Biopharma
Simris Biologics is advancing a pipeline of proprietary ADC payloads, initially focused on modified Microcystins – potent, naturally occurring peptides re-engineered for tumour selectivity and minimal off-target toxicity.
Our patented platform enables structural modification of cyanobacterial toxins as they are produced, generating variants optimised for safety and efficacy. These compounds demonstrate strong therapeutic potential in preclinical models.
What is an ADC?
An antibody-drug conjugate (ADC) is a type of cancer therapy that combines the targeting ability of monoclonal antibodies (mAbs) with the cancer-killing properties of chemotherapy drugs. The ADC is designed to target cancer cells specifically, leaving healthy cells unaffected, which can lead to fewer side effects than traditional chemotherapy.The ADC consists of three components: the monoclonal antibody, a linker, and a cytotoxic agent (chemotherapy drug). The monoclonal antibody is engineered to recognize and bind to a specific protein on the surface of cancer cells, called an antigen. The linker connects the monoclonal antibody to the cytotoxic agent, which is then delivered directly to the cancer cell.
Once the ADC binds to the cancer cell, the linker is broken down, releasing the cytotoxic agent directly into the cancer cell. The cytotoxic agent then kills the cancer cell by disrupting its DNA or cell division, preventing it from growing and dividing further.
The advantage of ADCs over traditional chemotherapy is that they can target cancer cells specifically, reducing the risk of damaging healthy cells and minimizing side effects. Additionally, because ADCs are highly specific, they may be more effective than chemotherapy at killing cancer cells.
ADCs have shown great promise in treating various types of cancer, including breast cancer, lymphoma, and leukemia, and are currently being investigated as potential treatments for many other types of cancer.
Mechanism of Action
Microcystins inhibit key protein phosphatases (PP1 and PP2A), disrupting critical cellular signalling pathways and triggering rapid cell death. Our engineered variants remain inactive in circulation, becoming selectively cytotoxic only when internalised by cancer cells via ADC delivery, thereby sparing healthy cells.
Therapeutic Advantage
Our lead Microcystin-containing ADC has demonstrated competitive in vitro efficacy compared to a commercially approved HER2-targeted ADC. Dimeric toxin variants currently in development have shown a tenfold increase in protein phosphatase inhibition.
Native Microcystins are unsuitable as therapeutics due to their uptake by hepatocytes via OATPs, leading to liver-specific toxicity. Through targeted structural modifications, we have significantly reduced this uptake, improving safety and enabling a more favourable therapeutic index.
An IND submission for our lead Microcystin ADC is planned for 2027, supported by a comprehensive preclinical data package.
Conjugation Chemistry
We are employing click chemistry to enable precise, efficient conjugation of our payloads to linker components. Internal linker-payload synthesis capabilities accelerate our development timelines and allow rapid iteration.
More Novel ADC Payload Classes to Explore
Beyond Microcystins, we have identified 15 additional non-ribosomal peptide toxin classes (e.g., cryptophycins, apratoxins, largazoles, aurilides) as candidates for ADC development.
Our natural compound library includes over 300 cytotoxic hits with tissue-specific activity, representing a rich pipeline of future opportunities.