Healthy donor hematopoietic stem cell mobilization with biosimilar granulocyte-colony-stimulating factor: safety, efficacy, and graft performance

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.

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.

Donor-intrinsic variables determine mobilization efficiency: analyses from a cohort of sixty twice-mobilized stem cell donors

Background

Healthy volunteer registry donors have become the backbone of stem cell transplantation programs. While most registrants will never become actual donors, a small minority are called upon twice, most commonly for the same patient because of poor graft function. Anecdotal evidence provides no hard reasons to disallow second-time mobilized apheresis, but few centers have treated enough two-time donors for definitive conclusions. Moreover, for reasons unknown, the efficiency of G-CSF varies greatly between donations.

Methods

Comparison of outcomes of first vs. second donations can formally confirm G-CSF responsiveness as intrinsically, likely genetically, determined. In our database, we identified 60 donors (1.3%) who received two cycles of G-CSF 24 days to 4 years apart and systematically compared mobilization outcomes.

Results

First and second mobilization and collection proceeded without severe or unusual adverse effects. First-time mobilization efficiency was highly predictive of second-time mobilization. Neither mobilization efficiency nor time lag between donations affected the similarity of first- and second-time mobilization outcomes.

Conclusions

With the caveat that only donors with an unremarkable first donation were cleared for a second, our data indicate that a second donation is feasible, equally tolerable as a first donation, and efficient. Moreover, the data strongly support the notion of donor-intrinsic variables dictating mobilization response and argue against relevant damage to the stem cell compartment during mobilization with rhG-CSF.

A survey of global biosimilar implementation practice conducted by the International Society of Oncology Pharmacy Practitioners

Background

The International Society of Oncology Pharmacy Practitioners (ISOPP) Biosimilars Task Force was charged to develop educational activities and resources to assist members when implementing biosimilar medicines into their local practice. To facilitate the process, the task force conducted a survey in order to understand biosimilar implementation practice by ISOPP members across the world and the challenges that oncology pharmacists face when adopting biosimilars into their clinical practice.

Methods

A cross-sectional survey was conducted between 20 April 2019 and 27 May 2019. Members of ISOPP and a number of national oncology pharmacy groups were invited to complete the survey. The survey contained 29 items and consisted of three sections: respondents’ demographics, respondents’ institutional practice relating to biosimilar implementation and post implementation practice at the respondents’ institutions. Descriptive statistics were utilized to analyze the survey results.

Results

A total of 265 ISOPP members were surveyed, with 50 members providing a response (response rate = 19%). In addition, 40 nonmembers participated in the survey, bringing the total to 90 respondents. The most common factors that influence the decision to implement use of a biosimilar as reported by respondents are medication costs/pricing (92%), available clinical data (73%), and product availability (63%). Respondents also commented on the barriers to biosimilar implementation at their institutions, which included a reluctance of prescribers to use biosimilars (due to the lack of familiarity or perceived inferiority), a reluctance to switch established patients from an originator to a biosimilar and the preferences of insurance companies or funding bodies.

Conclusion

The results of this survey reinforce the need for greater education and training for health care professionals in the use of biosimilars, the importance of sharing good practice, and a need for standardization.

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.

Biosimilars for breast cancer: a review of HER2-targeted antibodies in the United States

The utilization of trastuzumab biosimilar medications is of particular interest in HER2-positive breast cancer as these drugs have the potential for cost savings and increased utilization/access to HER2 targeted therapy in both early stage and metastatic HER2-positive breast cancers. Five trastuzumab biosimilars: MYL-1401O (Ogivri), CT-P6 (Herzuma), SB3 (Ontruzant), PF-05280014 (Trazimera), and ABP980 (Kanjinti), have now been approved by the US Food and Drug Administration (FDA) for use in HER2-positive breast cancers. This review provides an overview of these agents with special consideration of the development and approval process, including available clinical data results for these trastuzumab biosimilars. Adoption in the clinic will depend on the degree of comfort with the overall evidence.

Biosimilars in oncology: A decade of experience with granulocyte colony-stimulating factor and its implications for monoclonal antibodies

Biosimilars offer the potential for improved sustainability of cancer care. In oncology, granulocyte colony-stimulating factor and erythropoiesis-stimulating agent biosimilars have been available for almost a decade, with biosimilars of monoclonal antibodies a more recent development. Sandoz biosimilar filgrastim was approved based on Phase III confirmatory studies conducted in patients with breast cancer experiencing chemotherapy-induced neutropenia, with other indications granted based on extrapolation. Despite the fact that extrapolation is a well-established scientific principle in regulation of biological medicines, it is a commonly misunderstood part of the biosimilar concept. Broad experience from almost a decade of use of Sandoz biosimilar filgrastim includes >21 million patient-days exposure and >9 years of real-world clinical evidence, indicates extrapolation successfully at work. Together, this can help reassure oncologists that extrapolation is based on sound scientific principles. Efforts to improve understanding of extrapolation are critical to ensure the acceptance of future oncology biosimilar monoclonal antibodies.

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.

Comparison of filgrastim, pegfilgrastim, and lipegfilgrastim added to chemotherapy for mobilization of CD34+ cells in non-Hodgkin lymphoma patients

BACKGROUND

Data are limited on the long-acting granulocyte-colony stimulating factors (G-CSFs) pegfilgrastim (PEG) and lipegfilgrastim (LIPEG) compared with filgrastim (FIL) regarding the mobilization efficiency of CD34⁺ cells, graft cellular composition, and engraftment.

STUDY DESIGN AND METHODS

In this prospective nonrandomized study, 36 patients with non-Hodgkin lymphoma received FIL, 67 received PEG, and 16 patients received LIPEG as a cytokine after chemotherapy. We analyzed the mobilization and collection of CD34⁺ cells, cellular composition of blood grafts, and hematologic recovery after auto-SCT according to the type of G-CSF used.

RESULTS

Patients in the LIPEG group had fewer apheresis sessions (1 vs. 2, p = 0.021 for FIL and p = 0.111 for PEG) as well as higher median blood CD34⁺ cell counts at the start of the first apheresis (LIPEG 74 × 10⁶ /L vs. FIL 31 × 10⁶ /L, p = 0.084 or PEG 27 × 10⁶ /L, p = 0.021) and CD34⁺ yields of the first apheresis (FIL 5.1 × 10⁶ /kg vs. FIL 2.3 × 10⁶ /kg, p = 0.105 or PEG 1.8 × 10⁶ /kg, p = 0.012). Also, the costs associated with G-CSF mobilization and apheresis were lower in the LIPEG group. The graft composition was comparable except for the higher infused CD34⁺ cell counts in the LIPEG group. The engraftment kinetics were significantly slower in the FIL group.

CONCLUSION

LIPEG appears to be more efficient compared with PEG after chemotherapy to mobilize CD34⁺ cells for auto-SCT demonstrated as fewer sessions of aphereses needed as well as 2.8-fold CD34⁺ cell yields on the first apheresis day. Early hematologic recovery was more rapid in the LIPEG group. Thus further studies on LIPEG in the mobilization setting are warranted.

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.

Safety Profile of Biosimilar Filgrastim (Zarzio/Zarxio): A Combined Analysis of Phase III Studies

BACKGROUND

Evaluation of adverse events (AEs) in pivotal registration trials and ongoing postmarketing surveillance is important for all biologics, including biosimilars. A combined analysis of two pivotal registration studies was performed to strengthen evidence on safety for biosimilar filgrastim EP2006 in patients with breast cancer receiving myelosuppressive chemotherapy, a sensitive clinical setting to confirm biosimilarity of filgrastim.

MATERIALS AND METHODS

Data were combined from two phase III studies of biosimilar filgrastim EP2006. The U.S. registration study was a randomized, double-blind comparison of biosimilar and reference filgrastim in women aged ≥18 years with breast cancer, receiving (neo)adjuvant treatment with TAC (docetaxel + doxorubicin + cyclophosphamide). The European Union registration study was a single-arm, open-label study of biosimilar filgrastim in women aged ≥18 years with breast cancer receiving doxorubicin + docetaxel. Patients received filgrastim as a subcutaneous injection on day 2 of each cycle for <14 days or until the absolute neutrophil count reached 10 × 10⁹/L after the expected nadir. Results were combined for cycles 1-4.

RESULTS

A total of 277 patients received biosimilar filgrastim EP2006. Patients had a mean (± standard deviation) age of 51.1 (± 10.8) years, and 78.7% of patients had stage II or III breast cancer. A total of 46 (20.6%) patients receiving biosimilar filgrastim had AEs considered filgrastim-related. The most frequently reported filgrastim-related AEs were musculoskeletal or connective tissue disorders (15.2%), including bone pain (7.2%). One death (due to pulmonary embolism) occurred of a patient receiving biosimilar filgrastim (not considered filgrastim-related). No patient developed antidrug antibodies during the study.

CONCLUSION

Biosimilar filgrastim has a safety profile consistent with previous filgrastim studies and is effective in preventing febrile neutropenia in patients with breast cancer.

IMPLICATIONS FOR PRACTICE

The biosimilar filgrastim EP2006 (Zarzio, Zarxio, biosimilar filgrastim-sndz) has been approved in Europe since 2009 and in the U.S. since 2015. This combined analysis of two phase III studies provides additional clinical evidence that the biosimilar filgrastim EP2006 has a safety profile consistent with previous studies of reference filgrastim and supports large postmarketing studies of EP2006 in Europe. Strengthening the evidence for biosimilar filgrastim can help improve acceptance of biosimilars and increase patient access to biologics.

What is the role of biosimilar G-CSF agents in hematopoietic stem cell mobilization at present?

Mobilization of hematopoietic stem cells, which has largely replaced bone marrow harvesting as a source of hematopoietic stem cells, using recombinant agents such as filgrastim or lenograstim has become a standard procedure in both patients and healthy donors prior to peripheral blood stem cell collection for autologous and allogeneic stem cell transplantation. Published literature data suggest that mobilization with recombinant granulocyte-colony stimulating factor (G-CSF) is safe and mobilization outcomes are satisfactory. In recent years, besides G-CSF originators, biosimilar G-CSF agents have been approved by the regulatory agencies for the same indications. Current data showed that by using the biosimilar G-CSF, similar results regarding safety and efficacy of hematopoietic stem cell mobilization may be achieved compared to the originator G-CSF. Although the issues such as the similarity to a licenced biological medicine, differences in manufacturing processes, the potential to cause immunogenicity, extrapolation and interchangeability of these biosimilar products are still being discussed by the scientific area, however, more experience with these agents now exists in approved endications and there seems to be no reason to expect significant differences between biosimilar G-CSF and originator G-CSF regarding their efficacy and safety in both patients and healthy donors. Also, the significant cost savings of biosimilars in real life setting may enhance the use of these agents in the future. Nonetheless, the collection of long-term follow-up data is mandatory for both patients and healthy donors, and multicentre randomized clinical trials that directly compare biosimilar G-CSF with the originator G-CSF are needed in order to allow the transplant community to make informed decisions regarding the choice of G-CSF.

Short-term side effects and attitudes towards second donation: A comparison of related and unrelated haematopoietic stem cell donors

The Nordic Register of Haematopoietic Stem Cell Donors (NRHSD) has registered related and unrelated donors from 10 transplant centres in Sweden, Norway, Finland and Denmark since 1998. We present a prospective, observational study of 1,957 donors, focusing mainly on the differences between related and unrelated donors. Related donors are reported to have more comorbidities, but similar side effects compared with unrelated donors. Side effects after BM or PBSC donation are generally of short duration and in this study no deaths, myocardial infarctions, splenic ruptures, or thromboembolic events are reported. Interestingly, related donors express more hesitancy towards donating again when asked 1 month after donation.

Comparison of biosimilar filgrastim, originator filgrastim, and lenograstim for autologous stem cell mobilization in patients with multiple myeloma

BACKGROUND

Granulocyte-colony-stimulating factor (G-CSF) originators such as filgrastim (Neupogen) and lenograstim (Granocyte) are widely used for peripheral blood stem cell (PBSC) mobilization. In recent years, biosimilar agents have been approved for the same indications. The aim of this retrospective study was to compare the mobilization efficiency of the three G-CSF variants originator filgrastim, lenograstim, and the biosimilar Filgrastim Hexal in a homogeneous group of multiple myeloma (MM) patients in first-line therapy.

STUDY DESIGN AND METHODS

Overall mobilization data of 250 patients with MM were included. Of these patients, 74 (30%), 131 (52%), and 45 (18%) were mobilized with originator filgrastim, biosimilar Filgrastim Hexal, or lenograstim, respectively, at a dose of 5 to 10 µg/kg body weight subcutaneously starting from Day 5 after chemomobilization with CAD (cyclophosphamide, doxorubicin, dexamethasone) until completion of PBSC collection.

RESULTS

All but one patient reached the collection goal of a minimum of at least 2 × 10⁶ CD34+ cells/kg body weight during a median of one (range, one to three) leukapheresis session. No significant differences in CD34+ mobilization and collection yields between the filgrastim-mobilized (median, 10.5; range, 2.7-40.4), Filgrastim Hexal-mobilized (median, 9.9; range, 0.2-26.0), and lenograstim-mobilized (median, 10.7; range, 3.1-27.9 CD34+ cells × 10⁶ /kg body weight) patients were observed.

CONCLUSION

Concerning the clinically relevant efficiencies of PBSC mobilization and in terms of reaching the individual collection target, this retrospective study did not detect any significant differences between the three G-CSF variants in the analyzed patient cohort.