Single-arm, Single-center, Exploratory Phase II Clinical Study of Envafolimab Combined With Chemoradiotherapy in the Treatment of Locally Advanced pMMR/MSS Rectal Cancer
Preoperative radiotherapy combined with 5-fluorouracil/capecitabine is currently the standard treatment for locally advanced rectal cancer. Although this strategy effectively reduces the risk of local recurrence, it fails to effectively improve the overall survival rate of patients . The root cause is that 5-fluorouracil/capecitabine based local radiotherapy is not effective in controlling potential micrometastases. Therefore, many studies try to combine preoperative radiotherapy with more intense chemotherapy and targeted drugs at the same time, as well as induction chemotherapy before preoperative radiotherapy and consolidation chemotherapy after, in order to obtain better efficacy. However, a number of studies have shown that increasing cytotoxic drugs fail to effectively improve pathologic complete response rate (pCR) and long-term survival rate, and significantly increase therapeutic toxicity . Therefore, the idea of trying to increase the efficacy of cytotoxic drugs by accumulating them does not work.Based on the use of PD-1/PD-L1 antibody in colorectal cancer and other solid tumors, and referring to the scheme of PD-1/PD-L1 antibody combined with radiotherapy in other solid tumors, we added envafolimab to local radiotherapy for advanced rectal cancer for exploration, with a view to further improving the pCR rate and long-term survival of patients.
• 1\) Disease characteristics
‣ Histologically confirmed rectal adenocarcinoma; Immunohistochemical confirmation as pMMR or/and pCR or/and NGS test as MSS;
⁃ Tumor location within 12cm from anal margin;
⁃ Locally advanced rectal cancer (stage II-III, i.e. cT3-4 and/or N+) as assessed by the UICC/AJCC TNM staging system (8th edition, 2017);
‣ \* Preoperative staging method: pelvic MRI/ transrectal ultrasound combined with preoperative staging.
⁃ No signs of intestinal obstruction; Or intestinal obstruction has been relieved after proximal colostomy surgery;
⁃ Preoperative chest, abdominal and pelvic CT to exclude distant metastasis. 2) Patient characteristics
⁃ Age: 18 \
∙ 75 years old;
⁃ Activity status score: ECOG 0-1;
⁃ Life expectancy: more than 2 years;
⁃ Hematology: WBC\>3500×106/L; PLT\>100000×106/L; Hb\>10g/dL;
⁃ Liver function: SGOT and SGPT are less than 1.5 times of normal value; Bilirubin less than 1.5mg/dL;
⁃ Kidney function: creatinine \<1.8mg/dL;
⁃ Other: non-pregnant or breastfeeding women; No other malignant disease (other than non-melanoma or carcinoma in situ of the cervix) within 5 years or during the same period; Does not have a mental illness that prevents informed consent; There were no other serious diseases associated with shorter survival.
⁃ Patients or family members can understand the study protocol and are willing to participate in the study, and sign a written informed consent;
⁃ Good patient compliance, voluntary follow-up, treatment, laboratory tests, and other research steps as scheduled.
‣ 3\) Prior treatment
⁃ No previous rectal cancer surgery;
⁃ No previous chemotherapy or radiation therapy;
⁃ No previous biotherapy;
⁃ Previous endocrine therapy: No restriction.