A phase 1 study of RTX-321, an engineered red blood cell as an artificial antigen-presenting cell expressing HLA-A*02 with the HPV-16 E7 peptide and 4-1BB ligand with membrane-bound IL-12 for the treatment of HPV 16-positive cancers.

Abstract

TPS2664 Background: High-risk strains of HPV (HPV 16/18) have been associated with the development of multiple cancers, and the associated viral antigens are validated targets from immunotherapy approaches. We engineered red blood cells into allogeneic, off-the-shelf, artificial antigen-presenting cells (aAPCs) that express a human papillomavirus (HPV) 16 E7 peptide bound to human leukocyte antigen (HLA)-A*02:01, the costimulatory molecule 4-1BB ligand (L), and the cytokine interleukin (IL)-12 on the cell surface. This aAPC, RTX-321, activated HPV specific T-cells and promoted effector function in vitro. In animal models using a murine surrogate system, this aAPC approach resulted in robust antigen-specific T-cell expansion, NK cell expansion, tumor control, memory formation and antigen spreading, which led to a broad and robust antitumor immune response . The presence of 4-1BBL and IL-12 induced minimal toxicities in these models due to restriction of the biodistribution of the aAPC to the vasculature and spleen. RTX-321 is a potential in vivo cellular immunotherapy for treating HPV 16-positive cancers including cervical, head and neck and anal cancers. Methods: The RTX-321-01 study is a phase 1 multi-center, dose-escalation study of RTX-321 administered intravenously every 3 weeks in HLA-A*02:01-positive patients with relapsed or refractory HPV 16-positive cancers of the cervix or anal canal, or squamous cell cancers of the head and neck (HNSCC). Patients with cervical cancer or HNSCC will undergo testing for the presence of the HPV 16 virus or provide confirmation from archival tumor tissue prior to enrollment. Patients with anal cancer will not be required to have prospective determination of HPV 16-positive status prior to enrollment given the high incidence in this indication (approximately 80-85 percent of anal cancers). Approximately 18 patients will be enrolled across dose level cohorts to identify the recommended phase 2 dose (RP2D) of RTX-321, followed by RP2D expansion cohorts in specific indications. The starting dose is 1 billion (1x109) cells administered intravenously every 3 weeks (Q3W) and the dose will escalate by half-log increments, following a Bayesian logarithmic regression model (BLRM) with overdose control. Translational studies will investigate the activation and expansion of HPV16 E7 antigen-specific responses as well as broad innate and adaptive responses in multiple peripheral blood samples over the first 3 cycles of therapy as well as in optional paired tumor biopsies. At this time, the study is open and enrolling patients in the first dose escalation cohort (NCT04672980). Clinical trial information: NCT04672980.

Human Papillomavirus–Directed Therapeutics for Human Papillomavirus–Associated Oropharyngeal Cancer

“…This allogeneic therapy provides multiple signals to stimulate and activate T cells, including the E7-bound peptide-HLA*A02 complex, a costimulatory molecule, 4-1BBL, and IL-12. 44 Squeeze Bio (Watertown, MA) is developing an autologous approach with a similar theme. A patient's RBCs are exposed to HPV peptides or proteins under specific microfluidic conditions creating an "activating antigen carrier."…”

“…The genetically engineered RBCs express the transgenes after enucleation, even though the genetic modifications are no longer present in the final cell product. This allogeneic therapy provides multiple signals to stimulate and activate T cells, including the E7-bound peptide–HLA*A02 complex, a costimulatory molecule, 4-1BBL, and IL-12 44 . Squeeze Bio (Watertown, MA) is developing an autologous approach with a similar theme.…”