A phase I/II study of chemotherapy followed by donor lymphocyte infusion plus interleukin-2 for relapsed acute leukemia after allogeneic hematopoietic cell transplantation

The role of immune reconstitution in relapse after allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Leukemia relapse following stem cell transplantation remains a significant barrier to long-term remission. Timely and balanced immune recovery after transplantation is crucial for preventing leukemia relapse.

AREAS COVERED

After an extensive literature search of PubMed and Web of Science through October 2023, we provide an overview of the dynamics of immune reconstitution and its role in controlling leukemia relapse. We also discuss strategies to promote immune reconstitution and reduce disease recurrence following allogeneic hematopoietic stem cell transplantation.

EXPERT OPINION

Immune reconstitution after transplantation has substantial potential to prevent relapse and might predict disease recurrence and prognosis. High dimensional cytometry, multi-omics, and T cell repertoire analysis allow for a more comprehensive and detailed understanding of the immune system's dynamics post-transplantation, and contribute to the identification of rare immune cell subsets or potential biomarkers associated with successful immune reconstitution or increased risk of complications. Strategies to enhance the immune system, such as adoptive immunotherapy and cytokine-based therapy, have great potential for reducing leukemia relapse after transplantation. Future research directions should focus on refining patient selection for these therapies, implementing appropriate and timely treatment, investigating combination approaches to maximize therapeutic outcomes, and achieving a robust graft-versus-leukemia (GVL) effect while minimizing graft-versus-host disease (GVHD) for optimal results.

Novel agents targeting leukemia cells and immune microenvironment for prevention and treatment of relapse of acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation

Relapse remains the worst life-threatening complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with acute myeloid leukemia (AML), whose prognosis has been historically dismal. Given the rapid development of genomics and immunotherapies, the interference strategies for AML recurrence have been changing these years. More and more novel targeting agents that have received the U.S. Food and Drug Administration (FDA) approval for de novo AML treatment have been administrated in the salvage or maintenance therapy of post-HSCT relapse. Targeted strategies that regulate the immune microenvironment of and optimize the graft versus leukemia (GVL) effect of immune cells are gradually improved. Such agents not only have been proven to achieve clinical benefits from a single drug, but if combined with classic therapies, can significantly improve the poor prognosis of AML patients who relapse after allo-HSCT. This review will focus on currently available and promising upcoming agents and also discuss the challenges and limitations of targeted therapies in the allogeneic hematopoietic stem cell transplantation community.

Ibrutinib as a salvage therapy after allogeneic HCT for chronic lymphocytic leukemia

The purpose of our study is to provide information on safety and efficacy of ibrutinib as salvage treatment after allo-HSCT for CLL. A total of 56 patients were included, 36 (64%) males; median age at transplantation was 48 years (range: 35-64) and the median number of treatment lines prior to transplantation was 3 (1-10). The median time between allo-HSCT and Ibrutinib was 30 months (range: 1-140). Overall, 40 (71%) patients responded to Ibrutinib; 23 (41%) PR, and 17 (30%) CR. At time of ibrutinib initiation, ten patients had active chronic GVHD that resolved under Ibrutinib, whilst a single patient developed limited de novo chronic GVHD on Ibrutinib. Fourteen patients discontinued ibrutinib, four because of toxicity and ten because of disease progression. Overall, 14 patients progressed (median PFS = 24 months) among them 10 died. Two-year OS and PFS probabilities were 72% (95% CI: 52-84) and 50% (95% CI: 32-66), respectively. Patients with late relapse after allo-HSCT (≥24 months) had a better PFS after ibrutinib. Our study shows that ibrutinib can be safely administered for CLL relapse after allo-HSCT, with comparable efficacy to non-transplanted patients with high-risk disease.

Recombinant human thrombopoietin combined with interleukin-2 improves the effects of chemosensitivity and thrombocytopenia on a basic gemcitabine and carboplatin combination therapy for non-small cell lung cancer in a nude mouse model

Background

To investigate the effects of recombinant human thrombopoietin (rhTPO) and interleukin-2 (IL-2) on a basic gemcitabine (GEM) plus carboplatin (GC) treatment regimen in a murine lung carcinoma model.

Methods

Fifty nude mice with subcutaneous tumors derived from human lung cancer cells were divided into 5 groups, each comprised of 10 mice: A blank group (intraperitoneal injection of saline), a control group (GC) (intraperitoneal injections of GC), a rhTPO group (same as the control group plus subcutaneous injection of rhTPO), an IL-2 group (same as the control group plus subcutaneous injection of IL-2) and a rhTPO + IL-2 group (same as the rhTPO group plus subcutaneous injection of IL-2). Tumor development and histology as well as CD4+, phosphorylated-adenosine monophosphate-activated protein kinase (p-AMPK), phosphorylated-protein kinase B (p-AKT), phosphorylated-extracellular signal-regulated kinase (p-ERK), phosphorylated-phosphoinositide 3-kinase (p-pI3K) and GTPase RAS1 expression in tumor tissues were measured and blood analyses performed.

Results

Tumor sizes from all treated mice were significant smaller than the controls, as were the tumors of IL-2 plus GC treated mice compared to other treated groups. CD4+ expressing cells were increased in tumors after IL-2 and rhTPO treatment and the application of rhTPO significantly restored the blood platelet count. The expression of p-AMPK, p-AKT, p-ERK, p-pI3K and RAS1 in tumor cells were all significantly diminished after the addition of rhTPO and IL-2 to the GC regimen.

Conclusions

The supplementation of rhTPO and IL-2 to a GC regime effectively reduced tumor sizes and restored the platelet count in a human lung cancer mouse model.

Novel Immunotherapies for T Cell Lymphoma and Leukemia

PURPOSE OF REVIEW

Novel immunotherapies such as checkpoint inhibitors, bispecific antibodies, and chimeric antigen receptor T cells are leading to promising responses when treating solid tumors and hematological malignancies. T cell neoplasms include leukemia and lymphomas that are derived from T cells and overall are characterized by poor clinical outcomes. This review describes the rational and preliminary results of immunotherapy for patients with T cell lymphoma and leukemia.

RECENT FINDINGS

For T cell neoplasms, despite significant research effort, only few agents, such as monoclonal antibodies and allogeneic stem cell transplantation, showed some clinical activity. One of the major hurdles to targeting T cell neoplasms is that activation or elimination of T cells, either normal or neoplastic, can cause significant toxicity. A need to develop novel safe and effective immunotherapies for T cell neoplasms exists. In this review, we will discuss the rationale for immunotherapy of T cell leukemia and lymphoma and present the most recent therapeutic approaches.

New interleukin-15 superagonist (IL-15SA) significantly enhances graft-versus-tumor activity

Interleukin-15 (IL-15) is a potent cytokine that increases CD8⁺ T and NK cell numbers and function in experimental models. However, obstacles remain in using IL-15 therapeutically, specifically its low potency and short in vivo half-life. To help overcome this, a new IL-15 superagonist complex comprised of an IL-15N72D mutation and IL-15RαSu/Fc fusion (IL-15SA, also known as ALT-803) was developed. IL-15SA exhibits a significantly longer serum half-life and increased in vivo activity against various tumors. Herein, we evaluated the effects of IL-15SA in recipients of allogeneic hematopoietic stem cell transplantation. Weekly administration of IL-15SA to transplant recipients significantly increased the number of CD8⁺ T cells (specifically CD44⁺ memory/activated phenotype) and NK cells. Intracellular IFN-γ and TNF-α secretion by CD8⁺ T cells increased in the IL-15SA-treated group. IL-15SA also upregulated NKG2D expression on CD8⁺ T cells. Moreover, IL-15SA enhanced proliferation and cytokine secretion of adoptively transferred CFSE-labeled T cells in syngeneic and allogeneic models by specifically stimulating the slowly proliferative and nonproliferative cells into actively proliferating cells.

We then evaluated IL-15SA's effects on anti-tumor activity against murine mastocytoma (P815) and murine B cell lymphoma (A20). IL-15SA enhanced graft-versus-tumor (GVT) activity in these tumors following T cell infusion. Interestingly, IL-15 SA administration provided GVT activity against A20 lymphoma cells in the murine donor leukocyte infusion (DLI) model without increasing graft versus host disease. In conclusion, IL-15SA could be a highly potent T- cell lymphoid growth factor and novel immunotherapeutic agent to complement stem cell transplantation and adoptive immunotherapy.

Ibrutinib efficacy and tolerability in patients with relapsed chronic lymphocytic leukemia following allogeneic HCT

Ibrutinib, a potent and irreversible small-molecule inhibitor of both Bruton's tyrosine kinase and interleukin-2 inducible kinase (ITK), has been used to treat relapsed/refractory chronic lymphocytic leukemia (CLL) with prolongation of progression-free and overall survival. Here, we present 27 patients with relapsed CLL following allogeneic hematopoietic cell transplant (HCT) who subsequently received ibrutinib salvage therapy. Sixteen of these patients were part of multi-institutional clinical trials and achieved an overall response rate of 87.5%. An additional 11 patients were treated at Stanford University following US Food and Drug Administration approval of ibrutinib; 7 (64%) achieved a complete response, and 3 (27%) achieved a partial response. Of the 9 patients treated at Stanford who had mixed chimerism-associated CLL relapse, 4 (44%) converted to full donor chimerism following ibrutinib initiation, in association with disease response. Four of 11 (36%) patients evaluated by ClonoSeq achieved minimal residual disease negativity with CLL <1/10 000 white blood cells, which persisted even after ibrutinib was discontinued, in 1 case even after 26 months. None of the 27 patients developed graft-versus-host-disease (GVHD) following ibrutinib initiation. We postulate that ibrutinib augments the graft-versus-leukemia (GVL) benefit through a T-cell-mediated effect, most likely due to ITK inhibition. To investigate the immune modulatory effects of ibrutinib, we completed comprehensive immune phenotype characterization of peripheral B and T cells from treated patients. Our results show that ibrutinib selectively targets pre-germinal B cells and depletes Th2 helper cells. Furthermore, these effects persisted after drug discontinuation. In total, our results provide evidence that ibrutinib effectively augments GVL without causing GVHD.

Strategies before, during, and after hematopoietic cell transplantation to improve T-cell immune reconstitution

T-cell immune reconstitution (IR) after allogeneic hematopoietic cell transplantation (allo-HCT) is highly variable between patients and may take several months to even years. Patients with delayed or unbalanced T-cell IR have a higher probability of developing transplantation-related morbidity, mortality, and relapse of disease. Hence, there is a need for strategies to better predict and improve IR to reduce these limitations of allo-HCT. In this review, we provide an update of current and in-near-future clinically relevant strategies before, during, and after transplantation to achieve successful T-cell IR. Potent strategies are choosing the right HCT source (eg, donor-recipient matching, cell dose, graft manipulation), individualized conditioning and serotherapy (eg, antithymocyte globulin), nutritional status, exercise, home care, modulation of microbiota, enhancing homeostatic peripheral expansion, promoting thymopoiesis, and the use of adjuvant-targeted cellular immunotherapies. Strategies to prevent graft-versus-host disease are important as well because this complication and the subsequent need for immunosuppression affects T-cell IR and function. These options aim for personalized precision transplantation, where allo-HCT therapy is designed to boost a well-balanced T-cell IR and limit complications in individual patients, resulting in overall lower morbidity and higher survival chances.

Improving engraftment and immune reconstitution in umbilical cord blood transplantation

Umbilical cord blood (UCB) is an important source of hematopoietic stem cells (HSC) for allogeneic transplantation when HLA-matched sibling and unrelated donors (MUD) are unavailable. Although the overall survival results for UCB transplantation are comparable to the results with MUD, UCB transplants are associated with slow engraftment, delayed immune reconstitution, and increased opportunistic infections. While this may be a consequence of the lower cell dose in UCB grafts, it also reflects the relative immaturity of cord blood. Furthermore, limited cell numbers and the non-availability of donor lymphocyte infusions currently prevent the use of post-transplant cellular immunotherapy to boost donor-derived immunity to treat infections, mixed chimerism, and disease relapse. To further develop UCB transplantation, many strategies to enhance engraftment and immune reconstitution are currently under investigation. This review summarizes our current understanding of engraftment and immune recovery following UCB transplantation and why this differs from allogeneic transplants using other sources of HSC. It also provides a comprehensive overview of promising techniques being used to improve myeloid and lymphoid recovery, including expansion, homing, and delivery of UCB HSC; combined use of UCB with third-party donors; isolation and expansion of natural killer cells, pathogen-specific T cells, and regulatory T cells; methods to protect and/or improve thymopoiesis. As many of these strategies are now in clinical trials, it is anticipated that UCB transplantation will continue to advance, further expanding our understanding of UCB biology and HSC transplantation.

Immune-modulating drugs and hypomethylating agents to prevent or treat relapse after allogeneic stem cell transplantation

Allogeneic stem cell transplantation is a curative treatment option for many hematological diseases, and the numbers of transplantations are steadily increasing worldwide. Major progress has been made in lowering treatment-related mortality by reducing intensity of the conditioning regimen and by improving supportive care (eg, for infectious complications). Accordingly, relapse after allogeneic stem cell transplantation has become the major cause for treatment failure. Major efforts to prevent or treat relapse are focused on cellular- (T cell, natural killer cell), cytokine-, or antibody-based strategies to enhance the graft-versus-tumor effect or circumvent immunoescape. In the more recent years, new classes of agents have shown activity in several hematological malignancies, and besides their immediate antitumor activity, most of them also possess immune-modulatory qualities that may be useful alone or in combination with adoptive immunotherapy after allogeneic stem cell transplantation to enhance graft-versus-tumor effects. Here, we summarize the current knowledge and potential use of 2 of these compounds in preventing or treating relapse after allogeneic stem cell transplantation, namely immune-modulating drugs and hypomethylating agents.

Donor lymphocyte infusion for relapsed hematological malignancies after allogeneic hematopoietic cell transplantation: prognostic relevance of the initial CD3+ T cell dose

The impact of donor lymphocyte infusion (DLI) initial cell dose on its outcome is known in patients with chronic myeloid leukemia but limited in patients with other hematological malignancies. In this retrospective study, we evaluated the effect of initial DLI CD3(+) cell dose on graft-versus-host disease (GVHD) and overall survival after DLI given for relapse of any hematological malignancies after allogeneic hematopoietic cell transplantation (HCT) with high- or reduced-intensity conditioning. The cohort included 225 patients. Initial DLI CD3(+) cell dose per kilogram of recipient body weight was ≤ 1 × 10(7) (n = 84; group A), >1.0 to <10 × 10(7) (n = 58; group B), and ≥ 10 × 10(7) (n = 66; group C). The initial cell dose was unknown for the remaining 17 patients. Cumulative incidence rates of GVHD at 12 months after DLI were 21%, 45%, and 55% for groups A, B, and C, respectively. Multivariate analysis showed that initial DLI CD3(+) cell ≥ 10 × 10(7) dose per kilogram is associated with an increased risk of GVHD after DLI (P = .03). Moreover, an initial DLI CD3(+) cell dose of 10 × 10(7) or higher did not decrease the risk of relapse and did not improve overall survival. Thus, these results support the use of less than 10 × 10(7) CD3(+) cell per kilogram as the initial cell dose of DLI for treatment of persistent or recurrent hematological malignancy after HCT.

Complete remission following chemotherapy with low-dose cytosine arabinoside and macrophage colony-stimulating factor/granulocyte colony-stimulating factor in a patient with relapsed acute myeloid leukemia after stem cell transplantation

The prognosis of patients who relapse with acute myeloid leukemia (AML) after undergoing stem cell transplantation (SCT) is poor. There exist some treatments for relapsed AML; however, almost all treatments are associated with a high level of regimen-related toxicities (RRTs). The RRT of donor lymphocyte infusion is lower than that of other treatments; however, the efficacy of this treatment in treating patients with relapsed AML is lower than that observed in patients with chronic myelomonocytic leukemia. We herein report a case of relapsed AML after SCT in a 65-year-old man. We performed donor lymphocyte infusion; however, it was not effective. We then administered chemotherapy with cytosine arabinoside and macrophage colony-stimulating factor/granulocyte colony-stimulating factor and complete remission was achieved. Since graft-versus-host disease occurred after the administration of low-dose chemotherapy in this case, we speculated that the chemotherapy induced a graft-versus-leukemia effect.

Successful remission rates and survival after lymphodepleting chemotherapy and donor lymphocyte infusion for relapsed hematologic malignancies postallogeneic hematopoietic cell transplantation

Few therapeutic strategies exist for hematologic malignancies relapsing post allogeneic hematopoietic cell transplantation. We present outcomes on 35 patients with nonchronic myelogenous leukemia (CML) hematologic malignancies, the majority having acute myelogenous leukemia (AML) or myelodysplastic syndromes/myeloproliferative disorders (MDS/MPD) (n = 22) receiving lymphodepleting chemotherapy followed by donor lymphocyte infusion (DLI) at 2 T cell dose levels (0.5 and 1.0 × 10(8) CD3/kg). Forty-nine percent of patients achieved complete remission (CR), with a median duration of remission of 6 months (range: 2-71+). CR rates were similar between the 2 groups. The incidence of acute graft-versus-host disease (aGVHD) of any grade was 49%. We saw a higher incidence of grade II-IV aGVHD, with a rate of 66% using the higher-dose DLI (grade III, 33% and grade 4, 20%) versus only 25% (10% grade III-IV) with the lower-dose DLI (P = .06). Overall survival at 1 and 2 years was 30% (95% confidence interval [CI], 16%-45%) and 19% (95% CI, 8%-34%); however, for those achieving CR, 1- and 2-year survival was improved at 44% (95% CI, 20%-66%) and 28% (95% CI, 8%-52%) (P = .03), respectively. These results demonstrate that DLI after lymphodepleting chemotherapy for relapsed hematologic malignancies results in frequent CRs. The lower DLI dose regimen improved the tolerability of this therapeutic approach, with modest rates of severe aGVHD.