Phase 1 Study Progress of Ceralasertib in Combination with Durvalumab for Advanced NSCLC and HNSCC

　　1.Treatment Background and Mechanism of Action

　　For patients with recurrent or metastatic non-small cell lung cancer and head and neck squamous cell carcinoma,the efficacy of existing treatment regimens remains limited,and there is an urgent need to explore more effective novel therapeutic strategies.The combination therapy of Ceralasertib and Durvalumab provides a completely new treatment direction for these patients through the dual mechanisms of targeting the tumor cell DNA damage repair pathway and activating the body's immune system.

　　Ceralasertib is a highly selective ATR kinase inhibitor that blocks the DNA damage repair mechanism of tumor cells.When the DNA of tumor cells is damaged,ATR kinase initiates repair programs to help cells survive.By inhibiting this process,Ceralasertib prevents tumor cells from repairing damaged DNA,leading to cell death.Durvalumab is a PD-L1 monoclonal antibody that removes the inhibitory effect of tumor cells on immune cells,reactivating the body's own immune system to recognize and attack tumor cells.The combination of these two drugs produces a synergistic effect,fighting tumors more effectively than single-agent therapy.

　　2.Study Design

　　This multicenter,modular phase 1 clinical trial aimed to evaluate the safety,tolerability,pharmacokinetic profile,and preliminary antitumor activity of Ceralasertib in combination with Durvalumab in patients with advanced/metastatic non-small cell lung cancer and head and neck squamous cell carcinoma.

　　The study enrolled eligible patients with advanced solid tumors who received Ceralasertib at different doses and schedules in combination with a fixed dose of Durvalumab.The specific dosing regimens were:Ceralasertib at 80mg,160mg,or 240mg twice daily(BID),or 320mg once daily(QD),administered for either 7 days(days 22-28)or 14 days(days 15-28);combined with Durvalumab 1500mg administered intravenously on day 1 of each 28-day treatment cycle.

　　3.Efficacy Results

　　A total of 60 patients were enrolled and treated in the study,and the results showed that the combination regimen demonstrated encouraging preliminary antitumor activity.Among them,5 patients achieved an objective response,with an objective response rate of 8.3%;an additional 31 patients achieved stable disease,resulting in a disease control rate of 60%.This means that more than 60%of patients had effective control of tumor growth after receiving treatment.

　　Furthermore,clear pharmacodynamic activity was observed in 10/14 paired biopsy samples,manifested as a significant increase in pRAD50 expression levels.This change in biomarker directly demonstrates that Ceralasertib effectively inhibits the ATR kinase pathway in vivo,and the drug is indeed acting according to the expected mechanism.

　　4.Safety and Tolerability

　　Overall,the combination of Ceralasertib and Durvalumab had a manageable safety profile and was well tolerated.Treatment-related adverse events occurred in 59 patients,with an incidence rate of 98.3%;among them,31 patients experienced grade 3 or higher treatment-related adverse events,accounting for 51.7%.The most common treatment-related adverse events included anemia,thrombocytopenia,neutropenia,fatigue,and nausea,most of which were mild to moderate and could be controlled through symptomatic supportive treatment or dose adjustment.

　　Only 2 dose-limiting toxicity events were observed in the study,namely grade 3 thrombocytopenia and grade 3 febrile neutropenia.Based on the safety and efficacy data,the study determined the recommended phase 2 dose for this combination regimen as:Durvalumab 1500mg administered intravenously on day 1 of each 28-day cycle;combined with Ceralasertib 240mg twice daily,administered orally on days 15-28 of each cycle.

　　5.Conclusion and Outlook

　　The results of this phase 1 clinical trial demonstrate that Ceralasertib in combination with Durvalumab has a manageable safety profile and definite antitumor activity in patients with advanced/metastatic non-small cell lung cancer and head and neck squamous cell carcinoma.This combination regimen provides a new option for the treatment of these two types of refractory cancers and lays a solid foundation for subsequent larger-scale phase 2 and phase 3 clinical trials.

　　Although still in the early stages of clinical research,this novel immunotherapy and targeted therapy combination shows promising application prospects.With further research,it is expected to bring survival benefits to more patients with advanced cancers in the future.Relevant patients are advised to consult their specialist physicians promptly to learn about the latest clinical research progress and treatment options.