Follicular lymphoma: in vitro effects of combining lymphokine-activated killer (LAK) cell-induced cytotoxicity and rituximab- and obinutuzumab-dependent cellular cytotoxicity (ADCC) activity

Ex vivo expansion of natural killer cells for hematological cancer immunotherapy: a systematic review and meta-analysis

The present systematic review aimed to investigate natural killer (NK) cell ex vivo expansion protocols within the scope of clinical trials targeting hematological cancer and to conduct a meta-analysis to assess the effect of NK cell infusion on survival. Research articles of clinical studies in which cell products produced by ex vivo expansion, consisting of a certain amount of NK cells and infused to patients with hematological cancer, were included in the systematic review. We conducted a proportion analysis with random effects for product purity and viability values. Studies having control groups were included in the survival meta-analysis. Among 11.028 identified records, 21 were included in the systematic review. We observed statistically significant heterogeneity for viability (I2 = 97.83%, p < 0.001) and purity values (I2 = 99.95%, p < 0.001), which was attributed to the diversity among isolation and expansion protocols. In addition, the survival meta-analysis findings suggested that NK cell therapy favors disease-free survival (DFS) of patients with myeloid malignancies but limited to only two clinical studies (odds ratio = 3.40 (confidence interval:1.27-9.10), p = 0.01). While included protocols yielded cell products with acceptable viability, the utility of immunomagnetic methods; feeder cells such as K562 expressing membrane-bound IL15 and 4-1BBL or expressing membrane-bound IL21 and 4-1BBL might be preferable to achieve better purity. In conclusion, NK cell therapy has a potential to improve DFS of patients with myeloid malignancies.

Serology-based therapeutic strategy in SARS-CoV-2-infected patients

SARS-CoV-2 infection can be a life-threatening disease. The optimal treatment of patients is not yet standardized. We use a serology-based therapeutic strategy based on the presence of antibodies against the SARS-CoV-2 virus, in which patients with positive serology receive aggressive anti-inflammatory treatment with high-dose dexamethasone and/or tocilizumab and patients with negative serology receive early convalescent plasma therapy. We also analyze the immunological impact of this therapy in the recovery of T cells, B cells and NK cells during hospitalization in a COVID-19 infectious ward. Our results suggest that aggressive therapy with early administration of convalescent plasma and high-dose dexamethasone may be of benefit in patients with SARS-CoV-2 infection and might avoid progression of lung damage or need of admission in intensive care. This strategy did not impair immune responses against SARS-CoV-2, as 93% of the patients generated antibodies against the virus. Independently of previous immunological status of the patients, serology-guided therapy might benefit even patients with a high CIRS-G score, immunosuppressed or medically debilitated individuals and elderly patients. T cell disturbances were most frequent in patients who required high-dose dexamethasone, and B cell depletion was most frequent in patients who received tocilizumab. Early passive immunotherapy with convalescent plasma does not affect lymphoid recovery.

Oxidized-Desialylated Low-Density Lipoprotein Inhibits the Antitumor Functions of Lymphokine Activated Killer Cells

Elevated concentrations of circulating low density lipoprotein (LDL) that is abnormally oxidized and desialylated is both a precursor to and a hallmark of atherosclerosis. Peripheral blood mononuclear cells (PBMCs) treated in vitro with interleukin-2 (IL-2) become lymphokine activated killer (LAK) cells, the primary effectors of which are NK cells and NKT cells. LAK cells display antitumor functions such as increased cytotoxicity and IFN-γ production, and they have been evaluated as a potential cancer therapeutic. Atherosclerotic processes may influence innate immunity against cancer. Because prior studies have shown that low density lipoprotein (LDL) reduces T-cell and NK cell antitumor functions, we asked whether oxidized-desialylated LDL affects the functionality of LAK cells in vitro. We show here that LAK cells take up oxidized-desialylated LDL to a significantly greater extent than native LDL over a period of 72 hours. This resulted in a significant downregulation of LAK cell cytotoxicity against K562 cells. In particular, the expression of IFN-γ, CD56, and NKG2D were reduced upon oxidized-desialylated LDL treatment of LAK cells and, conversely, their expression was enhanced with native LDL. It was also observed that as the number of CD56 and NKG2D positive cells decreased upon treatment with oxidized-desialylated LDL, the number of CD3 positive cells increased in proportion. Additionally, only a slight inhibition of LAK cell cytotoxicity was observed with desialylation alone of LDL, and no significant inhibition was observed with oxidation alone of LDL. Thus, this study describes a new role of oxidized-desialylated LDL as an inhibitor of the antitumor functions of LAK cells. These observations have implications for how atherosclerosis processes, namely oxidation and desialylation of LDL, may influence LAK cell antitumor activity.

Recent advances in cellular therapy for malignant lymphoma

Cellular therapies for malignant lymphoma include autologous or allogeneic hematopoietic stem cell transplantation (HSCT) and adaptive cellular therapy using EBV-specific T cells, cytokine-induced killer (CIK) cells, NKT cells, NK cells, chimeric antigen receptor T (CAR-T) cells and chimeric antigen receptor NK (CAR-NK) cells. In this review we discusses recent advances of these cellular therapies and consider ways to optimize these therapies. Not only a single strategy using one of these cellular therapies, but also multi-disciplinary treatment combines with antibodies, such as an anti-tumor antibody and an immune checkpoint antibody, may be more effective for relapsed and refractory lymphoma.

Improving Immunotherapy Against B-Cell Malignancies Using γδ T-Cell-specific Stimulation and Therapeutic Monoclonal Antibodies

Tumor antigen-targeting monoclonal antibodies (mAbs) are an important element of current cancer therapies. Some of these therapeutic mAbs enable antibody-dependent cell mediated cytotoxicity (ADCC) against tumor cells. However, cancer-related functional impairment of immune effector cells may limit the clinical efficacy of antibody treatments. We reckoned that combining mAbs with cell-based immunotherapies would provide a clinically relevant synergism and benefit for cancer patients. Here, we focus on γδ T cells, as earlier studies demonstrated that γδ T-cell-based therapies are safe and promising for several types of malignancies. Similar to natural killer cells, their antitumor effects can be enhanced using antibodies, and they could, therefore, become a versatile effector cell platform for use with a variety of licensed therapeutic mAbs against cancer. In this study, we explore the potential of a combination therapy of activated γδ T cells with rituximab and the more recently developed mAbs (obinutuzumab and daratumumab) in different B-cell malignancies in vitro. Obinutuzumab outperformed the other mAbs with regard to direct target cell lysis and ADCC by γδ T cells in several CD20 cell lines and primary lymphoma specimens. We demonstrate that comparatively few CD16 γδ T cells are sufficient to mediate a strong ADCC. Using Fc-receptor-positive B-cell lymphomas as target cells, ADCC cannot be blocked by high concentrations of immunoglobulins or anti-CD16 antibodies, but both substances can promote cell mediated target cell lysis. This study expands on earlier reports on the therapeutic potential of distinctive tumor antigen-targeting mAbs and facilitates the understanding of the mechanism and potential of ADCC by γδ T-cell subsets.

Maintenance therapy with ex vivo expanded lymphokine-activated killer cells and rituximab in patients with follicular lymphoma is safe and may delay disease progression

Anti-cluster of differentiation 20 (CD20) monoclonal antibodies (mAbs) have shown promise in follicular lymphoma (FL) as post-induction therapy, by enhancing antibody-dependent cellular cytotoxicity (ADCC). However, cytotoxic cells are reduced after this treatment. We hypothesised that ex vivo expanded lymphokine-activated killer (LAK) cells administered to FL-remission patients are safe and improve anti-CD20 efficacy. This open, prospective, phase II, single-arm study assessed safety and efficacy of ex vivo expanded LAK cells in 20 FL-remission patients following rituximab maintenance. Mononuclear cells were obtained in odd rituximab cycles and stimulated with interleukin 2 (IL-2) for 8 weeks, after which >5 × 10⁸ LAK cells were injected. Patients were followed-up for 5 years. At the end of maintenance, peripheral blood cells phenotype had not changed markedly. Natural killer, LAK and ADCC activities of mononuclear cells increased significantly after recombinant human IL-2 (rhIL-2) stimulation in all cycles. Rituximab significantly enhanced cytotoxic activity. No patients discontinued treatment. There were no treatment-related serious adverse events. Three patients had progressed by the end of follow-up. After a median (interquartile range) follow-up of 59.4 (43.8-70.9) months, 85% of patients remained progression free. No deaths occurred. Quality-of-life improved throughout the study. Post-induction LAK cells with rituximab seem safe in the long term. Larger studies are warranted to confirm efficacy.

Battle of Thermopylae: 300 Spartans (natural killer cells plus obinutuzumab) versus the immortal warriors (chronic lymphocytic leukemia cells) of Xerxes' army

Aim:

To analyze the effects of subcutaneous or intravenous rituximab + lymphokine-activated killer cells, obinutuzumab or ibrutinib on natural killer (NK) cell levels in chronic lymphocytic leukemia and follicular lymphoma patients.

Patients & methods:

The distribution of peripheral blood NK cells of 31 patients was analyzed by flow cytometry.

Results:

We detected a decrease of NK cells in peripheral blood below normal range after obinutuzumab treatment. During maintenance treatment with subcutaneous rituximab, an NK cell reduction was less pronounced than after intravenous rituximab treatment, despite lymphokine-activated killer cell infusions.

Conclusion:

After one dose of obinutuzumab, each NK cell in peripheral blood destroys 25 leukemic cells.

The standard treatment of chronic lymphocytic leukemia and follicular lymphoma is chemotherapy in combination with anti-CD20 monoclonal antibodies, resulting in the destruction of the immune system, or a ‘Kamikaze effect’. Unfortunately, immunotherapy with rituximab or obinutuzumab may be of limited efficacy when the immunological system is overwhelmed by abundant tumor cells or is diminished by chemotherapy, which eliminates effector immune cells such as natural killer cells before they would be able to kill the whole tumor. Hence, it is important to measure the number of immune cells to ensure that during the encounter of effector cells with tumor cells, sufficient ‘warriors’ can win the battle against the tumor. Otherwise, something akin to the Battle of Thermopylae can happen where a limited number of Spartan warriors faced a huge army and were defeated in the end.

Obinutuzumab induces depletion of NK cells in patients with chronic lymphocytic leukemia

AIM

Obinutuzumab induces NK cell antibody-dependent cell-mediated cytotoxicity.

OBJECTIVE

Investigate the effects on the human immune system after obinutuzumab monotherapy treatment in patients with chronic lymphocytic leukemia (CLL).

METHOD

To evaluate these effects, we analyzed the distribution of CD4⁺ and CD8⁺ T cells, B cells and NK cells in the peripheral blood of eight CLL patients who were treated with obinutuzumab in monotherapy. The distribution of peripheral blood lymphocytes was examined prior to each dose of obinutuzumab and 24-72 h after the first 1000 mg complete dose (cycle 1 day 2). We also repeated measurements 3 months after the last obinutuzumab dose. In total we obtained ten samples of each patient. Analyses were performed by flow cytometry with monoclonal antibodies against CD3, CD4, CD8, CD19 and CD56⁺.

RESULTS

After the first 1000 mg obinutuzumab infusion (cycle 1 day 2), CD4⁺ T cells and CD8⁺ T cells were significantly decreased in peripheral blood compared with prior to therapy. This reduction in the CD4⁺ T cells persisted after six cycles of obinutuzumab (1235 cells/μl basal vs 662 cells/μl after six cycles, p ≤ 0.05), but not in CD8⁺ T cells (987 cells/μl basal vs 837 cells/μl after six cycles). Interestingly, we also observed significant differences in the NK cell compartment after the first 1000 mg drug infusion (490 cells/μl basal vs 23 cells/μl postinfusion, p ≤ 0.05), and after cycle 6 (490 cells/μl basal vs 149 cells/μl after six cycles, p ≤ 0.05).

CONCLUSION

Obinutuzumab induces depletion of NK cells in CLL.

Cellular Immunotherapy for Hematologic Malignancies: Beyond Bone Marrow Transplantation

Immunotherapy has changed treatment practices for many hematologic malignancies. Even in the current era of targeted therapy, chemotherapy remains the backbone of treatment for many hematologic malignancies, especially in acute leukemias, where relapse remains the major cause of mortality. Application of novel immunotherapies in hematology attempts to harness the killing power of the immune system against leukemia and lymphoma. Cellular immunotherapy is evolving rapidly for high-risk hematologic disorders. Recent advances include chimeric antigen-receptor T cells, mesenchymal stromal/stem cells, dendritic cell tumor vaccines, cytokine-induced killer cells, and virus-specific T cells. The advantages of nontransplantation cellular immunotherapy include suitability for patients for whom transplantation has failed or is contraindicated, and a potentially less-toxic treatment alternative to transplantation for relapsed/refractory patients. This review examines those emerging cellular immunotherapies that are changing treatment paradigms for patients with hematologic malignancies.