Ifosfamide‐induced encephalopathy: Brand‐name (HOLOXAN®) vs generic formulation (IFOSFAMIDE EG®)

Switch to generic formulation of temozolomide results in statistically significant increase in grade 3 and 4 bone marrow toxicity in glioma patients in the province of Alberta

Background

Temozolomide (TMZ) is an oral, systemic chemotherapy used chiefly for treating high-grade glioma. Due to the rising costs of systemic chemotherapy, many jurisdictions have replaced brand name with generic formulations. The aim of this study was to determine whether or not there was difference in the incidence of grade 3 or 4 bone marrow toxicity and median overall survival in patients treated with brand name versus generic TMZ in the province of Alberta, Canada. The province suspended the use of generic TMZ based on preliminary data pointing to excess toxicity.

Methods

This multicenter, retrospective study included data from patients with newly diagnosed high-grade glioma that received treatment with TMZ in Alberta. Multivariate logistic regression analysis was performed to determine the association between grade 3 or 4 toxicity to generic versus brand name TMZ exposure, ECOG score, and age. Kaplan-Meier survival estimates and log-rank testing were used to determine differences in overall survival between the brand name and generic TMZ cohorts, as well as the cytopenic versus non-cytopenic patients. Furthermore, a screening analysis for grade 3 or 4 bone marrow toxicity was conducted on all de novo glioma patients treated with brand name TMZ after Alberta preemptively stopped generic TMZ.

Results

Grade 3 or 4 neutropenia and thrombocytopenia were observed in 15% and 19% of patients treated with generic TMZ (n = 156) as compared to 3% and 5% of patients (n = 100) treated with brand name TMZ-treated patients; P= .003 and .001. A trend toward increased median overall survival in glioblastoma patients treated with generic TMZ (13.7 months) versus brand name (15.8 months, P = .178.) was also observed through meeting statistical significance. Based on these results, the province stopped the use of generic TMZ and reverted to the Merck TMZ. An initial review of all new glioma patients (n = 89) treated with Merck TMZ since the province stopped the generic drug demonstrated 3.4% and 10.1% grade 3 or 4 neutropenia, respectively.

Conclusions

The statistically significant difference in toxicity profile has prompted the province of Alberta to replace generic TMZ with brand name TMZ in high-grade glioma patients pending more detailed analysis. Our study provides evidence supporting the importance of conducting prospective studies on long-term safety for generic chemotherapies.

Generic substitution of amlodipine is not associated with increased risk of mortality or adverse cardiovascular events: An observational cohort study

This study aims to assess clinical outcomes following switching from originator to generic amlodipine. This population-based, matched, cohort study included users of originator amlodipine using claims data during 2018-2020 from a health system in Tianjin, China, in which usage of generic amlodipine was promoted by a drug procurement policy, the national volume-based procurement. Non-switchers refer to those remained on originator after the policy, while pure-switchers were those who switched to and continued using generic amlodipine, and back-switchers were those switched to generic amlodipine but then back to the originator. Propensity score matching generates comparable non-switchers and pure-switchers pairs, and non-switchers and back-switchers pairs. The primary outcome was major adverse cardiovascular events (MACEs), defined as all-cause mortality, stroke, and myocardial infarction during follow-up (April 1, 2019 to December 30, 2020). Secondary outcomes included heart failure, atrial fibrillation, and adherence to amlodipine. The hazard ratio (HR) for each clinical outcome was assessed through Cox proportional hazard regression. In total, 5943 non-switchers, 2949 pure-switchers, and 3061 back-switchers were included (mean age: 62.9 years; 55.5% men). For the matched pairs, pure-switchers (N = 2180) presented no additional risks of clinical outcomes compared to non-switchers (N = 4360) (e.g., MACEs: 2.86 vs. 2.95 events per 100 person-years; HR = 0.97 [95%CI: 0.70-1.33]). Back-switchers (N = 1998) also presented no additional risk compared to non-switchers (N = 3996) for most outcomes except for stroke (HR = 1.55 [95%CI: 1.03-2.34]). Pure-switchers and back-switchers all had better amlodipine adherence than non-switchers. Generic substitution of amlodipine is not associated with increased risk of cardiovascular events or all-cause mortality, but improves medicine adherence.

Randomised phase 2 study comparing the efficacy and safety of the oral tyrosine kinase inhibitor nintedanib with single agent ifosfamide in patients with advanced, inoperable, metastatic soft tissue sarcoma after failure of first-line chemotherapy: EORTC-1506-STBSG "ANITA"

PURPOSE

EORTC-1506-STBSG was a prospective, multicentric, randomised, open-label phase 2 trial to assess the efficacy and safety of second-line nintedanib versus ifosfamide in patients with advanced, inoperable metastatic soft tissue sarcoma (STS). The primary end-point was progression-free survival.

PATIENTS/METHODS

Patients with a variety of STS subtypes were randomised 1:1 to nintedanib (200 mg b.i.d. p.o. until disease progression) or ifosfamide (3 g/m² i.v. days 1-3, every 21 days for ≤6 cycles). A Korn design was applied aiming to detect an improvement in median progression-free survival (mPFS) from 3 to 4.5 months (HR = 0.667). An interim look was incorporated to stop the trial for futility if <19 of the first 36 patients treated with nintedanib were progression-free at week 12.

RESULTS

At the interim analysis, among the first 36 eligible and evaluable patients randomised for nintedanib, only 13 (36%) were progression-free at week 12. The trial was closed for further accrual as per protocol. In total, 80 patients were randomised (40 per treatment group). The mPFS was 2.5 months (95% CI: 1.5-3.4) for nintedanib and 4.4 months (95% CI: 2.9-6.7) on ifosfamide (adjusted HR = 1.56 [80% CI: 1.14-2.13], p = 0.070). The median overall survival was 13.7 months (95% CI: 9.4-23.4) on nintedanib and 24.1 months (95% CI: 10.9-NE) on ifosfamide (adjusted HR = 1.65 [95%CI:0.89-3.06], p = 0.111). The clinical benefit rate for nintedanib and ifosfamide was 50% versus 62.5% (p = 0.368), respectively. Common treatment-related adverse events (all grades) were diarrhoea (35.9% of patients), fatigue (25.6%) and nausea (20.5%) for nintedanib; and fatigue (52.6%), nausea (44.7%) and vomiting, anorexia and alopecia (28.9% each) for ifosfamide.

CONCLUSION

The trial was stopped for futility. The activity of nintedanib did not warrant further exploration in non-selected, advanced STSs.

Incidence of ifosfamide induced encephalopathy in patients receiving concomitant fosaprepitant

INTRODUCTION

The incidence of Ifosfamide-induced encephalopathy (IIE) ranges from 5-30%. Aprepitant and fosaprepitant may increase the risk of IIE; however, data is limited. The objective of this study was to characterize the incidence of IIE in patients receiving concomitant fosaprepitant.

METHODS

This single-center, retrospective chart review included adult patients diagnosed with sarcoma who received at least one administration of high dose ifosfamide (≥1800mg/m²) and fosaprepitant between January 2017 and June 2018. The primary endpoint was the percentage of patient cycles in which IIE was experienced. Secondary endpoints included characterization of IIE management strategies, time to IIE resolution, and the incidence of IIE upon ifosfamide re-challenge. Subgroup analyses were performed to assess whether the following variables predisposed a patient to neurotoxicity: elevated serum creatinine, hypoalbuminemia, metabolic acidosis, hyperbilirubinemia, shorter infusion time, and higher body mass index. The role of CYP2B6 inhibitors and prior cisplatin use were also examined.

RESULTS

Fifty-one patients who received 215 total cycles of ifosfamide were included. Twenty (9.3%) patient cycles included documented evidence of IIE. The most common management strategies were to prolong the infusion time and administer methylene blue. The mean time to resolution of IIE was 2.58 days. The incidence of secondary IIE upon re-challenge was 26.3%. Baseline albumin <3.5 g/dL (p<0.001) was statistically associated with the development of IIE.

CONCLUSION

Co-administration of fosaprepitant and ifosfamide in sarcoma appears to be safe. Hypoalbuminemia was a notable risk factor confirmed in this study. Further research is needed to delineate IIE risk factors.

Deleterious impact of a generic temozolomide formulation compared with brand-name product on the kinetic of platelet concentration and survival in newly diagnosed glioblastoma

Chemo-induced thrombocytopenia is a limiting toxicity among patients receiving temozolomide (TMZ) as first-line treatment for glioblastoma. We aimed to compare early platelet concentration kinetics, hematological safety profile, and impact on survival following the initiation of either the brand-name or a generic TMZ formulation. A retrospective trial was conducted in patients suffering from newly diagnosed glioblastoma. Patients were treated with TMZ at 75 mg/m² per day during six weeks, concomitantly with radiotherapy. Platelet concentration was collected each week. Primary endpoint was to perform a linear mixed-effect model of platelet concentration kinetic over weeks. A total of 147 patients were included as follows: 96 received the brand-name TMZ, and 51 received a generic TMZ formulation. Exposition to the generic was a significant variable that negatively influenced the platelet kinetics in the radiotherapy and concomitant TMZ phase, P = 0.02. Grade ≥3 chemo-induced thrombocytopenia was more frequent in the generic group: 19.6% [95% CI 8.7-30.5%] vs 3.1% [0-6.6%], P = 0.001. Exposition to the generic formulation of TMZ led to increase early treatment discontinuation due to TMZ-induced thrombocytopenia and was a worsening independent prognostic factor on overall survival: adjusted HR 1.83 [1.21-2.8], P = 0.031. These data suggest that exposition to a generic formulation of TMZ vs the brand-name product is associated with higher early platelet decrease leading to clinically relevant impacts on treatment schedule in glioblastoma. Further prospective trials are needed to confirm these results.

Liquid formulation of ifosfamide increased risk of encephalopathy: A case-control study in a pediatric population

BACKGROUND

Several clusters of encephalopathy occurred after the market change from Holoxan® (ifosfamide lyophilized powder) to Ifosfamide EG® (liquid formulation) and justified a formal survey in 2015. In June 2016, the regulatory authority decided to apply a precautionary measure in reducing the shelf life of Ifosfamide EG® at 7 months. One-year study from spontaneous reports lead to suspect a potential residual risk. Due to the many limitations associated with spontaneous notifications, we performed a multicentric observational study, aiming to better explore this pharmacovigilance signal.

METHODS

We performed a case-control study in pediatric oncology Departments of 25 university hospitals between July 1st, 2016 and July 1st, 2018. All children (<18 y.o.) receiving liquid formulation or lyophilized powder formulation during the study period were included. Patients with at least one occurrence of encephalopathy were considered as cases. Logistic regression model was used to estimate the odds ratio of encephalopathy between exposure groups.

RESULTS

During the study period, 52 cases and 495 controls were included. A residual over-risk of encephalopathy was associated with ifosfamide 7-month shelf-life liquid formulation compared to lyophilized powder (adjusted OR 1.91, 95% CI: 1.03-3.53).

CONCLUSIONS

Observed difference does not seem to be related to the pathology treated, the doses used, the co-medications, a meningeal localization and/or an irradiation of the central nervous system. This study confirms data from spontaneous reports that led to the precautionary measure for the liquid formulation. Even if the risk of encephalopathy seems reduced, our study suggests the persistence of a residual risk of encephalopathy associated with liquid formulation compared to the lyophilized powder.