Probability Of Treatment-free Remission Research Articles

Age-Related Clonal Hematopoiesis Mutations Detected at the Time of Stopping Tyrosine Kinase Inhibitor Therapy Predict the Achievement of Treatment-Free Remission for Patients with CML

Background The gain of mutations with a competitive advantage in hematopoietic cells of healthy individuals is common with aging and termed clonal hematopoiesis of indeterminate potential (CHIP). Through sequencing studies we detected CHIP related mutants in chronic myeloid leukemia (CML) patients in deep molecular response. CHIP mutants may provide a selective growth advantage to non-leukemic cells, driving their clonal expansion in remission and potentially influencing treatment-free remission (TFR) if CHIP clones outcompete an emerging BCR:: ABL1 clone. Aim To determine if CHIP mutants detected at the time of stopping tyrosine kinase inhibitor (TKI) therapy could influence achievement of TFR. Methods An RNA-based sequencing method targeting 17 of the most frequently mutated CHIP genes was developed and applied to blood samples of 150 patients who attempted TFR. The median follow up of patients in TFR was 71 months. CHIP mutants met strict criteria for pathogenicity based on their potential to confer growth and survival advantages, i.e. the same criteria as cancer driver mutations. Variant allele frequency (VAF) of ≥0.4% was reproducibly detected. CHIP at the time of cessation, termed CHIP TOC, was defined as 1) ≥1 CHIP mutant with VAF ≥2.0% (n=30 patients) or 2) a novel criterion for patients with multiple CHIP mutants where the combined VAF was ≥2.0% (n=7). Overall, 25/37 patients (68%) with CHIP TOC had multiple mutations, range 2-7. Results CHIP TOC was detected in 37/150 patients (25%). The average age of patients with CHIP TOC was 66.3 years vs 58.0 for those without, P=.0004, which is consistent with the age related nature of CHIP. No patient aged <40 had CHIP TOC, whereas 44% of patients ≥70 had CHIP TOC. Twelve genes were mutated and the most frequent were TET2, DNMT3A, ASXL1 and PPM1D. The overall probability of TFR was 60.4% at 12 months and 53.0% at 84 months. CHIP TOC was associated with TFR. At 12 months, 83.6% of patients with CHIP TOC maintained TFR versus 52.9% of patients without CHIP TOC, P=.002. At 84 months, 62.9% of patients with CHIP TOC maintained TFR versus 49.6% of patients without CHIP TOC, P=.014. We previously demonstrated that e13a2 transcripts and a slow initial decline of BCR:: ABL1 after starting frontline TKI therapy, measured as the number of days over which BCR:: ABL1 halved, were our strongest predictors of relapse. Prognostic factors for the achievement of TFR at 12 and 84 months were examined in multivariable analysis. Candidate prognostic factors were CHIP TOC, BCR:: ABL1 halving time, BCR:: ABL1 transcript type, age at diagnosis, gender, duration of MR4.5 and time on TKI before TKI stop. The independent predictors of TFR at 12 and 84 months were the presence of CHIP TOC at TKI stop, a shorter BCR:: ABL1 halving time (indicating a more rapid initial BCR:: ABL1 decline) and the e14a2 (plus e14a2/e13a2) BCR:: ABL1 transcript type (Table 1). The rate of late relapse, defined as loss of MMR >12 months after cessation, was higher in patients with CHIP TOC. Overall, 85 patients had TFR at 12 months and late relapse occurred in 8. A landmark analysis demonstrated that the probability of maintaining TFR at 84 months for these 85 patients was 93.8% for those without CHIP TOC (n=57) and 75.2% for those with CHIP TOC (n=28), P=.007. The only variable associated with late relapse among the patients with CHIP TOC was fluctuation of BCR:: ABL1 within the first 12 months after cessation, defined as irregular rise and fall comprising 2 consecutive BCR:: ABL1 ratios with loss of MR4.5, or a single loss of MR4. Overall, 13 patients had fluctuation within the first 12 months and 5 of these had late relapse. All 5 had CHIP TOC. Patients with CHIP TOC and stable MR4.5 by 12 months had a 93.8% probability of TFR at 84 months (Table 2). Conclusion The presence of CHIP TOC at TKI cessation, a shorter BCR:: ABL1 halving time and e14a2 BCR:: ABL1 transcripts were independent predictors of TFR at 12 and 84 months. Delayed loss of MMR that occurred for a minority of patients with CHIP TOC may be associated with competition between CHIP clones and a residual leukemic clone. These patients had fluctuating BCR:: ABL1 over the first 12 months after cessation and prior to late relapse. Novel strategies may be warranted to reduce the risk of late relapse for these patients. Patients who sustained TFR by 12 months in stable MR4.5 had a reassuringly low risk of late relapse. CHIP status could be a key variable to guide TFR decision-making and monitoring.

Single-Cell Analysis of Immune Recognition in Chronic Myeloid Leukemia Patients Following Tyrosine Kinase Inhibitor Discontinuation

Background: Modern treatment goal for patients with chronic myeloid leukemia (CML) is to maintain treatment-free remission (TFR) following tyrosine kinase inhibitor (TKI) discontinuation. The control of residual leukemia cells may occur with immunological mechanisms as several studies have shown that a higher proportion of CD56 dim NK cells before TKI discontinuation is associated with a better probability of TFR. In addition, CD8+ T cell abundances and phenotypes have been associated with responses to TKIs. However, the more detailed phenotypes and mechanisms and how to translate these findings to increased TFR rates have remained unknown. Methods: We analyzed 55 single-cell RNA and T cell receptor (TCR) sequenced (scRNA+TCRαβ-seq) samples from patients with CML ( n=13, N=25), other cancers (AML n=11, CLL n=13, solid tumors n=4), and healthy ( n=7). Additionally, we profiled 90 CML and 786 healthy TCRβ-seq samples, and sorted T cells specific to leukemia-associated antigen PR1 and matched these back to the scRNA+TCRαβ-seq and TCRβ-seq data. To validate and refine our findings, we performed co-culture of primary and expanded NK cells with CML cell lines (K562 and LAMA84) with a multiplexed scRNA-seq readout. Results: In the pan-cancer scRNA+TCRαβ-seq comparison of >250,000 cells, CML was separated from other cancers and healthy by the high number and active phenotype NK cells. The other phenotype more pronounced in CML was CD8+ T EM/T EMRA phenotype. Most NK cells in CML had an active CD56 dim phenotype with high expression of GZMA/B, PRF1, CCL3/4 and IFNG. In the off-TKI samples from patients with TFR, these NK cells upregulated NK cell activation genes such as TNFRSF4/OX40, TNFRSF9/4-1BB, and TNFRSF18/GITR. The most important predicted interactions between NK cells and CD34+ leukemic cells were inhibitory LGALS9- TIM3 and PVR- TIGIT interactions. Following TKI discontinuation, the inhibitory markers HAVCR2/TIM3 and TIGIT decreased in patients with TFR, which was not seen in patients with relapse following TFR. Accordingly, in our co-culture data of NK cells with CML cell lines, we noted activation of NK cells to a similar phenotype as noted in ex vivo off-TKI samples. In co-culture with CML target cells, NK cells gained an activation by upregulation of genes like TNFRSF4/OX40, TNFRSF9/4-1BB, TNFRSF18/GITR and the inhibitory markers HAVCR2/TIM3 and TIGIT. In co-culture with NK cells, CML target cells upregulated the IFN-γ response pathway including elevated HLA-expression and accordingly, upregulation of LGALS9 and PVR. The CD8+ T EM/EMRA cells that were expanded in CML diagnosis were suppressed following TKI treatment and decreased following TKI discontinuation. To track anti-CML T cells, we created a classifier to identify TCRs targeting leukemia-associated antigen PR1 from the TCRb-sequenced samples. As a validation of our classifier, we noticed that anti-PR1 T cells were more prevalent in CML than in healthy ( P adj<0.0001) or melanoma ( P adj<0.0001), more expanded than similar anti-viral T cells ( P adj<0.0001) and enriched in bone marrow samples compared to peripheral blood ( P adj<0.0001). From different TKIs, dasatinib expanded anti-PR1 T cells the most ( P adj<0.01). In the scRNA+TCRαβ-seq data, anti-PR1 T cells were enriched in the mature, cytotoxic CD8+ T EMRA phenotype ( P adj<0.0001). In a patient maintaining TFR, anti-PR1 T cells had a highly cytotoxic profile ( GZMB, PRF1) throughout the therapy with upregulated NK receptors like FCGR3A/CD16 and KIR2DL2, even more so than T cells targeting other targets e.g., different viruses. In comparison, the anti-PR1 T cells in a patient with early relapse had an exhausted profile with upregulation of memory marker GZMK and exhaustion markers like LAG3 and HAVCR2/TIM3. Conclusions: With our in-depth analysis of cellular and molecular immune responses in CML, we identified the active NK cells and anti-PR1 T cells that could help maintain TFR in patients discontinuing TKI treatment. Different immune-checkpoint blockade therapies such as anti-TIM3 could be considered as future strategies to improve the TFR rates.

Clonal Hematopoiesis Detected at the Time of Tyrosine Kinase Inhibitor Cessation Is Associated with Delayed Molecular Recurrence after Treatment-Free Remission in Patients with CML

Background Treatment-free remission (TFR) is a goal of therapy. However, ~50% of patients who attempt TFR will relapse, which mostly occurs by 6 months. The acquisition of somatic mutations in hematopoietic cells is common with age (clonal hematopoiesis, CH). Through next-generation sequencing studies we identified CH in patients in deep molecular remission. CH variants provide a selective growth advantage to cells, driving their clonal expansion. The clones also give rise to mutated immune effector cells with a proinflammatory profile that exacerbate diseases with a chronic inflammatory component, such as atherosclerosis. CH variants could potentially influence TFR, either by outcompeting an emerging residual CML clone or by altering immune function, which is known to play an important role in TFR. Aim To determine whether CH variants present at the time of therapy cessation could influence TFR. Methods An RNA-based hybridization capture sequencing method targeting 17 of the most frequently mutated CH genes was developed and applied to samples of 138 patients who attempted TFR. CH variants met strict criteria for pathogenicity based on their potential to confer growth and survival advantages. The CH status was confirmed by repeat testing of samples of 28 patients. The method reproducibly detected variants with a variant allele frequency (VAF) of ≥0.4%. Results The median follow-up for the 138 patients was 66 months from the TFR attempt. Molecular recurrence was defined as loss of major molecular response (MMR, BCR::ABL1 ≤0.1%). The probability of TFR was 64.5% at 6 months, 59.4% at 12 months and 51.0% at 84 months. CH variants were detected in 61/138 patients (44%): 107 variants in 12 genes. Multiple variants, range 2 - 7, were detected in 26 patients (19%). The median VAF was 0.9%, range 0.4 - 44%. Variants most frequently occurred in TET2 (44% of variants), DNMT3A (25%), PPM1D (7.4%) and ASXL1 (6.5%). The average age at cessation was 59.6 years, range 33 - 85. The average age of patients with CH was higher than those without CH: 64.7 versus 55.5 years, P < .0001. Only 3/13 patients (15%) aged ≤40 had CH compared with 6/7 patients (86%) ≥80. CH was significantly associated with TFR to 36 months after cessation. The optimal criteria for TFR prediction were at least one CH variant of VAF >2% or >2 variants (CH >2%/>2). Thirty-one of 138 patients (22%) had CH of VAF >2% (n = 24) or >2 variants (n = 7). The probability of TFR for these 31 patients was significantly higher than for the remaining patients when assessed at 6, 12, 24 and 36 months after cessation, Figure. The probability of TFR at 6 months was 90.3% for patients with CH >2%/>2 versus 57.0% for the remaining patients, P = .001. The probability of TFR at 36 months was 65.9% versus 51.2%, P = .049. A landmark analysis was performed at 12 months for the 74 patients who maintained TFR at 12 months. MMR was subsequently lost in 8/74 patients and the probability of TFR at 84 months was 86.9%. CH >2%/>2 occurred for 23/74 patients (31%). The probability of late molecular recurrence was higher among the patients with CH >2%/>2: 27.3% versus 5.5% for the remaining patients, P = .009. Overall, molecular recurrence occurred for 12/31 patients (39%) with CH >2%/>2 and 53/107 of remaining patients (50%). Time to molecular recurrence after cessation was longer for patients with CH >2%/>2 than the remaining patients: median 12.5 months versus 3.5 months, P < .0001. The longer time to molecular recurrence was linked to a different pattern of loss of MMR. The median time between first loss of MR4 (BCR::ABL1 ≤0.01%) and loss of MMR was 145 days for patients with CH >2%/>2 and 28 days for remaining patients, P = .0007. BCR::ABL1 values more frequently fluctuated before loss of MMR in patients with CH >2%/>2: 8/12 patients (67%, fluctuation over 120-1335 days) versus 6/53 (11%, fluctuation over 85-715 days) in the remaining patients, P =.016. Conclusion CH may improve the probability and duration of TFR, delaying the time to molecular recurrence, which has implications for patient selection and monitoring. Patients with CH who are eligible for therapy cessation have an excellent prospect of remaining drug-free for 1-2 years but their long term prospects of sustained TFR may be less certain compared to other patients, given the slower dynamics of relapse. Delayed relapse could be due to competition for clonal dominance between residual leukemic cells and larger CH clones, or modulation of the immune microenvironment. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Single-Cell Roadmap of Immune Cell Response in Chronic Myeloid Leukemia

Only half of chronic myeloid leukemia (CML) patients in deep molecular remission are able to maintain treatment free remission (TFR) after tyrosine kinase inhibitor (TKI) discontinuation. Identifying predictive markers for TFR remains a key issue. The immunological control or eradication of TKI insensitive leukemic stem cells may contribute to successful cessation, as recent work has demonstrated that differences in immune cell compositions can be associated with better probability of TFR. In order to understand the precise immunological changes in CML, we profiled over 170,000 cells from 25 CML samples from different clinical phases (untreated, during TKI therapy and after TKI cessation) using single-cell RNA and T cell receptor (TCR) αβ sequencing (scRNA+TCRab-seq). We profiled both CD45+ sorted peripheral blood samples (n=20) and CD34+ sorted bone marrow samples (n=5). To understand antigen-specific responses, we profiled TCRs specific to tumor-antigen PR1 (n=12) and compared these to unsorted TCRβ-sequenced samples from CML (n=137) and healthy donors (n=786). To understand the distinctive immunological features in CML, we compared the immune system in CML (n=20) to those in other hematological and solid malignancies profiled with scRNA+TCRab-seq (n=9). We discovered NK cells to be the most unique feature in CML, as NK CD56dim cells were more abundant in CML patients (Padj&amp;lt;0.001) and the NK cell repertoire was more transcriptionally heterogenous and included otherwise rarely seen exhausted NK population with upregulated HAVCR2 and TIGIT expression (Padj &amp;lt;0.0001). Further, the NK cell maturation changed during TKI-treatment from an effector CD56dim state towards an adaptive NK-cell state. We sought to understand whether the immunological activity differs before and after TKI discontinuation in different clinical outcomes following discontinuation. Therefore, we reclustered the discontinuation samples from three different outcomes: TFR, early relapse (&amp;lt;6 months after cessation) or late relapse (&amp;gt;6 months). In all clinical outcomes, TKI cessation invigorated NK cell exhaustion and the most upregulated pathways included IFNg and TNFa via NFkB pathways. Patients with successful TFR had less differences in their immune system after cessation in comparison to relapsing patients, which could hint that their immune subsets were better prepared for the cessation. Unlike the early relapse patients' quiescent immune cells, the late relapse patients' immune subsets were active, but under pronounced inhibitory Treg signals, providing a clinically interesting approach to alter the outcome of these patients. Next, to understand how malignant CML cells evade or interact with the immune system, we analyzed CD34+ cells and calculated a BCR-ABL1 activity score. The most primitive CD34+ cells had lower BCR-ABL1 score and not as many immunological ligand-receptor pairs as their less primitive, highly BCR-ABL1 pathway expressing, counterparts (P&amp;lt;0.0001). LGALS9, that is expressed on both BCR-ABL1 high and low CD34+ cells, arose as one of the most interesting ligands mediating tumor-immune cell interactions and it has many potential receptors expressed by NK cells, including HAVCR2. Finally, we found that tumor-antigen PR1 is preferentially expressed on CD34+ cells with high BCR-ABL1 score. Most TCRs recognizing PR1 are restricted to individuals, but they share short amino-acid motifs that are shared across patients. Thus, we were able to generate an in silico tool to recognize PR1-specific TCRs from unsorted TCR-seq samples with high accuracy (AUC 0.91 from 10-fold cross validation). With our tool, we were able to show that anti-PR1 responses were more frequent in CML than in healthy donors (P&amp;lt;0.0001), are more expanded in bone-marrow than in blood (P&amp;lt;0.0001) and diversified during TKI treatment (P&amp;lt;0.0001). In the scRNA+TCRab-seq data, the anti-PR1 response differed between TFR and early relapse patient significantly at phenotype level, where the TFR patient had cytotoxic anti-leukemic response before TKI cessation, in comparison to the early relapse patient's exhausted and less cytotoxic PR1-specific cells. In conclusion, our results provide high-resolution insights into anti-leukemic immune responses in CML and how we could harness and monitor them to enable successful TKI cessations. Figure Disclosures Olsson-Strömberg: Pfizer: Research Funding. Hjorth-Hansen:Pfizer: Honoraria, Research Funding; Austrian Orphan Pharma: Honoraria, Research Funding; Bristol-Myers Squibb: Research Funding. Mustjoki:Pfizer: Research Funding; Novartis: Research Funding; BMS: Honoraria, Research Funding.

A Phase I Trial of Incorporating Natural Killer (K-NK) Cells for Patients with Chronic Myeloid Leukemia (CML) and Molecular Residual Disease after Tyrosine Kinase Inhibitor (TKI) Therapy

Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of patients with chronic myeloid leukemia (CML) ushering in an era where, in select patient populations, treatment planning goals have shifted towards the achievement of treatment free remission (TFR) after TKI cessation. Both duration and depth of response to TKI therapy are predictors of future success in achieving a lasting TFR and with improved outcomes independent of TKI cessation. Unfortunately, molecular residual disease (MRD) persists in many patients despite optimal therapy and predicts for worse outcomes over time and decreased ability to maintain a TFR after TKI cessation. Achievement of a major molecular response (MMR) and probability of TFR have been associated with increased numbers of NK cells, particularly mature cytolytic NK cells. Kiadis K-NK003 cells are off-the-shelf NK cells from a universal donor expanded using PM21, proprietary membrane particles modified to express membrane bound IL-21 and 4-1bb ligand. The resulting expanded K-NK003 cells have a hyperfunctional phenotype that are simultaneously highly cytotoxic with high release of perforin and Granzyme B, and potent producers of the cytokines IFN-γ, TNF-α and IL-2. This is an open label, non-randomized, prospective phase I pilot study designed to evaluate safety and to examine whether the addition of K-NK003 to ongoing TKI therapy for CML patients with persistent MRD will allow patients to achieve MRD negative status. Patients will be treated with K-NK003 on day 1 of each 14 day cycle, for a total of 6 cycles, in conjunction with their ongoing TKI therapy. The primary endpoint is safety. The efficacy objective is to estimate the rate of optimal molecular responses (negative to at least MR4.5). Secondary and exploratory endpoints include the proportion of patients with a reduction in BCR-ABL transcripts and NK cell number and function. Adult patients with chronic phase CML who have been on TKI therapy for at least 1 year prior to enrollment in the study will be eligible. Patients must have been on their most recent TKI consistently for at least 6 months prior to enrollment on study and must be expected to remain on current TKI for the duration of the study. Patients with current accelerated or blast crisis phase disease will be excluded. Disclosures Rein: Celgene: Consultancy; Blueprint Medicine: Consultancy; Novartis: Consultancy; Clinical Care Options: Consultancy, Other: Speaker. Rizzieri:Bayer: Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees; Celltrion: Membership on an entity's Board of Directors or advisory committees; abbvie: Membership on an entity's Board of Directors or advisory committees; Mustang: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees; Acrobiotech: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Stemline: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Introducing a Predictive Score for Successful Treatment Free Remission in Chronic Myeloid Leukemia (CML)

Claudiani: Pfizer: Honoraria; Incyte: Honoraria. Byrne:Ariad/Incyte: Honoraria, Speakers Bureau. Rothwell:Incyte: Speakers Bureau; Novartis: Honoraria, Other: advisory board; Pfizer: Speakers Bureau. Copland:Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Honoraria, Speakers Bureau; Cyclacel: Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Clark:Ariad/Incyte: Honoraria; Pfizer: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Milojkovic:BMS: Honoraria, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Apperley:Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

PF407 TREATMENT‐FREE REMISSION IN PATIENTS WITH CHRONIC MYELOGENOUS LEUKEMIA FOLLOWING FIRST‐LINE DASATINIB, 1ST DADI/IMIDAS4

Background:The main treatment goal for patients with chronic phase chronic myelogenous leukemia (CML‐CP) is discontinuation of tyrosine kinase inhibitor (TKI) therapy. In the previous DAsatinib Discontinuation (DADI) trial, we showed that 44.4% of CML patients treated with second‐line or subsequent dasatinib could stop dasatinib safely if they sustained DMR (0.01% ≥ IS)for a minimum of 1 year. No study has examined treatment free remission (TFR) in a large cohort after discontinuation of first‐line dasatinib treatment.Aims:We report the the results of a phase II trial designed to investigate TFR after dasatinib discontinuation in CML patients who sustained DMR for at least 1 year after treatment with first‐line dasatinib (the 1st DADI / IMIDAS4 trial).Methods:In this trial, we enrolled patients with CML‐CP at 23 Japanese centers. Patients with CML‐CP with DMR and more than 24 months of first‐line dasatinib were enrolled. Patients with sustained DMR during the 1‐year dasatinib consolidation phase were eligible into the TFR phase. Molecular responses were assessed every 3 months during the consolidation phase and every month during the TFR phase by real‐time quantitative polymerase chain reaction.The primary end point was TFR at 6 months, and the secondary end point was TFR at 12 months. Molecular relapse was defined as loss of DMR at two consecutive times points or loss of major molecular response (MMR; 0.1% ≥ IS); in these cases, the patient was re‐administered dasatinib at the previously effective dose. Analysis of natural killer (NK) and T‐cell profiles was performed to identify the factors responsible for molecular relapse throughout the preregistration period of the study.Results:Patients (n = 68) diagnosed with CML‐CP and achieving DMR after receiving first‐line dasatinib treatment for at least 24 months, were eligible for the 1‐year consolidation phase. Nine patientswere excluded from the discontinuation phase.Fifty‐ nine patients were enrolled into the TFR phase of the study. The median age was 63 (31–94). Forty‐three patients had low Sokal risk scores and 16 patients had high or intermediate scores. The median duration of DMR and total time dasatinib treatment were 23.3 (11.1–56.2) months and 40.2 (35.1–111) months, respectively. The median dose of dasatinib during DMR and the total dose from initiation of treatment were 21,840 (3,600–38,700) mg and 67,100 (5,350–332,480) mg, respectively. Thirty‐three patients sustained TFR for a median follow‐up of 23.3 months (11.7 –31.0 months). Both overall probability of TFR at 6 and 12 months was 55.9% (95% CI, 44.6–70.1, Figure). The duration of first‐line dasatinib treatment (≥40 months or &lt;40 months; P = 0.72) did not correlate with the TFR rate, which had been thought to correlate with duration of TKI treatment. Overall, 26 patients experienced loss of DMR within 6 months; all received dasatinib at the previously effective dose, resulting in rapid achievement of MMR (24 of the 26 patients achieved DMR). Univariate and multivariate analyses revealed that low CD4/CD8 ratio was a significant favorable prognostic factor [Hazard ratio, 0.33 (0.14–0.79; P = 0.012), meanwhile, NK cell counts did not affect TFR.Summary/Conclusion:The TFR rate of 55.9% (the present study used very stringent criteria for molecular relapse) is a clinically important outcome with the shortest treatment time among previous TKI discontinuation studies. T cell‐mediated immune responses have a greater impact on TFR in CML than NK cell‐mediated immune responses. This trial was registered as number UMIN000011099.image

Prognostic Model of Successful Tyrosine Kinase Inhibitors Discontinuation Based on the Russian RU-SKI Multicenter Prospective Study

Background: A large number of tyrosine kinase inhibitors (TKI) discontinuation studies has shown that about 50% of chronic myeloid leukemia (CML) patients (pts) after TKI cessation lose a major molecular response (MMR) and should return to therapy. Despite the fact that, after TKI resumption, almost all patients re-achieve deep molecular remission, facilitating a more accurate selection process for therapy cessation remains topical.Aim: Develop a prognostic model for the better selection of CML patients for TKI discontinuation.Methods: The base for the training set was the Russian multicenter prospective study RU-SKI on the discontinuation of TKI in pts with CML and deep molecular response (DMR). Ninety-eight CML pts with chronic phase (CP), TKI therapy for at least three years and a stable DMR (BCR-ABL<0.01%) for at least two years were enrolled. Seven Pts with a previous history of unsuccessful treatment-free remission (TFR) were excluded from the analysis. The BCR-ABL level was evaluated by RQ-PCR according to the international scale (IS). The schedule of molecular tests was as follows: monthly during the first six months (mo) after TKI cessation, every two mo from six to 12 mo and every three mo thereafter. Treatment by the same TKI was resumed in case of MMR loss (BCR-ABL>0.1%). We used the Kaplan-Meier method for calculating the probability of TFR. Univariate analyses were performed using the log-rank test to identify prognostic factors for TFR. Variables found to be significant at the p<0.10 level were entered into a proportional hazards regression analysis. We categorized each independently significant factor into two groups, depending on the optimal cutoff level obtained by ROC analysis and the minimum P-value approach. The next step was a second multivariate analysis including categorized variables. A favorable factor from each variable was scored as 1, while the adverse factor was scored proportionally to the level of hazard ratio. The cumulative score for each patient was calculated. Patients were allocated to either a high or a low risk group concerning MMR loss after the cutoff level was determined by ROC analysis. The validation set included a series of 48 retrospective cases of discontinued patients selected according to RU-SKI inclusion criteria.Results: Baseline characteristics of the training set (n=91): male: 48%; median (Mе) age at TKI cessation 46 years (range 22 to 80); Me duration of TKI therapy 8.3 years (range three to 16.2); Me duration of DMR 3.2 years (range two to 10.7). Therapy before treatment cessation: imatinib in 63 (69%) pts, second-generation (2G) TKI in 28 (31%) pts. Me follow-up time after TKI cessation was 14 mo (range three to 36). Probability of TFR was 55% after 12 mo of follow-up. We analyzed the following factors: age, gender, history of previous resistance to imatinib, type and line of TKI, duration of therapy, length of DMR, depth of molecular response before cancellation, Sokal risk group. Age, Sokal risk group, duration of therapy and depth of molecular response were found to be independently significant factors and included in the survival prognostic model (Table 1). 73% (n=66) of pts scored 5.5 points or less and were assigned to the low risk group. The probability of TFR was 64% and 33% for the low risk and high risk groups, respectively (p=0.001) (Figure 1). Baseline characteristics of validation set (n=48): male: 36%; Ме age at TKI cessation 46 years (range 22 to 76); Me duration of TKI therapy six years (range 3.5 to 13.2); Me duration of DMR 2.8 years (range two to 10). Therapy before treatment stopped: imatinib in 31 (65%) pts, 2G TKI in 17 (35%) pts. Me follow-up time after TKI cessation was 36 mo (range six to 116). Probability of TFR was 47% after 30 mo of follow-up. In the validation set, 77% (n=37) of pts were assigned to the low risk group. The probability of TFR was 56% and 18% for the low risk and high risk groups, respectively (p=0.007) (Figure 2).Conclusion: RU-SKI prognostic model is effective in prediction of successful TFR and can be used for better selection of CML pts for TKI discontinuation. [Display omitted] DisclosuresShukhov:Novartis: Other: provided consultations and performed lectures ; Bristol Myers Squibb: Other: provided consultations and performed lectures . Chelysheva:Novartis: Other: provided consultations and performed lectures; Fusion Pharma: Other: provided consultations ; Bristol Myers Squibb: Other: provided consultations and performed lectures. Turkina:Novartis: Other: provided consultations; Bristol Myers Squibb: Other: provided consultations; Phizer: Other: provided consultations; Fusion Pharma: Other: provided consultations.

Jak-2 and Nfkbia Gene Expression Play a Strategic Role in Chronic Myeloid Leukemia (CML) Molecular Response during Early Nilotinib Treatment: The PhilosoPhi34 Data

Jak-2 and Nfkbia Gene Expression Play a Strategic Role in Chronic Myeloid Leukemia (CML) Molecular Response during Early Nilotinib Treatment: The PhilosoPhi34 Data

Feasibility of Treatment Discontinuation in Chronic Myeloid Leukemia in Clinical Practice in Spain: Results from a Nationwide Series of 236 Patients

Introduction: Over half of patients with chronic myeloid leukemia (CML) in sustained deep molecular remission do not lose the major molecular response (MMR) after stopping treatment with tyrosine kinase inhibitors (TKI). This strategy is safe in controlled clinical trials, but there is scarce information on its applicability in the real-life setting. We aimed to assess if treatment cessation was feasible in clinical practice in a large nationwide series of CML patients from Spain.Methods: This retrospective study comprised a series of 236 patients in chronic-phase CML who discontinued TKI treatment outside of clinical trials between April 2009 and February 2018 in 33 Spanish institutions. Inclusion criteria were: a) TKI treatment duration >3 years; b) sustained MR4.5 in >4 consecutive determinations (one single point in MR4 was acceptable) during >2 years; c) molecular monitoring in a reference laboratory expressing the results on the International Scale (IS). Patients who had undergone allogeneic hematopoietic stem-cell transplantation were excluded. Molecular relapse was defined as consecutively detectable BCR-ABL1 transcripts showing a ≥1 log increase or loss of MMR in any single sample. Treatment-free remission (TFR) was estimated by the method of Kaplan-Meier and defined as the time from TKI discontinuation to the date of restarting therapy for any reason or, if treatment was not restarted, the date of last contact. Incidence of molecular relapse was calculated using the cumulative incidence function with resumption of TKI treatment in the absence of molecular relapse and death in MMR as competing events. Analysis of factors predicting molecular relapse was done by the method of Fine and Gray.Results: Table 1 shows the main characteristics of the series. Median follow-up from treatment discontinuation was 21.5 months, and 5 patients died in MMR due to CML unrelated causes. TKI therapy was reinitiated due to molecular relapse (MMR loss: n=52, increase >1 log in BCR-ABL transcript level at two consecutive assessments without losing MMR: n=12), patient preference (n=2), and severe withdrawal syndrome (n=1). One additional patient lost MMR after 20 months from treatment cessation but decided not to be retreated, with spontaneous recovery of MMR. The probability of TFR at 4 years was 64% (95% Confidence Interval [CI]: 55%-72%)(Figure 1). The cumulative incidence of molecular recurrence was 33% (95% CI: 26%-38%) at 3 years (Figure 2). Forty-nine relapses (75% of total) occurred in the first 6 months. The latest MMR loss was detected 30 months after treatment stop. One patient restarted treatment 44 months after TKI discontinuation due to ≥1 log increase in BCR-ABL1 transcripts in two consecutive samples without losing MMR. In univariate analysis, duration of TKI treatment of less than 5 years (P=0.005) and time in RM4.5 shorter than 4 years before TKI discontinuation (P=0.003) were both significantly associated with a higher incidence of molecular recurrence.No patient progressed to the advanced phases of CML. At the time of restarting treatment, the median BCR-ABL1 IS was 0.3%, with this value being >5% in only 7 instances. Most patients (81%) received the same TKI that they were taking before the trial of treatment cessation. Median follow-up after treatment resumption was 20 months. Among the 64 patients who restarted treatment due to molecular relapse, 46 of 52 cases regained MMR after a median time of 3 months, and 47 of 64 regained MR4.5 after a median time of 5 months. Response status at last control was: MR4.5 (n=196), MR4 (n=15), MMR (n=14), complete cytogenetic response (n=10), and other (n=1).Fifty-one patients (22%) developed musculoskeletal or joint pain after treatment cessation. In patients stopping imatinib, a significant increase in Hb levels, leukocyte counts, total lymphocyte counts, platelet counts, and cholesterol levels was observed. At 6 months, an increase in Hb level >2 g/dL was observed in 47% of patients with anemia. By contrast, nilotinib discontinuation was not followed by any relevant change in laboratory values.Conclusions: Our results confirm that treatment discontinuation is feasible and safe in clinical practice in Spain. Duration of TKI treatment of less than 5 years and a time in RM4.5 shorter than 4 years before TKI discontinuation were significantly associated with a higher incidence of molecular recurrence. DisclosuresHernandez Boluda:Incyte: Consultancy; Novartis: Consultancy. García Gutiérrez:Incyte: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Ferrer Marin:Incyte: Consultancy; Novartis: Consultancy, Research Funding. Cervantes:Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hospital Clinic Barcelona: Employment.