BACKGROUND: The chemotherapy regimens recommended for both rhabdomyosarcoma (RMS) and Ewing sarcoma (ES) patients are myelosuppressive and can reduce the absolute neutrophil count (ANC) and subsequently increase the risk of febrile neutropenia (FN). However, only a few studies have focused on the efficacy and safety of granulocyte-colony stimulating factor (G-CSF) drugs in pediatric and adolescent patients with RMS and ES. Our objective was to investigate the efficacy and safety of mecapegfilgrastim, a biosimilar of pegfilgrastim, in prophylaxis of FN for pediatric and adolescent patients with RMS or ES.
METHODS: In this single-arm, single-center, prospective study, pediatric and adolescent patients with RMS or ES were enrolled to receive either VAC (vincristine, cyclophosphamide, dactinomycin) regimen or VDC (vincristine, cyclophosphamide, doxorubicin) regimen in a 3-week cycle, followed by treatment with mecapegfilgrastim (100 μg/kg, maximum 6 mg) given at 24 h after completing chemotherapy. The primary endpoint was the incidence rate of FN. Secondary endpoints included the incidence rate of grade 4 neutropenia, duration of ANC ≤ 0.5 × 109/L, incidence rate of chemotherapy delay or reduction, use of antibiotics, and safety profile.
RESULTS: In total, 2 of the 30 (6.7%, 95% CI: 0.82-22.07) patients experienced FN after the first cycle of chemotherapy. Eight (26.7%, 95% CI: 12.28-45.89) patients experienced grade 4 neutropenia after receiving prophylactic mecapegfilgrastim. Eight patients experienced ANC ≤ 0.5 × 109/L with a median duration of 4.5 days; among them, 6 patients reached the lowest point of their ANC level on day 7, and 5 of them recovered by day 10. No dose reductions, delays, or discontinuation of chemotherapy was reported. Twenty-one (70.0%) patients received antibiotics during the treatment period. No patient experienced FN in the 0-5 years and the 13-18 years groups, and 2 patients experienced FN in the 6-12 years group. Two patients, 6 patients, and no patient experienced grade 4 neutropenia in the 0-5 years, 6-12 years, and 13-18 years groups, respectively.
CONCLUSIONS: Mecapegfilgrastim showed acceptable efficacy and safety profile in pediatric and adolescent patients with RMS or ES. Further randomized studies with large sample size are warranted.
BACKGROUND: This clinical trial was registered at Chictr.org.cn (No.ChiCTR1900022249). Registered on March 31, 2019.

Biosimilars offer the potential for cost savings and expanded access to biologic products; however, there are concerns regarding the rate of biosimilar uptake. We assessed the relationship between biosimilar and originator pricing, coverage, and market share by describing four case studies that fall into two categories: (1) sole preferred coverage strategy (ie, aim is to have originator product preferred; biosimilar(s) non-preferred), defined as steep average sales price (ASP) reductions for originator products (decline in net prices by at least 50% following the introduction of biosimilar competition by 2022) and (2) non-sole preferred coverage strategy (ie, aim is to have originator product preferred alongside biosimilar products), defined as moderate ASP reductions for originator products with (net prices did not decline by at least 50% of its pre-biosimilar competition value). We found that originators with sole preferred coverage strategies maintained formulary preference and market share relative to originators with non-sole preferred coverage strategies. Regardless of strategy, the market-weighted ASP for all four product families (originator and biosimilars) declined significantly in the years following the introduction of biosimilars, suggesting that biosimilar uptake alone may not be a complete measure of whether the biosimilar market is facilitating competition and lowering prices.

BACKGROUND: Pegfilgrastim-cbqv/CHS-1701 (UDENYCA®) (hereafter referred to as pegfilgrastim-cbqv) was approved in 2018 by the US Food and Drug Administration as a biosimilar for pegfilgrastim (Neulasta®) (hereafter referred to as pegfilgrastim). Both pegfilgrastim-cbqv and pegfilgrastim are conjugates of recombinant human granulocyte colony stimulating factor (r-metHuG-CSF) with a 20 kDa polyethylene glycol (PEG) indicated to decrease the incidence of infection, as manifested by febrile neutropenia, in patients receiving myelosuppressive anticancer drugs. The demonstration of analytical similarity for PEG-protein conjugates presents unique challenges since both the protein and PEG attributes must be characterized.
OBJECTIVE: The current study demonstrates the analytical similarity of pegfilgrastim-cbqv and the reference product, pegfilgrastim. In addition to the physicochemical and functional characterization of the protein, the study assessed attributes specific to PEGylation including PEG size and polydispersity, site of attachment, linker composition, and PEGylation process-related variants.
METHODS: The structural, functional, and stability attributes of pegfilgrastim-cbqv and pegfilgrastim were compared using state-of-the-art analytical methods. For the protein, the primary structure, disulfide structure, and secondary and tertiary structures were assessed using traditional protein characterization techniques such as mass spectrometry (MS), circular dichroism (CD), intrinsic fluorescence, and differential scanning calorimetry (DSC), as well as more advanced techniques such as two-dimensional (2D) nuclear magnetic resonance (NMR) and hydrogen deuterium exchange (HDX). For the PEG moiety, the site of attachment, occupancy, linker composition, size and polydispersity were compared using mass spectrometry (both intact and after endoprotease digestion), multiangle light scattering detection (MALS), and Edman degradation. Purity assessments included the assessment of both protein variants and PEGylation variants using chromatographic and electrophoretic analytical separation techniques. The functional similarity between pegfilgrastim-cbqv and pegfilgrastim was compared using both a cell-based bioassay and surface plasmon resonance (SPR). The degradation rates and stability profiles were compared under accelerated and stressed conditions.
RESULTS: Biosimilarity was demonstrated by a thorough assessment of physiochemical and functional attributes, as well as comparative stability, of pegfilgrastim-cbqv relative to pegfilgrastim. These studies demonstrated identical primary structure and disulfide structure, highly similar secondary and tertiary structure, as well as functional similarity. The impurity profile of pegfilgrastim-cbqv was comparable to that of pegfilgrastim with only minor differences in PEGylation variants and a slight offset in the PEG molar mass. These differences were not clinically relevant. The degradation profiles were qualitatively and quantitatively similar under accelerated and stress conditions.
CONCLUSIONS: The structural, functional, and stability data demonstrate that pegfilgrastim-cbqv is highly similar to the reference product, pegfilgrastim.

BACKGROUND: Successful engraftment in hematopoietic stem cell transplantation necessitates the collection of an adequate dose of CD34+ cells. Thus, the precise estimation of CD34+ cells harvested via apheresis is critical. Current CD34+ cell yield prediction models have limited reproducibility. This study aims to develop a more reliable and universally applicable model by utilizing a large dataset, enhancing yield predictions, optimizing the collection process, and improving clinical outcomes.
METHODS: A secondary analysis was conducted using the Center for International Blood and Marrow Transplant Research database, involving data from over 17 000 healthy donors who underwent filgrastim-mobilized hematopoietic progenitor cell apheresis. Linear regression, gradient boosting regressor, and logistic regression classification models were employed to predict CD34+ cell yield.
RESULTS: Key predictors identified include pre-apheresis CD34+ cell count, weight, age, sex, and blood volume processed. The linear regression model achieved a coefficient of determination (R2) value of 0.66 and a correlation coefficient (r) of 0.81. The gradient boosting regressor model demonstrated marginally improved results with an R2 value of 0.67 and an r value of 0.82. The logistic regression classification model achieved a predictive accuracy of 96% at the 200 × 106 CD34+ cell count threshold. At thresholds of 400, 600, 800, and 1000 × 106 CD34+ cell count, the accuracies were 88%, 83%, 83%, and 88%, respectively. The model demonstrated a high area under the receiver operator curve scores ranging from 0.90 to 0.93.
CONCLUSIONS: This study introduces advanced predictive models for estimating CD34+ cell yield, with the logistic regression classification model demonstrating remarkable accuracy and practical utility.

OBJECTIVE: To examine the cost-effectiveness of using granulocyte colony-stimulating factor (G-CSF) for primary or secondary prophylaxis in patients with breast cancer from the perspective of Taiwan\'s National Health Insurance Administration.
METHODS: A Markov model was constructed to simulate the events that may occur during and after a high-risk chemotherapy treatment. Various G-CSF prophylaxis strategies and medications were compared in the model. Effectiveness data were derived from the literature and an analysis of the National Health Insurance Research Database (NHIRD). Cost data were obtained from a published NHIRD study, and health utility values were also obtained from the literature. Sensitivity analyses were performed to assess the uncertainty of the cost-effectiveness results.
RESULTS: In the base-case analysis, primary prophylaxis with pegfilgrastim had an incremental cost-effectiveness ratio (ICER) of NT$269,683 per quality-adjusted life year (QALY) gained compared to primary prophylaxis with lenograstim. The ICER for primary prophylaxis with lenograstim versus no G-CSF prophylaxis was NT$61,995 per QALY gained. The results were most sensitive to variations in relative risk of febrile neutropenia (FN) for pegfilgrastim versus no G-CSF prophylaxis. Furthermore, in the probabilistic sensitivity analysis, at a willingness-to-pay threshold of one times Taiwan\'s gross domestic product per capita, the probability of being cost-effective was 88.1% for primary prophylaxis with pegfilgrastim.
CONCLUSIONS: Our study suggests that primary prophylaxis with either short- or long-acting G-CSF could be considered cost-effective for FN prevention in breast cancer patients receiving high-risk regimens.

BACKGROUND: Nivestym, a biosimilar granulocyte colony-stimulating factor (G-CSF) to the originator filgrastim (Neupogen), is now being used for the mobilization of peripheral blood stem cells (PBSC) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aim to compare the efficacy of Nivestym and Neupogen for PBSC mobilization in healthy allogeneic donors.
METHODS: We conducted a retrospective single-center study including 541 adult allo-HSCT donors receiving Nivestym (January 2013-July 2020), or Neupogen (July 2020-June 2023) for donor PBSC mobilization. Bivariate analysis was conducted using SPSS version 28. Statistical significance was determined at a p-value <.05.
RESULTS: Our study included 541 allo-HSCT donors who received Neupogen (n = 345, 64%) or Nivestym (n = 196, 36%) for PBSC mobilization. The median age was 47 years (range 17-76). The median donor weight was 86 kg (95% confidence interval [CI]: 87-91). Donors receiving Neupogen had similar pre-G-CSF white blood cell count, CD34+ percentages, and circulating CD34+ count compared with donors receiving Nivestym. The Neupogen group had similar median PBSC product total neutrophil count, CD34+ percentage, absolute CD34+ count, and infused CD34+ dose compared with the Nivestym group. For donors aged 35 years or younger, the median CD34+ dose was higher in donors who received Neupogen compared with Nivestym (6.9 vs. 6.3 million cells/kg, p = .044).
CONCLUSIONS: Nivestym demonstrated similar efficacy for PBSC mobilization compared with Neupogen among allo-HSCT donors. In donors aged 35 years or younger, a slightly lower PBSC product CD34+ count was noted with Nivestym compared with Neupogen.

OBJECTIVE: To evaluate the impact of the entry of biosimilars on the pricing of eight biologic products in 57 countries and regions.
METHODS: We utilized an interrupted time series design and IQVIA MIDAS® data to analyze the annual sales data of eight biologic products (adalimumab, bevacizumab, epoetin, etanercept, filgrastim, infliximab, pegfilgrastim, and trastuzumab) across 57 countries and regions from January 1, 2012, to December 31, 2019. We examined the immediate and long-term changes in biologics ex-manufacturer pricing following the entry of biosimilars to the market.
RESULTS: Following the entry of biosimilars, the average price per dose of biologic product was immediately reduced by $438 for trastuzumab, $112 for infliximab, and $110 for bevacizumab. The persistent effect of biosimilars\' market entry led to further reductions in price per dose every year: by $49 for adalimumab, $290 for filgrastim, $21 for infliximab, and $189 for trastuzumab. Similarly, we analyzed the impact of biosimilars on four biologics\' prices in the US, where the prices of three biologics significantly decreased every year, with filgrastim, pegfilgrastim, and infliximab decreasing by $955, $753, and $104, respectively.
CONCLUSIONS: The introduction of biosimilars has significantly reduced the prices of biologics both globally and in the US. These findings not only demonstrate the economic benefits of increasing biosimilar utilization, but also emphasize the importance of biosimilars in controlling healthcare costs. Policies should aim to expand the availability of biosimilars to counteract the exponential growth of medical spending caused by the use of biologics.

Human granulocyte colony-stimulating factor (G-CSF) is a granulopoietic growth factor used in the treatment of neutropenia following chemotherapy, myeloablative treatment, or healthy donors preparing for allogeneic transplantation. Few hypersensitivity reactions (HRs) have been reported, and its true prevalence is unknown. We aimed to systematically characterize G-CSF-induced HRs while including a comprehensive list of adverse reactions. We reviewed articles published before January 2024 by searching in the PubMed, Embase, Cochrane Library, and Web of Science databases using a combination of the keywords listed, selected the ones needed, and extracted relevant data. The search resulted in 68 entries, 17 relevant to our study and 7 others found from manually searching bibliographic sources. A total of 40 cases of G-CSF-induced HR were described and classified as immediate (29) or delayed (11). Immediate ones were mostly caused by filgrastim (13 minimum), with at least 9 being grade 5 on the WAO anaphylaxis scale. Delayed reactions were mostly maculopapular exanthemas and allowed for the continuation of G-CSF. Reactions after first exposure frequently appeared and were present in at least 11 of the 40 cases. Only five desensitization protocols have been found concerning the topic at hand in the analyzed data. We believe this study brings to light the research interest in this topic that could benefit from further exploration, and propose regular updating to include the most recently published evidence.

UNASSIGNED: Allogeneic hematopoietic cell transplantation is a life-saving procedure used to treat a variety of devastating diseases. It requires hematopoietic stem cells collected via filgrastim-mobilized peripheral blood stem cells (PBSCs) or bone marrow (BM) harvest from volunteer unrelated donors (URDs). There is a paucity of safety data regarding donors\' long-term adverse events. This prospective, observational study combined PBSC donors enrolled in the NMDP Investigational New Drug trial and BM donors between 1 July 1999 and 30 September 2015. The primary objective was to describe the long-term incidence of myeloid malignancies. The secondary objectives included describing the long-term incidence of lymphoid malignancies, nonhematologic malignancies, autoimmune disorders, and thrombotic events. A total of 21 643 donors (14 530 PBSCs and 7123 BM) were included. The incidence rate of myeloid disorders per 100 000 person-years in donors of PBSCs was 2.53 (95% confidence interval [CI], 0.82-7.84) and in donors of BM, it was 4.13 (95% CI, 1.33-12.8). The incidence rate ratio of PBSCs/BM donors was 0.61 (95% CI, 0.12-3.03; P = .55). The incidence of other malignancies, autoimmunity, and thrombosis did not differ between the donor types. This comprehensive study of the long-term effects of filgrastim in URDs of PBSCs provides strong evidence that donors who receive filgrastim are not at an increased risk of these events compared with BM donors. It also provides reassurance to current donors undergoing stem cell mobilization as well as individuals considering joining stem cell registries, such as NMDP.

Hematopoietic hormones such as granulocyte-colony stimulating factors are commonly used prevent neutropenia in patients undergoing chemotherapy and to prepare patients for bone marrow donations. In rare cases, splenic injury can result from exposure to this medication. We present the case of a 30-year-old man who presented to the emergency department the day after a bone marrow donation procedure complaining of severe, acute onset left upper quadrant abdominal pain, radiating to the shoulder. Neither the patient nor his family reported any abdominal trauma prior to or following the marrow donation procedure. An initial bedside ultrasound examination was positive for peritoneal fluid and distortion of the normal splenic architecture, raising suspicion for possible intraabdominal or splenic injury. An emergent confirmatory CT with contrast of the abdomen confirmed the initial ultrasound examination suspicion of an atraumatic splenic rupture and with evidence of venous bleeding but without active arterial extravasation. An emergent trauma surgery consultation was placed, and he underwent embolization with an uneventful recovery. This case report highlights the need for a high index of suspicion for atraumatic splenic rupture in patients exposed to these types of granulocyte-colony stimulating factors.