On November 1st 2018, after being fully informed in the prior weeks, all patients attending a large teaching hospital in the Netherlands who were using the adalimumab originator were switched to the biosimilar Amgevita® for economic reasons. No significant loss of effectiveness or unsuspected safety issues were observed among switched RA patients. Most patients were satisfied with the switch and continued treatment with the biosimilar. These findings are consistent with findings from previous switch studies [13–16] and a trial in which the efficacy and safety of Amgevita® was compared to that of Humira® [29].
In the current study there was a small numerical increase in the number of relevant disease activity increases and flares between consecutive measurements of the DAS28 before and after the switch. However, mean disease activity scores were not significantly different from the measurement before the switch and most patients remained in the same category of disease activity throughout the observation period. The percentage of patients who ended up in a different category of disease activity due to an increase in DAS28 scores was the same before and after the switch, 60.9% and 61.3% respectively. In the majority of cases, the DAS28 score had decreased again by the next measurement, so patients were not in a higher category of disease activity for a long time.
Based on the survey, 7.9% of the patients discontinued the biosimilar for reasons other than being in remission. This is slightly lower than in other large switch studies like the PLANETRA extension cross-over study [16], in which 11.1% discontinued, excluding patients who discontinued because of remission, and the Humira® to Imraldi® switch study [15], in which 8.5% discontinued, excluding patients who discontinued because of remission, and the DANBIO-study [14], in which 18.0% discontinued, including patients who discontinued because of remission.
In the current study, only one patient switched back to the originator adalimumab. In an open-label switch study of a etanercept biosimilar, 2.72% of the 625 patients switched back to the originator biological [30], in the DANBIO study 6.42% of the 1621 patients switched back to the originator biological [14] and in an open label switch study by Tweehuysen et al. 18.9% of the 192 patients switched back to their originator biological [31]. Notably, the high percentage of patients who switched back to the originator biological in the study by Tweehuysen et al. seemed to be mainly due to subjective complaints. The percentage of patients that reported side effects in the current study was also relatively low. Twelve patients (31.6%) reported side effects, which led to discontinuation of Amgevita® in three patients. In the large comparison trial by Cohen et al. [29] 50% of the Amgevita® users and 54.6% of the Humira® users reported any kind of side effect The study population in the current study, however, might be too small to provide accurate estimations.
We started the patient selection with 239 unique patients who had switched from the originator biological adalimumab to the biosimilar adalimumab. Because of the strict selection criteria with a focus on RA patients only, 52 patients were available for analysis. Although this is a relatively small size, this approach did improve the quality of the data and the external validity of the findings for typical real-world RA patients.
The combined use of clinical data, patient-reported outcome data and pharmacy dispensing data is another strength of this study. By combining clinical and pharmacy data for the patient selection, we could accurately determine the exact switch date for the individual patients and patient medication compliance could be reasonably assessed. In addition, this study specifically examined the satisfaction of patients themselves with the course of the switch and the use of the Amgevita® syringe. In other switch studies little or no attention has been paid to these patient experiences, while it can lead to new insights and improvements. Combining the different clinical databases and also examining patient experiences offers a unique complete view of what a hospital-wide switch to a biosimilar means to patients.
The study also has some limitations. The reported side effects atributed to Amgevita® are completely based on the patients’ reports and were not clinically verified. Secondly, this study is a retrospective observational study, with consequently some missing data and a higher possibility of bias. In patients knowing they are receiving a biosimilar, there may be a greater chance of a nocebo effect [32]. The way information is conveyed in case of a potential switch can also contribute to a nocebo effect [33]. By avoiding negative associations, one can keep the nocebo effect as small as possible [34]. However, the development of negative associations cannot be fully controlled and can always influence the outcomes to some extent. For example, people may look up information by themselves and care workers cannot fully control what patients read and how they interpret this. Especially the lower costs of biosimilars may influence negative associations [35].
With a total expenditure of €216 million in 2016, the Netherlands annually spent most on the drug adalimumab of all biologicals [6, 7]. Due to the expiration of patents, room is created on the market for biosimilars, which are usually cheaper and can therefore contribute to lowering healthcare costs. In daily practice, the advent of biosimilars often means that newly starting patients are prescribed the biosimilar, while patients who are already using the originator biological continue to use the originator. By demonstrating in the current study that patients who are already using an originator biological can effectively and safely switch to a biosimilar, the decision to switch these patients to the biosimilar may be made more often in the future. This can further help to reduce healthcare costs and keeping healthcare accessible for everyone.
In conclusion, in patients with RA, switching from Humira® to Amgevita® for economic reasons did not significantly increase disease activity or impairments in physical function and did not decrease quality of life over an observation period of 12 months. Also, there was no apparent indication of increased side effects. Patients themselves were mostly satisfied with the switch.