Re-infused autologous graft natural killer cells correlates with absolute lymphocyte count recovery after autologous stem cell transplantation

Predictive Factors for Early Immune Recovery in NHL Patients after Autologous Transplantation: A Multicenter Prospective Study

Early lymphocyte recovery as manifested by an absolute lymphocyte count at d+15 (ALC-15) ≥ 0.5 × 109/L after autologous hematopoietic stem cell transplantation (AHCT) has been associated with a better outcome. This prospective multicenter study aimed to clarify factors associated with ALC-15 ≥ 0.5 × 109/L after AHCT among 178 patients with non-Hodgkin lymphoma. The mobilization capacity, as manifested by peak blood CD34+ cell numbers > 45 × 106/L correlated with higher ALC-15 levels (p = 0.020). In addition, the amount of CD3+CD4+ T cells > 31.8 × 106/kg in the infused graft predicted ALC-15 ≥ 0.5 × 109/L (p < 0.001). Also, the number of infused graft CD3+CD8+ T cells > 28.8 × 106/kg (p = 0.017) and NK cells > 4.4 × 106/kg was linked with higher ALC-15 (p < 0.001). The two-year progression-free survival after AHCT was significantly better in patients with ALC-15 ≥ 0.5 × 109/L (74 vs. 57%, p = 0.027). The five-year OS in patients with higher ALC-15 was 78% vs. 60% in those with lower ALC-15 (p = 0.136). To conclude, the mobilization capacity of CD34+ cells and detailed measures of graft cellular content mark prognostic tools that predict ALC-15 ≥ 0.5 × 109/L, which is associated with a better outcome in NHL patients after AHCT.

Autologous hematopoietic stem cell transplantation for multiple myeloma in the age of CAR T cell therapy

Chimeric antigen receptor (CAR) T cell therapy has revolutionized the management of relapsed and refractory myeloma, with excellent outcomes and a tolerable safety profile. High dose chemotherapy with autologous hematopoietic stem cell transplantation (AHCT) is established as a mainstream of newly diagnosed multiple myeloma (NDMM) management in patients who are young and fit enough to tolerate such intensity. This standard was developed based on randomized trials comparing AHCT to chemotherapy in the era prior to novel agents. More recently, larger studies have primarily shown a progression free survival (PFS) benefit of upfront AHCT, rather than overall survival (OS) benefit. There is debate about the significance of this lack of OS, acknowledging the potential confounders of the chronic nature of the disease, study design and competing harms and benefits of exposure to AHCT. Indeed upfront AHCT may not be as uniquely beneficial as we once thought, and is not without risk. New quadruple-agent regimens are highly active and effective in achieving a deep response as quantified by measurable residual disease (MRD). The high dose chemotherapy administered with AHCT imposes a burden of short and long-term adverse effects, which may alter the disease course and patient's ability to tolerate future therapies. Some high-risk subgroups may have a more valuable benefit from AHCT, though still ultimately suffer poor outcomes. When compared to the outcomes of CAR T cell therapy, the question of whether AHCT can or indeed should be deferred has become an important topic in the field. Deferring AHCT may be a personalized decision in patients who achieve MRD negativity, which is now well established as a key prognostic factor for PFS and OS. Reserving or re-administering AHCT at relapse is feasible in many cases and holds the promise of resetting the T cell compartment and opening up options for immune reengagement. It is likely that personalized MRD-guided decision making will shape how we sequence in the future, though more studies are required to delineate when this is safe and appropriate.

NK cell therapy in relapsed refractory multiple myeloma

Recent advances in adoptive cell therapy have considerably changed the paradigm of cancer immunotherapy. Although current immunotherapies could cure many patients with multiple myeloma (MM), relapsed/refractory MM (RR/MM) is still challenging in some cases. Natural killer (NK) cells are innate immune cells that exert effective cytotoxic activity against malignant cells like myeloma cells. In addition to their antitumor properties, NK cells do not induce graft versus host disease following transplantation. Therefore, they provide a promising approach to treating RR/MM patients. Currently, attempts have been made to produce large-scale and good manufacturing practices (GMP) of NK cells. Ex vivo expanded/activated NK cells derived from the own patient or allogenic donors are potential options for NK cell therapy in MM. Besides, novel cell-based products such as NK cell lines and chimeric antigen receptor (CAR)-NK cells may provide an off-the-shelf source for NK cell therapy. Here, we summarized NK cell activity in the MM microenvironment and focused on different NK cell therapy methods for MM patients.

A NK Cell Odyssey: From Bench to Therapeutics Against Hematological Malignancies

In 1975 two independent groups noticed the presence of immune cells with a unique ability to recognize and eliminate transformed hematopoietic cells without any prior sensitization or expansion of specific clones. Since then, NK cells have been the axis of thousands of studies that have resulted until June 2021, in more than 70 000 publications indexed in PubMed. As result of this work, which include approaches in vitro, in vivo, and in natura, it has been possible to appreciate the role played by the NK cells, not only as effectors against specific pathogens, but also as regulators of the immune response. Recent advances have revealed previous unidentified attributes of NK cells including the ability to adapt to new conditions under the context of chronic infections, or their ability to develop some memory-like characteristics. In this review, we will discuss significant findings that have rule our understanding of the NK cell biology, the developing of these findings into new concepts in immunology, and how these conceptual platforms are being used in the design of strategies for cancer immunotherapy.

Novel Cell and Immune Engagers in Optimizing Tumor- Specific Immunity Post-Autologous Transplantation in Multiple Myeloma

Autologous stem cell transplantation (ASCT) is an important component of treatment of multiple myeloma (MM). The post-ASCT setting offers a unique opportunity to increase myeloma specific immunity through enhancement of T and NK cell responses. The vast array of therapeutics being developed for MM, including cell-based therapies, dendritic vaccines, bispecific antibodies, and IL-15 agonists, provide the opportunity to increase tumor-specific immunity. Maintenance therapies, including immunomodulatory drugs, proteasome inhibitors, and daratumumab, exhibit a significant anti-myeloma response by modulating the immune system. Lenalidomide promotes an antitumoral immune microenvironment, whereas daratumumab can potentially cause NK cell fratricide. Thus, understanding the effects of commonly used maintenance drugs on the immune system is important. In this review, we look at current and emerging therapeutics and their integration post-ASCT in the context of immune reconstitution to improve clinical responses in patients with MM. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Long-acting granulocyte colony-stimulating factor pegfilgrastim (lipegfilgrastim) for stem cell mobilization in multiple myeloma patients undergoing autologous stem cell transplantation

Autologous stem cell transplantation (ASCT) is a standard of care in newly-diagnosed multiple myeloma (MM) patients. Several studies before the introduction of novel therapies in MM, demonstrated a pegylated G-CSF to be successful in mobilizing peripheral blood stem cells (PBSCs). Lipegfilgrastim is a novel long-acting G-CSF that is produced by the conjugation of a single 20-kDa polyethelene glycol to the natural O-glycosylation site of G-CSF. Twenty-four MM patients were included for PBSCs mobilization with a single SC injection of 6 mg lipegfilgrastim. PBSC collection was started when the CD34⁺ count was > 10 × 10⁶ cells/L. The target progenitor cells were 6 × 10⁶ cells/kg. The median day of apheresis was + 3 (range 2-5) following lipegfilgrastim. Median peripheral blood CD34⁺ count pre-mobilization was of 22.65 (range 3.36-105) × 10⁶ cells/L. The median number of leukaphaeresis procedures was 2 (range 1-4). The median mobilized CD34⁺ cells/kg were 8.26 (range 0.77-12.42). One patient failed to mobilize and two patients mobilized < 6 × 10⁶ cells/kg. Toxicity was mild and transient. Twenty-three patients underwent ASCT following high dose melphalan. All patients engrafted. As lipegfilgrastim is administered only once, it is conceivable that it improves both compliance and quality-of-life (NCT02488382).

Human NK Cells in Autologous Hematopoietic Stem Cell Transplantation for Cancer Treatment

Simple Summary

Natural killer (NK) cells are key elements of the innate immune system that have the ability to kill transformed (tumor and virus-infected) cells without prior sensitization. Hematopoietic stem cell transplantation (HSCT) is a medical procedure used in the treatment of a variety of cancers. The early reconstitution of NK cells after HSCT and their functions support the therapeutic potential of these cells in allogenic HSCT. However, the role of NK cells in autologous HSCT is less clear. In this review, we have summarized general aspects of NK cell biology. In addition, we have also reviewed factors that affect autologous HSCT outcome, with particular attention to the role played by NK cells.

Abstract

Natural killer (NK) cells are phenotypically and functionally diverse lymphocytes with the ability to recognize and kill malignant cells without prior sensitization, and therefore, they have a relevant role in tumor immunosurveillance. NK cells constitute the main lymphocyte subset in peripheral blood in the first week after hematopoietic stem cell transplantation (HSCT). Although the role that NK cells play in allogenic HSCT settings has been documented for years, their significance and beneficial effects associated with the outcome after autologous HSCT are less recognized. In this review, we have summarized fundamental aspects of NK cell biology, such as, NK cell subset diversity, their effector functions, and differentiation. Moreover, we have reviewed the factors that affect autologous HSCT outcome, with particular attention to the role played by NK cells and their receptor repertoire in this regard.

Circulating monocyte subsets in multiple myeloma patients receiving autologous stem cell transplantation - a study of the preconditioning status and the course until posttransplant reconstitution for a consecutive group of patients

BACKGROUND

Induction therapy of multiple myeloma patients prior to autologous stem cell transplantation has changed from conventional chemotherapy to treatment based on proteasome inhibitors or immunomodulatory drugs. We used flow cytometry to analyze total monocyte and monocyte subset (classical, intermediate and non-classical monocytes) peripheral blood levels before and following auto-transplantation for a consecutive group of myeloma patients who had received the presently used induction therapy.

RESULTS

The patients showed normal total monocyte concentrations after induction/stem cell mobilization, but the concentrations of classical monocytes were increased compared with healthy controls. Melphalan conditioning reduced the levels of total CD14⁺ as well as classical and non-classical monocytes, whereas intermediate monocytes were not affected. Thus, melphalan has a non-random effect on monocyte subsets. Melphalan had a stronger effect on total and classical monocyte concentrations for those patients who had received induction therapy including immunomodulatory drugs. Total monocytes and monocyte subset concentrations decreased during the period of pancytopenia, but monocyte reconstitution occurred before hematopoietic reconstitution. However, the fractions of various monocyte subsets varied considerably between patients.

CONCLUSIONS

The total level of circulating monocytes is normalized early after auto-transplantation for multiple myeloma, but pre- and post-transplant levels of various monocyte subsets show considerable variation between patients.

Comparison of Immune Reconstitution After Allogeneic Versus Autologous Stem Cell Transplantation in 182 Pediatric Recipients

Hematopoietic stem cell transplantation (HSCT) is a life-saving procedure for children with a variety of malignant and nonmalignant conditions. However, even if immune reconstitution after HSCT has been studied extensively, until now, data on the comparison of immune reconstitution after autologous versus allogeneic HSCT are scarce, but might provide important clinical implications. We examined immune reconstitution (T cells, B cells, and NK cells) at defined timepoints in 147 children who received 182 HSCTs. Differences in the time course of immune reconstitution were analyzed in autologous versus allogeneic HSCT. We identified a quicker immune reconstitution in the T-cell compartment, especially in the CD4 and naive subset after autologous HSCT, whereas recipients of allogeneic transplants showed a higher TCRgd proportion. B-cell reconstitution showed a delayed immune reconstitution after allogeneic HSCT in the first 2 years after HSCT. However, a reconstitution of all lymphocyte subsets after HSCT could be achieved in all patients. Children undergoing an HSCT show a different pattern of immune reconstitution in the allogeneic and autologous setting. This might influence the outcome and should affect the clinical handling of infectious prophylaxis and revaccinations.

Importance of early immune recovery after autologous hematopoietic cell transplantation in lymphoma patients

Lymphomas constitute the second most common indication for autologous hematopoietic cell transplantation (AHCT). Graft infusion is followed by a rapid hematological recovery and slower immune recovery. The number of natural killer cells and CD3⁺ T lymphocytes achieve normal counts usually within a month, whereas the recovery of CD3⁺CD4⁺ T lymphocytes is much slower. Early immune recovery is usually defined as the absolute lymphocyte count (ALC) ≥0.5 × 10⁹/L, which has been associated with improved progression-free and even overall survival. Several factors have been associated with early immune recovery, including higher infused lymphocyte and CD34⁺ cell doses, both of which are affected by the choice of mobilization. This review summarizes the clinical importance of early immune recovery for long-term success of AHCT in lymphomas. Factors known to affect early immune recovery are discussed and suggestions made how to improve mobilization and collection processes to optimize immune recovery and post-transplant outcomes.

Translating the anti-myeloma activity of Natural Killer cells into clinical application

Natural Killer cells (NK) are innate effector cells with a critical role in immunosurveillance against different kinds of cancer cells, including Multiple Myeloma (MM). However, the number and/or function of these lymphocytes are strongly reduced during MM progression and in advanced clinical stages. A better understanding of the mechanisms controlling both MM and NK cell biology have greatly contributed to develop novel and combined therapeutic strategies in the treatment of this incurable hematologic malignancy. These include approaches to reverse the immunosuppressive MM microenvironment or potentiate the natural or antibody-dependent cellular cytotoxicity (ADCC) of NK cells. Moreover, chemotherapeutic drugs or specific monoclonal antibodies (mAbs) can render cancer cells more susceptible to NK cell-mediated recognition and lysis; direct enhancement of NK cell function can be obtained by means of immunomodulatory drugs, cytokines and blocking mAbs targeting NK cell inhibitory receptors. Finally, adoptive transfer of ex-vivo expanded and genetically manipulated NK cells is also a promising therapeutic tool for MM. Here, we review current knowledge on complex mechanisms affecting NK cell activity during MM progression. We also discuss recent advances on innovative approaches aimed at boosting the functions of these cytotoxic innate lymphocytes. In particular, we focus our attention on recent preclinical and clinical studies addressing the therapeutic potential of different NK cell-based strategies for the management of MM.

Activation of NK cells and disruption of PD-L1/PD-1 axis: two different ways for lenalidomide to block myeloma progression

Natural Killer (NK) cells play a critical role against tumor cells in hematological malignancies. Their activating receptors are essential in tumor cell killing. In Multiple Myeloma (MM) patients, NK cell differentiation, activation and cytotoxic potential are strongly impaired leading to MM escape from immune surveillance in tissues and bone marrow. Mechanisms used by MM to affect NK cell functions are mediated by the release of soluble factors, the expression of activating and inhibitory NK cell ligands, and the expression of immune check-point inhibitors. Lenalidomide represents an efficient clinical approach in MM treatment to improve patients' survival. Lenalidomide does not only promotes tumor apoptosis, but also stimulates T and NK cells, thereby facilitating NK-mediated tumor recognition and killing. This occurs since Lenalidomide acts on several critical points: stimulates T cell proliferation and cytokine secretion; decreases the expression of the immune check-point inhibitor Programmed Death-1 (PD-1) on both T and NK cells in MM patients; decreases the expression of both PD-1 and PD-L1 on MM cells; promotes MM cell death and abrogates MM/stromal microenvironment cross-talk, a process known to promote the MM cell survival and proliferation. This leads to the inhibition of the negative signal induced by PD-1/PD-L1 axis on NK cells, restoring NK cell cytotoxic functions. Given the importance of an effective immune response to counteract the MM progression and the promising approaches using anti-PD-1/PD-L1 strategies, we will discuss in this review how Lenalidomide could represent an adequate approach to re-establish the recognition against MM by exhausted NK cell.

Preemptive plerixafor injection added to pegfilgrastim after chemotherapy in non-Hodgkin lymphoma patients mobilizing poorly

Filgrastim is usually combined with chemotherapy to mobilize hematopoietic progenitor cells in non-Hodgkin lymphoma (NHL) patients. Limited information is available on the efficacy of a preemptive plerixafor (PLER) injection in poor mobilizers after chemotherapy and pegfilgrastim. In this prospective study, 72 patients with NHL received chemotherapy plus pegfilgrastim, and 25 hard-to-mobilize patients received also PLER. The usefulness and efficacy of our previously developed algorithm for PLER use in pegfilgrastim-containing mobilization regimen were evaluated as well as the graft cellular composition, hematological recovery, and outcome after autologous stem cell transplantation (auto-SCT) according to the PLER use. A median 3.4-fold increase in blood CD34⁺ cell counts was achieved after the first PLER dose. The minimum collection target was achieved in the first mobilization attempt in 66/72 patients (92%) and 68 patients (94%) proceeded to auto-SCT. An algorithm for PLER use was fulfilled in 76% of the poor mobilizers. Absolute numbers of T-lymphocytes and NK cells were significantly higher in the PLER group, whereas the number of CD34⁺ cells collected was significantly lower. Early neutrophil engraftment was slower in the PLER group, otherwise hematological recovery was comparable within 12 months from auto-SCT. No difference was observed in survival according to the PLER use. Chemotherapy plus pegfilgrastim combined with preemptive PLER injection is an effective and convenient approach to minimize collection failures in NHL patients intended for auto-SCT. A significant effect of PLER on the graft cellular composition was observed, but no difference in outcome after auto-SCT was detected.

Adoptive cell therapy in multiple Myeloma

INTRODUCTION

Recent breakthrough advances in Multiple Myeloma (MM) immunotherapy have been achieved with the approval of the first two monoclonal antibodies, elotuzumab and daratumumab. Adoptive cell therapy (ACT) represents yet another, maybe the most powerful modality of immunotherapy, in which allogeneic or autologous effector cells are expanded and activated ex vivo followed by their re-infusion back into patients. Infused effector cells belong to two categories: naturally occurring, non-engineered cells (donor lymphocyte infusion, myeloma infiltrating lymphocytes, deltagamma T cells) or genetically- engineered antigen-specific cells (chimeric antigen receptor T or NK cells, TCR-engineered cells). Areas covered: This review article summarizes our up-to-date knowledge on ACT in MM, its promises, and upcoming strategies to both overcome its toxicity and to integrate it into future treatment paradigms. Expert opinion: Early results of clinical studies using CAR T cells or TCR- engineered T cells in relapsed and refractory MM are particularly exciting, indicating the potential of long-term disease control or even cure. Despite several caveats including toxicity, costs and restricted availability in particular, these forms of immunotherapy are likely to once more revolutionize MM therapy.

Aerobic exercise in humans mobilizes HSCs in an intensity-dependent manner

Hematopoietic stem and progenitor cells are necessary to maintain, repair, and reconstitute the hematopoietic blood cell system. Mobilization of these cells from bone marrow to blood can be greatly increased under certain conditions, one such being exercise. The purpose of this study was to identify the importance of exercise intensity in hematopoietic mobilization, to better understand the mobilization kinetics postexercise, and to determine if exercise is capable of mobilizing several specific populations of hematopoietic cells that have clinical relevance in a transplant setting. Healthy individuals were exercised on a cycle ergometer at 70% of their peak work rate (WRpeak) until volitional fatigue and at 30% of their WRpeak work matched to the 70% WRpeak bout. Blood was collected before, immediately post, and 10, 30, and 60 min postexercise. Total blood cells, hematocrit, and mononuclear cells isolated by density gradient centrifugation were counted. Specific populations of hematopoietic stem cells were analyzed by flow cytometry. Mononuclear cells, CD34+, CD34+/CD38-, CD34+/CD110+, CD3-/CD16+/CD56+, CD11c+/CD123-, and CD11c-/CD123+ cells per millilter of blood increased postexercise. Overall, the 70% WRpeak exercise group showed greater mobilization immediately postexercise, while there was no observable increase in mobilization in the work matched 30% WRpeak exercise group. Mobilization of specific populations of hematopoietic cells mirrored changes in the general mobilization of mononuclear cells, suggesting that exercise serves as a nonspecific mobilization stimulus. Evidently, higher intensity exercise is capable of mobilizing hematopoietic cells to a large extent and immediately postexercise is an ideal time point for their collection.

NEW & NOTEWORTHY

Here we demonstrate for the first time that mobilization of hematopoietic stem cells (HSCs) through exercise is intensity dependent, with the greatest mobilization occurring immediately after high-intensity exercise. As well, we show that exercise is a general stimulus for mobilization: increases in specific HSC populations are reliant on general mononuclear cell mobilization. Finally, we demonstrate no differences in mobilization between groups with different aerobic fitness.

Cellular and vaccine immunotherapy for multiple myeloma

Allogeneic hematopoietic cell transplantation and donor lymphocyte infusion for multiple myeloma (MM) can induce graft-versus-myeloma immunity and long-term survivorship, but limited efficacy and associated toxicities have prevented its widespread use. Cellular immunotherapies and vaccines seek to induce more specific, reliable, and potent antimyeloma immune responses with less treatment-related risk than is possible with allogeneic transplantation. Advances in molecular biology, and basic and applied immunology, have led to promising approaches such as genetically engineered T cells with chimeric antigen receptors and T-cell receptors targeting myeloma-specific epitopes, vaccine primed ex vivo expanded autologous T cells, expanded marrow-infiltrating lymphocytes, and plasma cell/dendritic cell fusion vaccines. The addition of these emerging therapies to immunomodulatory drugs and inhibitors of programmed death-1 T-cell regulatory pathways are poised to improve outcome for our patients with myeloma.

Blood graft cellular composition and posttransplant outcomes in myeloma patients mobilized with or without low-dose cyclophosphamide: a randomized comparison

BACKGROUND

Autologous stem cell transplantation is a standard treatment in multiple myeloma (MM). Blood grafts are usually collected after mobilization with granulocyte-colony-stimulating factor (G-CSF) alone or in a combination with cyclophosphamide (CY). There is limited knowledge of the possible effects of different mobilization regimens on blood graft characteristics and posttransplant outcomes.

STUDY DESIGN AND METHODS

Thirty-eight patients with MM were included in this study. The patients were randomly assigned at registration to mobilization with either low-dose CY plus G-CSF (Arm A) or G-CSF alone (Arm B) and received three cycles of lenalidomide, bortetzomib, and dexamethasone induction. Flow cytometry analysis of lymphocyte subsets in the blood grafts after cryopreservation was performed. Hematologic and immune recovery were evaluated up to 12 months posttransplant.

RESULTS

The blood grafts in Arm A contained significantly more CD34+ cells but in Arm B there was a greater proportion of CD34+CD38- cells and higher numbers of T and B lymphocytes as well as natural killer (NK) cells. The engraftment was comparable but lymphocyte count at 15 days posttransplant was higher in Arm B (0.8 × 10(9) /L vs. 0.5 × 10(9) /L, p = 0.033). At 3 and 6 months posttransplant the total number of NK cells was also higher in G-CSF-mobilized patients. There was no difference in progression-free survival between the study arms.

CONCLUSION

CY plus G-GSF yields more CD34+ cells but seems to diminish lymphocyte and NK cell counts in the grafts and hampers immune recovery after transplantation. Thus G-CSF alone might be a preferred mobilization method due to more rapid immune recovery posttransplant.

KIR and HLA genotypes predictive of low-affinity interactions are associated with lower relapse in autologous hematopoietic cell transplantation for acute myeloid leukemia

Killer cell Ig-like receptors (KIRs) bind cognate HLA class I ligands with distinct affinities, affecting NK cell licensing and inhibition. We hypothesized that differences in KIR and HLA class I genotypes predictive of varying degrees of receptor-ligand binding affinities influence clinical outcomes in autologous hematopoietic cell transplantation (AHCT) for acute myeloid leukemia (AML). Using genomic DNA from a homogeneous cohort of 125 AML patients treated with AHCT, we performed KIR and HLA class I genotyping and found that patients with a compound KIR3DL1(+) and HLA-Bw4-80Thr(+), HLA-Bw4-80Ile(-) genotype, predictive of low-affinity interactions, had a low incidence of relapse, compared with patients with a KIR3DL1(+) and HLA-Bw4-80Ile(+) genotype, predictive of high-affinity interactions (hazard ratio [HR], 0.22; 95% confidence interval [CI], 0.06-0.78; p = 0.02). This effect was influenced by HLA-Bw4 copy number, such that relapse progressively increased with one copy of HLA-Bw4-80Ile (HR, 1.6; 95% CI, 0.84-3.1; p = 0.15) to two to three copies (HR, 3.0; 95% CI, 1.4-6.5; p = 0.005) and progressively decreased with one to two copies of HLA-Bw4-80Thr (p = 0.13). Among KIR3DL1(+) and HLA-Bw4-80Ile(+) patients, a predicted low-affinity KIR2DL2/3(+) and HLA-C1/C1 genotype was associated with lower relapse than a predicted high-affinity KIR2DL1(+) and HLA-C2/C2 genotype (HR, 0.25; 95% CI, 0.09-0.73; p = 0.01). Similarly, a KIR3DL1(+) and HLA-Bw4-80Thr(+), HLA-Bw4-80Ile(-) genotype, or lack of KIR3DL1(+) and HLA-Bw4-80Ile(+) genotype, rescued KIR2DL1(+) and HLA-C2/C2 patients from high relapse (p = 0.007). These findings support a role for NK cell graft-versus-leukemia activity modulated by NK cell receptor-ligand affinities in AHCT for AML.

Current and future immunotherapeutic approaches to multiple myeloma therapy

SUMMARY 

Multiple myeloma (MM) is a hematologic malignancy associated with heterogeneous treatment and survival outcomes due in part to the ability of MM to evade and suppress the immune system. Research has focused on finding ways to modulate and enhance immunity while targeting the bone marrow microenvironment. Contemporary therapies include immunomodulatory drugs, proteasome inhibitors and autologous and allogeneic stem cell transplant and have improved outcomes for patients with MM. Future therapies, including monoclonal antibodies, chimeric antigen receptor cells and MM vaccines, show promise to further improved outcomes, particularly when used in combination with existing therapies. This review covers the mechanism of action of currently available and future therapies and explores ways in which treatment may be more specifically directed in the future.

Absolute lymphocyte count as predictor of overall survival for patients with multiple myeloma treated with single autologous stem cell transplant

Post-autologous stem cell transplant (ASCT) studies have demonstrated that absolute lymphocyte count (ALC) recovery is associated with prolonged survival in some hematological malignancies. To assess whether ALC recovery has prognostic significance in patients with multiple myeloma (MM) undergoing single ASCT, we conducted a retrospective analysis of ALC at different time-points in patients with MM. In total 769 consecutive patients who underwent single ASCT from January 2000 to December 2007 were evaluated. An ALC of ≥ 1400 cells/μL at day 0, day 15 and day 90 significantly correlated with a better overall survival (OS) (median OS of 111, 90.7 and 84 months vs. 74, 70.5 and 65 months, respectively, p < 0.001 for all time-points). Multivariate analysis showed that ALC is an independent prognostic factor for OS after ASCT. In conclusion, ALC is a surrogate marker of the host immune system that correlates with better survival in patients with MM undergoing single ASCT. Immunomodulatory drugs, vaccination strategies and cellular therapies in MM should be investigated.

Mobilized peripheral blood grafts include more than hematopoietic stem cells: the immunological perspective

Although stem cell mobilization has been performed for more than 20 years, little is known about the effects of mobilizing agents on apheresis composition and the impact of graft cell subsets on patients' outcome. With the increasing use of plerixafor and the inclusion of poor mobilizers in autologous transplant procedures, new parameters other than CD34(+) stem cell dose are emerging; plerixafor seems to mobilize more primitive CD34(+)/CD38(-) stem cells compared with G-CSF, but their correlation with stable hematopoietic engraftment is still obscure. Immune recovery is as crucial as hematopoietic reconstitution, and higher T and natural killer cells infused within the graft have been correlated with better outcome in autologous transplant; recent studies showed increased mobilization of immune effectors with plerixafor compared with G-CSF, but further data are needed to clarify the clinical impact of these findings. In the allogeneic setting, much evidence suggests that mobilized T-cell alloreactivity is tempered by G-CSF, probably with the mediation of dendritic cells, even though no clear correlation with GVL and GVHD has been found. Plerixafor is not approved in healthy donors yet; early data suggest it might mobilize a GVHD protective balance of immune effectors, but further studies are needed to define its role in allogeneic transplant.

Impact of clinical factors and allograft leukocyte content on post-transplant lymphopenia, monocytopenia, and survival in patients undergoing allogeneic peripheral blood haematopoietic cell transplant

BACKGROUND

We have previously shown that lymphopenia and monocytopenia at 2-3 months post-allogeneic haematopoietic cell transplant (HCT) is associated with poor survival in recipients of both myeloablative and reduced intensity conditioning regimens. It is not known whether the graft leukocyte content has a role in early lymphocyte and monocyte recovery following allogeneic T-cell replete peripheral blood HCT.

METHODS

Haematologic recovery data, including absolute lymphocyte and monocyte counts (ALC and AMC, respectively) at day +15, +30, +60, and +100, and outcomes data were pooled from two prior independent cohorts, and parameters were correlated with leukocyte graft content in those individuals receiving peripheral blood progenitor cell grafts. 216 consecutive patients from 2001-2010 were included in the analysis.

RESULTS

Neither infused allograft lymphocyte, monocyte, granulocyte, nor CD34+ cell number per kilogram recipient body weight correlated with haematologic recovery parameters or overall survival in this cohort. Prognostic factors for overall survival based on multivariate analysis were as expected from the results of the previous independent cohorts and included severity of chronic GVHD (p < 0.001), development of post-transplant relapse (p = 0.001), day +60 AMC > 0.3 x 10(9) cells/L (p = 0.0015), and day +100 ALC > 0.3 x 10(9) cells/L (p < 0.001). Low monocyte and lymphocyte counts at the day +60 and day +100 time points were significantly associated with acute GVHD and/or CMV viraemia.

CONCLUSIONS

This study suggests that graft cell count does not influence post-transplant monocyte and lymphocyte recovery following T-cell replete allogeneic peripheral blood HCT. Post-transplant complications such as acute GVHD and/or CMV viraemia negatively influenced monocyte and lymphocyte recovery, and hence the survival. Further studies aimed at understanding the mechanisms behind sustained lymphopenia and monocytopenia post-transplant are needed.

Autologous haematopoietic stem cell mobilisation in multiple myeloma and lymphoma patients: a position statement from the European Group for Blood and Marrow Transplantation

Autologous haematopoietic SCT with PBSCs is regularly used to restore BM function in patients with multiple myeloma or lymphoma after myeloablative chemotherapy. Twenty-eight experts from the European Group for Blood and Marrow Transplantation developed a position statement on the best approaches to mobilising PBSCs and on possibilities of optimising graft yields in patients who mobilise poorly. Choosing the appropriate mobilisation regimen, based on patients' disease stage and condition, and optimising the apheresis protocol can improve mobilisation outcomes. Several factors may influence mobilisation outcomes, including older age, a more advanced disease stage, the type of prior chemotherapy (e.g., fludarabine or melphalan), prior irradiation or a higher number of prior treatment lines. The most robust predictive factor for poor PBSC collection is the CD34(+) cell count in PB before apheresis. Determination of the CD34(+) cell count in PB before apheresis helps to identify patients at risk of poor PBSC collection and allows pre-emptive intervention to rescue mobilisation in these patients. Such a proactive approach might help to overcome deficiencies in stem cell mobilisation and offers a rationale for the use of novel mobilisation agents.

Plerixafor for mobilization of blood stem cells in autologous transplantation: an update

INTRODUCTION

About 99% of all autologous transplants are now performed with blood stem cells. G-CSF alone or combined with chemotherapy have been used to mobilize CD34(+) cells. Plerixafor is a novel drug used for mobilization purposes.

AREAS COVERED

We have evaluated recent data in regard to plerixafor use in predicted or proven poor mobilizers. In addition, we have looked for preemptive strategies to optimize the use of this expensive drug. Also cost-efficacy issues and effects of plerixafor on graft composition and post-transplant outcomes will be discussed.

EXPERT OPINION

Plerixafor added to G-CSF is superior than G-CSF alone for mobilization of CD34(+) cells. This combination is also efficient in patients who have failed a previous mobilization attempt with other methods or in patients with risk factors for poor mobilization. Addition of plerixafor to G-CSF or chemotherapy plus G-CSF mobilization in patients who appear to mobilize poorly is under active investigation and algorithms for a preemptive use of this expensive agent have been proposed. Grafts collected after plerixafor appear to contain more lymphoid cells than the grafts collected without it. Whether this affects post-transplant outcomes such as immune reconstitution and risk of relapse needs to be evaluated.

Immunotherapy of multiple myeloma: the start of a long and tortuous journey

The field of tumor immunotherapy is still in its infancy. It is becoming clear that the human immune response is the result of highly complex, continuously evolving interactions between cells of the adaptive and innate arms of the immune system, the internal and external environments, and normal and abnormal cells (e.g., myeloma plasma cells). Despite the considerable advances in our knowledge over the past 30 years, we have still only scratched the surface of the immune system's interaction with malignant diseases such as myeloma and to date, this has not translated into significantly better outcomes for patients with this disease. This review will summarize our current knowledge of the fundamental immunology of myeloma, review immunotherapy trials reported to date and discuss whether, in light of the current information, immunotherapy of multiple myeloma is an achievable goal.

Cellular immunotherapy for plasma cell myeloma

Allogeneic hematopoietic cell transplantation for plasma cell myeloma can lead to graft-vs-myeloma immunity and long-term survivorship, but limited efficacy and associated toxicities have prevented its widespread use. Cellular immunotherapies seek to induce more specific, reliable and potent antimyeloma immune responses with less treatment-related risk than is possible with allogeneic transplantation. Strategies under development include infusion of vaccine-primed and ex vivo expanded/costimulated autologous T cells after high-dose melphalan, genetic engineering of autologous T cells with receptors for myeloma-specific epitopes, administration of DC/plasma cell fusions and administration expanded marrow-infiltrating lymphocytes. In addition, novel immunomodulatory drugs such as inhibitors of the programmed death-1 T cell regulatory pathway may synergize with cellular immunotherapies.

CD34+ cell subclasses and lymphocyte subsets in blood grafts collected after various mobilization methods in myeloma patients

BACKGROUND

Cyclophosphamide (CY) combined with granulocyte-colony-stimulating factor (G-CSF) is commonly used to mobilize stem cells in multiple myeloma (MM). Plerixafor may also be used with G-CSF in patients who mobilize poorly or it may be added to chemomobilization to boost mobilization. Limited data are available on graft content collected after various mobilization methods.

STUDY DESIGN AND METHODS

Blood grafts collected from 21 MM patients were retrospectively analyzed. We analyzed CD34+ subclasses and lymphocyte subsets from cryopreserved grafts collected on the next morning after plerixafor injection in nine MM patients mobilized with G-CSF with (n = 5) or without preceding CY (n = 4). As controls we had the first collections from 12 MM patients mobilized with low-dose CY with G-CSF.

RESULTS

The proportion of the most primitive stem cells (CD34+CD133+CD38-) from all CD34+ cells in the graft was higher in the plerixafor-treated patients but there was no significant difference in the total number of these cells. The numbers of CD19+ B lymphocytes and natural killer cells were higher in patients collected after G-CSF plus plerixafor when compared to the patients mobilized with CY plus G-CSF. Early engraftment after high-dose melphalan was comparable between the groups.

CONCLUSION

Plerixafor appears to have effects on blood stem cell graft composition in myeloma patients. A higher number of grafts should be evaluated in regard to cellular content and longer follow-up of the patients is needed to evaluate the potential clinical impact of graft content.

Blood graft composition after plerixafor injection in patients with NHL

BACKGROUND

Plerixafor is used to mobilize CD34(+) hematopoietic stem cells from bone marrow to circulation. Limited data are available in regard to graft cellular content collected after plerixafor.

OBJECTIVES

The aim of this study was to assess effects of plerixafor added to chemomobilization on graft CD34(+) cell subclasses, lymphocyte subsets, engraftment, and post-transplant course in non-Hodgkin lymphoma (NHL) patients.

METHODS

Thirty-four patients with NHL were included. All patients received chemotherapy plus G-CSF to mobilize stem cells. Nineteen patients received plerixafor pre-emptively owing to poor mobilization or poor collection yields. The rest of the patients constituted the control group. Flow cytometric analyzes were performed from cryopreserved graft samples. Also, data on post-transplant engraftment and outcome were collected.

RESULTS

The proportion of primitive stem cells (CD34(+)  CD133(+)  CD38(-) ) was significantly higher after the plerixafor injection when compared to the first collection in the control group. The amount of T cells (CD3(+) ), helper (CD3(+)  CD4(+) ) T subsets, and suppressor (CD3(+)  CD8(+) ) T subsets in the graft was all significantly higher in the plerixafor group. Also, the amount of NK cells (CD3(-)  CD16/56(+) ) was higher. Engraftment after high-dose therapy was comparable between the groups, but leukocyte and platelet count at 6 months were higher in patients receiving plerixafor-mobilized grafts.

CONCLUSION

Plerixafor, when used pre-emptively in addition to chemomobilization, seems to mobilize more primitive CD34(+) stem cells, T lymphocytes, and NK cells. Whether these differences are associated with immune reconstitution, long-term engraftment, or patient outcomes needs to be evaluated in larger patient groups with longer follow-up.

Novel strategies for immunotherapy in multiple myeloma: previous experience and future directions

Multiple myeloma (MM) is a life-threatening haematological malignancy for which standard therapy is inadequate. Autologous stem cell transplantation is a relatively effective treatment, but residual malignant sites may cause relapse. Allogeneic transplantation may result in durable responses due to antitumour immunity mediated by donor lymphocytes. However, morbidity and mortality related to graft-versus-host disease remain a challenge. Recent advances in understanding the interaction between the immune system of the patient and the malignant cells are influencing the design of clinically more efficient study protocols for MM. Cellular immunotherapy using specific antigen-presenting cells (APCs), to overcome aspects of immune incompetence in MM patients, has received great attention, and numerous clinical trials have evaluated the potential for dendritic cell (DC) vaccines as a novel immunotherapeutic approach. This paper will summarize the data investigating aspects of immunity concerning MM, immunotherapy for patients with MM, and strategies, on the way, to target the plasma cell more selectively. We also include the MM antigens and their specific antibodies that are of potential use for MM humoral immunotherapy, because they have demonstrated the most promising preclinical results.

The role of natural killer cells in immunity against multiple myeloma

Multiple myeloma (MM) is an essentially incurable malignancy associated with profound immune dysregulation. Despite the advent of novel therapies and improvements in survival over the last 10 years, death from progressive disease and infection remains a common outcome. Natural killer (NK) cells are CD56(+)CD3(-) large granular lymphocytes that constitute a key cellular subset of the innate immune system. For over 30 years, the relationship between NK cells and MM has been described in the clinical setting and characterized in the laboratory. Data suggest that NK cells may play a role in the immune response to MM; however, this effect is lost due to immunoevasive strategies utilized by MM. Nevertheless, progress in the understanding of the mechanisms perpetuating this effect have led to new opportunities to recover or augment NK cell function therapeutically in MM. In fact, the novel agents thalidomide, lenalidomide and bortezomib all confer anti-MM effects, in part, through enhancement of NK cell function. Currently, the development of therapies designed specifically to increase NK cell cytotoxicity against MM is under way. The present review summarizes the current understanding of the NK cell versus MM effect and characterizes therapeutic interventions that exert anti-MM efficacy via NK cell function against the disease.

Mobilisation strategies for normal and malignant cells

This review evaluates the latest information on the mobilisation of haemopoietic stem cells for transplantation, with the focus on what is the current best practice and how new understanding of the bone marrow stem cell niche provides new insights into optimising mobilisation regimens. The review then looks at the mobilisation of mesenchymal stromal cells, immune cells as well as malignant cells and what clinical implications there are.

Tumor-primed natural killer cells from patients with multiple myeloma lyse autologous, NK-resistant, bone marrow-derived malignant plasma cells

Natural killer (NK) cells are cytotoxic lymphocytes able to kill tumor cells and virus-infected cells. Human-resting NK cells can be activated by co-culture with NK-resistant CTV-1a cells. These tumor-activated cells (TaNKs) are cytotoxic to a range of NK-resistant tumor cells in vitro. This potential, however, has not been explored in multiple myeloma (MM). In this study, we demonstrate that TaNK cells from 21 MM patients lyse a variety of myeloma targets, including primary isolates of autologous and allogeneic CD138+ myeloma cells whilst sparing CD138-ve bone marrow cells. Myeloma patients' TaNK-induced lysis of the U266 cell line was significantly higher compared to normal controls (median-specific lysis 79.1% vs. 69.5%) (P = 0.003). In addition, TaNKs induced substantial lysis of autologous and allogeneic CD138+ myeloma cells (median-specific lysis 52.5% and 37.4%, respectively). The percentage of specific lysis did not correlate with important disease characteristics (ISS, age, and high-risk molecular abnormalities) or with the disease status and antimyeloma treatment, including novel agents and dexamethasone. In conclusion, tumor-primed NK cells are able to induce substantial lysis of myeloma targets including autologous and allogeneic CD138+ myeloma plasma cells and could be an additional therapeutic approach in MM, particularly in the era of novel agents.

Autograft mediated adoptive immunotherapy of cancer in the context of autologous stem cell transplantation

The infused stem cell autograft in autologous stem cell transplantation (ASCT) has been viewed mainly as hematologic rescue from the myelosuppressive side effect of conditioning regimens. However, recent reports have shown that the immune effector cells collected at the same time as the stem cells can produce an autologous graft-versus-tumor effect, similar to the graft-versus-tumor effect seen in allogeneic stem cell transplantation without the detrimental effects of graft-versus-host disease. In this article, we review the different immune effector cells collected and infused from the stem cell autograft and their association with clinical outcome post-ASCT, suggesting that ASCT can be viewed not only as a therapeutic maneuver to recover bone marrow function after deliver high-dose chemotherapy, but also as an adoptive immunotherapeutic intervention capable of eradicating residual tumor cells in patients with cancer.

A randomized study comparing chemotherapy followed by G-CSF alone or in combination with GM-CSF for mobilization of peripheral blood stem cells in patients with non-Hodgkin's lymphomas

OBJECTIVE

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) are the two most commonly used cytokines for mobilization of stem cells in patients undergoing high dose chemotherapy with stem cell support. Both cytokines increase the peripheral blood white blood cell count and the stem cell count but there are other differences in the stem cell products mobilized by G-CSF versus those mobilized with GM-CSF. Generally higher numbers of dendritic cells are mobilized with GM-CSF than by G-CSF. The primary objective of this randomized study was to evaluate the safety and efficacy of chemotherapy plus G-CSF versus chemotherapy plus G-CSF and GM-CSF in patients with B-cell non-Hodgkin's lymphoma (NHL) who were undergoing chemo-mobilization. Secondary objectives were to determine the expression of various dendritic cell subsets in the two groups and to determine the incidence of disease progression or relapse at 12 months.

METHODS

We prospectively evaluated 84 patients with relapsed NHL who were candidates for high dose therapy (HDT). All patients underwent chemo-mobilization using ifosfamide, etoposide, and rituximab. All patients were randomized in an adaptive manner to receive either G-CSF or G-CSF plus GM-CSF (G+GM) starting 24 hours after completion of chemotherapy and continuing until completion of apheresis. The stem cell yield/kg, the number of apheresis procedures needed in the two groups, and the toxicity were recorded. We also enumerated dendritic cell subsets, myeloid DCs (mDC) and plasmacytoid DCs (pDC), in apheresis products and in peripheral blood (PB) samples collected pre-chemotherapy. The data were expressed as a percentage of peripheral blood mononuclear cells.

RESULTS

A total of 84 patients were treated. Forty-three patients received G-CSF and 41 received G+GM. Both regimens were well tolerated. The median CD34+ cell dose collected was similar in the two groups. A total of 54 (G-CSF N = 25 and G+GM N = 29) paired samples from baseline and post-apheresis were available for analysis of dendritic cell subsets. There was no significant difference in the percentages of mDC subsets between baseline and post-apheresis collected with G-CSF or G+GM mobilization. However, there was a significant increase in the percentage of pDC subsets in the G-CSF alone when compared to the G+GM arm (P = 0.002). Furthermore, the ratio of mDC and pDC was significantly lower after mobilization with G-CSF versus G+GM (P = 0.029).

CONCLUSION

Addition of GM-CSF to G-CSF to the mobilization regimen resulted in lower percentages of pDC in the apheresis products when compared to those with G-CSF alone. This shifts the mDC/pDC ratio in the apheresis grafts in favor of mDC in the combination arm. However, these differences did not seem to impact the clinical outcomes in the two groups. (ClinicalTrials.gov Identifier: NCT00499343).

Comparison of unmobilized and mobilized graft characteristics and the implications of cell subsets on autologous and allogeneic transplantation outcomes

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) are considered the standard of care for many malignancies, including lymphoma, myeloma, and some leukemias. In many cases, mobilized peripheral blood has become the preferred source of hematopoietic stem cells. The efficacy of different mobilization regimens and transplantation outcomes based on cell doses has been well studied; however, the characteristics of the stem cell graft may be of equal importance with respect to patient outcomes following autologous or allogeneic HSCT. This review summarizes available preclinical and clinical data for bone marrow and mobilized peripheral blood HSCT characteristics, defined as the cell types found in the graft as well as their gene expression profiles. It also explores how graft characteristics can affect bone marrow homing, engraftment, immune reconstitution, and other posttransplantation outcomes in both the allogeneic and autologous HSCT settings.

Advances in Immunotherapy of Multiple Myeloma: From the Discovery of Tumor-Associated Antigens to Clinical Trials

Tumors aberrantly express tumor-associated antigens that can be specifically recognized by T-cells, thereby providing a scientific rationale for the design and clinical testing of immunotherapeutic strategies targeting these antigens. Multiple myeloma is a fatal hematologic malignancy. Here, we review techniques to discover new tumor-associated antigens in multiple myeloma and the latest immunotherapeutic strategies employed in this disease.

High CD8+ lymphocyte dose in the autograft predicts early absolute lymphocyte count recovery after peripheral hematopoietic stem cell transplantation

Early lymphocyte recovery (ELR) after autologous peripheral hematopoietic stem cell transplantation (ASCT) is an independent predictor for survival in patients with hematological and non-hematological cancers. Sixty-five ASCT for hematological cancers were retrospectively analyzed to identify the factors associated with ELR and to assess the impact of different mobilization regimens on the pre-collection absolute lymphocyte count (ALC). The CD8+ lymphocyte dose in the autograft and the pre-mobilization ALC were independently associated with ELR (P < 0.001 and P = 0.008, respectively). CD8+ lymphocyte doses higher than 0.1 x 10(9)/kg were strongly associated with ELR [P < 0.001, odds ratio 25.22, 95% confidence interval (CI) 4.98-127.69] and this cutoff may be used to predict ELR (P = 0.001, area under the curve 0.75, 95% CI 0.62-0.88). Mobilization with granulocyte colony-stimulating factor (G-CSF) alone, the pre-collection ALC and the number of apheresis sessions were independently associated with the CD8+ lymphocyte dose (P = 0.04, P = 0.001, and P < 0.001, respectively). The number of aphereses was the variable with the strongest correlation to the CD8+ lymphocyte dose (r(s) = 0.68, P < 0.001). Median pre-mobilization ALC was higher than pre-collection ALC in the subgroup of patients without ELR mobilized with chemotherapy followed by G-CSF (1090 vs. 758 lymphocytes/microL; P < 0.001). This reduction was not significant in the subgroup with ELR mobilized with chemotherapy plus G-CSF (1920 vs. 1539/microL, respectively; P = 0.23). These results suggest that the CD8+ lymphocyte dose in the autograft is critical for ELR after ASCT and also demonstrates that mobilization with chemotherapy followed by G-CSF significantly decreases the pre-collection ALC, especially in patients with low pre-mobilization ALC.

Absolute lymphocyte count is a novel prognostic indicator in ALL and AML: implications for risk stratification and future studies

BACKGROUND

Leukemia is the leading cause of disease-related death in children, despite significant improvement in survival and modern risk stratification. The prognostic significance of absolute lymphocyte counts (ALC) was evaluated in young patients with acute myeloblastic leukemia (AML) and acute lymphoblastic leukemia (ALL).

METHODS

In all, 171 consecutive de novo cases of AML and ALL, age <or=21 years, were analyzed. Age, initial white blood cell count, cytogenetics, and bone marrow response were compared with lymphocyte, neutrophil, and platelet counts at weekly intervals during induction chemotherapy.

RESULTS

ALC is a significant independent predictor of relapse and survival. For example, in patients with AML an ALC on Day 28 of induction (ALC-28) <350 cells/microL predicts very poor survival, with a 5-year relapse-free survival (RFS) of only 10% (hazard ratio [HR] 3.7, P= .003). In contrast, an ALC-15 >350 cells/microL carries an excellent prognosis, with a 5-year overall survival (OS) of 85% (HR 0.2, P= .012). Similarly in ALL, an ALC-15 <350 cells/microL predicts poor survival, with a 6-year RFS of 43% (HR 4.5, P= .002), whereas an ALC-15 >350 cells/microL predicts excellent outcome, with a 6-year OS of 87% (HR 0.2, P= .018). Importantly, ALC remains a strong predictor in multivariate analysis with known prognostic factors.

CONCLUSIONS

ALC is a simple, statistically powerful measurement for patients with de novo AML and ALL. The results, when combined with previous studies, demonstrate that ALC is a powerful new prognostic factor for a range of malignancies. These findings suggest a need for further exploration of postchemotherapy immune status and immune-modulating cancer therapies.