Asciminib Shows Strong Real-World Results in Hard-to-Treat Leukaemia Patients

Chronic myeloid leukaemia, once a near-certain death sentence, has been transformed over the past two decades by tyrosine kinase inhibitors, drugs that shut down the aberrant molecular engine driving the disease. Yet a stubborn minority of patients either fail to respond to these therapies or cannot tolerate their side effects, and many of them carry additional burdens such as cardiovascular disease that make standard treatment choices risky. A new real-world study from Italian haematology centres, published in the Annals of Hematology, offers a detailed look at how one of the newest members of this drug class, asciminib, performs outside the tightly controlled environment of clinical trials. The findings, drawn from a small but carefully documented case series, suggest that the drug can deliver sustained molecular responses even in heavily pretreated patients with significant comorbidities, while avoiding the cardiovascular complications that have shadowed some older therapies.

The study, led by Gianni Binotto of the University of Padova and Carmen Fava of the University of Turin, together with colleagues from major Italian haematology centres in Milan, Turin, Bari, Pavia and Bologna, focused on six adult patients with Philadelphia chromosome–positive chronic myeloid leukaemia in chronic phase. This form of leukaemia is defined by a characteristic genetic swap between chromosomes 9 and 22, which creates the BCR-ABL1 fusion gene encoding a constitutively active tyrosine kinase. It is this rogue enzyme that tyrosine kinase inhibitors are designed to block, and the Philadelphia chromosome serves as the molecular fingerprint of the disease. All six patients in the series had already been exposed to at least two prior tyrosine kinase inhibitors and had either become resistant to them or suffered intolerable side effects, placing them among the most challenging cases that clinicians encounter in routine practice.

What set these patients apart was not only their treatment history but their overall health profile. The cohort carried a substantial burden of comorbidities, predominantly cardiovascular in nature. Hypertension, peripheral arterial disease, ischaemic heart disease and metabolic disorders featured prominently among their conditions. This detail matters because several first- and second-generation tyrosine kinase inhibitors, notably nilotinib and ponatinib, have been associated with arterial occlusive events, including heart attacks, strokes and peripheral vascular complications. For patients whose blood cancer is under control but whose arteries are compromised, the choice of therapy becomes a delicate balancing act between suppressing the leukaemia and protecting the cardiovascular system. Asciminib, with its distinctive mechanism of action, has been proposed as a particularly attractive option for exactly this population.

The reason lies in the drug’s unusual binding mode. Whereas earlier tyrosine kinase inhibitors target the ATP-binding site of the ABL1 kinase, asciminib selectively targets the myristoyl pocket, a regulatory region of the protein that is otherwise not exploited by any other approved drug in the class. This allosteric mechanism gives asciminib high specificity for its target and is thought to underpin its potentially improved safety profile. Because the myristoyl pocket is a distinct structural feature of ABL1, the drug can remain active against certain mutations that confer resistance to ATP-site competitors. Among these is the notorious T315I mutation, often described as the most formidable resistance mutation in chronic myeloid leukaemia, which has historically limited treatment options dramatically. Asciminib’s efficacy has been demonstrated in both clinical trials and real-world settings, including heavily pretreated patients and those carrying the T315I mutation, making it a valuable addition to the therapeutic arsenal.

In the Italian case series, asciminib was administered for a median duration of 16.5 months, providing a meaningful window in which to observe both efficacy and tolerability. The results were strikingly consistent. All six patients achieved or maintained clinically meaningful molecular responses, including major molecular responses and deep molecular responses. These endpoints are measured by tracking the level of BCR-ABL1 transcript in the blood using sensitive polymerase chain reaction assays, and deeper responses correlate with better long-term outcomes and, in some cases, the possibility of treatment-free remission. For patients who had already cycled through multiple therapies without success, the ability of asciminib to induce or sustain such responses represents a significant clinical benefit.

Equally important was the drug’s tolerability. Treatment was well tolerated across the cohort, with no discontinuations due to adverse events. No arterial occlusive events were observed, and no significant cardiovascular worsening occurred during the observation period. This is a notable finding given the cardiovascular vulnerability of the patients involved. Even more remarkably, no haematologic toxicity was recorded, even in a patient with underlying bone marrow hypoplasia, a condition in which the bone marrow’s capacity to produce blood cells is already diminished. Myelosuppression is a common concern with many anticancer therapies, and the absence of this toxicity in a compromised patient suggests that asciminib’s high target specificity translates into a genuinely gentler profile at the level of normal blood-forming tissue.

The authors are careful to frame these observations appropriately. With only six patients, the series cannot deliver the statistical power of a randomised trial, and the findings are presented as a summary of the drug’s clinical data alongside real-world experience rather than as definitive evidence. Nevertheless, the study argues that real-world data of this kind play an essential role in supporting treatment decisions, because patients seen in everyday practice are often older, more comorbid and more heavily pretreated than those enrolled in pivotal clinical trials. Regulatory trials typically exclude individuals with uncontrolled hypertension, prior arterial events or reduced bone marrow reserve, precisely the characteristics that defined this Italian cohort. Demonstrating that asciminib can be used safely and effectively in such patients fills an important evidence gap that trial data alone cannot address.

The broader context of chronic myeloid leukaemia treatment makes these findings resonate. Since the introduction of imatinib at the turn of the millennium, survival in chronic myeloid leukaemia has risen to near-normal life expectancy for many patients, turning a fatal disease into a chronic condition managed with daily oral therapy. But this success has created its own challenges: patients now live for decades with their disease and their medication, so long-term tolerability, cardiovascular safety and quality of life have become central concerns. Second-generation inhibitors improved response rates but introduced new toxicity profiles, and resistance mutations continue to emerge. Drugs that combine deep molecular activity with a favourable cardiovascular and haematologic safety profile address the most pressing unmet needs in the field, particularly for the growing population of long-term survivors with age-related comorbidities.

Asciminib’s allosteric mechanism also represents a conceptual milestone in targeted cancer therapy. Rather than competing with ATP at the active site, the drug locks the kinase into its inactive conformation by engaging a pocket used naturally by the protein’s own regulatory lipid, myristate. This approach, sometimes described as a STAMP inhibitor, an acronym for specifically targeting the ABL myristoyl pocket, illustrates how structural biology can be exploited to design molecules with exquisite selectivity. The Italian case series adds a practical, bedside-level dimension to this molecular story, showing that the elegance of the mechanism is reflected in clinical outcomes for patients who have few alternatives left.

For clinicians managing chronic myeloid leukaemia, the message from this small study is one of cautious encouragement. In a real-world cohort of heavily pretreated patients with substantial comorbidity burden, asciminib demonstrated sustained efficacy and a favourable safety profile, with cardiovascular tolerability standing out as a particular strength. The authors conclude that these findings reinforce the potential role of asciminib for patients with resistance or intolerance to multiple tyrosine kinase inhibitors, as well as for those at high cardiovascular risk. As more real-world data accumulate across centres and countries, the picture of who benefits most from this allosteric inhibitor will continue to sharpen, helping physicians tailor therapy to the individual patient rather than to the average trial participant. For the six Italian patients documented here, and for the many others like them worldwide, that individualisation may make all the difference between merely surviving with leukaemia and truly living well with it.

Subject of Research: Real-world efficacy and safety of the allosteric BCR-ABL1 inhibitor asciminib in heavily pretreated chronic myeloid leukaemia patients

Article Title: Real-world Italian experience with asciminib in chronic myeloid leukaemia–chronic phase: case series and drug profile overview

Article References: Binotto, G., Cattaneo, D., Di Biase, F., Ditonno, P., Elena, C., Restuccia, R., & Fava, C. (2026). Real-world Italian experience with asciminib in chronic myeloid leukaemia–chronic phase: case series and drug profile overview. Annals of Hematology. https://doi.org/10.1007/s00277-026-07284-7

Image Credits: AI Generated

DOI: 10.1007/s00277-026-07284-7

Keywords: asciminib, chronic myeloid leukaemia, tyrosine kinase inhibitors, BCR-ABL1, myristoyl pocket, cardiovascular safety, molecular response, T315I mutation, real-world evidence, haematology, drug resistance, Annals of Hematology