Efﬁcacy and Safety of Combining Short-Course Neoadjuvant Chemoradiotherapy with Envafolimab in Locally Advanced Rectal Cancer Patients with Microsatellite Stability - a Phase II PRECAM Experimental Study

Sep 23, 2026

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Conventional neoadjuvant chemoradiotherapy for locally advanced rectal cancer achieves a pathologic complete response (pCR) rate of 15–30%. The phase II PRECAM study prospectively evaluates a paradigm shift by adding Envafolimab, a PD-L1 antibody, to short-course nCRT in microsatellite-stable (MSS) tumors. In 34 enrolled patients, 32 completed the protocol. Preoperative chemoradiotherapy plus Envafolimab produced a 62.5% pCR rate and 75% pathologic response rate. Adverse events were manageable; two Grade 3 events occurred, and follow-up reported no recurrence or death at 12–20 months.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages12

Reading Time30 min

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Introduction

Materials and methods

Results

Conclusion

Keywords

’Experimental Research Efﬁcacy and safety of combining short-course neoadjuvant chemoradiotherapy with envafolimabin locally advanced rectal cancer patients with microsatellite stability: a phase II PRECAM experimental study Fei Wang, MDa,b , Chuanxi Lai, MDa,b , Yiming Lv, MDa,b , Feixiang Zhang, MDa,b , Liming Shi, MDc , Yunfei Wang, MDd , Yanbin Shen, MDa,b , Lingna Xu, MDa,b , Peng Hu, MDe , Wen Tang, MDf, Dengyong Xu, MDa,b , Gaoyang Cao, MDa,b , Lina Shan, MDa,b , Xiya Jia, MDa,b , Yiyi Chen, MDa,b , David W. Larson, MDh , Da Wang, MDa,b , Weifeng Lao, MDa,b , Hongcang Gu, PhDg,*, Xiaonan Sun, MDc,*, Xuefeng Huang, MDa,b,*, Sheng Dai, MD, PhDa,b,* Background: Conventional neoadjuvant chemoradiotherapy (nCRT) yields a pathologic complete response (pCR) rate of 15–30% for locally advanced rectal cancer (LARC) . This study ventures to shift this paradigm by incorporating short-course nCRT with immunotherapy, speciﬁcally Envafolimab, to achieve improved treatment efﬁcacy and possibly redeﬁne the standard of care for LARC. Materials and methods: The PRECAM study is a prospective, single-arm, phase 2 clinical trial for LARC in patients with microsatellite stable (MSS) tumors. Participants received short-course radiotherapy (25Gy/5f), followed by two cycles of CAPEOX chemotherapy and six weekly doses of Envafolimab, a PD-L1 antibody, before total mesorectal excision surgery. The primary endpoint was the pCR rate. Results: From April to December 2022, 34 patients were enrolled, of whom 32 completed the study, each diagnosed with an MSS rectal adenocarcinoma. All patients underwent preoperative CRT combined with Envafolimab. Remarkably, a pCR rate of 62 .5%(20/ 32) was attained, and a signiﬁcant pathologic response rate of 75%(24/32) was achieved. Additionally, 21 of 32 participants achieved a neoadjuvant rectal (NAR) score below 8, suggesting an effective treatment response. Common adverse events included tenesmus (78 . 1%), diarrhea (62 .5%), and leukocyte decrease (40 .6%) . Two Grade 3 adverse events were noted, one related to liver function abnormality and the other to a decrease in platelet count. Surgical procedures were performed in all cases, with minor complications, including ileus, infections, and anastomotic leakage. As of this report, there have been no reported cases of recurrence or death during the follow-up period, ranging from 12 to 20 months. Conclusion: In LARC patients exhibiting MSS tumors, combining short-course nCRT with Envafolimab demonstrated favorable efﬁcacy, leading to a signiﬁcant pCR rate. Minor adverse effects and surgical complications were observed. These preliminary but promising results underscore the potential of this approach and call for further exploration and validation through a randomized controlled trial. aDepartment of Colorectal Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, bKey Laboratory of Biotherapy of Zhejiang Province, cDepartment of Radiation Oncology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, dHangzhou Shengting Medical Technology Co., Ltd, eDepartment of Radiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, fDepartment of Pathology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, gAnhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, People ’s Republic of China and hDepartment of Surgery, Division of Colon and Rectal Surgery, Mayo Clinic, 200 First Street Southwest, Rochester, Minnesota, USA Fei Wang, Chuanxi Lai, Yiming Lv, and Feixiang Zhang contributed equally to this work. Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article. *Corresponding authors. Address: Department of Colorectal Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhej

FAQs

What is the purpose of the PRECAM phase II study?

To assess whether combining short-course neoadjuvant chemoradiotherapy with Envafolimab improves treatment efficacy in locally advanced rectal cancer patients with microsatellite stability (MSS).

How was Envafolimab administered in the treatment regimen?

After short-course radiotherapy (25Gy/5f), patients received two cycles of CAPEOX chemotherapy followed by six weekly doses of Envafolimab before total mesorectal excision surgery.

What were the primary efficacy results and key safety findings?

The study achieved a 62.5% pCR rate (20/32) and a 75% pathologic response rate (24/32). Adverse events were mainly tenesmus, diarrhea, and leukocyte decrease, with two Grade 3 events reported.

Sep 23, 2026

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