Additional plerixafor to granulocyte colony-stimulating factors for haematopoietic stem cell mobilisation for autologous transplantation in people with malignant lymphoma or multiple myeloma

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.

Identifying and Assessing Putative Allosteric Sites and Modulators for CXCR4 Predicted through Network Modeling and Site Identification by Ligand Competitive Saturation

The chemokine receptor CXCR4 is a critical target for the treatment of several cancer types and HIV-1 infections. While orthosteric and allosteric modulators have been developed targeting its extracellular or transmembrane regions, the intramembrane region of CXCR4 may also include allosteric binding sites suitable for the development of allosteric drugs. To investigate this, we apply the Gaussian Network Model (GNM) to the monomeric and dimeric forms of CXCR4 to identify residues essential for its local and global motions located in the hinge regions of the protein. Residue interaction network (RIN) analysis suggests hub residues that participate in allosteric communication throughout the receptor. Mutual residues from the network models reside in regions with a high capacity to alter receptor dynamics upon ligand binding. We then investigate the druggability of these potential allosteric regions using the site identification by ligand competitive saturation (SILCS) approach, revealing two putative allosteric sites on the monomer and three on the homodimer. Two screening campaigns with Glide and SILCS-Monte Carlo docking using FDA-approved drugs suggest 20 putative hit compounds including antifungal drugs, anticancer agents, HIV protease inhibitors, and antimalarial drugs. In vitro assays considering mAB 12G5 and CXCL12 demonstrate both positive and negative allosteric activities of these compounds, supporting our computational approach. However, in vivo functional assays based on the recruitment of β-arrestin to CXCR4 do not show significant agonism and antagonism at a single compound concentration. The present computational pipeline brings a new perspective to computer-aided drug design by combining conformational dynamics based on network analysis and cosolvent analysis based on the SILCS technology to identify putative allosteric binding sites using CXCR4 as a showcase.

Economic evaluation of plerixafor addition in the mobilization and leukapheresis of hematopoietic stem cells for autologous transplantation: a systematic review

INTRODUCTION

Although plerixafor in association with granulocyte colony-stimulating factor (G-CSF) can improve mobilization and collection of hematopoietic stem cells (HSC) by leukapheresis, cost may limit its clinical application. The present study systematically reviews economic evaluations of plerixafor plus G-CSF usage compared to G-CSF alone and compares different strategies of plerixafor utilization in multiple myeloma and lymphoma patients eligible for autologous HSC transplantation.

AREAS COVERED

Relevant economic evaluations, partial or complete, were searched on PubMed, Embase, LILACS, and Cochrane Central Register of Controlled Trials for a period ending 30 June 2021. This systematic review was reported following the PRISMA Statement. Six economic evaluations were included, considering the use of upfront or just-in-time plerixafor compared to G-CSF alone or other plerixafor strategies. Most comparisons showed both increased cost and health benefits with the addition of plerixafor. Most analyses favored just-in-time plerixafor compared to upfront plerixafor, with a probable preference for broader cutoffs for just-in-time plerixafor initiation.

EXPERT OPINION

Plerixafor is a potentially cost-effective technology in the mobilization of HSC in patients with multiple myeloma and lymphomas eligible for autologous HSC transplantation. There is a decreased number of leukapheresis sessions and remobilizations and a higher yield of CD34+ cells.

Clinical outcomes of multiple myeloma patients who undergo autologous hematopoietic stem cell transplant with G-CSF or G-CSF and plerixafor mobilized grafts

Impact of Plerixafor (P) mobilized stem cells on immune reconstitution, such as absolute lymphocyte count at day 30 (ALC30), and on long-term outcomes of Multiple Myeloma (MM) patients undergoing autologous stem cell transplant (ASCT) has not been well established. We evaluated total of 469 patients mobilized with G-CSF (G) alone, and 141 patients mobilized with G-CSF plus plerixafor (G+ P). Patients only received plerixafor if they had peripheral blood CD34⁺   blood count <20/μL on first planned day of collection. Primary endpoint, ALC30, was 1.3 K/μL (range, 0.1-4.5) and 1.2 K/μL (range, 0.1-5.1) for G and G + P, respectively (P =. 61). The median PFS was 2.5 years (95% CI, 2.1-3.2) and 2.8 years (95% CI, 2.0-3.3) for G and G + P, respectively (HR: 1.13; 95% CI, 0.84-1.50; P = .42). The median OS was 6.1 years (95% CI, 4.6-NR) for G group compared to 3.7 years (95% CI, 3.2-NR) for the G + P group (HR: 1.64; 95% CI, 1.12-2.40; P = .01). The median follow-up time for OS was 2.53 years (95% CI, 2.13-2.99) and 1.59 years (95% CI, 1.17-2.02) for G and G+ P group, respectively. In this large retrospective analysis of MM patients mobilized with G-CSF vs G-CSF + P, there was no significant difference in lymphocyte recovery or PFS. There was an overall survival difference in patients who were poor mobilizers and could not be mobilized with G-CSF alone.

The Biological and Clinical Relevance of G Protein-Coupled Receptors to the Outcomes of Hematopoietic Stem Cell Transplantation: A Systematized Review

Hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for several malignant and non-malignant diseases at the cost of serious treatment-related toxicities (TRTs). Recent research on extending the benefits of HSCT to more patients and indications has focused on limiting TRTs and improving immunological effects following proper mobilization and engraftment. Increasing numbers of studies report associations between HSCT outcomes and the expression or the manipulation of G protein-coupled receptors (GPCRs). This large family of cell surface receptors is involved in various human diseases. With ever-better knowledge of their crystal structures and signaling dynamics, GPCRs are already the targets for one third of the current therapeutic arsenal. The present paper assesses the current status of animal and human research on GPCRs in the context of selected HSCT outcomes via a systematized survey and analysis of the literature.

Efficacy and safety of plerixafor for hematopoietic stem cell mobilization for autologous transplantation in patients with non-Hodgkin lymphoma and multiple myeloma: A systematic review and meta-analysis

Plerixafor in combination granulocyte-colony stimulating factor (G-CSF) has been used for the mobilization of hematopoietic stem cells (HSCs) to the peripheral blood for collection and subsequent autologous transplantation in patients with non-Hodgkin lymphoma (NHL) and multiple myeloma (MM). The aim of this study was to systematically search the published literature and analyze evidence on the efficacy of additional plerixafor for successful HSC mobilization in patients with NHL and MM, and to evaluate the safety of the drug. The PubMed, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL) and Google scholar databases were searched electronically for studies published in the English language up to March, 2019. Five studies (3 on NHL and 2 on MM) were included in this review article. The meta-analysis of data of 364 patients in the treatment group and 368 patients in the control group, indicated that the mobilization of ≥5/6×10⁶ CD34⁺ cells/kg in 4 or less apheresis days was superior with plerixafor + G-CSF than with G-CSF alone (RR=2.59, 95% CI: 1.40 to 4.81; P<0.0001). Similarly, a greater proportion of patients in the treatment group exhibited the mobilization of ≥2×10⁶ CD34⁺ cells/kg in 4 or less apheresis days (RR=1.46, 95% CI: 1.01 to 2.12; P=0.04). The addition of plerixafor significantly increased the total collection of CD34⁺ cells (random: MD=4.21; 95% CI: 2.85 to 5.57; P<0.00001). Meta-analysis indicated no significant increase in adverse events with the addition of plerixafor for HSC mobilization (RR=1.03, 95% CI: 0.99 to 1.06; P=0.16). On the whole, the findings of this study indicate that the addition of plerixafor to G-CSF leads to an increased HSC collection in a shorter period of time with no concomitant increase in adverse events. Further randomized controlled trials with a larger sample size evaluating short term efficacy, as well as long term survival would help to further strengthen the evidence on this subject.

Potential Role of CXCR4 Targeting in the Context of Radiotherapy and Immunotherapy of Cancer

Cancer immunotherapy has been established as standard of care in different tumor entities. After the first reports on synergistic effects with radiotherapy and the induction of abscopal effects-tumor shrinkage outside the irradiated volume attributed to immunological effects of radiotherapy-several treatment combinations have been evaluated. Different immunotherapy strategies (e.g., immune checkpoint inhibition, vaccination, cytokine based therapies) have been combined with local tumor irradiation in preclinical models. Clinical trials are ongoing in different cancer entities with a broad range of immunotherapeutics and radiation schedules. SDF-1 (CXCL12)/CXCR4 signaling has been described to play a major role in tumor biology, especially in hypoxia adaptation, metastasis and migration. Local tumor irradiation is a known inducer of SDF-1 expression and release. CXCR4 also plays a major role in immunological processes. CXCR4 antagonists have been approved for the use of hematopoietic stem cell mobilization from the bone marrow. In addition, several groups reported an influence of the SDF-1/CXCR4 axis on intratumoral immune cell subsets and anti-tumor immune response. The aim of this review is to merge the knowledge on the role of SDF-1/CXCR4 in tumor biology, radiotherapy and immunotherapy of cancer and in combinatorial approaches.

A role for the CXCR4-CXCL12 axis in the little skate, Leucoraja erinacea

The interaction between C-X-C chemokine receptor type 4 (CXCR4) and its cognate ligand C-X-C motif chemokine ligand 12 (CXCL12) plays a critical role in regulating hematopoietic stem cell activation and subsequent cellular mobilization. Extensive studies of these genes have been conducted in mammals, but much less is known about the expression and function of CXCR4 and CXCL12 in non-mammalian vertebrates. In the present study, we identify simultaneous expression of CXCR4 and CXCL12 orthologs in the epigonal organ (the primary hematopoietic tissue) of the little skate, Leucoraja erinacea. Genetic and phylogenetic analyses were functionally supported by significant mobilization of leukocytes following administration of Plerixafor, a CXCR4 antagonist and clinically important drug. Our results provide evidence that, as in humans, Plerixafor disrupts CXCR4/CXCL12 binding in the little skate, facilitating release of leukocytes into the bloodstream. Our study illustrates the value of the little skate as a model organism, particularly in studies of hematopoiesis and potentially for preclinical research on hematological and vascular disorders.

Plerixafor in non-Hodgkin's lymphoma patients: a German analysis of time, effort and costs

Mobilization and collection of peripheral blood stem cells is part of the standard treatment procedure for non-Hodgkin’s lymphoma patients eligible for high-dose chemotherapy with autologous stem cell transplantation. Mobilization is usually achieved with chemotherapy and/or cytokines, but plerixafor might be added in case of poor mobilization. Due to the high cost several institutions have developed their own management pathway to optimize use of plerixafor. Such models are however rarely generalizable; in a multi-center, European, non-interventional study, evaluating the impact of plerixafor in poor mobilizers, country specific differences in patient treatment and cost structure were obvious. For German centers, there was a non-significant reduction in the number of apheresis sessions carried out and in apheresis costs. In contrast to other European countries the majority of German Plerixafor patients were very poor mobilizing patients with initial CD34+ cell count ≤ 10/µl (40/51). In this group the number of apheresis sessions decreased from 2.1 to 1.6 sessions per patient (p = 0.01) and costs decreased from €6246 to €4758 (p = 0.01). Our results show that preemptive plerixafor use has a strong effect in poor mobilizers with an initial CD34+ cell count ≤ 10 cells/µl.

Plerixafor Plus Granulocyte Colony-Stimulating Factor for Patients with Non-Hodgkin Lymphoma and Multiple Myeloma: Long-Term Follow-Up Report

The purpose of this report is to analyze long-term clinical outcomes of patients exposed to plerixafor plus granulocyte colony-stimulating factor (G-CSF) for stem cell mobilization. This was a study of patients with non-Hodgkin lymphoma (NHL; n = 167) and multiple myeloma (MM; n = 163) who were enrolled in the long-term follow-up of 2 pivotal phase III studies (NCT00741325 and NCT00741780) of 240 µg/kg plerixafor plus 10 µg/kg G-CSF, or placebo plus 10 µg/kg G-CSF to mobilize and collect CD34⁺ cells for autologous hematopoietic stem cell transplantation. Overall survival (OS) and progression-free survival (PFS) were evaluated over a 5-year period following the first dose of plerixafor or placebo. The probability of OS was not significantly different in patients with NHL or MM treated with plerixafor or placebo (NHL: 64%; 95% confidence interval [CI], 56% to 71% versus 56%; 95% CI, 44% to 67%, respectively; MM: 64%; 95% CI, 54% to 72% versus 64%; 95% CI, 53% to 73%, respectively). In addition, there was no statistically significant difference in the probability of PFS over 5 years between treatment groups in patients with NHL (50%; 95% CI, 44% to 67% for plerixafor versus 43%; 95% CI, 31% to 54% for placebo) or those with MM (17%; 95% CI, 10% to 24% for plerixafor versus 30%; 95% CI, 21% to 40% for placebo). In this long-term follow-up study, the addition of plerixafor to G-CSF for stem cell mobilization did not affect 5-year survival in patients with NHL or patients with MM.

Monocytes/Macrophages Mobilization Orchestrate Neovascularization after Localized Colorectal Irradiation

In patients undergoing radiotherapy for cancer, radiation dose to healthy tissue can occur, causing microvascular damage. Monocytes that have been shown to promote tissue revascularization comprise the subsets: CD11b⁺Ly6G^-7/4^hi/monocytes^hi and CD11b⁺Ly6G^-7/4^lo/monocytes^lo. We hypothesized that monocytes were implicated in postirradiation blood vessel formation. C57Bl6 mice underwent localized colorectal irradiation and were sacrificed at different times after exposure. Bone marrow, spleen, blood and colon were collected. Fourteen days postirradiation, colons expressed proangiogenic actors and adhesion molecules. Monocytes^hi, which were the main subset of infiltrating monocytes, mobilized to the blood from spleen and bone marrow, peaking at day 14 postirradiation, and were associated with lymphocyte Th1 polarization. At day 28 postirradiation, angiographic score and capillary density increased by ∼1.8-fold, and then returned to nonirradiated levels at day 60. Clodronate-mediated depletion of circulating monocytes prior to irradiation resulted in a ∼1.4-fold decrease in angiographic score and capillary density compared to the nontreated control. Histological analysis of the colon in clodronate-treated mice revealed a massive decrease of macrophage and lymphocyte infiltration as well as reduced collagen deposition in crypt area at day 21. However, late depletion of monocytes from day 25 postirradiation had no effect on fibrotic process. These findings demonstrate a central role for monocyte/macrophage activation in the orchestration of a neovascularization mechanism after localized colorectal irradiation.

A single center's experience using four different front line mobilization strategies in lymphoma patients planned to undergo autologous hematopoietic cell transplantation

In an otherwise eligible patient with relapsed lymphoma, inadequate mobilization of peripheral blood stem cells is a limiting factor to proceeding with an autologous hematopoietic cell transplantation (auto-HCT). Multiple strategies have been used to mobilize an adequate number of hematopoietic stem cells (HSCs) with no obvious front-line strategy. We report a single institutional experience mobilizing HSCs using four different approaches in lymphoma patients. We prospectively collected mobilization outcomes on patients planning to undergo auto-HCT at Ohio State University. We report results of first mobilization attempt for all relapsed or refractory lymphoma patients between 2008–2014. We identified 255 lymphoma patients who underwent mobilization for planned auto-HCT. The 255 lymphoma patients underwent the following front line mobilization strategies: 95 (37%) GCSF alone, 38 (15%) chemomobilization (GCSF+chemotherapy), 97 (38%) preemptive day 4 plerixafor, and 25 (10%) rescue day 5 plerixafor. As expected, there were significant differences between cohorts including age, comorbid indices, histology, and amount of prior chemotherapy. After controlling for differences between groups, the odds of collecting 2×10⁶/kg HSCs on the first day of collection and 5×10⁶/kg HSCs in total was highest in the cohort undergoing chemomobilization. In conclusion, our experience highlights the effectiveness of chemomobilization.