T315I mutation exerts a dismal prognosis on adult BCR-ABL1-positive acute lymphoblastic leukemia, and salvage therapy with ponatinib or CAR-T cell and bridging to allogeneic hematopoietic stem cell transplantation can improve clinical outcomes

How to Manage Philadelphia-Positive Acute Lymphoblastic Leukemia in Resource-Constrained Settings

Recent studies have indicated that more than half of adult patients newly diagnosed with Ph+ ALL can now achieve a cure. However, determining the most suitable protocol for less-resourced settings can be challenging. In these situations, we must consider the potential for treatment toxicity and limited access to newer agents and alloSCT facilities. Currently, it is advisable to use less intensive induction regimens for Ph+ ALL. These regimens can achieve high rates of complete remission while causing fewer induction deaths. For consolidation therapy, chemotherapy should remain relatively intensive, with careful monitoring of the BCR-ABL1 molecular transcript and minimal residual disease. AlloSCT may be considered, especially for patients who do not achieve complete molecular remission or have high-risk genetic abnormalities, such as IKZF1-plus. If there is a loss of molecular response, it is essential to screen patients for ABL mutations and, ideally, change the TKI therapy. The T315I mutation is the most common mechanism for disease resistance, being targetable to ponatinib. Blinatumomab, a bispecific antibody, has shown significant synergy with TKIs in treating this disease. It serves as an excellent salvage therapy, aside from achieving outstanding results when incorporated into the frontline.

Detection of Hybrid Fusion Transcripts, Aberrant Transcript Expression, and Specific Single Nucleotide Variants in Acute Leukemia and Myeloid Disorders with Recurrent Gene Rearrangements

INTRODUCTION

A variety of gene rearrangements and molecular alterations are key drivers in the pathobiology of acute leukemia and myeloid disorders; current classification systems increasingly incorporate these findings in diagnostic algorithms. Therefore, clinical laboratories require versatile tools, which can detect an increasing number and variety of molecular and cytogenetic alterations of clinical significance.

METHODS

We validated an RNA-based next-generation sequencing (NGS) assay that enables the detection of: (i) numerous hybrid fusion transcripts (including rare/novel gene partners), (ii) aberrantly expressed EVI1 (MECOM) and IKZF1 (Del exons 4-7) transcripts, and (iii) hotspot variants in KIT, ABL1, NPM1 (relevant in the context of gene rearrangement status).

RESULTS

For hybrid fusion transcripts, the assay showed 98-100% concordance for known positive and negative samples, with an analytical sensitivity (i.e., limit of detection) of approximately 0.8% cells. Samples with underlying EVI1 (MECOM) translocations demonstrated increased EVI1 (MECOM) expression. Aberrant IKZF1 (Del exons 4-7) transcripts detectable with the assay were also present on orthogonal reverse transcription PCR. Specific hotspot mutations in KIT, ABL1, and NPM1 detected with the assay showed 100% concordance with orthogonal testing. Lastly, several illustrative samples are included to highlight the assay's clinically relevant contributions to patient workup.

CONCLUSION

Through its ability to simultaneously detect various gene rearrangements, aberrantly expressed transcripts, and hotspot mutations, this RNA-based NGS assay is a valuable tool for clinical laboratories to supplement other molecular and cytogenetic methods used in the diagnostic workup and in clinical research for patients with acute leukemia and myeloid disorders.

Determination of olverembatinib in human plasma and cerebrospinal fluid by an LC-MS/MS method: validation and clinical application

A sensitive and robust LC-MS/MS method has been developed and validated for olverembatinib quantification in human plasma and cerebrospinal fluid (CSF). The method involved liquid-liquid extraction with methyl tertiary butyl ether for plasma pretreatment and precipitation enrichment with methanol for CSF pretreatment. Separation was achieved on the C18 column with gradient elutions of 10 mM ammonium formate in water and methanol-acetonitrile (50:50,v/v). Analyte detection was conducted by electrospray ionization (ESI) in a positive ion mode using multiple reaction monitoring (MRM). The m/z transitions were 533.4→433.2 for olverembatinib and m/z 502.4→394.2 for the internal standard (IS, Imatinib-d8). Calibration curves ranged from 0.500 to 50.0 ng/mL for plasma and from 0.0100 to 1.00 ng/mL for CSF. The intra- and inter-day precision and accuracy were < 15% for both plasma and CSF with four different quality control concentrations. The relative matrix effect was < 10% in plasma and artificial CSF. This method was successfully utilized for the measurement of olverembatinib concentrations in plasma and CSF from chronic myeloid leukemia patients.

Pre-conditioning intervention in patients with relapsed or refractory acute lymphoblastic leukemia who underwent allogeneic hematopoietic cell transplantation: a KSGCT multicenter retrospective analysis

The efficacy and clinical significance of pre-conditioning intervention (PCI) before allogeneic hematopoietic cell transplantation (HCT) in patients with acute lymphoblastic leukemia (ALL) not in remission remain inconclusive. The purpose of this multicenter retrospective study was to clarify the clinical significance of PCI before HCT in patients with non-remission ALL. Patients with non-remission ALL who received HCT between 2005 and 2015 at 16 institutions were included. PCI was objectively defined and classified to three groups according to the intensity of PCI (no, intensive, or moderate). The study cohort consisted of 104 patients with a median age of 38 (range 17-68). A significant decrease of blast percentage in the peripheral blood (PB) was confirmed in both PCI groups, suggesting that PCIs were effective to stabilize the disease activity. The group with moderate PCI had higher nucleated cell count in the BM compared to the group with intensive PCI or the group without PCI. The overall survival (OS) rates of groups with intensive and no PCI showed comparable and significantly better compared to the group with moderate PCI (P = 0.009). Multivariate analysis demonstrated that the OS of moderate PCI group was significantly worse compared to that of intensive PCI group (HR = 2.43, 95% CI: 1.32-4.14, P = 0.004), while the OS of intensive PCI group was comparable to that of the group without PCI. These results suggest that the intensity of PCI rather than the response to PCI may contribute to improve the transplant outcome in patients with ALL not in remission.

Axitinib in Ponatinib-Resistant B-Cell Acute Lymphoblastic Leukemia Harboring a T315L Mutation

Adult acute lymphoblastic leukemia (ALL) with BCR-ABL1 rearrangement (Philadelphia chromosome, Ph) is a hematological aggressive disease with a fatal outcome in more than 50% of cases. Tyrosine kinase inhibitors (TKIs) targeting the activity of BCR-ABL1 protein have improved the prognosis; however, relapses are frequent because of acquired somatic mutations in the BCR-ABL1 kinase domain causing resistance to first, second and third generation TKIs. Axitinib has shown in vitro and ex vivo activity in blocking ABL1; however, clinical trials exploring its efficacy in ALL are missing. Here, we presented a 77-year-old male with a diagnosis of Ph positive ALL resistant to ponatinib and carrying a rare threonine to leucine (T315L) mutation on BCR-ABL1 gene. The patient was treated with axitinib at 5 mg/twice daily as salvage therapy showing an immediate although transient benefit with an overall survival of 9.3 months. Further dose-finding and randomized clinical trials are required to assess the real efficacy of axitinib for adult Ph positive ALL resistant to third generation TKIs.