Biosimilar G-CSF versus filgrastim and lenograstim in healthy unrelated volunteer hematopoietic stem cell donors

Filgrastim biosimilar (EP2006): A review of 15 years' post-approval evidence

Filgrastim is approved for several indications, including reduction of the incidence and duration of chemotherapy-induced neutropenia and for stem cell mobilization. The filgrastim biosimilar, EP2006, has been available in Europe since 2009, and in the United States since 2015. In this time, preclinical and clinical data used to support the approval of EP2006 have been published. These data established the biosimilarity of EP2006 to reference filgrastim in terms of structure, pharmacokinetics, pharmacodynamics, efficacy, safety, and immunogenicity. Additional real-world evidence studies have also demonstrated equivalent efficacy and safety of EP2006 compared with reference filgrastim, both in the reduction of neutropenia and in stem cell mobilization in clinical practice. This review summarizes these preclinical, clinical, and real-world data, as well as the available cost-effectiveness data, for EP2006 since its approval 15 years ago.

Semisynthesis of Homogeneous, Active Granulocyte Colony-Stimulating Factor Glycoforms

Granulocyte colony stimulating factor (G-CSF) is a cytokine used to treat neutropenia. Different glycosylated and non-glycosylated variants of G-CSF for therapeutic application are currently generated by recombinant expression. Here, we describe our approaches to establish a first semisynthesis strategy to access the aglycone and O-glycoforms of G-CSF, thereby enabling the preparation of selectively and homogeneously post-translationally modified variants of this important cytokine. Eventually, we succeeded by combining selenocysteine ligation of a recombinantly produced N-terminal segment with a synthetic C-terminal part, transiently equipped with a side-chain-linked, photocleavable PEG moiety, at low concentration. The transient PEGylation enabled quantitative enzymatic elongation of the carbohydrate at Thr133. Overall, we were able to significantly reduce the problems related to the low solubility and the tendency to aggregate of the two protein segments, which allowed the preparation of four G-CSF variants that were successfully folded and demonstrated biological activity in cell proliferation assays.

An open-label pilot study of recombinant granulocyte-colony stimulating factor in Friedreich's ataxia

Friedreich's ataxia (FA) is an inherited progressive neurodegenerative disease for which there is no proven disease-modifying treatment. Here we perform an open-label, pilot study of recombinant human granulocyte-colony stimulating factor (G-CSF) administration in seven people with FA (EudraCT: 2017-003084-34); each participant receiving a single course of G-CSF (Lenograstim; 1.28 million units per kg per day for 5 days). The primary outcome is peripheral blood mononuclear cell frataxin levels over a 19-day period. The secondary outcomes include safety, haematopoietic stem cell (HSC) mobilisation, antioxidant levels and mitochondrial enzyme activity. The trial meets pre-specified endpoints. We show that administration of G-CSF to people with FA is safe. Mobilisation of HSCs in response to G-CSF is comparable to that of healthy individuals. Notably, sustained increases in cellular frataxin concentrations and raised PGC-1α and Nrf2 expression are detected. Our findings show potential for G-CSF therapy to have a clinical impact in people with FA.

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.

Seasonal variation of human physiology does not influence the harvest of peripheral blood CD34+ cells from unrelated hematopoietic stem cell donors

There are many reports on factors predicting the outcome of PBSC (peripheral blood stem cell) mobilization, such as the donor's gender, age, weight, white blood cell count, platelets pre apheresis, LDH and iron status. Although there are reports of seasonal variation in the physiology of the human immune system and hematopoiesis there are no data that such differences play a role in the response to G-CSF in healthy hematopoietic stem cell donors. The response to G-CSF could also impact the collection results during different seasons. To assess the possible impact of seasonal variation we performed a retrospective, single-center analysis of mobilization and harvest of PBSC in 330 healthy unrelated donors. We found no significant differences in the number of CD34+ cells in peripheral blood after G-CSF mobilization and in collection results when all donors were analyzed. In the subgroup of male donors the number of CD34+ stem cells after G-CSF mobilization was higher than average in summer and autumn (p = 0.036), however, it did not translate into clinically relevant differences in stem cell harvest. We conclude that although there is possible seasonal variation in the response to G-CSF in male donors there is no impact on PBSC harvest in healthy unrelated donors.

Monocentric Analysis of the Effectiveness and Financial Consequences of the Use of Lenograstim versus Filgrastim for Mobilization of Peripheral Blood Progenitor Cells in Patients with Lymphoma and Myeloma Receiving Chemotherapy and Autologous Stem Cell Transplantation

Purpose

Granulocyte-colony stimulating factors (G-CSFs) are widely used to mobilize CD34⁺ stem cells and to support the engraftment after hematopoietic stem cell transplantation (HSCT). A budget impact analysis and an incremental cost-effectiveness study of two G-CSFs (Lenograstim and Filgrastim biosimilar), considering engraftment, number of hospitalization days and number of G-CSF vials administered were performed.

Patients and Methods

Between 2009 and 2016, 248 patients undergoing autologous HSCT have been evaluated and divided into three groups (100 Leno-Leno, 93 Leno-Fil, 55 Fil-Fil) according to the type of G-CSF used for hematopoietic stem cell mobilization and hematopoietic stem cell recovery after transplant.

Results

The following statistically significant differences have been observed between Leno-Leno, Leno-Fil, Fil-Fil groups: a higher number of harvested CD34⁺ cells (10.56 vs 8.00 vs 7.20; p=0.0003) and a lower number of G-CSF vials (8 vs 8 vs 9; p=0.00020) used for full bone marrow recovery favoring Lenograstim. No statistically significant differences were found regarding the number of G-CSF vials used for mobilization, apheresis number and CD34⁺ cell peak. The post-transplant hematological recovery was faster in Lenograstim group than Filgrastim group: median time to neutrophil count engraftment (>500/mmc) was 12 vs 13 days; median time for platelets recovery (>20.000/mmc) was 12 vs 15 days (p=0.0001). The use of Lenograstim achieved cost savings of €566/patient over Filgrastim biosimilar, related to a decreased number of days of hospitalization (16 vs 17 days; p=0.00012), a lower overall incidence of adverse events, laboratory tests, transfusions for platelet recovery following discharge.

Conclusion

In our experience, Lenograstim outperforms Filgrastim in terms of effectiveness and lower cost. This study shows a clinical superiority of Lenograstim over Filgrastim suggesting a potential cost savings favoring Lenograstim.

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.

Evaluation of a biosimilar granulocyte colony-stimulating factor for peripheral blood stem cell mobilization in Japanese healthy donors: a prospective study

A "biosimilar" is a biotechnological product with a lower cost profile and equivalent efficacy and safety to the originator, but post-marketing clinical evaluation of biosimilar products has not been adequately conducted. We prospectively investigated the utility of biosimilar filgrastim in 13 peripheral blood stem cell (PBSC) donors from June 2014 to January 2017. In addition, we retrospectively compared these to another 13 PBSC donors mobilized with the originator filgrastim in the same period. Donor characteristics were equivalent between the groups. The median number of CD34⁺ cells per donor body weight (BW) and blood volume processed (BV) were 4.87 × 10⁶/kg and 25.5 × 10³/mL in the biosimilar group and 4.93 × 10⁶/kg and 16.6 × 10³/mL in the originator group, respectively. There were no significant differences between the groups in the number of CD34⁺ cells per donor BW or BV. All adverse events associated with G-CSF were permissive. The total G-CSF cost was significantly lower in the biosimilar group than in the originator group. These findings suggest that biosimilar filgrastim has the same efficacy and short-term safety as originator filgrastim for PBSC mobilization in healthy donors, with economic superiority. Longer follow-up studies are needed to evaluate the incidence of long-term adverse events.

Challenge to Predict Mobilized Peripheral Blood Stem Cells on the Fourth Day of Granulocyte Colony-Stimulating Factor Treatment in Healthy Donors: Predictive Value of Basal CD34+ Cell and Platelet Counts

A longitudinal, prospective, observational, single-center cohort study on healthy donors was designed to identify predictors of CD34⁺ cell mobilization on day 4 after granulocyte colony-stimulating factor (G-CSF) administration. As potential predictors of mobilization, age, sex, body weight, height, blood volume, WBC count, peripheral blood (PB) mononuclear cell count, platelet (Plt) count, and hematocrit and hemoglobin levels were considered. Two different evaluations of CD34⁺ cell counts were determined for each donor: baseline (before G-CSF administration) and in PB on day 4 after G-CSF administration. One hundred twenty-two consecutive healthy donors with a median age of 47.5 years were enrolled. The median value of CD34⁺ on day 4 was 43 cells/µL (interquartile range, 23 to 68), and 81.1% of donors had ≥20 cells/µL. Basal WBC count, Plt count, and CD34⁺ were significantly higher for the subjects with CD34⁺ levels over median values on day 4. A multivariate quartile regression analysis, adjusted by sex, age, basal CD34⁺, and basal Plt count, showed a progressively stronger relationship between baseline CD34⁺ and Plt levels and the CD34⁺ levels on day 4. The basal CD34⁺ cut-off level to predict the levels of CD34⁺ on day 4 was either ≤2 cells/μL or ≥3 cells/μL and that of basal Plt count was ≤229 × 10⁹/L or ≥230 × 10⁹/L, respectively, to determine whether mobilization therapy should or should not be attempted. PB stem cell mobilization with G-CSF was highly effective on day 4, and herein we describe a model for predicting the probability of performing PB stem cell collection after a short course of G-CSF.

Ex vivo Manufactured Neutrophils for Treatment of Neutropenia-A Process Economic Evaluation

Neutropenia is a common side-effect of acute myeloid leukemia (AML) chemotherapy characterized by a critical drop in neutrophil blood concentration. Neutropenic patients are prone to infections, experience poorer clinical outcomes, and require expensive medical care. Although transfusions of donor neutrophils are a logical solution to neutropenia, this approach has not gained clinical traction, primarily due to challenges associated with obtaining sufficiently large numbers of neutrophils from donors whilst logistically managing their extremely short shelf-life. A protocol has been developed that produces clinical-scale quantities of neutrophils from hematopoietic stem and progenitor cells (HSPC) in 10 L single-use bioreactors (1). This strategy could be used to mass produce neutrophils and generate sufficient cell numbers to allow decisive clinical trials of neutrophil transfusion. We present a bioprocess model for neutrophil production at relevant clinical-scale. We evaluated two production scenarios, and the impact on cost of goods (COG) of multiple model parameters including cell yield, materials costs, and process duration. The most significant contributors to cost were consumables and raw materials, including the cost of procuring HSPC-containing umbilical cord blood. The model indicates that the most cost-efficient culture volume (batch size) is ~100 L in a single bioreactor. This study serves as a framework for decision-making and optimization strategies when contemplating the production of clinical quantities of cells for allogeneic therapy.

Trends in peripheral stem/progenitor cell manipulation and clinical application

Transplants using peripheral blood hemopoietic stem/progenitor (PBHS) cells are widely performed for the treatment of patients with hematologic disorders in routine practice and clinical trials. Although the process from mobilization to infusion of PBHS cells has been mostly established, optimal conditions for each process remain undetermined. Adverse reactions caused by PBHS cell infusions have not been systematically recorded. In transplants using PBHS cells, a number of problems still exist. In this section, the current status of and future perspectives regarding PBHS cells are described.

Medical and ethical considerations on hematopoietic stem cells mobilization for healthy donors

Hematopoietic stem cell transplantation is a common procedure potentially beneficial to many individuals with cancer, hematological, or inherited disorders, and has highlighted the need of related or unrelated donors to perform allograft. Donation of hematopoietic stem cells, either through bone marrow harvest or peripheral blood stem cell collection, is well-established and widespread. Over the past two decades, the peripheral blood stem cell collection by aphaeresis has become the main source of hematopoietic stem cells for transplantation, due to faster engraftment and practicability and lower risk of relapse for high-risk patients. For peripheral blood stem cell donation, donors require mobilization of hematopoietic stem cells from bone marrow into the blood stream. This is performed by growth factors injections. This article is a review of reported applications of growth factors (original granulocyte colony stimulating factor and its biosimilars), for healthy donors' peripheral blood stem cell mobilization, in terms of toxicity, side effects, efficacy and follow-up. There is still an ethical dilemma for clinicians involved in allograft, because they expose healthy donors to drugs. It is important to dispel some of the critical concerns regarding their use in healthy volunteers, particularly because they receive no personal therapeutic benefit from this procedure.