The Challenge:

Recent advancements in immuno-oncology and CAR-T cell therapies have led to significant changes in the standard of care of patients with cancer but these benefits remain accessible to only a fraction of individuals. Current cellular therapies, proven effective in B cell malignancies, exhibit only modest gains against solid tumors, and many carry the risk of severe adverse effects that handicap the ability sustain a response or engender combination strategies.

Mongoose Bio is advancing a therapeutic approach that will fulfill the promise of T cell therapy for patients with solid tumors by addressing two of the major challenges limiting the efficacy and broader applicability of conventional T cell therapy:

1. A limited portfolio of immunogenic antigens for targeting the vast majority of cancers, and;
2. Limited persistence of transferred T cells to sustain a clinical response and provide long term immunoprotection.

The Solution:

Mongoose Bio addresses both major challenges by advancing an approach based on TCRs directed against important immunogenic pan-cancer antigens and a memory programming module that will confer in vivo longevity to transferred T cells.

1. Novel targets for TCR-based cell therapy:

TCR-T therapies utilize the T cell receptor (TCR) to engage tumor targets. Because TCRs recognize surface MHC presented fragments of protein (peptides) that can originate from any cellular compartment, TCR targets can be a transcription factor, oncogene, cancer-testis antigen, DNA repair gene, chemoresistance gene or any of the thousands of tumor-associated proteins found in solid tumors. Mongoose Bio has interrogated its database of peptide target spectra and we have selected the highest-ranking antigens for our drug development portfolio.

The Tumor Immunopeptidome Discovery Platform

2. T Cell Persistence:

The second major challenge to effective T cell therapy has always been the limited persistence in vivo of the adoptively transferred T cells, leading to relapse rates as high as 60% despite patients achieving complete remission following CAR-T cell therapy. In large part, this is attributable to the absence of “T cell memory” in the transferred cells – a feature absent from almost every cell therapy modality to date.

Clinical Evidence shows Epigenetic Tcm Reprogramming​ Prevents Recurrence of High-risk AML

Patients receiving Teff CTL for high-risk AML relapse when WT1-CTL do not persist​

Patients receiving WT-1 specific Tcm CTL remain in CR; WT1-specific CTL persist​

Epigenetic Reprogramming leads to Persistence​ of T cells and Clinical Benefit​​

Patient failing anti CTLA4 monotherapy, Rx with MART-1 specific Tcm + ICI complete → response of intrathoracic metastases​​

MART-1 specific Tcm persist long term (> 40 weeks)​


  1. Highly Immunogenic Tumor Selective Native T Cell Receptor Targets
    • Immunopeptidome Discovery Platform identifies and characterizes bona fide MHC-presented tumor derived peptides
      • 250 high value TCR target antigens have been empirically validated with an ex vivo workflow
      • 4 top scoring targets that cover > 80% of Class I MHC (HLA) already selected for the pipeline
  2. Native TCR Isolation Precludes Synthetic TCR Binding Optimization or Inappropriate CD28- / 41BB Signaling
    • High affinity MHC-restricted target specific patient derived CTL’s identified
    • Bespoke TCRa & TCRβ chains sequenced and expressed in a characterized retroviral vector
  3. Clinically Proven Epigenetic Central Memory T Cell Reprogramming
    • IL-21 and HDACi based protocols drive T cells into central memory state
    • Patients receiving target specific Tcm demonstrate complete and durable responses in clinical trials
  4. Autologous CTL-T Therapy Does Not Require Aggressive Lymphodepletion
    • Several first-in-human clinical studies demonstrate long-term in vivo persistence of transferred central memory CD8+ T cells without any requirement for high dose lymphodepletion
    • Favors therapy shaping by combinations with immuno-modulators (ex. anti-CTLA4, anti-PD1/PD-L1)

Lead asset: MGB-001

Our MGB-001 TCR-T is a high-affinity T cell receptor engineered T cell. It was sourced from T cells created using a highly immunogenic HLA-A2-restricted epitope identified by a proprietary mass spectrophotometry (MS)-based immunopeptidome discovery platform (IDP). Unlike other TCRs on the market, ID/validation of this TCR epitope was rigorously selected from among an unbiased pool of 1000s of well-curated MHC-eluted peptides, empirically validated, and clinically annotated to target pan-cancers. Our product is highly immunogenic, targets a protein broadly expressed by many solid tumors, and addresses HLA subtypes representing at least 60% of the global patient population in common cancers. Importantly, there is no off-target activity due to high specificity for the expected target tumor cells – expression of our target (MGB-001) is not seen in normal cells (germinal tissues only).

Lead Asset: MGB-001

  • A classic cancer-testis antigen
  • Expressed in over 60% of breast cancers
  • Expressed in approximately 45% of prostate, lung, bladder, gastric, ovarian, head/neck cancers
  • Presented by both HLA-A2 and A3/A11 subtypes representing >60% of all Western & Asian cancer patients
  • No previously known TCR targets
  • Highly tumor selective and tumorigenic
  • Associated with epithelial mesenchymal transformation (EMT) and DNA repair following radiation and chemotherapy
  • Expressed at high levels across multiple common and rare cancers


The company’s proprietary Immunopeptidome Discovery Platform (IDP) uniquely uses mass spectrometry to identify immunogenic autochthonous T cell target antigens and has already produced > 2 million spectra from common and rare tumors and the validation of 250 high value TCR target antigens. Of these, four targets covering > 80% of Class I MHC (HLA) have been selected as the first development candidates and are moving through development, with the lead now poised to enter the clinic.
Antigen HLA Epitopes Defined Common Cancers Rare Cancers T Cell Lines TCR-T Viral Vector
MGB-001 HLA-A2
HNSCC, Cervical, Bladder
YES YES (pre-clinical)
MGB-002 HLA-A2
Prostate, TNBC, Lung, Colorectal Chordoma YES YES (pre-clinical)
MGB-003 HLA-A2
Breast Cancer YES YES (pre-clinical)
MGB-004 HLA-A2 AML, Bladder Cancer
Breast, Cervical, Esophageal, Lymphoma, Sarcoma
Anaplastic Thyroid
YES YES (pre-clinical)