Immunosynthen ADC Platform & Pipeline

Immunosynthen, Mersana’s proprietary STING agonist platform, generates systemically administered ADCs that locally activate STING signaling in both ​tumor-resident immune cells and in antigen expressing cells, unlocking the anti-tumor potential of innate immune stimulation.​ Through the delivery of a novel immunomodulatory STING agonist, ADCs created with our Immunosynthen platform have the potential to address the challenges of efficacy, delivery and tolerability.

Stimulator of Interferon Genes (STING) is a well-studied innate immune pathway capable of inducing anti-tumor immune activity. Our preclinical data show that the anti-tumor activity of Immunosynthen ADCs involves the targeted activation of the STING pathway in both tumor-resident immune cells and in tumor cells, in an antigen binding-dependent manner. This “one-two punch” provides the potential for enhanced anti-tumor activity when compared to other innate immune approaches that activate only the immune cells. Further, we have generated preclinical data across multiple targets and tumor models showing complete regression of tumors in vivo after a single low, well-tolerated dose, consistent with increased cytokine expression and immune cell infiltration within the tumor and immune memory. In addition, we have demonstrated the tolerability and favorable pharmacokinetic profile of Immunosynthen ADCs in non-human primates, after multiple IV doses and at exposures significantly higher than those required for robust efficacy in mice.

To learn more, see our Immunosynthen STING-Agonist ADC Platform and Pipeline webinar

We are building a deep pipeline of Immunosynthen ADCs for a broad range of clinical indications and potential partnerships. Our lead Immunosynthen ADC development candidate, XMT-2056, is expected to enter a Phase 1 dose escalation clinical trial in the second half of 2022.

Immunosynthen Advantages

ADCs are ideally suited to overcome the limitations of free STING agonists and offer a highly differentiated approach from other innate immune activators

  • Systemic Administration with Targeted Delivery: ADCs have the convenience of systemic administration while providing targeted delivery specifically to the tumor, including metastatic lesions.
  • Improved Therapeutic Index: Conjugation of the STING agonist provides protection in the systemic circulation to minimize off-target effects.
  • Enhanced Pharmacokinetic (PK) Properties: The prolonged PK of ADCs and active uptake through internalization can overcome PK and permeability issues of the free agonists, resulting in sustained activation of the innate immune response.
  • Immunosynthen STING ADCs Deliver a One-Two Knockout Punch: Target-dependent delivery to both tumor cells and tumor-resident immune cells results in innate immune activation of both cell types and potent and robust antitumor responses and immune memory.