A recent systematic review of 36 studies on the use of generic imatinib suggests that generic imatinib has performed similarly to branded imatinib regarding efficacy and safety in treatment of chronic myeloid leukemia (CML). Results of this review were reported in the journal Blood Advances.
Imatinib was the first BCR-ABL1 tyrosine kinase inhibitor that was approved for management of CML. Generic versions of imatinib have since become available, and the research team performing the systematic review aimed to determine how the pharmacology, efficacy, safety, and impact on health systems compare between generic and branded/original imatinib.
Studies were identified through the PubMed database with search terms that included “generic” and “imatinib.” Included articles were written in English, resulting in 91 articles, of which 36 were eligible for analysis. Of these, 33 were full-text articles and 3 were letters.
There were 8 studies evaluating the pharmacologic properties and bioequivalence of generic and original imatinib. For most metrics in these analyses, generic imatinib showed similar pharmacologic properties compared with the original form. While the original form of imatinib is present in the b-crystal form, generic imatinib tends to be produced in the less stable a-crystal form. Both in vitro and in vivo studies, however, indicated the generic and original forms possessed similar pharmacologic properties otherwise.
Regarding efficacy, the researchers found some cases in which responses were lost upon a switch to generic imatinib from the original form, and a study reported on 4 patients with newly diagnosed CML who did not achieve a major cytogenetic response following 3 to 5 months on generic imatinib. However, in most cases the researchers reported that efficacy was similar between generic and original imatinib, in both newly diagnosed patients and in those who had previously received the original imatinib.
Safety comparisons between generic and original imatinib did not include statistical analyses, but in a few studies, there were reports of worsening adverse events after a switch to imatinib. One recent study demonstrated improvements in some adverse events following a switch to generic imatinib, and other studies indicated similar safety results between generic and original imatinib. The researchers considered contradictory results for efficacy and safety across different studies to be attributable to variation in manufacturing of generics in different countries.
In terms of impacts on health care costs, the authors noted that the release of generic imatinib was associated with a global reduction in the cost of original imatinib. Overall, imatinib affordability and accessibility reportedly increased. In the 2020 recommendations of the European LeukemiaNet, generic imatinib was regarded as the most cost-effective frontline therapy for CML-chronic phase.
Disclosures: Some authors have declared affiliations with or received grant support from the pharmaceutical industry. Please refer to the original study for a full list of disclosures.
ErçalışkanA, Seyhan ErdoğanD, Eşkazan AE. Current evidence on the efficacy and safety of generic imatinib in CML and the impact of generics on health care costs. Blood Adv. 2021;5(17):3344-3353. doi:10.1182/bloodadvances.2021004194