Safety and efficacy of switching from branded to generic imatinib in chronic phase chronic myeloid leukemia patients treated in Italy

Comparable efficacy and safety of generic and branded imatinib for patients with chronic myeloid leukemia in China

Background

Generics imatinib became an alternative treatment option for chronic myeloid leukemia (CML) patients in China. However, clinicians and patients alike harbor concerns regarding the long-term safety of generic imatinib.

Objectives

Patients with chronic phase CML receiving frontline imatinib treatment.

Design

A retrospective study was used to evaluate the blood concentration, effectiveness, and safety of generic in 170 CML patients.

Methods

Imatinib plasma concentrations were detected by high-performance liquid chromatography-tandem mass spectrometry.

Results

Among the 170 patients, 73 (42.9%) patients treated with branded imatinib as first-line therapy, while 22 (12.9%) switched to generic imatinib during treatment due to economic considerations. No significant differences in trough concentrations between branded and generic imatinib (1549.9 ± 648.8 ng/mL vs 1479.0 ± 507.0 ng/mL; p = 0.95). During the 2-year follow-up, there were no significant differences in molecular response rates (major molecular response (MMR): 33.3% vs 37.0%; deep molecular response: 56.9% vs 42.9%, p = 0.17) between the branded and generic imatinib. Both groups showed similar rates of switching to second-generation tyrosine kinase inhibitor (11.8% vs 15.1%, p = 0.56). Furthermore, there were no significant differences in event-free survival or failure-free survival between branded and generic imatinib. Twenty-two (12.9%) switched to generic imatinib during treatment, 68.2% maintained their level of response, 27.3% improved, and only one patient (4.5%) lost MMR. There were no significant differences in the incidence of various adverse events.

Conclusion

Generic imatinib are equally effective and safe compared to branded molecules, both for newly diagnosed patients and those who switch from branded.

Determinants of frontline tyrosine kinase inhibitor choice for patients with chronic-phase chronic myeloid leukemia: A study from the Registro Italiano LMC and Campus CML

BACKGROUND

Imatinib, dasatinib, and nilotinib are tyrosine kinase inhibitors (TKIs) approved in Italy for frontline treatment of chronic-phase chronic myeloid leukemia (CP-CML). The choice of TKI is based on a combined evaluation of the patient's and the disease characteristics. The aim of this study was to analyze the use of frontline TKI therapy in an unselected cohort of Italian patients with CP-CML to correlate the choice with the patient's features.

METHODS

A total of 1967 patients with CP-CML diagnosed between 2012 and 2019 at 36 centers throughout Italy were retrospectively evaluated; 1089 patients (55.4%) received imatinib and 878 patients (44.6%) received a second-generation (2G) TKI.

RESULTS

Second-generation TKIs were chosen for most patients aged <45 years (69.2%), whereas imatinib was used in 76.7% of patients aged >65 years (p < .001). There was a predominant use of imatinib in intermediate/high European long-term survival risk patients (60.0%/66.0% vs. 49.7% in low-risk patients) and a limited use of 2G-TKIs in patients with comorbidities such as hypertension, diabetes, chronic obstructive pulmonary disease, previous neoplasms, ischemic heart disease, or stroke and in those with >3 concomitant drugs. We observed a greater use of imatinib (61.1%) in patients diagnosed in 2018-2019 compared to 2012-2017 (53.2%; p = .002). In multivariable analysis, factors correlated with imatinib use were age > 65 years, spleen size, the presence of comorbidities, and ≥3 concomitant medications.

CONCLUSIONS

This observational study of almost 2000 cases of CML shows that imatinib is the frontline drug of choice in 55% of Italian patients with CP-CML, with 2G-TKIs prevalently used in younger patients and in those with no concomitant clinical conditions. Introduction of the generic formulation in 2018 seems to have fostered imatinib use.

Chronic myeloid leukaemia

Tyrosine-kinase inhibitors have changed the natural history of chronic myeloid leukaemia in such a way that patients with adequate access to these agents, who are properly managed, and who respond well to this treatment can expect a near-normal life expectancy. Achieving this goal requires an adequate understanding of the patient's treatment goals, careful monitoring for the achievement of optimal response hallmarks, implementation of proper interventions according to the attainment of such endpoints, adequate recognition and management of adverse events, and acknowledgment of the relevance of comorbidities. Treatment with tyrosine-kinase inhibitors, once considered lifelong, has become terminable for at least some patients, and promising new agents are emerging for those whose disease does not respond to any of the multiple therapeutic options currently available. If these advances reach all patients with chronic myeloid leukaemia, cure might eventually become a reality in most instances.

Current evidence on the efficacy and safety of generic imatinib in CML and the impact of generics on health care costs

Since the introduction of imatinib, the management of chronic myeloid leukemia (CML) has changed considerably. Tyrosine kinase inhibitors (TKIs) are the mainstay of CML treatment; however, the high financial burden of TKIs can be problematic for both the patients and health care systems. After the emergence of generics, reimbursement policies of many countries have changed, and generics offered an alternative treatment option for CML patients. There are many papers published on the use of generics in CML patients with conflicting results regarding both efficacy and safety. In this paper, we systematically reviewed the current literature on generic imatinib use in CML, and 36 papers were evaluated. Both in vitro and in vivo studies of generic imatinib showed comparable results with branded imatinib in terms of bioequivalence and bioavailability. In most studies, generics were comparable with the original molecule in terms of efficacy and safety, both in newly diagnosed patients and after switching from Gleevec. Some generic studies showed contradictory findings regarding efficacy and toxicity, and these differences can be attributed to some factors including the use of different generics in different countries. Both in hypothetical models and in real life, introduction of generic imatinib caused significant reduction in health care costs. In conclusion, generics are not inferior to original imatinib in terms of efficacy with an acceptable toxicity profile. Notwithstanding the generally favorable efficacy and safety of generics worldwide to date, we most probably still need more time to draw firmer conclusions on the longer-term outcomes of generics.

Use of generic imatinib as first-line treatment in patients with chronic myeloid leukemia (CML): the GIMS (Glivec to Imatinib Switch) study

Background

Generic formulations of imatinib mesylate have been introduced in Western Europe since 2017 to treat patients with chronic myeloid leukemia (CML). However, results on the safety and efficacy of generic formulations are contrasting. The aim of this study was to investigate the safety and efficacy of generic imatinib in CML patients treated in 12 Italian institutes.

Methods

This is an observational, retro-prospective analysis of patients with CML for whom the treatment was switched from brand to generic imatinib. We analyzed and compared the variation in quantitative PCR values before and after the switch, and the proportion of patients who maintained molecular response after changing from brand to generic imatinib. Adverse events (AEs) were also evaluated.

Results

Two hundred patients were enrolled. The median PCR value after the switch was reduced by 0.25 compared to the values before the switch. A significant difference was found between median PCR values before and after the switch in favor of generic imatinib (P= 0.003). Molecular responses remained stable in 69.0%, improved in 25.5%, and worsened in 5.5% of patients. AEs were similar in the pre- and post-switch periods; however, a significant difference was found in favor of generic imatinib for muscular cramps (P< 0.0001), periorbital edema (P=0.0028), edema of the limbs (P<0.0001), fatigue (P=0.0482), and diarrhea (P=0.0027).

Conclusion

Our data indicate that generic imatinib does not have deleterious effects on CML control and present an acceptable safety profile, similar or better than brand imatinib.

Chronic Myeloid Leukemia in Children: Challenges and Opportunities : Based on 7th Dr. I. C. Verma Excellence Award for Young Pediatricians Delivered as Oration on 29th Sept. 2019

Treatment with tyrosine kinase inhibitors (TKI) is an effective therapy for children and adolescents with chronic phase of chronic myeloid leukemia (CML). For the majority of patients with CML in low- and middle-income countries (LMIC), imatinib is the TKI of choice for reasons of cost, availability, and experience. Children are exposed to therapy for a greater proportion of their lifetime as compared to adults. The adverse effects of prolonged administration of TKI is a subject of ongoing research, as more experience is collected. Therapy with TKI is currently considered to be life-long. Trials on stopping treatment are ongoing to explore if it may be feasible in selected patients, as reported in adults. Growth-failure is a concerning adverse effect. Currently, it seems unclear if the final height attained is within the expected range of the mid-parenteral height and growth standards. Whether the children will achieve a normal height at the end of their growth potential or remain below the predicted range is critical to decide if therapeutic interventions (E.g., growth hormone therapy, or interruption in TKI) should be considered during the period of growth potential. Research on CML in children is at a relatively slow pace, largely due to the rarity of the disease. This provides a unique opportunity for research in population-dense LMICs, as several tertiary centers tend to have a sizable cohort of children and adolescents with CML on follow-up. This narrative summarises the challenges and opportunities in dealing with CML in children, particularly in reference to a center in LMIC.

Comparable Efficacy and Safety of Generic Imatinib and Branded Imatinib in Patients With Newly Diagnosed Chronic Myeloid Leukemia With a Consideration of Socioeconomic Characteristics: A Retrospective Study From a Single Center

INTRODUCTION

To compare the efficacy and safety of generic and branded imatinib in adults with newly diagnosed chronic myeloid leukemia in the chronic phase (CML-CP), we retrospectively reviewed data from patients CML-CP who received generic or branded imatinib.

PATIENTS AND METHODS

A propensity score matching (PSM) study was performed. A Cox regression model was used to identify factors associated with responses and outcomes.

RESULTS

Four hundred forty-two adults receiving generic imatinib (n = 236) or Glivec (Novartis, Basel, Switzerland; n = 206) were included. There were more patients with rural household registration (P < .001), lower education level (P < .001), divorced or widowed status (P = .009), higher white blood cell counts (P = .019), splenomegaly (P < .001), and longer intervals from diagnosis to imatinib initiation (P = .033) in the generic cohort. During the follow-up, there was no significant difference between the 2 cohorts in the 4-year probabilities of achieving a complete cytogenetic response (97.0% vs. 97.3%; P = .736), major molecular response (87.8% vs. 90.1%; P = .113), and molecular response^4.5 (32.5% vs. 38.8%; P = .186), as well as failure-free survival (77.3% vs. 81.4%; P = .313), progression-free survival (94.4% vs. 95.8%; P = .489), and overall survival (96.8% vs. 98.3%; P = .088). Multivariate analyses showed that the drug type was not associated with responses and outcomes. After the PSM procedure, 177 pairs of patients with comparable baseline characteristics were reanalyzed. Multivariate analyses confirmed that generic or branded imatinib used as first-line therapy was not associated with either responses or outcomes.

CONCLUSION

Sociodemographic characteristics might influence the tyrosine kinase inhibitor that patients chose. Generic and branded imatinib as first-line therapy had comparable efficacy and safety in CML-CP patients.

[Comparison of the efficacy and safety of Chinese generic imatinib and branded imatinib in patients with chronic myeloid leukemia in consideration of demographic characteristics]

Objectives: To compare the efficacy and safety of Chinese generic imatinib with branded imatinib as frontline therapy in adults with newly diagnosed chronic myeloid leukemia in chronic phase (CML-CP) (Frontline group) , and to explore the efficacy and safety of Chinese generic imatinib in CML-CP patients switching from branded imatinib (Switching group) . Methods: Frontline group: Data of adults with newly diagnosed CML-CP receiving Chinese generic imatinib (Xinwei(®)) or branded imatinib (Glivec(®)) between October 2013 and August 2018 were retrospectively collected and analyzed. Switching group: Data of adults diagnosed with CML-CP who received branded imatinib and then switched to Chinese generic imatinib after achieving at least complete cytogenetic response (CCyR) were retrospectively collected and analyzed. Results: Frontline group: In total, 409 adult patients receiving Chinese generic imatinib (n=201) or Glivec (n=208) were included in this study. Median age was 42 years (range, 18-83 years) . Comparison of baseline showed significant difference on demographic characteristics among two cohorts: lower education level (P<0.001) , and divorced or widowed status (P=0.004) and rural household registration (P<0.001) were more common in the generic imatinib cohort than those in the Glivec cohort. There was no significant difference on age, gender, Sokal risk score, WBC and HGB between the 2 cohorts. With a median follow-up of 25 months (range, 3-62 months) , there was no significant difference on the 3-year cumulative incidence of achieving CCyR (97.5% vs 94.5%, P=0.592) , major molecular response (MMR) (84.3% vs 93.1%, P=0.208) , molecular response(4.0) (MR(4.0)) (42.7% vs 41.7%, P=0.277) , molecular response(4.5) (MR(4.5)) (25.4% vs 33.0%, P=0.306) as well as the 3-year probabilities of failure free survival (FFS) (76.7% vs 81.0%, P=0.448) , progression free survival (PFS) (91.8% vs 96.3%, P=0.325) and overall survival (OS) (95.8% vs 98.5%, P=0.167) between the generic and branded imatinib cohorts. Multivariate analysis showed the type of imatinib was not associated with treatment responses and outcomes. The incidences of adverse effects were comparable in the 2 cohorts. Switching group: In total, 39 patients switching from branded imatinib to Chinese generic imatinib after achieving at least CCyR were included in this study. Median age was 42 years (range, 23-80 years) . With a median follow-up of 39 months (range, 6-63 months) , molecular responses were maintained in 23 (58.9%) patients and improved in 12 (39.8%) patients. Adverse effects were tolerable. Conclusion: Demographic characteristics might influence the choice of the type of TKI used in CML-CP patients. There was a comparable efficacy and safety between the Chinese generic imatinib and the branded imatinib in adults with newly diagnosed CML-CP under standard management and closely monitoring. Patients could safely switch from the branded imatinib to the Chinese generic imatinib.

Efficacy and safety of generic imatinib after switching from original imatinib in patients treated for chronic myeloid leukemia in the United States

Introduction

Imatinib is standard therapy for patients with chronic myeloid leukemia (CML). In February 2016, a generic formulation entered the US market. Physicians and patients are frequently concerned about whether switching from original to generic drugs may affect the efficacy and/or safety.

Materials and methods

This is an observational retrospective study using medical charts of patients diagnosed with CML in the chronic phase who were treated with original imatinib from the year 2000 to 2017 and who were subsequently switched to generic imatinib.

Results

In this study, 38 patients have switched to generic imatinib. Before the switch, responses were assessed on all patients, all of them were in CCyR and 36 (95%) were in MMR, including 28 (74%) with MR4.5. Patients have received generic imatinib for a median of 19.4 (range, 3.4‐46.3) months. Molecular responses after switching were stable in 89%, improved in 8%, and worsened in 3% of patients. After switching, 15 (39%) patients reported new or worsening adverse events, including 5 (13%) patients with edema, 8 (21%) muscle cramps, 7 (18%) nausea, 6 (16%) diarrhea, and 5 (13%) fatigue.

Discussion

Bioequivalence studies demonstrated the same rate and extent of absorption of generic imatinib compared to the original form, which led to the FDA approval. In our observational series, most of the patients maintained their responses and none lost MMR. Adverse events noted were mild and well tolerated.

Conclusion

A change from original to generic imatinib appears to maintain efficacy and be generally safe. More patients and longer follow‐up are required to confirm these observations.