For Health Care Professionals

Red Cell Therapeutics™:
A New Era of Medicine for the Treatment of Cancer

Our innovations in creating human red blood cells and genetic engineering have made it possible to explore using these cells as a foundation for an entirely new class of cellular therapies, which we call Red Cell Therapeutics™. Red Cell Therapeutics product candidates are manufactured from CD34+ hematopoietic progenitor cells from blood type O, Rh-negative, Kell-negative donors. The cells are expanded and transduced with a lentiviral vector to insert a gene or genes of interest, followed by further expansion and differentiation into enucleated red blood cells that express one or more therapeutic proteins inside or on the cell surface, resulting in cellular therapies for the potential treatment of cancer.

About RTX‑321

RTX-321 is an investigational cellular therapy that is being evaluated in a Phase 1 clinical trial for the treatment of patients with human leukocyte antigen (HLA) A*02:01 positive cancers associated with HPV 16, including cervical cancer, anal cancer, and head and neck squamous cell carcinoma.

RTX-321 is engineered to potentially induce a tumor-specific immune response by expanding antigen-specific T cells. RTX-321 expresses an HPV peptide antigen bound to MHC Class I proteins, 4-1BBL – a co-stimulatory signal – and IL-12 – a cytokine – on the cell surface intended to mimic human T cell-antigen-presenting cell interactions.

In preclinical studies, RTX-321 was shown to boost HPV 16 E7-specific CD8+ T cell responses and promote HPV 16-independent stimulation of innate (NK cells) and adaptive immune (non-HPV antigen-specific CD8+ T cells) responses. This dual mechanism of action is a key part of the development of epitope spreading, meaning that RTX-321 may induce the expansion of an immune response to secondary epitopes that are not expressed on RTX-321, and potentially the development of a potent memory response.

The IND for RTX-321 has been cleared by the FDA and we are now enrolling patients into our ongoing Phase 1 clinical trial.

About the RTX-321 Phase 1 Clinical Trial

This is a Phase 1, open label, multicenter, multidose, first-in-human (FIH) dose escalation and expansion study to determine the safety and tolerability, recommended phase 2 dose, pharmacodynamics, and preliminary antitumor activity of RTX-321 in adult patients with persistent, recurrent, or metastatic, unresectable cervical cancer (squamous cell carcinoma, adenocarcinoma, or adenocarcinoma and squamous cell carcinoma), HNSCC, or squamous cell cancer of the anal canal that is not amenable to curative therapy.

Prior to study screening, all patients must be confirmed to be HLA-A*02:01 positive. Documentation of an HPV 16-positive tumor is required at prescreening for patients with cervical cancer and HNSCC. Patients with anal cancer do not need to demonstrate HPV 16 status prior to enrollment in the study. The study will include a monotherapy dose escalation phase followed by an expansion phase.

Inclusion/Exclusion Criteria

Adults who meet the following criteria may be able to participate in the trial.

  • Men and women aged 18 or older.
  • Participants must be HLA-A*02:01 positive and have persistent, recurrent, or metastatic, unresectable cervical cancer (squamous, adeno, or adenosquamous histology), HNSCC, or squamous cell cancer of the anal canal that is not amenable to curative therapy.
  • Participants must have confirmed HPV 16-positive status (either with a test or medical history, using an FDA approved test in cervical cancer patients only); patients with anal cancer will not be required to have prospective determination of HPV 16-positive status prior to enrollment.
  • All participants must have experienced disease progression following platinum-based or mitomycin C-based chemotherapy administered in the persistent, recurrent, or metastatic setting.
  • All patients with programmed death-ligand 1 (PD-L1) positive cervical cancer and those with HNSCC must have received or have been determined to be ineligible for immunotherapy with a PD-1 or PD-L1 inhibitor.
  • Participants must have completed prior therapy, including radiation, at least 28 days prior to study treatment.
  • For females of reproductive potential, agreement to use highly effective contraceptive throughout and for six months following last dose study treatment.

If you are interested in becoming a potential clinical trial site or would like more information about RTX‑321, please contact us at