Diffuse large B-cell lymphoma successfully treated with amplified natural killer therapy alone: A case report.

BACKGROUND: The prognosis of patients with advanced diffuse large B-cell lymphoma (DLBCL) is poor, with a 5-year survival rate of approximately 50%. The mainstay of treatment is multidrug combination chemotherapy, which has been associated with serious side effects. Amplified natural killer (ANK) cell therapy amplifies and activates natural killer (NK) cells to attack only malignant tumors. As ANK cells attack programmed death ligand 1 (PD-L1)-positive tumor cells, ANK therapy is considered effective against adult T-cell lymphoma and malignant lymphoma. CASE SUMMARY: Herein, we report a case of an older patient with advanced DLBCL who was successfully treated with ANK immunotherapy. A 91-year-old female visited our hospital with sudden swelling of the right axillary lymph node in April 2022. The patient was diagnosed with stage II disease, given the absence of splenic involvement or contralateral lymphadenopathy. ANK therapy was administered. Six rounds of lymphocyte sampling were performed on July 28, 2022. To reduce the occurrence of side effects, the six samples were diluted by half to obtain 12 samples. Cultured NK cells were administered twice weekly. The treatment efficacy was evaluated by performing computed tomography and serological tests every 1 or 2 mo. The treatment suppressed lesion growth, and the antitumor effect persisted for several months. The patient experienced mild side effects. PD-L1 immunostaining was positive, indicating that the treatment was highly effective. CONCLUSION: ANK therapy can be used as a first-line treatment for malignant lymphoma; the PD-L1 positivity rate can predict treatment efficacy.

ANK Therapeutic Prospects and Usefulness of PD-L1 and NK Activity as Biomarkers for Predicting Treatment Efficacy Revealed from the Treatment Course of Patients with HTLV-1-Associated Bronchioloalveolar Disease.

Adult T-cell leukemia/lymphoma (ATL) is a peripheral T-cell neoplasm with poor prognosis that can present as HTLV-1-associated bronchioloalveolar disease (HABA). Chemotherapy is recommended for ATL; however, it is not very effective against all types of ATL. Furthermore, there are no effective treatments for smoldering HABA-associated ATL. We present a case in which amplified natural killer cell (ANK) therapy was effective in a woman in her early 80s who was previously diagnosed with ATL-related smoldering HABA and presented with dyspnea and productive cough on exertion. The symptoms were suppressed for approximately 10 months after the first treatment, but then gradually worsened. About a year later, a second treatment was followed by mild side effects. Suppression of ATL cell proliferation by repeated doses of ANK therapy appears to be effective in this patient. The therapeutic effect was high even with long treatment intervals, and the efficacy and safety of repeated treatments have been demonstrated. ANK therapy is expected to be the mainstay of treatment ATL and HABA. ANK therapy has been reported to kill PD-L1 positive tumor cells and some solid tumors with excellent responses have many PD-L1-positive tumor cells. ANK therapy is thought to be effective for ATL because there are many PD-L1-positive tumor cells. Furthermore, administration of activated NK cells may increase tumor-killing activity in those patients with reduced NK activity. While future studies are needed, PD-L1 positive rate and NK activity may be biomarkers for the effectiveness of ANK therapy.

Novel humanized anti-CD20 monoclonal antibodies with unique germline VH and VL gene recruitment and potent effector functions.

The anti-CD20 chimeric monoclonal antibody (mAb) rituximab is the most widely used therapeutic antibody for B-cell malignancies. However, approximately 50% of non-Hodgkin's lymphoma (B-NHL) patients respond to treatment with this antibody. Novel humanized antibodies target membrane CD20 with enhanced effector properties should improve treatment for a broader patient population with relapsed and refractory disease. A novel chimerized form of the murine anti-CD20 1K1791 exerts more potent antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) activities and induces cell death by a non-caspase dependent process. Humanized mAbs derived from 1K1791 were designed using four different humanization techniques and characterized. In contrast to rituximab or 2F2 (human anti-CD20 mAb), several of these exhibited superior ADCC, CDC, inhibition of cell growth and cell death. There was a wide range of functional differences among the humanized forms of 1K1791 despite a modest replacement of amino acid residues in the CDRs. To determine whether the superior activities exhibited by parental murine mAb 1K1791 were due to differences in VH and VL rearrangement, we analyzed its germline and compared it to other anti-CD20 mAbs. A remarkable conservation of VH and Vk (VL kappa) gene usage was observed in the murine anti-CD20 mAbs. 18/23 used the same germline gene J558.42 and 4/23 used closely related genes of the 'J558' group. Thus, 22/23 belonged to VH1 family. One exception was the mAb 1K1791, which was derived from the VH9.12 germline gene. 1K1791 was also unique in its use of a Vk19/28 family gene whereas most other mAbs (21/23) used Vk4/5 family genes. A formal relationship between the particular germline gene recruitment and antibody functionality has not been established, however, the present findings identified humanized mAbs with functional activities that were superior to rituximab and 2F2. These in vitro results support future in vivo animal testing and subsequent clinical trials.

Characterization of novel murine anti-CD20 monoclonal antibodies and their comparison to 2B8 and c2B8 (rituximab).

Rituximab is the first anti-cancer antibody approved by the FDA for the treatment of B-cell non-Hodgkin lymphoma (B-NHL), alone or in combination with chemotherapeutic drugs. Further, rituximab is now being examined in a variety of CD20+ neoplastic diseases as well as B-cell-induced autoimmune diseases. The clinical response to rituximab is significant, resulting not only in tumor regression but also prolongation of survival. However, a subset of patients does not initially respond to rituximab or develops resistance to its further treatment. Therefore, alternative therapies for these patients are strongly desired. Rituximab activity has been thought to be by antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity and apoptosis, and studies in model systems established the role of rituximab in cell signaling-induced perturbation of anti-apoptotic survival pathways, suggesting that the patients unresponsive to rituximab may be overcome with other CD20 antibodies with different activities. This study investigated eight novel murine antibodies directed against CD20 for their physical and biological properties in comparison with 2B8 and c2B8 (rituximab). These antibodies were derived by various antigenic and immunization procedures and selected for CD20 activity. Analysis of these antibodies revealed that they all bound to various B-cell lines and CD20-transfected CHO cells. Six of the eight antibodies shared similar variable-region amino acid sequences that were also shared by 2B8 while two monoclonal antibodies did not. Of them, 1K1791 has a distinct heavy chain and both 1K1791 and 1K1782 have distinct light chains. Not all of the antibodies inhibited cell growth and only two antibodies reacted with fixed GST-CD20 recombinant fusion protein. Noteworthy, 1K1791 was found to inhibit cell proliferation and also induced caspase-independent apoptosis in the absence of cross-linker. These findings identified new antibodies with properties and epitope specificities different from 2B8. The potential clinical application of such antibodies in the treatment of B-NHL and rituximab-resistant B-NHL is discussed.