468 was significantly higher compared to patients with dPCR ≥ 0.468 (TFR at 2 years 83% vs 52% P = 0.0017, respectively). In conclusion, dPCR resulted in an improved recognition of stable DMR and of candidates to TKI discontinuation.

Tyrosine kinase inhibitor discontinuation in patients with chronic myeloid leukemia: a single-institution experience.

BACKGROUND: Patients with CML treated with TKI can have a life expectancy comparable to that of the general population. Due to the extended duration of TKI administration, treatment discontinuation has been increasingly sought. METHODS: Medical records of 100 patients with CML who were in MR4.5 and discontinued their TKI outside clinical trials were reviewed. RESULTS: After a median follow-up of 30 months (range, 5-112 months) after discontinuation, 35% and 17% lost MR4.5 and major molecular response (MMR), respectively. Only six patients lost MMR 12 months or more after discontinuation. Loss of MR4.5 was observed in 29% and 7% of patients with sustained MR4.5 duration of more than 2 and 6 years before discontinuation, respectively. By univariate analysis, there was a higher risk of loss of MR4.5 for patients who were treated for less than 87 months, received second or subsequent line TKI, never received interferon, or those with sustained MR4.5 for less than 6 years. By multivariate analysis, sustained MR4.5 for 6 years or more was the only significant predictor for durable response. Overall, 30% of patients who discontinued while in MR4.5 were retreated with 93% regaining MR4.5 at a median of 5 months. CONCLUSION: These results demonstrate that under proper conditions, treatment discontinuation is feasible outside of clinical trial setting. MR4.5 duration of 6 years or more before discontinuation is associated with very low risk of loss of MR4.5.

Discontinuation of tyrosine kinase inhibitors in CML patients in real-world clinical practice at a single institution.

BACKGROUND: Most patients with chronic myeloid leukemia (CML) treated with tyrosine kinase inhibitors (TKIs) will relapse if treatment is withdrawn, but various trials have recently demonstrated that a significant proportion of patients who achieved a stable and deep molecular response (DMR) can stop therapy without relapsing. However, most information on treatment cessation was obtained from clinical trials with strict recruiting criteria. METHODS: We evaluated the outcome of 25 patients with CML that discontinued TKI therapy in our institute in real-world clinical practice. RESULTS: Of the 25 patients, 76% discontinued therapy in sustained deep molecular response (SDMR) and 24% were in unsustained DMR (UDMR). Discontinuation of therapy due to adverse effects was observed in 5 and 50% of the patients in the SDMR and UDMR groups, respectively. After TKI discontinuation, patients were followed for a median of 24 months. At the time of this analysis, 56% patients had a molecular relapse after a median of 4 months. SDMR and longer treatment duration were associated with lower probability of molecular relapse: 25% in SDMR patients with TKI treatment > 96 months and 85% in UDMR patients with TKI treatment ≤96 months. All relapsed patients promptly resumed TKI therapy and regained at least major molecular response (MMR). CONCLUSIONS: Our results suggest that TKI discontinuation is safe outside clinical trials and particularly effective in CML patients who are in SDMR with longer TKI treatment duration.

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.

Whole-exome sequencing reveals potential molecular predictors of relapse after discontinuation of the targeted therapy in chronic myeloid leukemia patients.

Chronic myeloid leukemia (CML) is a myeloproliferative disease well treated by tyrosine kinase inhibitors (TKIs). The aim was to identify genes with a predictive value for relapse-free survival after TKI cessation in CML patients. We performed whole-exome sequencing of DNA from six CML patients in long-lasting deep molecular remission. Patients were divided into two groups with relapse (n = 3) and without relapse (n = 3) after TKI discontinuation. We found variants in genes CYP1B1, ALPK2, and IRF1 in group of patients with relapse and one variant in gene PARP9 in group of patients without relapse. We verified prognostic value of the found markers in a small group of patients with TKI discontinuation and demonstrated their high sensitivity (77%), specificity (86%), positive (85%), and negative (79%) predictive values. Thus we revealed genetic variants, which are potential markers of outcome prediction in CML patients after TKI discontinuation.