On November 9, 2021 I-Mab (Nasdaq: IMAB), a clinical-stage biopharmaceutical company committed to the discovery, development, and commercialization of novel biologics, and ABL Bio, Inc. (Kosdaq:298380, hereafter "ABL"), a clinical-stage biotech developing bispecific antibody technology for immune-oncology and neurodegenerative diseases, reported preclinical data of their 4-1BB bispecific antibodies at the 2021 Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) Annual Meeting (Press release, I-Mab Biopharma, NOV 9, 2021, View Source [SID1234594924]). The new data demonstrate the unique mechanisms of action of TJ-CD4B/ABL111 and TJ-L14B/ABL503 which have resulted in localized drug action and reduced systemic toxicity, as well as sustained anti-tumor efficacy.

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Stimulation of 4-1BB is a promising therapeutic strategy for improving the current immunotherapy for multiple cancers. TJ-CD4B/ABL111 and TJ-L14B/ABL503, both jointly developed by I-Mab and ABL, are undergoing phase 1 clinical studies in the United States.

"Bispecific antibodies are rapidly recognized for their transformative potential, and our pipeline of highly-differentiated 4-1BB bispecific therapies are key components of our biologics pipeline development strategy," said Dr. Taylor Guo, Chief Scientific Officer of I-Mab. "Dose-limiting toxicities have hampered clinical development of 4-1BB targeting molecules as a drug class. The studies being presented at SITC (Free SITC Whitepaper) suggested that both our bispecific assets could have the ability to overcome this common problem, and we are confident that this differentiation places TJ-CD4B/ABL111 and TJ-L14B/ABL503 at the forefront of 4-1BB bispecific development."

"The preclinical data from this pair of bispecific molecules prove that our ‘Grabody-T’ platform effectively reduces peripheral toxicity by allowing the activation of T cells only in the tumor microenvironment," said Dr. Sang Hoon Lee, CEO of ABL Bio. "We look forward to further validating its therapeutic potential in the ongoing clinical studies and as we continue to develop 4-1BB bispecific antibodies in various cancer indications."

Key data highlights:

TJ-CD4B/ABL111

Poster title (#702): TJ-CD4B (ABL111), a Claudin18.2-targeted 4-1BB tumor engager induces potent tumor-dependent immune response without dose-limiting toxicity in preclinical studies

The preclinical studies confirmed the unique pharmacodynamic data and safety of TJ-CD4B/ABL111 in animal models and cell cultures. Analysis of the data found:

Potent, anti-tumor activity was observed with the proliferation of immune cells in the tumor microenvironment (TME) as well as an increase in memory T cells in the peripheral blood, suggesting long-term immunity against the tumor.
TJ-CD4B/ABL111 was well tolerated in non-human primates and did not induce a systemic immune response or liver toxicity up to levels of 100mg/kg.
Activation of immune pathways by TJ-CD4B/ABL111 was demonstrated by a pro-inflammatory profile and increased gamma interferon-regulated gene expression in primary human CD8+ T cells co-cultured with CLDN18.2 expressing cells.
TJ-L14B/ABL503

Poster title (#892): ABL503 (TJ-L14B), PD-L1x4-1BB bispecific antibody induces superior anti-tumor activity by PD-L1-dependent 4-1BB activation with the increase of 4-1BB+CD8+ T cells in tumor microenvironment

The preclinical study data confirms the unique mechanism of action of TJ-L14B/ABL503 and its potential to treat resistance to PD-L1 therapies. Analysis of the data found:

PD-L1-dependent stimulation of the 4-1BB signaling pathway was demonstrated in 4-1BB bioassays with PD-L1 expressing tumor cells
More potent 4-1BB activation by TJ-L14B/ABL503 was observed at higher PD-L1 expression confirming the requirement of PD-L1 on both tumor and immune cells for optimal activity. Cytokine release assays have also demonstrated minimal peripheral toxicity with TJ-L14B/ABL503
The in vivo efficacy of TJ-L14B/ABL503 was demonstrated in animal models with tumors expressing different levels of PD-L1. TJ-L14B/ABL503 showed anti-tumor efficacy across the PD-L1 levels. In particular, TJ-L14B/ABL503 demonstrated superior anti-tumor efficacy than atezolizumab in tumors with low PD-L1 expression
In vitro tumor-killing activity of TJ-L14B/ABL503 was superior compared to atezolizumab when tested in organoid system, even in organoids from atezolizumab non-responders
Pharmacodynamic changes in TILs and blood were evaluated in animal models. An increase in 4-1BB+ cells, CD8+ T cells, and effector memory T cells was observed in the TME and blood, indicating a strong and long-lasting anti-tumor immune response
Treatment with TJ-L14B/ABL503 increased MIG/CXCL9, MIP-1b/CCL4, and s4-1BB in the serum, and can potentially be used as pharmacodynamic markers in clinical trials
About TJ-CD4B/ABL111

TJ-CD4B, also known as ABL111, is a Claudin 18.2 and 4-1BB bispecific antibody capable of binding to tumor cells expressing Claudin 18.2, i.e., gastric cancer and pancreatic cancer cells, and stimulating intra-tumoral T cells by the 4-1BB arm designed to be activated only upon tumor engagement while silent elsewhere. TJ-CD4B/ABL111 effectively maintains a strong tumor binding property and anti-tumor activity attributable to a synergistic effect of both Claudin 18.2 antibody and 4-1BB antibody while it avoids or minimizes liver toxicity and systemic immunotoxicity commonly seen with 4-1BB antibodies as a drug class. Being developed under collaboration between I-Mab and ABL, TJ-CD4B/ABL111 is currently being investigated in a phase 1 clinical study in the U.S.

About TJ-L14B/ABL503

Being developed jointly with ABL, TJ-L14B/ABL503 is a differentiated PD-L1-based bispecific antibody with the PD-L1 arm as the tumor-dependent T-cell activator and the 4-1BB arm as the conditional T cell activator upon tumor engagement. Using ABL’s "Grabody-T" bispecific antibody platform technology, TJ-L14B/ABL503 stimulates 4-1BB activation only in the presence of PD-L1 expressing tumor cells to minimize the risk of off-tumor toxicity. Preclinical studies have demonstrated that the bispecific antibody shows better anti-tumor activity than equimolar doses of single agents alone or in combination. Phase 1 study in currently being conducted in the U.S.