DISCUSSION
cancers, neutropenia, breast cancer, cancer type, renal or hepatic dysfunction, carcinoma, pain, pyrexia, hematopoietic dysfunction, arthralgia
CANCERS, NEUTROPENIA, BREAST CANCER, ADVERSE EVENTS, ADVANCED CANCER, CARCINOMA, COMPLICATIONS
While our single‐arm study did not include a direct comparison of MD‐110 and the originator, the results of the primary endpoint suggest that MD‐110 is comparable in efficacy to the originator in terms of DSN. The median DSN was 0 days (86.1% of patients had a DSN of 0 days), meaning that most patients' ANC did not drop below 500/mmThe FN incidence rate in this study was 6.9% (7/101) for all cycles, slightly higher than the FN incidence rate reported in the originator study, which was 1.2% (2/173). Notably, a significant difference in the FN incidence rate was observed in the first cycle, with our study reporting a rate of 6.0% (6/101) compared to 0.5% (1/173) in the originator study. Since our study excluded patients at risk for increased FN frequency, such as those with hematopoietic dysfunction, advanced cancer, or serious complications (renal or hepatic dysfunction), we attribute this difference to the higher frequency of ANC measurements in our study. Our study required ANC measurements on days 1–8, 11, and 15 of cycle 1 (10 times in total), whereas the originator study only had five measurements on Days 1, 2, 8, 11, and 15. Upon closer examination of the six cases of FN in the first cycle of our study, we found that ANC levels below 500/μL were only observed on Day 7 (Table The incidence of FN in TC‐treated breast cancer patients with pegfilgrastim ranged from 0% to 10% and varied from study to study.There was no additional safety concern observed compared with the originator. No unexpected SAEs related to the study drug occurred. Among study drug‐related AEs that occurred in at least 10% of patients (back pain, arthralgia, and pyrexia), the incidence of back pain (24.8%, 25/101) was slightly higher than that associated with the originator (17.3%, 30/173).ADAs were negative in this study, whereas the presence of ADAs has been reported for the originator.It is important to note several limitations of this study. Firstly, the study design was not a randomized controlled trial. Secondly, excluding patients aged 70 years or older may limit the generalizability of the findings to older populations. Thirdly, the small sample size may have limited the ability to detect rare adverse events previously reported with pegfilgrastim. Additionally, given the focus on a single cancer type and chemotherapy regimen, the efficacy and safety of MD‐110 in other cancers and treatment settings remain unknown. In order to fully assess the potential of MD‐110 in a broader range of patients, further research should explore its use in different cancers and treatment regimens, as well as with more diverse patient populations.In conclusion, this study demonstrated that MD‐110 is effective against chemotherapy‐induced neutropenia with no additional safety concern compared with the originator in patients with breast cancer receiving TC chemotherapy. MD‐110 is expected to be the first pegfilgrastim BS approved in Japan for prophylactic use regardless of carcinoma type. MD‐110 may help fill an unmet need by providing greater affordability compared to existing treatment.