ABL1 Y253H

Highly polymorphic BCR-ABL kinase domains have been reported to harbor more than a hundred mutations, and among these, 40-60% have been identified as influencers of imatinib mesylate (IM) resistance...A haplotype frequency distribution pattern analysis of ABL1 loci further identified the CGC haplotype as an independent predictor for IM resistance. As such the study highlights the importance of patient characteristics, genotype distribution, and haplotype frequency distribution in predicting the response to IM treatment and clinical outcomes of CML patients.

First-line therapy was available for 16 pts and was imatinib for 11 pts, nilotinib for 2 pts, dasatinib for 3 pts. Our data confirmed the efficacy of ponatinib in second or later lines of treatment. All pts, including those treated for resistance, achieved optimal responses at 3 mos. We also showed that TFR may be feasible for some pts treated in second or subsequent lines, not only for intolerance.

The 15 R/R patients (11, Ph + ALL; 4, CML-BP) received olverembatinib 30 or 40 mg on alternate days combined with VP (vindesine 4 mg once per week for 4 weeks and prednisone 1 mg/kg for 3 weeks and tapered at the fourth)...Among the 16 patients with molecular resistance to TKI-based chemotherapy (imatinib [n = 4]; dasatinib [n = 9]; flumatinib [n = 3]), 2 received olverembatinib monotherapy, 7 olverembatinib plus VP, and 7 hyper-CVAD, of whom 8 received subsequent allogeneic transplantation...Treatment-related nonhematologic severe adverse events were observed in 3 patients, including (each) stable angina pectoris, severe pneumonia, and fatal Klebsiella sepsis. Conclusions Olverembatinib-based chemotherapy is effective and safe in patients with R/R and molecular resistant Ph + ALL or CML-LBP.

Dasatinib in combination with a two-week vincristine and glucocorticoids regimen were administered, followed by sequential infusions of CD19 and CD22 CAR-T cells. Conclusions Dasatinib in combination with CAR-T cell therapy has enabled chemotherapy-free treatment in newly diagnosed Ph-positive ALL. This treatment is characterized by high complete molecular response, high long-term survival, low toxicity and short treatment cycles.

ABL1 is subject to auto-inhibition mediated by myristoylation-triggered conformational change, which can be exploited to overcome resistance, as validated by allosteric inhibitors such as GNF2, GNF5 and asciminib. Furthermore, TGRX-678 and ponatinib synergize to overcome the clinically challenging resistance conferred by T315M or T315I-inclusive compound mutations. This data warrant further clinical investigation of TGRX-678 for the treatment of resistant or refractory CML patients.

In summary, our newly developed assay can be used for kinase domain mutation analysis from clinical samples and with very good sensitivity of 2%, which is in a well-acceptable range of 1% to 3% and is available on commonly used the Ion Torrent platform. This ability of the assay in detecting low-level variants and even compound variants makes it very important for selection of appropriate TKIs for CML patients.

ASCEMBL trial showed superior efficacy of ASC to Bosutinib (BOS) with a higher molecular response rate, and a lower rate of discontinuation due to lack of efficacy (24.2% vs 35.5% at week 96)...A phase 1 study attempted to determine appropriate dose of ASC in combination with fixed dose of ABPIs including Imatinib (IMA), Dasatinib (DAS) and Nilotinib (NIL)...Each cell lines does have its inherent resistance level to double blockades, which needs to be further explored. A phase 1 study with reduced dose of ABPI in combination with fixed dose ASC is strongly warranted to define an optimal dose for combination.

It has been demonstrated better efficacy compared to imatinib in clinical trials of CML, but few reports are available in ALL...Once the diagnosis is confirmed, combination of flumatinib (600mg/day) and VIP-based chemotherapy regimen (Vincristine/Idarubicin/Prednisone) is administered promptly...Central nervous system (CNS) prophylaxis is regularly performed by intrathecal injection of methotrexate, cytarabine, and dexamethasone after remission induction course...Conclusion The combination of the second-generation TKI flumatinib and chemotherapy is quite effective and safe in Chinese adult pts with newly diagnosed Ph/BCR-ABL1+ ALL. This clinical trial is still ongoing, and the long-term follow-up data will be further investigated.

Methods In this exploratory study, adult Ph/BCR-ABL1+ ALL pts with T315I mutation or disease progression were treated with olverembatinib monotherapy (40 mg, every 2 days) or in combination with VP based low intensive chemotherapy (Vincristine/Prednisone) in our institution...Meanwhile, the olverembatinib-based therapy was well-tolerated, and the main adverse events of the third-generation TKIs, such as cytopenia, elevated transaminases, hypertension, and cardiovascular events, were less frequent than those reported relating to ponatinib...Conclusion This work suggests that Olverembatinib is a very promising 3rd-generation TKI. It is effective and safe in Chinese adult Ph/BCR-ABL1+ ALL with extremely poor prognosis, especially in T315I mutated or relapsed pts.

In conclusion, there is no significant difference in BCR-ABL1 KD mutations between Han and ethnic minority patients. NGS has a higher mutation detection rate than SS, and can detect compound variants and genes with lower mutation frequency that are not detected by SS.

Methods Isolated IR-clones (n=10) of KCL-22 were characterized by NGS and cultivated with 4µM imatinib (IM) and dilution series of BH3-mimetics (venetoclax – anti-BCL-2, S63845 – anti-MCL-1, A-1155463 - anti-BCL-XL) for 72 hours. Conclusion The preliminary data of this study showed that the MCL-1 inhibitor S63845 seems to be the most potent BH3-mimetic to induce apoptosis in BC-CML. The combined therapy of TKI and BH3-mimetics should reflect mutation status of BCR::ABL1 and other cancer related genes.

The probability of treatment discontinuation did not significantly differ for ponatinib in second, third or subsequent line of therapy (p=0.58). Conclusion This real-life investigation shows that ponatinib dose reductions were mainly performed in the absence of reported toxicity rather than owing to the occurrence of adverse reactions.

The presence of P-Loop domain mutations negatively impacted the prognosis of the disease in terms of disease advancement and overall survival. So, the timely performance of the BCR-ABL1 mutational analysis and the modifications in the treatment plan based on the mutation identified would help in a better outcome of the disease.

We screened 103 somatic mutations and found that mutations in the P-loop domain were the most frequent (173/454 mutations in the P-loop) and noted the presence of the V299 L mutation (dasatinib-resistant/nilotinib-sensitive) in 98 % of patients (49/50). In conclusion, ultra-deep sequencing is a sensitive method for genetic-based treatment decisions. Based on the results of these mutational analyses, nilotinib treatment is a promising option for Korean patients with CML.

Vodobatinib was evaluated over 9 escalating doses. Comparable and promising efficacy was noted in both PT (50% CCyR) and PN (67% CCyR) groups, meriting further study of vodobatinib as a potential new agent for treatment of previously treated CP-CML.

Nilotinib (NIL) 600 mg daily has demonstrated its superiority over Imatinib 400 mg daily in terms of response and incidence of deep molecular response in the front-line chronic phase (CP) CML setting...NIL first-line efficiently limits progression of newly diagnosed CP-CML patients and provides high rates of sustained MR4.5, allowing TFR in a substantial proportion of pts. However, the onset of arterial occlusive events, especially in the elderly is a matter of concern in the choice of this compound at treatment initiation.