Background Targeted T-cell-based immunotherapies, including CAR-T, have significantly advanced the treatment of relapsed or refractory B cell non-hodgkin lymphoma (R/R B-NHL). However, there is still an urgent need for novel therapeutic options. NK cell engager molecules have shown efficacy in acute myeloid lymphoma (IPH6101/SAR’579, NCT05086315). IPH6501, a tetraspecific antibody-based NK cell engager utilizing the ANKET® platform, is developed for B-NHL therapy. IPH6501 activates NK cells by engaging the activating receptors CD16, and NKp46, and together with a non-alpha IL-2 (IL2v) moiety selectively induces their proliferation. It targets CD20 on B-NHL cells, effectively inducing NK cell-mediated cytotoxicity.

Methods Anti-tumor activity, NK cell proliferation and accumulation at the tumor site were evaluated in mouse models. PBMCs from R/R B-NHL patients after at least one line of treatment, including rituximab, or post CAR-T cell therapy were analysed using flow cytometry. Furthermore, cytotoxic assays were performed to evaluate the ability of IPH6501 to stimulate patient cells to kill CD20+ tumor targets.

Results In vivo preclinical models show that an IPH6501 mouse surrogate enhances NK cell activation, proliferation, and cytotoxicity against CD20+ target cells. This molecule also promotes the accumulation of peripheral NK cells at the tumor site, indicating it may stimulate blood NK cell recruitment to tumors. In vitro, cytotoxicity assays reveal that IPH6501 stimulates PBMCs from post rituximab R/R B-NHL patients to kill a CD20+ lymphoma cell line. IPH6501 activity is observed with PBMCs from several B-NHL subtypes, including R/R DLBCL, and its effectiveness is dependent on the NK cell proportion in samples. IPH6501 targets (NKp46, CD16, and IL-2R) are expressed on blood NK cells from patients across R/R B-NHL subtypes. However, in tumor-involved lymph nodes, while NK cells consistently express NKp46, their CD16 expression is downregulated compared to blood. In addition, PBMCs from patients post-CAR-T cell therapy also express IPH6501 targets on NK cells and show effective IPH6501-induced killing of CD20+ B-NHL target cells.

Conclusions Preclinical studies using ex vivo samples from R/R B-NHL patients provide supporting evidence for exploring IPH6501 across B-NHL subtypes, in patients previously treated by rituximab or CAR-T cell therapy. By engaging NKp46, IPH6501 can effectively harness peripheral, but also tumor-infiltrated lymph nodes NK cells, highlighting its potential to eliminate tumors cells at the tumor site. IPH6501 is therefore a promising new candidate for treating R/R B-NHL. IPH6501 is under investigation in a global first-in-human Phase 1/2 study (NCT06088654).

Ethics Approval The animal studies obtained approval from the French ministery of superior training and research (MESR) ethics committee under approval # 47221-2024020216244671 v3 and 19272-2019021911102569 v5. The study was conducted in accordance with the Helsinki Declaration and performed with written informed patient consent. Cell collection were obtained through the CeVi_Collection Project from the CALYM Carnot Institute funded by the French National Research Council (ANR). Additional amples were collected and stored within the biobank of the CRB SUD, CRB HCL (BB-0033-00046), the CRB-Santé Rennes (BB-0033-00056), the CRB Cancer IUCTO (BB-0033-00014), the CRB CHU de Montpellier (BB-0033-00031) and CRB Gustave Roussy (2022- A00472-41) which has been declared to the Ministry of Higher Education and Research after receiving approval from the ethical committee.