The OPTIC Study: a Multi-Center, Randomized Phase 2 Trial with Response-Based Dose Reduction to Evaluate Three Starting Doses of Ponatinib

Expert opinion-management of chronic myeloid leukemia after resistance to second-generation tyrosine kinase inhibitors

Regardless of line of therapy, treatment goals in chronic phase chronic myeloid leukemia (CML) are: avoid progression to accelerated phase or blast crisis CML such that patients achieve a life expectancy comparable with that of the general population; avoid adverse events (AEs); and restore and maintain quality of life. The most important prognostic factor for achieving these goals is response to tyrosine kinase inhibitors (TKIs) at key milestones. For patients failing a TKI, a treatment change is mandatory to limit the risk of progression and death. There is currently no precise guideline for patients that fail a second-generation TKI, and there is a paucity of data to guide clinical decision making in this setting. There is, therefore, an unmet need for practical and actionable guidance on how to manage patients who fail a second-generation TKI. Although the term 'failure' includes patients failing for resistance or intolerance, the focus of this paper is failure of a second-generation TKI because of resistance. CML patients who fail their first second-generation TKI for true resistance need a more potent therapy. In these patients, the key issues to consider are the relative appropriateness of early allogeneic hematopoietic stem cell transplantation or the use of a further TKI. Selection of the next line of treatment after second-generation TKI resistance should be individualized and must be based on patient-specific factors including cytogenetics, mutation profile, comorbidities, age, previous history of AEs with prior TKI therapy, and risk profile for AEs on specific TKIs. This expert opinion paper is not in conflict with existing recommendations, but instead represents an evolution of previous notions, based on new data, insights, and clinical experience. We review the treatment options for patients resistant to second-generation TKI therapy and provide our clinical opinions and guidance on key considerations for treatment decision making.

Novel tyrosine kinase inhibitors for patients with inadequate response in chronic myeloid leukemia

PURPOSE OF REVIEW

The purpose of this review is to summarize treatment expectations and response milestones, to conceptualize the approach to defining inadequate response to therapy and critically appraise current available strategies, as well to highlight novel agents under development to address unmet needs in chronic myeloid leukemia (CML) therapy.

RECENT FINDINGS

Given excess risk with currently available highly potent ABL1 (Abelson murine leukemia viral oncogene homolog 1) inhibitors, a number of alternate, highly potent compounds have entered the clinic to address select resistance such as the T315I mutation with the promise of greater selectivity and better adverse event profile. In addition, alternate approaches to ABL1 inhibition, targeting the myristoyl pocket of ABL1, are showing promising early results and are moving into later phase trials.

SUMMARY

CML is a highly treatable form of leukemia with multiple orally available small molecule inhibitors of the activated BCR-ABL1 (breakpoint cluster region-ABL1) kinase. Despite such an array of therapy options, inadequate response to therapy remains a challenge with a substantial minority of patients facing tyrosine kinase inhibitor (TKI) resistance, intolerance, or both. Unmet needs in Ph+ leukemia include highly selective resistant disease, multi-TKI resistant CML, and advanced phase disease.