Comparison of Branded and Generic Imatinib Plasma Concentrations in Patients With Chronic Myelogenous Leukemia: Unicentric Study

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.

Adherence to tyrosine kinase inhibitors among adult chronic myeloid leukemia patients in a Malaysia hospital

Background Tyrosine kinase inhibitors have been demonstrated to improve the survival of patients with chronic myeloid leukaemia. However, medication adherence is vital for patients on chronic treatment. Objective The objective of the current study was to evaluate response to treatment, adherence by patients to tyrosine kinase inhibitors and factors associated with adherence and response. Setting A haematology clinic in a regional referral hospital in Malaysia. Method Patients aged ≥ 13 years who had been on imatinib or nilotinib for ≥ 12 months were included in this cross-sectional study. An optimal response was defined as the achievement of major molecular response at 12 months of treatment. Patient medication adherence was determined using the average medication possession ratio based on the dispensing records. The patients were considered adherent if the medication possession ratio was > 90%. Multiple logistic regression was performed to evaluate the factors associated with adherence. The association of adherence with molecular response was analysed by univariate logistic regression. Main outcome measure The primary outcome measures were the proportion of patients who achieved optimal response and the medication possession ratio. Results A total of 151 patients were screened, and 71 patients were included. Twenty-eight patients (39%) achieved major molecular response at 12 months of treatment. The median time to achieve this was 15.5 months (an interquartile range of 15). The mean medication possession ratio for imatinib and nilotinib was 0.94 (± 0.14) and 0.96 (± 0.10), respectively, but this difference was without statistical significance (t  =  - 0.517, p  =  0.610). Nausea and vomiting (odds ratio [OR] of 0.25, 95% confidence interval [CI]: 0.07-0.83, p  =  0.023) and disease phase at diagnosis (OR of 0.20, 95% CI 0.04-1.06, p  =  0.059) were associated with patient adherence. An association was not found between patient adherence and molecular response (OR of 1.03, 95% CI 0.35-3.09, p  =  0.956). Conclusion The patients in this study demonstrated a relatively deep molecular response and optimal adherence. Nevertheless, one fourth of them were noncompliant with imatinib. Therefore, active interventions are warranted to prevent treatment-associated adverse events and improve adherence.

Utility of Therapeutic Drug Monitoring of Imatinib, Nilotinib, and Dasatinib in Chronic Myeloid Leukemia: A Systematic Review and Meta-analysis

PURPOSE

This study examined the utility of therapeutic drug monitoring (TDM) of imatinib, nilotinib, and dasatinib in adult patients with chronic-phase chronic myeloid leukemia (CML). TDM in CML entails the measurement of plasma tyrosine kinase inhibitor (TKI) concentration to predict efficacy and tolerability outcomes and to aid in clinical decision making. TDM was to be deemed useful if it could be used for predicting the effectiveness of a drug and/or the occurrence of adverse reactions. It was expected that the findings from the present study would allow for the definition of a therapeutic range of each TKI.

METHODS

A systematic review of studies reporting trough TKI levels (C_min) and clinical outcomes was performed. We included randomized clinical trials, nonrandomized controlled studies, interrupted time series studies, and case series studies that provided information about plasma levels of imatinib, nilotinib, or dasatinib and relevant clinical end points in adult patients with chronic-phase CML treated with the corresponding TKI as the single antiproliferative therapy. Meta-analyses, Student t tests, and receiver operating characteristic analyses were performed to detect mean differences between groups of patients with or without: (1) the achievement of major molecular response and (2) adverse reactions.

FINDINGS

A total of 38 studies (28 for imatinib, 7 for nilotinib, and 3 for dasatinib) were included in the systematic review. TDM was found useful in predicting the efficacy of imatinib, with a C_min cutoff value of 1000 ng/mL, consistent with guideline recommendations. We suggest a therapeutic range of imatinib at a C_min of 1000-1500 ng/mL because higher concentrations did not increase efficacy. The findings from the rest of the comparisons were inconclusive.

IMPLICATIONS

TDM is useful in predicting the efficacy of imatinib in CML. Further research is needed to determine its validity with nilotinib and dasatinib.

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.

Generic Imatinib in Chronic Myeloid Leukemia Treatment: Long-Term Follow-up

BACKGROUND

Similar to the application of other generic drugs, the use of generic imatinib in the treatment of chronic myeloid leukemia (CML) leads to significant cost savings, but it also raises issues related to efficacy, safety, and quality. This study assessed the long-term outcome of CML patients after administration of generic imatinib.

PATIENTS AND METHODS

The cohort of 83 patients was divided into 2 groups depending on whether generic imatinib was applied in the front-line setting or after switching from original imatinib. The groups were compared regarding rates of optimal treatment response, adverse events, and survival.

RESULTS

In the first group, at the time of switching, rates of complete cytogenetic response experienced, and major molecular response were 95% and 87.5% of patients in the front-line generic imatinib group and the group that switched from original to generic imatinib, respectively. After 24 months of treatment with generic imatinib, the rates of sustained, lost, and experienced major molecular response were 72.5%, 15%, and 12.5%, respectively. In the group treated with front-line generic imatinib at 6 months, 67.4% experienced complete cytogenetic response, while for major molecular response at 12 and 24 months, it was 58.1% and 69.8%, respectively. Estimated 5-year overall survival in the group treated with front-line generic imatinib was 86.1%, while 10-year overall survival in the group treated with second-line generic imatinib was 93.8%.

CONCLUSION

Results of this study with long-term follow-up are further evidence that generic imatinib is at least noninferior to original imatinib regarding efficacy and survival, both when provided initially and as a subsequent replacement for original imatinib.

Generic formulations of imatinib for treatment of Philadelphia chromosome-positive leukemia in pediatric patients

Since the patent for imatinib has expired, the role of generic imatinib (GI) in the management of Philadelphia chromosome-positive (Ph+) leukemia in pediatric patients has had ongoing discussion. Some studies in adults demonstrated that equivalent doses of GI and branded imatinib (BI) result in comparable plasma concentrations and clinical efficacy. However, other studies found that GI users are more likely to stop imatinib, with intolerance and decreased persistence as the main causes. Economic factors also heavily influence GI selection. This article aims to review the present knowledge to support further discussion on the role of GI in the management of pediatric Ph+ leukemia.

Outcome of Frontline Treatment with "Generic" Imatinib In Adult Patients with Chronic Myeloid Leukemia in Algerian Population: A Multicenter Study

Introduction

In a developing country like Algeria, such expensive therapy is not available. Alternative approaches are needed to help these adult. In Algeria 'imatib' (CIPLA-India) was introduced in 2006; but no study has been published yet in the North Africa region regarding response and outcome of this copy in CML patients. The goal of this multicenter study is to characterize newly adult CML in the western region of Algeria and to assess the effectiveness and safety of imatib (IM, copy) as frontline therapy for patients with CML.

Patients and Methods

The study was carried out in 7 hematology centers in the western Algeria. Patients, who were diagnosed to be suffering from CML between January 1st, 2007 and December 31st, 2014 were selected for data analysis. All patients received a copy preparation, consisting of the alpha crystal form of imatinib, (IM, copy) at an oral dose of 400 mg daily and monitored for tolerance and side effects while on therapy.

Results

Between January 2007 and December 2014, 355 patients with CML were treated with imatib (Copy). The median follow- up of the study was 46 months (range: 13-107 months). Complete hematological response (CHR) was seen in 83% of patients within 3 months. According to the Sokal score, 72% patients with low, 78% with intermediate and 69% with high risk disease achieved a CHR in 3 months (p=0.26) and according to the EUTOS score, 81% of patients with low and 70% with high risk disease achieved a CHR in 3 months (p=0.08). The major molecular response (MMR) at six months (M6), M9, M12, M18 and M24 was 21%, 38%, 35%, 51% and 67% respectively and 34% of patients achieved a complete molecular response (CMR). The projected 5-year overall survival (OS) rate was 83%. Side effects of imatib (copy) in this study were similar to those reported previously for the entire imatinib mesylate treatment study and only 8% of patients were intolerant to imatib (copy) and treated with a second generation of BCR-ABL inhibitor.

Conclusion

This study reflects real world experience treating patients with CML in a developing country and thus sheds light on differences in this population compared to Western countries. In conclusion, imatib (copy) is effective and safe in treating patients with CML in chronic phase and proves to have a durable outcome. To our knowledge this is the first study reporting the response to imatib (copy) in an Algerian population.

Insights into the management of chronic myeloid leukemia in resource-poor settings: a Mexican perspective

INTRODUCTION

The arrival of targeted therapy for chronic myeloid leukemia (CML) was revolutionary. However, due to the high cost of tyrosine kinase inhibitors, access to this highly effective therapy with strict monitoring strategies is limited in low to middle-income countries. In this context, following standard recommendations proposed by experts in developed countries is difficult. Areas covered: This review aims to provide an insight into the management of patients with CML living in a resource-limited setting. It addresses several issues: diagnosis, initial treatment, disease monitoring, and additional treatment alternatives including allogeneic hematopoietic stem cell transplantation. Expert commentary: Imatinib is probably the most cost-effective TKI for initial treatment in developing and underdeveloped countries. Generic imatinib preparations should be evaluated before considering their widespread use. Adherence to treatment should be emphasized. Adequate monitoring can be performed through several methods successfully and is important for predicting outcomes, particularly early in the first year, and if treatment suspension is being considered. Access to further therapeutic alternatives should define our actions after failure or intolerance to imatinib, preferring additional TKIs if possible. Allogeneic transplantation in chronic phase is a viable option in this context.

The Efficacy of Generic Imatinib as First- and Second-line Therapy: 3-Year Follow-up of Patients With Chronic Myeloid Leukemia

INTRODUCTION

Generics of imatinib mesylate, the first tyrosine kinase inhibitor targeting the BCR-ABL1 fusion protein, have recently been approved in many countries as the alternative, low-cost forms for the treatment of patients with chronic myeloid leukemia (CML). The aim of this study was to evaluate the long-term clinical outcomes of patients with CML receiving first-line and second-line generic imatinib in Bosnia and Herzegovina.

PATIENTS AND METHODS

This was a multicenter retrospective cohort study of patients (n = 41) treated with generic imatinib in Bosnia between September 1, 2013 and August 5, 2016. Patients were categorized into 2 study groups: Group 1 (n = 27) included newly diagnosed patients with CML receiving front-line generic imatinib, and Group 2 (n = 14) consisted of patients who started with front-line Glivec and were mandated to switch to the second-line generic imatinib.

RESULTS

The median follow-up for Group 1 (first-line generic imatinib) and Group 2 (second-line generic imatinib) was 16 and 36 months, respectively. At 36 months, the overall survival for patients in Group 1 was 85%, and the achievement of complete cytogenetic response was 81%. At 24 months, the major molecular response rate was 48%. Overall, 52% of patients switched from first-line generic imatinib to nilotinib owing to treatment failure and side-effects. In Group 2, 93% of patients sustained cytogenetic and molecular response at 3 years after the switch from branded to generic imatinib.

CONCLUSION

Our results lead us to conclude that generic imatinib as second-line therapy does not have deleterious effects on patient outcomes. However, first-line generic imatinib showed suboptimal efficacy compared with branded imatinib.