Tyrosine Kinase Inhibitors Dasatinib Research Articles

Interaction of the chemotherapeutic agent oxaliplatin and the tyrosine kinase inhibitor dasatinib with theorganic cation transporter 2.

Oxaliplatin (OHP) is effective in colorectal cancer treatment but induces peripheral neurotoxicity (OHP-induced peripheral neurotoxicity, OIPN), diminishing survivor quality of life. Organic cation transporter 2 (OCT2) is a key OHP uptake pathway in dorsal root ganglia. Competing for OCT2-mediated OHP uptake, such as with the tyrosine kinase inhibitor dasatinib, may mitigate OHP side effects. We investigated OHP and dasatinib interaction with OCT2 in human embryonic kidney 293 (HEK293) cells expressing OCT2 within a 10-3 to 10-7M concentration range. Uptake competition experiments using fluorescent organic cation 4-(4-dimethylaminostyryl)-N-methylpyridinium (ASP+, 1µM) and mass spectrometry (MS) to determine cellular platinum content indicated that OHP (100µM) is an OCT2 substrate, mediating OHP cellular toxicity. ASP+ and MS analysis revealed dasatinib as a non-transported inhibitor of hOCT2 (IC50 = 5.9µM) and as a regulator of OCT2 activity. Dasatinib reduced transporter Vmax, potentially via Y544 phosphorylation suppression. MS analysis showed cellular dasatinib accumulation independent of hOCT2. Although 3µM dasatinib reduced 100µM OHP accumulation in hOCT2-HEK293 cells, co-incubation with dasatinib and OHP did not prevent OHP toxicity, possibly due to dasatinib-induced cell viability reduction. In summary, this study demonstrates OHP as an OCT2 substrate and dasatinib as a non-transported inhibitor and regulator of OCT2, offering potential for OIPN mitigation.

Pharmacokinetics of Dasatinib in Rats: a Potential Food-Drug Interaction with Naringenin.

The novel tyrosine kinase inhibitor (TKI) dasatinib, a multitarget inhibitor of Bcr-Abl and Src family kinases, has been licensed for the treatment of Ph+ acute lymphoblastic leukemia and chronic myeloid leukemia. Many citrus-based foods include the flavonoid naringenin, which is commonly available. Dasatinib is a Cyp3a4, P-gp, and Bcrp1 substrate, which makes it sensitive to potential food-drug interactions. The concurrent use of naringenin may change the pharmacokinetics of dasatinib, which could result in adverse effects and toxicity. The present investigation examined the impact of naringenin on the pharmacokinetics interactions of DAS and proposes a possible interaction mechanism in Wistar rats. Rats were provided with a single oral dose of dasatinib (25mg/kg) with or without naringenin pretreatment (150mg/kg p.o. daily for 7days, n = 6 in each group). Dasatinib was quantified in plasma by UHPLC MS/MS assay. Noncompartmental analysis was used to compute the pharmacokinetic parameters, and immunoblot was used to assess the protein expression in the hepatic and intestinal tissues. Following 7 days of naringenin pretreatment, the plasma mean concentration of dasatinib was enhanced compared with without pretreatment. In rats that were pretreated with naringenin, the pharmacokinetics of the orally administered dasatinib (25mg/kg) was shown to be significantly different from that of dasatinib given without pretreatment (p < 0.05). There was a significant enhancement in pharmacokinetic parameterselimination half-life (T1/2),time to maximum concentration ( Tmax), maximum concentration )Cmax), area under the concentration-time curve (AUC0-t),area under the moment curve (AUMC0-∞), and mean residence time (MRT) by 28.41%, 50%, 103.54%, 72.64%, 115.08%, and 15.19%, respectively (p < 0.05) and suppression in elimination rate constant (Kel), volume of distribution (Vd), and clearance (CL) by 21.09%, 31.13%, and 46.25%, respectively, in comparison with dasatinib alone group (p < 0.05). The enhancement in dasatinib bioavailability and systemic exposure resulted from the significant inhibition of Cyp3a2, Mdr1/P-gp, and Bcrp1 expression and suppression of the dasatinib hepatic and intestinal metabolism, which enhanced the rate of dasatinib absorption and decreased its elimination. Concurrent use of naringenin-containing supplements, herbs, or foods with dasatinib may cause serious and potentially life-threatening drug interactions. Further studies are necessary to determine the clinical significance of these findings.

Treatment-free remission after a second TKI discontinuation attempt in patients with Chronic Myeloid Leukemia re-treated with dasatinib – interim results from the DAstop2 trial

Tyrosine kinase inhibitor (TKI) discontinuation in chronic myeloid leukemia (CML) has become part of routine care for patients with a sustained deep molecular response (DMR). Approximately 50% experience a molecular relapse upon TKI cessation. Most of them quickly regain DMR upon TKI resumption. Whether these patients can achieve a second treatment-free remission (TFR) remains unclear. DAstop2 (ClinicalTrials.gov ID: NCT03573596) is a prospective study including patients with a failed first TFR attempt re-treated with any TKI for ≥ one year. Upon entering the study, patients received the TKI dasatinib for additional two years. Patients with sustained DMR for ≥1 year qualified for a second TKI stop. Ninety-four patients were included between Oct 2017-Dec 2021. At the time of data analysis, 62 patients had attempted a 2nd stop. After a median follow-up of 27 months from 2nd stop, TFR rates were 61, 56 and 46% at 6, 12 and 24 months respectively. No progression to advanced stage disease was seen and 87% had re-achieved MR4 within a median of 3 months from TKI re-initiation. In summary, we show that a 2nd TFR attempt after dasatinib treatment is safe, feasible and TFR rates seem in the range of those reported in trials of a first TKI stop.

HJKC3-0006: Outcome of Patients with CML Treated on Second Line or Later Therapy in Routine Clinical Practice

Background: First-line therapies for chronic-phase (CP) CML include the tyrosine kinase inhibitors(TKIs) dasatinib, nilotinib, bosutinib or imatinib, while ponatinib and asciminib are indicated only in later lines. There are typically high response rates to first-line therapy in CP-CML, with responses to second- and third-line therapy lower and highly dependent on the specific TKI. Our goal in this study is to evaluate the role of ponatinib in the treatment of patients with CML using data from routine clinical practice. Study design and methods: Data will come from the H. Jean Khoury Cure CML Consortium (HJKC3) CML registry, a North American multi-site research database. Participating sites include the HJKC3 members (curecml.org). Patient inclusion criteria include a diagnosis CML in chronic phase, receiving second line therapy after initial therapy with a second generation TKI (dasatinib, nilotinib, or bosutinib) or receiving third or later line TKI therapy for CML. Participating patients provide consent to collect their data both retrospectively and prospectively for 1 year. Clinical data, including toxicities and complications of TKI therapy, are abstracted from the electronic health record. Participating patients are invited to complete a questionnaire to assess health-related quality of life. Data are managed using REDCap, a secure web application. Study Objectives: The primary objective is to compare the outcome of patients treated with ponatinib vs. other TKIs as second or later line therapy. Secondary objectives are to evaluate patient-reported outcomes (PRO) for CML treated with second or later line therapy and to determine if there are any patient or disease characteristics that can predict outcomes. Statistical plan for clinical outcomes: Descriptive statistics will be used to compare baseline demographic characteristics. Categorical variables will be compared using the Chi-square test. Continuous variables will be compared using ANOVA. Overall survival will be calculated from the time of diagnosis to death from any cause and patients will be censored if they were alive at the last follow-up. Survival probabilities will be computed using the Kaplan-Meier method and compared with the log-ranktest. Cox regression analyses will be used to determine significant factors that influence survival, and hazard ratios with 95% confidence intervals will be presented. Event free survival (EFS) and transformation free survival (TFS) will be calculated for patients. For EFS, loss of complete hematologic remission, loss of major cytogenetic response, progression to accelerated or blast phase, or death from any cause at any time will be considered an event. For TFS, transformation to accelerated or blast phase while on therapy or death on study will be considered an event. Statistical plan for PRO: Different PRO domains will be analyzed separately (for example, depression separate from fatigue, etc.). Descriptive statistics for each PRO measure will be reported and compared to previously published studies. Differences by treatment type will be evaluated.

Accomplices in Cure: Blinatumomab + Dasatinib Reduces TCR Signaling and Effector Function Stronger Than Ponatinib and Ameliorates T-Cell Exhaustion

The tyrosine kinase inhibitors (TKIs) dasatinib (dasa) and ponatinib (pona) are being tested in clinical trials in philadelphia chromosome-positive (Ph +) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) patients in combination with the CD19xCD3 bispecific blinatumomab (blina). Pona but not dasa is able to bind the BCR-ABL T315I mutation, which frequently occurs in BCP-ALL patients. Therefore, clinical studies are moving away from dasa and favor pona. Nevertheless, both TKIs in combination with blina have led to striking remission rates in Ph + BCP-ALL (complete response dasa: 98%, Foá 2020; pona: 92%, Jabbour 2023). Interestingly, increased lymphocyte frequencies were reported in patients under blina + dasa therapy (Puzzolo 2021), indicating that the effect of dasa is not limited to toxicity towards ALL cells conferred by BCR-ABL inhibition. Indeed, dasa modulates T-cell function by interfering with TCR signaling (Mestermann 2019). Also, we have shown that resting of T cells by high-dose dasa treatment ameliorates bispecific-induced T-cell exhaustion (Philipp 2022). In contrast, less is known about the effect of pona on T-cell function. Based on these data, we hypothesize that TKIs fine-tune TCR signaling, which ameliorates T-cell exhaustion during continuous blina infusion. Here, we systematically compared the influence of dasa and pona on blina-mediated TCR signaling and T-cell function. Inhibition of T-cell activation and function by dasa or pona at 0.3 - 100 nM was tested in vitro over 3 days: (1) CD69 expression, (2) blina-mediated killing as specific lysis of CD19 + tumor cells (3) T-cell expansion analyzed by dye dilution or CD2+ fold change (FC), (4) cytokine secretion measured by cytokine catch or cytometric bead array. Inhibition of TCR signaling was evaluated using a Jurkat-NFAT T-cell line stimulated for 6h with blina and CD19 + tumor cells. Phosphoflow of pAKT and pZAP70 was performed on CD3/CD28 activated primary human T cells. Toxicity of the TKIs against BCR-ABL +/- cell lines was evaluated after 3 days. T-cell exhaustion upon continuous blina + dasa stimulation was assessed in an in vitro long-term culture system for continuous bispecific exposure (Philipp 2022). Functional assays as described in (1)-(4) were performed every 7 days with isolated T cells from long-term cultures. Both TKIs inhibited T-cell function in a dose-dependent manner. Surprisingly, dasa was more potent than pona at low-intermediate doses in reducing T-cell function, shown by CD69 expression (mean % at TKI = 3 nM: basal = 70, dasa = 25, pona = 64, p&amp;lt;0.0001), cytotoxic function (mean % specific lysis at TKI = 12.5 nM: basal = 55, dasa = 0, pona = 54, p&amp;lt;0.0001), T-cell proliferation (mean % proliferated at TKI = 1.5 nM: basal = 62, dasa = 25, pona = 51, p&amp;lt;0.0001), as well as IFN secretion (normalized mean fluorescence intensity (MFI) at TKI = 12.5 nM: basal = 655, dasa = 0, pona = 924, p&amp;lt;0.0001). We also observed that NFAT engagement was significantly lower in dasa-treated Jurkat-NFAT cells (relative luminescence units at TKI 12.5 nM: basal = 1620, dasa = 392, pona = 996, p&amp;lt;0.001). Similarly, phosphoflow analyses revealed lower levels of pAKT and pZAP70 upon CD3/CD28 + dasa versus pona treatment (MFI of pAKT at TKI = 25 nM: basal = 2347, dasa = 1642, pona = 2045). Importantly, both TKIs induced cell death of BCR-ABL + but not BCR-ABL - cell lines at concentrations &amp;gt;3 nM. Interestingly, 14 days continuously stimulated T cells with blina + dasa (12.5 nM) did not lead to co-expression of inhibitory checkpoints (mean % of PD-1 +Tim-3 +LAG-3 + T cells on day 14: blina = 31, +dasa = 0.6, p&amp;lt;0.01). Furthermore, when isolated from long-term cultures and tested in functional assays, blina + dasa treated T cells maintained high cytokine secretion (mean IL-2 in pg/ml on day 14: blina = 730, blina + dasa = 5638, p&amp;lt;0.01), granzyme B expression (mean MFI ratio of CD8 + on day 14: blina = 96, blina + dasa = 335, p&amp;lt;0.01) and cytotoxic activity (mean % specific lysis on day 14: blina = 61, blina + dasa = 80). Together, these findings indicate that while both TKIs confer comparable toxicity to BCR-ABL + leukemia cells, dasa dampens TCR signaling and T-cell effector function more potently than pona. Strikingly, dasa can ameliorate T-cell exhaustion upon continuous blina exposure. Our data suggest that low-dose TKIs can fine-tune T-cell activity and might play a considerable role for the clinical success of combinatorial bispecific and TKI therapy in Ph + BCP-ALL.

Improvement of Treatment-Free Remission Rate Following Discontinuation of BCR::ABL1 Tyrosine Kinase Inhibitors in Chronic Phase, Chronic Myeloid Leukemia

Backgrounds: Several studies have shown that approximately one-half of patients with chronic phase chronic myeloid leukemia (CP-CML) who receive sufficient tyrosine kinase inhibitors (TKIs) and achieve and maintain a deep molecular response (DMR) are able to successfully discontinue therapy. The main factors affecting Treatment free remission (TFR) are the duration of TKIs treatment and the duration of DMR maintenance during TKI treatment. Aims: To investigate impact of longer duration of DMR, we analyzed the outcome of patients with CP-CML who maintained DMR for more than 6 years during TKIs treatment and discontinued TKIs. The clinical and molecular immunological application criteria were also investigated for safer and more successful TFR. Methods: Among patients newly diagnosed with CP-CML and treated at least one of TKIs (Imatinib, Nilotinib, Dasatinib, Bosutinib, and Radotinib) as the first treatment, patients who maintained MR4.5 (BCR::ABL1 IS ≤0.0032%) continuously for at least 6 years through qRT-PCR tests were enrolled in this study. After discontinuation, molecular responses were monitored for up to six months per month, up to 12 months every two months, and every three months thereafter using the qRT-PCR method. In the case of relapse, defined as loss of major molecular response (MMR), the last TKI therapy was reintroduced and molecular responses after resumption were monitored monthly until achievement of MMR using qRT-PCR. Results: Altogether 116 patients (50 males and 66 females) discontinued TKI. Median age at diagnosis was 43.0 years (range, 40.8-45.3) and the percentages of patients with low, intermediate and high Sokal risk scores ware 58 (50.0%), 35 (30.2%) and 18 (15.5%) patients, respectively with unknown Sokal risk scores in 5 (4.3%) patients. Prior to discontinuation, all patients received TKIs for a median of 120.6 months (range, 113.9-127.3), and the duration of sustained MR4.5 was 75.0 months (range, 70.7-79.3). At the time of discontinuation, 93 patients (80.2%) were receiving their first TKI (70 imatinib, 13 nilotinib, 6 radotinib, and 4 dasatinib) while 13 (11.2 %) and 10 (8.6%) patients were receiving their second and more than three TKIs respectively. All patients who received more than one TKI had changed to adverse events. After a median follow-up from treatment discontinuation of 42.2 months (range, 35.3-49.1), 28 (24.1%) patients have lost their response at a median of 8.4 months (range, 4.9-11.9) after discontinuation; 18 (64.3%) patients had molecular relapse within 6 months of TKI discontinuation and 7 (25.0%) patients lost MMR after 12 months from discontinuation. TFR rates at 12, 24, and 48 months were 81.9%, 76.0%, and 71.0%, respectively. No progression toward advanced-phase CML occurred, and when 28 patients who lost MMR were retreated with same TKI, 26 patients (92.9%) re-achieved MMR with a median of 5.6 months (range, 4.0-7.2). By univariate analysis, a TKI treatment duration of 10 years or more was the only significant predictor for maintained response (P&amp;lt;0.048). Conclusion: Our result demonstrates that TFR rate can be improved in patients who received TKI treatment for approximately 10 years and maintained DMR for more than 6 years regardless of the type of TKI. Based on results, we can confirm one of important factors for safer TFR in CP-CML patients.

A Phase I/II Study to Investigate the Addition of Venetoclax to Dasatinib and Steroids in Patients with Newly Diagnosed or Relapsed Philadelphia Chromosome Positive Acute Lymphoblastic Leukemia (Ph+ ALL): The Venda Trial, in Progress

Background: Acute Lymphoblastic Leukemia (ALL) is a hematologic malignancy of immature lymphocytes of either B cell or T cell origin. One particularly high -risk subset is Ph+ ALL, characterized by a translocation of chromosome 9 and 22, which generates the constitutively active BCR-ABL1 fusion tyrosine kinase capable of driving proliferation and survival of leukemic cells. Currently treatment options include multi-agent chemotherapy along with an ABL-specific tyrosine kinase inhibitor (TKI), though these regimens can lead to significant toxicity, particularly in older adults. Venetoclax is a potent and selective small molecule inhibitor of the B-cell lymphoma 2 (BCL-2) anti-apoptotic protein. Strong mechanistic and preclinical data have demonstrated strong synergistic activity between dasatinib and venetoclax I xenograft models and ex vivo patient samples, and provide an impetus to further explore the combination of BCR-ABL and BCL-2 inhibition in vivo. Based on these data, we designed a clinical trial to investigate the safety and preliminary efficacy of venetoclax in combination with the second generation TKI dasatinib in Ph+ ALL. Study Design and Methods This is an open label, Phase I/II investigator initiated trial evaluating the addition of venetoclax to dasatinib and steroids (with Rituximab in CD20+ patients). Phase I is the safety and dose-finding portion of the trial combining the BCL2 inhibitor venetoclax with dasatinib and steroids during the first 28 days of induction followed by dasatinib and venetoclax for the final 48 days of induction in newly diagnosed and relapsed Ph+ ALL and mixed phenotype acute leukemia (MPAL) patients, including patients with molecular only relapse. Primary inclusion criteria include a histologically confirmed diagnosis of Ph+ ALL or MPAL. Newly diagnosed Ph+ ALL or MPAL patients may not have received leukemia-directed therapy other than for steroids or hydrea, and relapsed patients must have not had prior dasatinib exposure. Key exclusion criteria include subjects with CML in myeloid blast crisis or Ph+ AML, ECOG &amp;lt; 2 and patients with a history of pleural effusions. n order to determine the maximum tolerated dose (MTD) and/or recommended phase 2 dose (RP2D), a Bayesian toxicity probability interval design applied to a pre-specified targeted dose limiting toxicity rate of 30%. Three dose cohorts investigating increasing doses of venetoclax will be enrolled. Once the RP2D dose has been identified, a Phase II expansion will examine preliminary efficacy of the combination. The primary endpoint is the rate of measureable residual disease (MRD) negative remission rate as assessed by both BCR-ABL RT-PCR and next generation sequencing (NGS) after induction. Secondary endpoints include relapse-free survival (RFS) and overall survival (OS). Correlative studies include BH3 profiling (measure of apoptosis) and ex vivo screening to dasatinib and venetoclax alone and in combination. Consolidation phase with blinatumomab plus dasatinib and venetoclax is planned for the cohort expansion group. Enrollment began in September 2022 and is expected to be complete by September 2025. This trial is registered at clinicaltrials.gov (NCT04872790).

Long-Term Follow up for SWOG 1318: Combination of Dasatinib, Prednisone, and Blinatumomab for Older Patients with Philadelphia-Chromosome (Ph) Positive Acute Lymphoblastic Leukemia (ALL)

Tyrosine kinase inhibitors (TKIs) have improved the outcomes of patients with Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL). Many older patients (pts) are not good candidates for intensive chemotherapy and are treated with TKIs plus corticosteroids or low-intensity chemotherapy. Although the remission rates with this approach have been high, the median disease-free survival (DFS) has been short. Therefore, novel treatment strategies are needed. This trial evaluated the feasibility of combining the TKI dasatinib with prednisone and blinatumomab in older pts with Ph+ ALL. Here we present updated results (median follow-up, 4.3 years). Methods: This trial was activated through the NCTN in January 2015 and closed to accrual in April 2021. Pt eligibility included: age ≥ 65 years; Ph+ or Ph-like ALL (with dasatinib-sensitive fusions or mutations); newly diagnosed or relapsed/ refractory; no evidence of central nervous system (CNS) disease; and adequate organ function. Treatment: For induction, pts received dasatinib 140 mg/d orally (PO) Days 1-56 along with prednisone 60 mg/m 2/d PO Days 1-24. Pts achieving complete remission (CR) or CR with incomplete count recovery (CRi) (Day 28 or Day 56) continued dasatinib until Day 84, followed by 3 cycles of post-remission therapy (PRT) with blinatumomab/ dasatinib. Pts not achieving CR or CRi by Day 56 received re-induction with blinatumomab. The response rate was assessed on Day 35 of blinatumomab. Pts not achieving CR/ CRi could receive a second cycle of blinatumomab. This was followed by 3 cycles of PRT with blinatumomab/ dasatinib. Maintenance therapy consisted of prednisone 60 mg/m 2/d x 5 days every 28 days for a total of 18 cycles, along with dasatinib 140 mg po qd indefinitely. CNS prophylaxis included intrathecal (IT) methotrexate every 4-6 weeks x 8 doses. IT methotrexate was given at least 2 days apart from blinatumomab. Response was assessed at Days 28, 56, and 84, and additional time points were dependent on response. Minimal residual disease (MRD) was assessed centrally by multi-color flow cytometry on Day 28. Statistics: A total of 24 eligible patients were accrued. The primary objective was the feasibility of the combination therapy. The combination was to be deemed feasible if the dose-limiting toxicity (DLT) was &amp;lt; 33%. DLT included: &amp;gt; Grade 3 non-hematologic toxicities (excluding nausea, vomiting, diarrhea) and Grade 4 neutropenia lasting &amp;gt; 42 days. The primary results were reported in 2022 with a median of 2.7 years of follow-up. Herein, we report long-term outcomes for these patients. Results: The median age was 73 years (range 65-87). All pts had newly diagnosed Ph+ ALL; 79% of Ph+ pts had additional cytogenetic abnormalities. During induction, 2 pts experienced treatment-related non-hematologic Grade 4 toxicities. No Grade 4 or higher treatment-related non-hematologic toxicities occurred during post-remission therapy or maintenance. The toxicity of the combination was deemed acceptable. Twenty-two of 24 pts (92%) achieved a CR during dasatinib and prednisone induction therapy. Four did not receive PRT (2 due to adverse events, 1 to receive a transplant, and 1 because of insurance issues). Sixteen pts who achieved CR had MRD data. Six of 16 pts (38%) were MRD undetectable by multi-color flow cytometry on Day 28. Most sites also monitored patients' blood or bone marrow with real-time quantitative PCR to quantify the BCR-ABL1 transcript for molecular response. Of 19 patients analyzed, 17 (89%) were in a major or complete molecular remission at some time point after treatment, with at least 12 of these patients achieving complete molecular remission. Four patients remain on maintenance. The median follow- up for pts who are alive is 4.3 years (range 2.6-6.5 years). The median overall survival (OS) is 6.5 years (95% CI 3-NA) and the median DFS has not been reached as of June 29, 2023. Kaplan-Meier 3-year estimates of OS and DFS are 75% (95% CI 52%-88%) and 72% (95% CI 49%-87%), respectively (Figure). Of the 8 relapses, 4 patients were CD19+ and 3 had T315I mutations. Conclusions: Median DFS and OS with dasatinib and blinatumomab in this older group of Ph+ ALL patients remain excellent despite only 1 patient proceeding to an allogeneic transplant. Further correlative studies (single cell transcriptomics and DNA methylation sequencing) are being planned to evaluate predictors of relapse and will be presented at the meeting.

Novel Insights in TKI Resistance in BCR:: ABL1-Positive B-Cell Acute Lymphoblastic Leukemia Beyond Kinase Domain Mutations

Background and Aim Despite the introduction of tyrosine kinase inhibitors (TKIs), approximately 30% of newly diagnosed pediatric and adult BCR:: ABL1-positive B-cell acute lymphoblastic leukemia (B-ALL) patients experience relapsed or refractory disease (Biondi et al, Lancet Haematology 2018; Bassan et al, Journal of Clinical Oncology 2010). ABL1 kinase domain mutations, hindering TKI binding, explain part of the relapses and are acquired during TKI therapy but are rarely detected in newly diagnosed BCR:: ABL1-positive B-ALL patients (Baer et al, Haematologica 2022). Intrinsic TKI resistance mechanisms in BCR:: ABL1-positive B-ALL present prior to TKI treatment are less well documented. Therefore, we aimed to identify potential biomarkers for TKI sensitivity at diagnosis using primary patient samples and newly generated cell lines made from patient-derived xenografts (PDX cell lines). Patients and Methods Leukemic cells from diagnosis of BCR:: ABL1-positive B-ALL patients without ABL1-kinase domain mutations were used to measure cell survival in an ex vivo co-culture assay after imatinib (1.95-125 μM), dasatinib (1.95-125 nM), or bosutinib (0.016-2 μM) exposure. TKI sensitivity was assessed using the area under the dose-response curve (AUC), with &amp;lt;80 arbitrary units (AU) classified as imatinib-sensitive, 80-120 AU as intermediate, and &amp;gt;120 AU as resistant. Multiplex ligation-dependent probe amplification, whole exome sequencing, and RNA sequencing were performed on diagnostic material if available. ABL1 phosphorylation and expression levels were measured using (phospho)flow cytometry in patient-derived xenografts from diagnostic samples and (PDX) cell lines. Results We determined ex vivo sensitivity to imatinib, dasatinib, and bosutinib in 32 pediatric and 19 adult BCR:: ABL1-positive B-ALL patient samples. We observed a substantial variability in ex vivo imatinib response in pediatric and adult patient samples (median AUC: 98 AU; range: 16 to 281 AU). The sensitivity towards imatinib strongly correlated with the sensitivity towards second-generation TKIs dasatinib and bosutinib (rho = 0.84; p &amp;lt; 0.001 and rho= 0.89; p &amp;lt;0.001). Moreover, imatinib's AUC of samples derived from newly diagnosed patients who relapsed after TKI treatment was higher compared with those derived from patients who did not suffer from a relapse (median AUC 123 vs 84 AU; p = 0.03). We observed that an increase in ex vivo imatinib resistance was correlated with a decreased amount of phosphorylated ABL1 protein (rho=-0.92; p=0.0013) and total ABL1 protein (rho=-0.82; p=0.01) in untreated, newly diagnosed samples. Ex vivo exposure to imatinib reduced the ABL1 phosphorylation levels in both sensitive and resistant samples but resistant cells exhibited lower levels of (p)ABL1 protein, indicating reduced dependence on BCR-ABL1 signaling. The ex vivo imatinib resistance in samples carrying deletions in B-cell development genes IKZF1 and/or PAX5 was higher than in samples without these deletions (median AUC: 122 versus 80 AU; p=0.01). In addition, one imatinib-resistant patient had a p.His1038Arg mutation in ZEB2, which is recurrent in B-ALL and this gene has also been described as B-cell development gene (Studd et al, Blood Cancer Journal 2021). Interestingly, another resistant patient had a mutation in SETD2,a gene previously associated with ex vivo TKI resistance in chronic myeloid leukemia cell lines (Sheng et al, Cell Proliferation 2019). Other secondary lesions included SH2B3 inactivation lesions and CRLF2 rearrangements. These lesions were present in intermediately sensitive and resistant BCR:: ABL1-positive samples and are expected to lead to increased JAK/STAT signaling, potentially serving as a resistance mechanism for TKI. Conclusion Our study revealed that the amount of total and phosphorylated ABL1 protein was correlated with ex vivo TKI sensitivity. Newly diagnosed TKI-resistant BCR:: ABL1 samples were further characterized by somatic lesions in B-cell development genes including IKZF1. These results link the known poor prognostic value of IKZF1 deletions in BCR:: ABL1-positive B-ALL patients (van der Veer et al. Blood 2014; Fedullo et al, Haematologica 2019) with intrinsic mechanisms of TKI resistance other than tyrosine kinase domain mutations.

Differential vascular endothelial cell toxicity of established and novel BCR-ABL tyrosine kinase inhibitors.

BCR-ABL tyrosine kinase inhibitors (TKIs) have dramatically improved survival in Philadelphia chromosome-positive leukemias. Newer BCR-ABL TKIs provide superior cancer outcomes but with increased risk of acute arterial thrombosis, which further increases in patients with cardiovascular comorbidities and mitigates survival benefits compared to imatinib. Recent studies implicate endothelial cell (EC) damage in this toxicity by unknown mechanisms with few side-by-side comparisons of multiple TKIs and with no available data on endothelial impact of recently approved TKIs or novels TKIs being tested in clinical trials. To characterize BCR-ABL TKI induced EC dysfunction we exposed primary human umbilical vein ECs in 2D and 3D culture to clinically relevant concentrations of seven BCR-ABL TKIs and quantified their impact on EC scratch-wound healing, viability, inflammation, and permeability mechanisms. Dasatinib, ponatinib, and nilotinib, the TKIs associated with thrombosis in patients, all significantly impaired EC wound healing, survival, and proliferation compared to imatinib, but only dasatinib and ponatinib impaired cell migration and only nilotinib enhanced EC necrosis. Dasatinib and ponatinib increased leukocyte adhesion to ECs with upregulation of adhesion molecule expression in ECs (ICAM1, VCAM1, and P-selectin) and leukocytes (PSGL1). Dasatinib increased permeability and impaired cell junctional integrity in human engineered microvessels, consistent with its unique association with pleural effusions. Of the new agents, bafetinib decreased EC viability and increased microvessel permeability while asciminib and radotinib did not impact any EC function tested. In summary, the vasculotoxic TKIs (dasatinib, ponatinib, nilotinib) cause EC toxicity but with mechanistic differences, supporting the potential need for drug-specific vasculoprotective strategies. Asciminib and radotinib do not induce EC toxicity at clinically relevant concentrations suggesting a better safety profile.

THU045 WIP1 Phosphatase Is A Novel Specific Target For Epithelial GH Action

Abstract Disclosure: T. Apaydin: None. S. Zonis: None. C. Zhou: None. R. Barrett: None. V. Chesnokova: None. S. Melmed: None. Deficient DNA repair and accumulated DNA damage underlie age-associated pathological changes, tissue fragility, and neoplastic development. ATM kinase, an activator of DNA damage responses (DDR), phosphorylates DDR effectors including CHK2, p53, and γH2AX to ensure DNA repair. We have shown that GH suppresses epithelial DDR activity by suppressing ATM phosphorylation, resulting in DNA damage accumulation due to repressed DNA repair. Wip1 dephosphorylates ATM thereby attenuating DNA damage repair. We found that GH significantly induced Wip1 expression (1.6-fold) in both human normal colon cells (hNCC) and in human 3-dimensional intestinal organoids, resulting in dephosphorylated ATM, CHK2, γH2AX, and p53. Mice bearing GH-secreting tumors with high circulating GH also exhibited induced colon Wip1 expression with lower phospho-ATM, γH2AX, and p53 as well as increased DNA damage. Twofold higher Wip1 expression was observed in blood buffy coats derived from patients with GH-secreting adenoma vs patients with non-functioning pituitary adenoma. Specificity of these observations was validated by showing that in GH-treated cells, blocking GH receptor (GHR) with pegvisomant or blocking STAT5 phosphorylation with the inhibitor CAS 285986-31-4 constrained Wip1 induction and restored ATM phosphorylation, indicating that GH effects on Wip1 are GHR/STAT5-mediated concordant with the observed decreased colon Wip1 expression in GHR-/- mice devoid of GH signaling. Furthermore, Wip1 inhibition with the small molecule inhibitor (GSK2830371) reversed GH-induced DNA damage by restoring phosphorylation of ATM and other key DDR proteins. To determine a mechanism for Wip1 induction, we tested homeodomain-interacting protein kinase 2 (HIPK2) which is regulated by AMPK and potentiates Wip1 proteasomal degradation and its activity. We observed that GH increased phospho-AMPK expression, while blocking AMPK kinase activity with Compound C abrogated GH induction of Wip1. Src upregulates AMPK and triggers HIPK2 cytoplasmic relocation thereby inactivating HIPK2. We found that GH, by activating Src/AMPK phosphorylation, elicits HIPK2 cytoplasmic relocation, thus suppressing Wip1 ubiquitination and increasing its stability. Consistent with these findings, blocking Src phosphorylation with the tyrosine kinase inhibitor dasatinib abolished Wip1 upregulation and induced phosphorylation of its downstream targets. These results indicate that GH suppresses DDR by inducing Wip1 expression, and suppression of Wip1 may prevent epithelial accumulation of unrepaired DNA damage. These findings identify Wip1 as a specific novel target for GH action mediating GH-attenuation of DNA repair. Presentation: Thursday, June 15, 2023

The tyrosine kinase inhibitor Dasatinib reduces cardiac steatosis and fibrosis in obese, type 2 diabetic mice

BackgroundCardiac steatosis is an early yet overlooked feature of diabetic cardiomyopathy. There is no available therapy to treat this condition. Tyrosine kinase inhibitors (TKIs) are used as first or second-line therapy in different types of cancer. In cancer patients with diabetes mellitus, TKIs reportedly improved glycemic control, allowing insulin discontinuation. They also reduced liver steatosis in a murine model of non-alcoholic fatty liver disease. The present study aimed to determine the therapeutic effect of the second-generation TKI Dasatinib on lipid accumulation and cardiac function in obese, type 2 diabetic mice. We also assessed if the drug impacts extra-cardiac fat tissue depots.MethodsTwo studies on 21-week-old male obese leptin receptor mutant BKS.Cg-+Leprdb/+Leprdb/OlaHsd (db/db) mice compared the effect of Dasatinib (5 mg/kg) and vehicle (10% DMSO + 90% PEG-300) given via gavage once every three days for a week or once every week for four weeks. Functional and volumetric indices were studied using echocardiography. Post-mortem analyses included the assessment of fat deposits and fibrosis using histology, and senescence using immunohistochemistry and flow cytometry. The anti-adipogenic action of Dasatinib was investigated on human bone marrow (BM)-derived mesenchymal stem cells (MSCs). Unpaired parametric or non-parametric tests were used to compare two and multiple groups as appropriate.ResultsDasatinib reduced steatosis and fibrosis in the heart of diabetic mice. The drug also reduced BM adiposity but did not affect other fat depots. These structural changes were associated with improved diastolic indexes, specifically the E/A ratio and non-flow time. Moreover, Dasatinib-treated mice had lower levels of p16 in the heart compared with vehicle-treated controls, suggesting an inhibitory impact of the drug on the senescence signalling pathway. In vitro, Dasatinib inhibited human BM-MSC viability and adipogenesis commitment.ConclusionsOur findings suggest that Dasatinib opposes heart and BM adiposity and cardiac fibrosis. In the heart, this was associated with favourable functional consequences, namely improvement in an index of diastolic function. Repurposing TKI for cardiac benefit could address the unmet need of diabetic cardiac steatosis.

Cold atmospheric plasma treated 3D printed polylactic acid film; application in thin film solid phase microextraction of anticancer drugs

Tyrosine Kinase Inhibitors (TKIs) represent a pharmacological category of targeted therapeutics deployed for the treatment of malignant pathologies. Considering the side effects of this class of drugs for humans, therapeutic drug monitoring (TDM) becomes important. Here, a novel and specific methodology is introduced for the quantification of two TKIs (dasatinib and erlotinib) in human plasma samples. Furthermore, this study investigates the successful application of 3D printer technology in analytical sample preparation methods. Employing a fused deposition modeling (FDM) 3D printer and polylactic acid (PLA) filament, adsorbent films were designed and produced to be utilized in thin film microextraction. The 3D printed polylactic acid film surface was modified using cold atmospheric plasma (CAP) as a fast, clean and dry surface modification method with low consumption of chemicals and energy. Subsequently, FESEM, AFM, ATR-FTIR, and WCA analysis studies were employed to effectively assess the efficacy of the plasma surface modification method for the 3D printed films. After the optimization of the plasma modification and extraction methods, human plasma samples were studied for the effectiveness of the aforementioned approach. So, the selected 3D printed films with excellent microextraction efficiency have been found to be effective in sample preparation of biological samples. The linear dynamic range (LDR), limit of detection (LOD) and limit of quantification (LOQ) were obtained 0.10–20 μgL-1, 0.03 μgL−1and 0.1 μgL−1 for dasatinib and 1.0–500 μgL-1, 0.3 μgL−1, and 1 μgL−1 for erlotinib. The results obtained indicate that the developed method proves to be successful in the effective separation of anticancer drugs.

Lyophilization Based Isolation of Exosomes.

Exosomes are nanoscale extracellular vesicles which regulate intercellular communication. They have great potential for application in nanomedicine. However, techniques for their isolation are limited by requirements for advanced instruments and costly reagents. In this study, we developed a lyophilization-based method for isolating exosomes from cultured cells. The isolated exosomes were characterized for protein content using Bradford assay, and for size distribution and shape using scanning electron microscopy (SEM) and nanoparticles tracking analysis (NTA). In addition, CD63, CD9, CD81, HSP70 and TSG101 were evaluated as essential exosomal surface markers using Western blot. Drug loading and release studies were performed to confirm their drug delivery properties using an in vitro model. Exosomes were also loaded with commercial dyes (Cy5, Eosin) for the evaluation of their drug delivery properties. All these characterizations confirmed successful exosome isolation with measurements of less than 150 nm, having a typical shape, and by expressing the known exosome surface protein markers. Finally, tyrosine kinase inhibitors (dasatinib and ponatinib) were loaded on the exosomes to evaluate their anticancer effects on leukemia cells (K562 and engineered Ba/F3-BCR-ABL) using MTT and Annexin-PI assays. The expression of MUC1 protein on the exosomes isolated from MCF-7 cells also indicated that their potential diagnostic properties were intact. In conclusion, we developed a new method for exosome isolation from cultured cells. These exosomes met all the essential requirements in terms of characterization, drug loading and release ability, and inhibition of proliferation and apoptosis induction in Ph+ leukemia cells. Based on these results, we are confident in presenting the lyophilization-based exosome isolation method as an alternative to traditional techniques for exosome isolation from cultured cells.

Effect of the tyrosine kinase inhibitors on the growth in children with Philadelphia chromosome–positive acute lymphoblastic leukemia: a case–control study

First-generation ABL-targeted tyrosine kinase inhibitor (TKI) imatinib is known to retard growth in children but it is not known if the second-generation ABL-targeted TKI dasatinib has the same effect. We aimed to determine the impact of the first- or second-generation TKI on the growth of children treated for Philadelphia chromosome-positive (Ph+) childhood acute lymphoblastic leukemia (ALL). We evaluated the longitudinal growth changes in 140 children with Ph+ALL treated with imatinib or dasatinib in additional to intensive cytotoxic chemotherapy and 280 matched controls treated with the same intensity of cytotoxic chemotherapy without TKI on Chinese Children's Cancer Group ALL-2015 protocol between 2015 and 2019. We retrospectively reviewed the height data obtained during routine clinic visits at 4 time points: at diagnosis, the end of therapy, 1 year and 2 years off therapy. Height z Scores were derived with the aid of WHO Anthro version 3.2.2 and WHO AnthroPlus version 1.0.4, global growth monitoring tool. This study consisted only patients who have completed all treatment in continuous complete remission without major events, including 33 patients randomized to receive imatinib, 43 randomized to receive dasatinib, and 64 assigned to receive dasatinib. Similar degree of loss of height z scores from diagnosis to the end of therapy was observed for the 33 imatinib- and the 107 dasatinib-treated patients (median △=-0.84 vs.-0.88, P=0.41). Adjusting for height z score at diagnosis, puberty status, and sex, there was no significant difference in the longitudinal mean height z scores between patients treated with imatinib and those with dasatinib (0.08, 95% CI,-0.22 to 0.38, P=0.60). The degree of loss of height z scores from diagnosis to end of therapy was significantly greater in the 140 TKI-treated patients than the 280 controls (median △=-0.88 vs.-0.18, P<0.001). The longitudinal mean height z scores in the TKI-treated patients were significantly lower than those of the controls (-0.84, 95% CI,-0.98 to-0.69; P<0.001). These data suggest that dasatinib and imatinib have the similar adverse impact on the growth of children with Ph+ALL. This study was supported by the National Natural Science Foundation of China (grant 81670136 [JCai and JT]), the fourth round of Three-Year Public Health Action Plan (2015-2017; GWIV-25 [SS]), Shanghai Health Commission Clinical Research Project (202140161 [JCai]), the US National Cancer institute (CA21765 [C-H Pui]), and the American Lebanese Syrian Associated Charities (CC, JJY, and C-HP). The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the US National Institutes of Health.

Efficacy and safety of ponatinib in management of chronic myeloid leukaemia: Experience from Kenya.

e19067 Background: BCR-ABL tyrosine kinase inhibitors imatinib, nilotinib, bosutinib, and dasatinib, are used upfront in the management of chronic myeloid leukaemia (CML). In terms of resistance, ponatinib is the most potent tyrosine kinase inhibitor used in CML. It is however not used as first line therapy because of the fear of cardiovascular toxicity. However, because of a lot of inconsistency in the way oncology and cardiovascular trials define adverse events, this risk is not well defined. Methods: To document the efficacy and safety of ponatinib among CML patients treated at the Max Access Solutions Clinic at the Nairobi Hospital retrospectively. Results: Fourty-five patients were included between 02-10-2017 and 03-12-2022; males 23(51.1%) and females 22 (48.9%). All patients took imatinib first line. Ponatinib was taken second line by 10 (22.2%), third line by 18 (40%) and 4th line by 17 (37.8%). Of these, 25 (55.6%) were in chronic phase, 10(22.2%) accelerated and 9(20%) blastic phases. Of 22 evaluable cases in chronic phase, 1 (4.5%) died after 9 months on ponatinib, the rest are on follow-up for 1 – 60 months with a mean of 16.8 months and median of 10 months. Of 8 evaluable in accelerated phase, one (12.5%) died after 36 months. The range of follow-up is 2-36 months and mean 19.4 months. Of 9 evaluable in blastic phase, two (22.2%) are still alive after 6 and 41 months respectively. Seven (77.8%) died after follow-up ranging from 2-18 months, mean of 9.3 months. Interquartile range (IQR) for total white blood cell (wbc) count dropped from 9.08 x 109/litre to 4.82 x 109/litre on ponatinib, absolute neutrophil count dropped from 6.70 x 109/litre to 2.29 x 109/litre and platelets IQR rose from 114 x 109/litre -163 x 109/litre. Adverse events were registered in 6 (13.3 %), mainly grade 1-2, none of which was cardiovascular. Conclusions: Ponatinib is an active in all phases of CML with manageable side effect profile.

Enhanced anti-tumor activity of CD5 CAR T cells manufactured with tyrosine kinase inhibitors in patients with relapsed/refractory T-ALL.

7002 Background: An effective CAR T cell platform for the therapy of T-ALL requires minimizing CAR-driven fratricide of normal T cells. CD5 is a pan-T-cell surface protein present in ~85% of T-ALL. We developed a 2nd generation CD5 CAR that produces minimal T cell fratricide without additional engineering. Tonic CAR signaling accelerated terminal differentiation of CD5 CAR T cells potentially reducing their potency. In this study, we evaluated whether blocking tonic signaling with tyrosine kinase inhibitors (TKI) ibrutinib and dasatinib improves anti-leukemic activity of CD5 CAR T cells in patients with r/r T-ALL (NCT03081910). Methods: In the initial cohort of patients (CH1, n = 8), we generated CD5 CAR T cells from autologous PBMCs followed by expansion in the presence of IL-7 and IL-15 without TKI. In the subsequent cohort (CH2, n = 7) we manufactured cells from autologous (Arm A; n = 4) or HSC donor-derived (Arm B; n = 3) PBMCs in the presence of TKI. A total of 14 pts were treated (9 adult and 5 pediatric; age 11-70 years [median 36 yrs]); one pediatric pt was treated on both cohorts. Results: In CH1, all pts received autologous CAR T cells: 1 pt on DL1 (1x107 CAR T cells/m2), 5 on DL2 (5x107 CAR T cells/m2), and 2 on DL3 (1x108 CAR T cells/m2). In CH2, we treated 4 pts on Arm A (one on DL2; 3 on DL3) and 3 pts on Arm B (all on DL1). The overall expansion of CAR T cells was comparable between cohorts, but we observed more sustained persistence of CD5 CAR T cells in pts on CH2. In CH1, one pt experienced a morphologic CR. Of 7 pts treated on CH2, we observed 4 MRD-negative CRs (2 on Arm A and 2 on Arm B). The CAR T cells produced minimal early toxicity with most grade ≥3 AEs related to cytopenias, febrile neutropenia and transient abnormal laboratory values. CRS occurred in 3 pts on CH1 and 4 on CH2 (Arm A: n = 1; Arm B: n = 3); all ≤ grade 2. No pts developed ICANS. Two pts in CH2 (one on Arm A and Arm B) developed EBV viremia and post-transplant/immunodeficient lymphoproliferative disease (LPD) at wks 5 and 7 post-infusion, respectively. Both were treated with intensive multiagent chemotherapy, and one pt also received EBV specific T cells (EBVSTs) with significant reduction in viral load. Unfortunately, both passed away from complications of treatment for PTLD (unrelated to EBVSTs) with no evidence of residual T-ALL. No other significant infections occurred. Conclusions: These results demonstrate CD5 CAR T cells can induce clinical responses in heavily treated patients with r/r T-ALL. Manufacturing CD5 CAR T cells with TKI improved their potency and anti-tumor activity but also possibly suppressed CD5+ virus-specific T-cells thus leading to 2 cases of EBV associated LPD. We have subsequently modified our clinical protocol to administer prophylactic rituximab to EBV seropositive pts and identify a partially matched EBVST line prior to CAR T cell infusion as a strategy to prevent additional cases of LPD in future subjects. Clinical trial information: NCT03081910 .

Dasatinib-induced spleen contraction leads to transient lymphocytosis.

The tyrosine kinase inhibitor dasatinib is approved for Philadelphia chromosome-positive leukemia, including chronic myeloid leukemia (CML). Although effective and well tolerated, patients typically exhibit a transient lymphocytosis after dasatinib uptake. To date, the underlying physiological process linking dasatinib to lymphocytosis remains unknown. Here, we used a small rodent model to examine the mechanism of dasatinib-induced lymphocytosis, focusing on lymphocyte trafficking into and out of secondary lymphoid organs. Our data indicate that lymphocyte homing to lymph nodes and spleen remained unaffected by dasatinib treatment. In contrast, dasatinib promoted lymphocyte egress from spleen with kinetics consistent with the observed lymphocytosis. Unexpectedly, dasatinib-induced lymphocyte egress occurred independently of canonical sphingosine-1-phosphate-mediated egress signals; instead, dasatinib treatment led to a decrease in spleen size, concomitant with increased splenic stromal cell contractility, as measured by myosin light chain phosphorylation. Accordingly, dasatinib-induced lymphocytosis was partially reversed by pharmacological inhibition of the contraction-promoting factor Rho-rho associated kinase. Finally, we uncovered a decrease in spleen size in patients with CML who showed lymphocytosis immediately after dasatinib treatment, and this reduction was proportional to the magnitude of lymphocytosis and dasatinib plasma levels. In summary, our work provides evidence that dasatinib-induced lymphocytosis is a consequence of drug-induced contractility of splenic stromal cells.

Inhibition of casein kinase 2 induces cell death in tyrosine kinase inhibitor resistant chronic myelogenous leukemia cells.

Chronic myelogenous leukemia (CML) is a myeloproliferative disease characterized by the BCR-ABL oncogene. Despite the high performance of treatment with tyrosine kinase inhibitors (TKI), about 30% of patients develop resistance to the therapy. To improve the outcomes, identification of new targets of treatment is needed. Here, we explored the Casein Kinase 2 (CK2) as a potential target for CML therapy. Previously, we detected increased phosphorylation of HSP90β Serine 226 in patients non-responding to TKIs imatinib and dasatinib. This site is known to be phosphorylated by CK2, which was also linked to CML resistance to imatinib. In the present work, we established six novel imatinib- and dasatinib-resistant CML cell lines, all of which had increased CK2 activation. A CK2 inhibitor, CX-4945, induced cell death of CML cells in both parental and resistant cell lines. In some cases, CK2 inhibition also potentiated the effects of TKI on the cell metabolic activity. No effects of CK2 inhibition were observed in normal mononuclear blood cells from healthy donors and BCR-ABL negative HL60 cell line. Our data indicate that CK2 kinase supports CML cell viability even in cells with different mechanisms of resistance to TKI, and thus represents a potential target for treatment.

Novel pharmacological and dietary approaches to target mTOR in B-cell acute lymphoblastic leukemia.

High-risk subtypes of B-cell acute lymphoblastic leukemia (B-ALL) are frequently associated with aberrant activation of tyrosine kinases (TKs). These include Ph+ B-ALL driven by BCR-ABL, and Ph-like B-ALL that carries other chromosomal rearrangements and/or gene mutations that activate TK signaling. Currently, the tyrosine kinase inhibitor (TKI) dasatinib is added to chemotherapy as standard of care in Ph+ B-ALL, and TKIs are being tested in clinical trials for Ph-like B-ALL. However, growth factors and nutrients in the leukemia microenvironment can support cell cycle and survival even in cells treated with TKIs targeting the driving oncogene. These stimuli converge on the kinase mTOR, whose elevated activity is associated with poor prognosis. In preclinical models of Ph+ and Ph-like B-ALL, mTOR inhibitors strongly enhance the anti-leukemic efficacy of TKIs. Despite this strong conceptual basis for targeting mTOR in B-ALL, the first two generations of mTOR inhibitors tested clinically (rapalogs and mTOR kinase inhibitors) have not demonstrated a clear therapeutic window. The aim of this review is to introduce new therapeutic strategies to the management of Ph-like B-ALL. We discuss novel approaches to targeting mTOR in B-ALL with potential to overcome the limitations of previous mTOR inhibitor classes. One approach is to apply third-generation bi-steric inhibitors that are selective for mTOR complex-1 (mTORC1) and show preclinical efficacy with intermittent dosing. A distinct, non-pharmacological approach is to use nutrient restriction to target signaling and metabolic dependencies in malignant B-ALL cells. These two new approaches could potentiate TKI efficacy in Ph-like leukemia and improve survival.