Monalizumab and MEDI5752 in Patients With MSI and/or dMMR Metastatic Cancer

Plain-language summary

MSI is a molecular indicator of defective DNA mismatch repair (dMMR). The MSI/dMMR status is observed in all tumor types, representing notably 5% of metastatic colorectal cancers (mCRC), 25% of advanced endometrial cancer and 8% of metastatic gastric cancer. MSI/dMMR cancers are highly immunogenic. MSI/dMMR tumors are characterized by a high tumor mutational burden with highly immunogenic neoantigens. These tumors are associated with an upregulation of immune checkpoints (PD1, PDL1, CTLA4, etc.) that protects MSI cancer cells from their hostile immune micro-environment, characterized by a high infiltration of activated cytotoxic T CD8+ and NK lymphocytes. Consequently, MSI/dMMR cancers are highly sensitive to ICIs, whatever the tumor location. MSI/dMMR status is a predictive biomarker for the efficacy of immunotherapy, regardless of the tumor type. Then, by several phase II and III studies The efficacy of immunotherapy has been demonstrated as front-line treatment for patients with chemotherapy-naive MSI/dMMR mCRC and gastric cancer. The phase III KEYNOTE-177 trial evaluating first-line treatment of pembrolizumab in patients with MSI/dMMR mCRC demonstrated its superiority over first-line chemotherapy, with a significant improvement of health-related quality of life. At final analysis, the median follow-up was 44.5 months. Median PFS was 16.5 versus 8.2 months (HR = 0.59; 95%CI 0.45-0.79). The hazard ratio favored pembrolizumab versus chemotherapy with a trend toward reduction in the risk of death (HR 0.74; 95% CI, 0.53-1.03; P=0.0359), despite a 60% effective crossover rate. Pembrolizumab has been approved by the FDA and the EMA for patients with newly diagnosed MSI/dMMR mCRC and is now the standard of care for this population. Also, the phase III CHECKMATE-649 trial reveal that the Combination of immunotherapy and cytotoxic chemotherapy is the new standard of care for patients with newly diagnosed metastatic oesogastric cancer. Importantly, results of the CHECKMATE-649 are outstanding for the subgroup population of MSI/dMMR gastric cancer patients (N = 44). Indeed, the unstratified hazard ratio for OS with nivolumab plus chemotherapy versus chemotherapy alone was 0.33 (95% CI 0.12-0.87) for patients with MSI/dMMR tumors. All in all, ICIs are the standard of care in first-line setting for patients with mCRC or metastatic oesogastric cancer. Besides, several phase II studies suggest that ICI combinations might overcome primary resistance to anti-PD1 monotherapy These data justify the development of bispecific monoclonal antibodies targeting both PD1 and CTLA4 such as MEDI5752. MEDI5752 has been developed based on the observation that there is a higher expression of PD-1/CTLA-4 on tumor resident versus peripheral T cells. Preclinical data show MEDI5752 fully suppresses PD-1 and preferentially inhibits CTLA-4 in the tumor versus the periphery, which is meant to uncouple CTLA-4 dependant peripheral toxicity from antitumor activity Natural killer cells are integral to the functioning of the innate immune system and play an important role in innate antitumor immunity. There is a growing body of evidence for targeting the NKG2A/HLA-E axis in combination with other ICIs to sensitize tumors to ICI therapy. NKG2A recognizes the non-classical HLA class I molecule HLA-E. The NKG2A receptor is found on peripheral NK cells and subsets of T cells in cancer patients. It is also present in tumor-infiltrating NK and cytotoxic T cells. Importantly, NK cells and the NKG2A/HLA-E axis play a crucial role in MSI/dMMR tumors. Therefore, a combined blockade of non-redundant checkpoint pathways to unleash NK and T cells seems particularly promising for MSI/dMMR neoplasms. Monalizumab specifically binds and blocks the inhibitory receptor NKG2A. Monalizumab has been investigated in combination with ibrutinib (in chronic lymphoid leukemia), cetuximab +/- durvalumab (in squamous cell carcinoma of the head and neck, and in solid tumors), durvalumab +/- FOLFOX (in solid tumors). In the first-in-human dose escalation of monalizumab plus durvalumab, a manageable toxicity profile was shown. Taken together, these data provide a strong rational to combine an inhibitor of the NKG2A/HLA-E axis with a bispecific monoclonal antibody targeting both PD1 and CTLA4 for patients with metastatic MSI/dMMR cancers.

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