Current use of biosimilar G-CSF for haematopoietic stem cell mobilisation

Effectiveness and safety of granulocyte colony-stimulating factor priming regimen for acute myeloid leukemia: A systematic review and meta-analysis of the Clinical Practice Guideline for the use of G-CSF 2022 from the Japan Society of Clinical Oncology

BACKGROUND

The outcomes of relapsed or refractory acute myeloid leukemia (AML) remain poor. Although the concomitant use of granulocyte colony-stimulating factor (G-CSF) and anti-chemotherapeutic agents has been investigated to improve the antileukemic effect on AML, its usefulness remains controversial. This study aimed to investigate the effects of G-CSF priming as a remission induction therapy or salvage chemotherapy.

METHODS

We performed a thorough literature search for studies related to the priming effect of G-CSF using PubMed, Ichushi-Web, and the Cochrane Library. A qualitative analysis of the pooled data was performed, and risk ratios (RRs) with confidence intervals (CIs) were calculated and summarized.

RESULTS

Two reviewers independently extracted and accessed the 278 records identified during the initial screening, and 62 full-text articles were assessed for eligibility in second screening. Eleven studies were included in the qualitative analysis and 10 in the meta-analysis. A systematic review revealed that priming with G-CSF did not correlate with an improvement in response rate and overall survival (OS). The result of the meta-analysis revealed the tendency for lower relapse rate in the G-CSF priming groups without inter-study heterogeneity [RR, 0.91 (95% CI 0.82-1.01), p = 0.08; I2 = 4%, p = 0.35]. In specific populations, including patients with intermediate cytogenetic risk and those receiving high-dose cytarabine, the G-CSF priming regimen prolonged OS.

CONCLUSIONS

G-CSF priming in combination with intensive remission induction treatment is not universally effective in patients with AML. Further studies are required to identify the patient cohort for which G-CSF priming is recommended.

Targeting the stem cell niche micro-environment as therapeutic strategies in aging

Adult stem cells (ASCs) reside throughout the body and support various tissue. Owing to their self-renewal capacity and differentiation potential, ASCs have the potential to be used in regenerative medicine. Their survival, quiescence, and activation are influenced by specific signals within their microenvironment or niche. In better words, the stem cell function is significantly influenced by various extrinsic signals derived from the niche. The stem cell niche is a complex and dynamic network surrounding stem cells that plays a crucial role in maintaining stemness. Studies on stem cell niche have suggested that aged niche contributes to the decline in stem cell function. Notably, functional loss of stem cells is highly associated with aging and age-related disorders. The stem cell niche is comprised of complex interactions between multiple cell types. Over the years, essential aspects of the stem cell niche have been revealed, including cell-cell contact, extracellular matrix interaction, soluble signaling factors, and biochemical and biophysical signals. Any alteration in the stem cell niche causes cell damage and affects the regenerative properties of the stem cells. A pristine stem cell niche might be essential for the proper functioning of stem cells and the maintenance of tissue homeostasis. In this regard, niche-targeted interventions may alleviate problems associated with aging in stem cell behavior. The purpose of this perspective is to discuss recent findings in the field of stem cell aging, heterogeneity of stem cell niches, and impact of age-related changes on stem cell behavior. We further focused on how the niche affects stem cells in homeostasis, aging, and the progression of malignant diseases. Finally, we detail the therapeutic strategies for tissue repair, with a particular emphasis on aging.

Is split-dose better than single-dose? Results of Turkish Stem Cell Coordination Center (TURKOK) donors in the era of rising biosimilar G-CSF

BACKGROUND

Turkish Stem Cell Coordination Center (TURKOK) carries out the procurement process of unrelated allogeneic hematopoietic stem cells in Turkey. This study aims to compare the efficacy of both once-daily and divided-dose G-CSF administration and the original and biosimilar G-CSF use and the frequency and severity of adverse events in TURKOK donors.

METHOD

The study was conducted retrospectively with 142 healthy TURKOK donors. For PBSC mobilization, two different subcutaneous G-CSF programs were used as 10 μ/kg/day single-dose and 5 μ/kg/12 h. Neupogen (Amgen, Puerto Rico) and Tevagrastim (Teva, Kfar Saba, Israel) were used as G-CSF. All donors started apheresis on the fifth day, and all side effects were recorded during the procedure.

RESULTS

Stem cell yield was similar between single-dose and divided-doses based on donor weight, favoring the split-dose based on recipient weight (P = .506 and P = .023, respectively). Both G-CSF posologies were comparable if the target CD34+ cell yield was ≥4 × 10⁶ /kg. CD34+ cell yield was equivalent when evaluated against recipient weight, significantly favoring Tevagrastim vs Neupogen by donor weight (P = .740 and P = .021, respectively). Side effects, duration of pain, and need for analgesia favor Tevagratim over Neupogen.

CONCLUSION

Split-dose may be recommended for cases where the need for large numbers of CD34+ cells to be harvested is anticipated due to significant cell yield relative to recipient weight. However, sufficient hematopoietic stem cells can be collected with both posology. Tevagrastim is non-inferiority effective to Neupogen. Side effects during administration are both low-grade and temporary.

Superior physical and mental health of healthy volunteers before and five years after mobilized stem cell donation

Background

Safety, tolerability and efficacy of granulocyte colony-stimulating factor (G-CSF) for mobilization of hematopoietic stem and progenitor cells (HSPCs) from healthy donors have been conclusively demonstrated. This explicitly includes, albeit for smaller cohorts and shorter observation periods, biosimilar G-CSFs. HSPC donation is non-remunerated, its sole reward being “warm glow”, hence harm to donors must be avoided with maximal certitude. To ascertain, therefore, long-term physical and mental health effects of HSPC donation, a cohort of G-CSF mobilized donors was followed longitudinally.

Methods

We enrolled 245 healthy volunteers in this bi-centric long-term surveillance study. 244 healthy volunteers began mobilization with twice-daily Sandoz biosimilar filgrastim and 242 underwent apheresis after G-CSF mobilization. Physical and mental health were followed up over a period of 5-years using the validated SF-12 health questionnaire.

Results

Baseline physical and mental health of HSPC donors was markedly better than in a healthy reference population matched for ethnicity, sex and age. Physical, but not mental health was sharply diminished at the time of apheresis, likely due to side effects of biosimilar G-CSF, however had returned to pre-apheresis values by the next follow-up appointment after 6 months. Physical and mental health slightly deteriorated over time with kinetics reflecting the known effects of aging. Hence, superior physical and mental health compared to the general healthy non-donor population was maintained over time.

Conclusions

HSPC donors are of better overall physical and mental health than the average healthy non-donor. Superior well-being is maintained over time, supporting the favorable risk–benefit assessment of volunteer HSPC donation.

Trial registration National Clinical Trial NCT01766934

Regulatory Evaluation of Biosimilars: Refinement of Principles Based on the Scientific Evidence and Clinical Experience

The World Health Organization (WHO) guidelines on evaluation of similar biotherapeutic products (SBPs; also called biosimilars) were adopted by the WHO Expert Committee on Biological Standardization (ECBS) in 2009. In 2019, the ECBS considered that a more tailored and potentially reduced clinical data package may be acceptable in cases where this was clearly supported by the available scientific evidence. The goal of this publication is to review the current clinical experience and scientific evidence and to provide an expert perspective for updating the WHO guidelines to provide more flexibility and clarity. As the first step, the relevant guidelines by other regulatory bodies were reviewed in order to identify issues that might help with updating the WHO guidelines. Next, a literature search was conducted for information on the long-term efficacy, safety, and immunogenicity of biosimilars to identify possible long-term problems. Finally, a search for articles concerning the role of clinical studies in the benefit-risk evaluation of biosimilars was conducted. The analysis of other guidelines suggested that the WHO guidelines may need more emphasis on the importance of the state-of-the-art physicochemical and structural comparability exercise and in vitro functional testing. The use of "foreign" reference product will also need clarifications. The value of in vivo toxicological tests in the development of biosimilars is questionable, and the non-clinical part needs revisions accordingly. The concepts of "totality of evidence," "stepwise development," and "residual uncertainty" were applied in the evaluation of the clinical sections of the guideline. The review of long-term safety and efficacy demonstrated the robustness of the current biosimilar development concept. The analysis of the roles of different development phases suggested that the large efficacy, safety, and immunogenicity studies are, in most cases, redundant. The residual uncertainty of safety, immunogenicity, and efficacy of biosimilars that has shaped the current regulatory guidelines is now substantially reduced. This will allow the re-evaluation of the non-clinical and clinical requirements of the current WHO main guideline. The shift of the relative impact of the development phases towards physico-chemical and in vitro functional testing will provide a relief to the manufacturers and new challenges to the regulators.

Innovator Filgrastim versus Generic Filgrastim in Hematopoietic Stem Cell Transplantation Mobilization

Methods This is a retrospective study. G-CSF was administered in the dose of 10 μg/kg subcutaneous as a single dose for 4 days. On day 5, peripheral blood stem cell (PBSC) apheresis was performed using Haemonetics MCS plus or COBE Spectra apheresis machine through a double-lumen central venous catheter. Primary outcome parameters were the total number of CD34+ HSCs/kg of recipient weight mobilized in peripheral blood and the number of days required for neutrophil and platelets engraftment, respectively.

Objective We compared the effectiveness and safety of innovator filgrastim versus generic filgrastim in patients who underwent hematopoietic stem cell transplantation (HSCT).

Results A total of 91 stem cell mobilizations was analyzed. There were 58 normal healthy donors for allogeneic HSCT and 33 patients for autologous HSCT. There was no statistically significant difference among groups in terms of total collected CD34+ cells value ( p = 0.609). The mean time to neutrophil engraftment was 13.7 days in the innovator group and 13.2 days in the Grafeel group ( p = 0.518). The mean time to platelet engraftment was 16.2 days in the innovator group and 14.8 days in the generic group ( p = 0.435). The patient who received generic filgrastim had more febrile episodes during the course of transplantation ( p = 0.020).

Conclusion Generic filgrastim was found to be comparable to original filgrastim for peripheral blood stem cell mobilization in normal healthy donors for allogeneic HSCT and patients for autologous HSCT.

Uncovering the multifaceted roles played by neutrophils in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a life-saving procedure used for the treatment of selected hematological malignancies, inborn errors of metabolism, and bone marrow failures. The role of neutrophils in alloHSCT has been traditionally evaluated only in the context of their ability to act as a first line of defense against infection. However, recent evidence has highlighted neutrophils as key effectors of innate and adaptive immune responses through a wide array of newly discovered functions. Accordingly, neutrophils are emerging as highly versatile cells that are able to acquire different, often opposite, functional capacities depending on the microenvironment and their differentiation status. Herein, we review the current knowledge on the multiple functions that neutrophils exhibit through the different stages of alloHSCT, from the hematopoietic stem cell (HSC) mobilization in the donor to the immunological reconstitution that occurs in the recipient following HSC infusion. We also discuss the influence exerted on neutrophils by the immunosuppressive drugs delivered in the course of alloHSCT as part of graft-versus-host disease (GVHD) prophylaxis. Finally, the potential involvement of neutrophils in alloHSCT-related complications, such as transplant-associated thrombotic microangiopathy (TA-TMA), acute and chronic GVHD, and cytomegalovirus (CMV) reactivation, is also discussed. Based on the data reviewed herein, the role played by neutrophils in alloHSCT is far greater than a simple antimicrobial role. However, much remains to be investigated in terms of the potential functions that neutrophils might exert during a highly complex procedure such as alloHSCT.

Getting blood out of a stone: Identification and management of patients with poor hematopoietic cell mobilization

Hematopoietic cell transplantation (HCT) has become a primary treatment for many cancers. Nowadays, the primary source of hematopoietic cells is by leukapheresis collection of these cells from peripheral blood, after a forced egress of hematopoietic cells from marrow into blood circulation, a process known as "mobilization". In this process, mobilizing agents disrupt binding interactions between hematopoietic cells and marrow microenvironment to facilitate collection. As the first essential step of HCT, poor mobilization, i.e. failure to obtain a desired or required number of hematopoietic cell, is one of the major factors affecting engraftment or even precluding transplantation. This review summarizes the available mobilization regimens using granulocyte-colony stimulating factor (G-CSF) and plerixafor, as well as the current understanding of the factors that are associated with poor mobilization. Strategies to mobilize patients or healthy donors who failed previous mobilization are discussed. Multiple novel agents are under investigation and some of them have shown the potential to enhance the mobilization response to G-CSF and/or plerixafor. Further investigation of the risk factors including genetic factors will offer an opportunity to better understand the molecular mechanism of mobilization and help develop new therapeutic strategies for successful mobilizations.

Improving the Expression of Human Granulocyte Colony Stimulating Factor in Escherichia coli by Reducing the GC-content and Increasing mRNA Folding Free Energy at 5'-Terminal End

Purpose: Strategy for improving the production of biopharmaceutical protein continues to develop due to increasing market demand. Human granulocyte colony stimulating factor (hG-CSF) is one of biopharmaceutical proteins that has many applications, and easily produced in Escherichia coli expression system. Previous studies reported that codon usage, rare codon, mRNA folding and GC-content at 5’-terminal end were crucial for protein production in E. coli. In the present study, the effect of reducing the GC-content and increasing the mRNA folding free energy at the 5’-terminal end on the expression level of hG-CSF proteins was investigated.

Methods: Synonymous codon substitutions were performed to generate mutant variants of open reading frame (ORF) with lower GC-content at 5’-terminal ends. Oligoanalyzer tool was used to calculate the GC content of eight codons sequence after ATG. Whereas, mRNA folding free energy was predicted using KineFold and RNAfold tools. The template DNA was amplified using three variant forward primers and one same reverse primer. Those DNA fragments were individually cloned into pJexpress414 expression vector and were confirmed using restriction and DNA sequencing analyses. The confirmed constructs were transformed into E. coli NiCo21(DE3) host cells and the recombinant protein was expressed using IPTG-induction. Total protein obtained were characterized using SDS-PAGE, Western blot and ImageJ software analyses.

Results: The result showed that the mutant variant with lower GC-content and higher mRNA folding free energy near the translation initiation region (TIR) could produce a higher amount of hG-CSF proteins compared to the original gene sequence.

Conclusion: This study emphasized the important role of the nucleotide composition immediately downstream the start codon to achieve high-yield protein product on heterologous expression in E. coli.

Mobilization of Hematopoietic Stem Cells into Peripheral Blood for Autologous Transplantation Seems Less Efficacious in Poor Mobilizers with the Use of a Biosimilar of Filgrastim and Plerixafor: A Retrospective Comparative Analysis

Introduction

Biosimilars of granulocyte colony-stimulating factors (G-CSF) have shown similar efficacy to originator filgrastim (Neupogen® [NEU]; Amgen Inc.) as prophylaxis in neutropenia and in the mobilization of stem cells in patients receiving combination chemotherapy with G-CSF.

Methods

This was a retrospective study in which the characteristics of stem cell mobilization treated with a G-CSF alone were compared in 216 patients and 56 donors. The two G-CSF compared were NEU and the biosimilar filgrastim Zarzio® (Sandoz GmbH) (referred to hereafter as BIO). Primary objectives were mobilization rate (minimum of 10 × 10³/ml CD34+ on day 4 of treatment [day +4]) and use of the immunostimulant plerixafor (PLEX) in each group.

Results

The general characteristics of the patients receiving NEU (n = 138) and those receiving BIO (n = 78) did not differ significantly. PLEX was used in 24% of BIO patients and in 25.7% of NEU patients. The median CD34+ cell count on day +4 was significantly lower in BIO patients who needed PLEX than in those who did not (2.4 vs. 4.8 × 10³/ml; p = 0.002), as was the final CD34+ cell count (2.5 vs. 3.3 × 10⁶/kg; p 0.03). Mobilization failure rate was higher in the BIO group than in the NEU group (20 vs. 0%; p = 0.01). With respect to donors, more than one apheresis was needed in three BIO donors, one of them with PLEX. The use of BIO was the only risk factor for mobilization failure in patients who needed PLEX (hazard ratio 10.3; 95% confidence interval 1.3–77.8).

Conclusion

The study revealed that BIO had a lower efficacy for stem cell mobilization when the only treatment was G-CSF, especially in poor mobilizers needing PLEX.

Extrapolation in Practice: Lessons from 10 Years with Biosimilar Filgrastim

Biosimilar filgrastim (Sandoz) was approved in Europe in 2009 and, in 2015, was the first biosimilar approved in the USA. These authorizations were based on the "totality of evidence" concept, an approach that considers data from structural and functional characterization and comparability analysis and non-clinical and clinical studies. For biosimilar filgrastim, phase III confirmatory clinical studies were performed in the most sensitive population, patients with breast cancer undergoing myelosuppressive chemotherapy. In Europe and the USA, approval was granted for all indications of the reference biologic. Hence, stem cell mobilization and severe chronic neutropenia indications were approved on the basis of extrapolation, with no clinical data available at the time of market authorization in the EU. Although extrapolation is well-accepted in biologic development and regulatory contexts, it remains a misunderstood part of the biosimilarity concept in the medical community. Since approval, more than a decade of obtained clinical experience supports the totality of evidence and reassures clinicians regarding the efficacy and safety of biosimilar filgrastim. This includes real-world data from MONITOR-GCSF, a multicenter, prospective, observational study describing treatment patterns and clinical outcomes of patients with cancer (n = 1447) receiving biosimilar filgrastim for the prophylaxis of chemotherapy-induced neutropenia in solid tumors and hematological malignancies. Evidence is also available from unrelated healthy donors and those with severe chronic neutropenia. Together, the experience from a decade of use of biosimilar filgrastim includes over 24 million patient-days of exposure, which can help reassure oncologists that extrapolation is based on strong scientific evidence and works in practice.