Locally Advanced Rectal Adenocarcinoma

This is a prospective, multicenter, randomized controlled trial aimed at comparing different radiotherapy fractionation regimens combined with sequential dual immunotherapy versus traditional chemoradiotherapy in neoadjuvant treatment for locally advanced rectal cancer (LARC). A total of 342 pMMR/MSS LARC patients will be enrolled and randomly assigned in a 1:1:1 ratio to short-course radiotherapy (5×5Gy) followed by sequential dual immunotherapy (paromlimab + tuvonralimab + CAPEOX), long-course radiotherapy followed by sequential dual immunotherapy, or conventional long-course chemoradiotherapy. The primary endpoint is the complete response rate (pCR + cCR). Secondary endpoints include the proportion of patients adopting the "watch-and-wait" strategy, disease-free survival, overall survival, and safety. This study innovatively explores the synergistic mechanism of different radiotherapy fractionations with dual immunotherapy, optimizes the timing of immunotherapy initiation, and constructs a clinical-imaging-pathology multimodal efficacy prediction model, aiming to advance LARC treatment from empirical to precision therapy while achieving organ and function preservation.

The purpose of this study is to find out whether the combination of botensilimab and balstilimab (BOT/BAL) is a safe and effective treatment that causes few or mild side effects for people with mismatch repair proficient (MMRp)/microsatellite stable (MSS) locally advanced rectal adenocarcinoma. The investigators will also find out whether BOT/BAL is an effective treatment when given in combination with standard chemotherapy.

The study researchers believe that a combination of the drugs trastuzumab and tucatinib, given with standard chemotherapy (capecitabine and oxaliplatin/FOLFOX), may help participants with rectal cancer.

This is a phase 2 pragmatic study to examine the utility of ctDNA-informed treatment management for participants with early-stage rectal cancer using the Signatera Genome assay. The primary aims are to 1) assess pathologic complete response (path CR) in the ctDNA informed management arm; 2) assess pathologic complete response (path CR) in the post total neoadjuvant therapy (TNT) standard of care (SOC) surgery arm; and 3) assess disease free survival (DFS) in the ctDNA informed management arm.

The goal of this clinical trial is to learn whether new adjuvant radiotherapy with gross tumor volume(GTV) escalated to 58.75 Gy can improve complete response (CR) rates compared with GTV dose of 50 Gy in adult patients (18-79 years) with locally advanced rectal adenocarcinoma (T3-T4/N+, M0) located ≤10 cm from the anal verge.The main questions it aims to answer are: 1. Does GTV simultaneously boost to 58.75 Gy/25f increase complete response (pCR or cCR) compared with 50 Gy/25f? 2. How do the two regimens differ in terms of progression-free survival (PFS), pelvic local control (LC), tumor regression grade (TRG), organ preservation, and treatment-related toxicity? Researchers will compare GTV 58.75 Gy/25f (experimental arm) versus GTV 50 Gy/25f (control arm) to see if dose escalation improves tumor response rate. Participants will: 1. Receive neoadjuvant radiotherapy with one of the two PGTV dose escalated regimens (with concurrent chemotherapy: oral capecitabine or XELOX). 2. Undergo restaging with imaging and clinical assessment before surgery or observation. 3. Proceed to total mesorectal excision (TME), local excision, or "watch-and-wait" strategy depending on treatment response and patient preference. 4. Be followed regularly with clinical exams, imaging, endoscopy, and laboratory tests to assess efficacy, safety, and long-term outcomes.

The primary objective of the NACRE-2 trial is to assess whether the addition of chemotherapy after short-course radiotherapy is more effective than short-course radiotherapy alone in elderly patients with locally advanced rectal cancer. Secondary objectives will assess the efficacy and safety profile of the combination, as well as its effect on patients' quality of life. Patients will be separated into two groups to receive their assigned treatment: * Group 1: Short-duration radiotherapy according to standard practice lasting one week, followed by chemotherapy with FOLFOX4s consisting of oxaliplatin (85 mg/m²), folinic acid (400 mg/m²) and 5-Fluoro-Uracil (400 mg/m² administered in hospital, followed by 2400 mg/m² administered over 46 hours at home) every two weeks for 3 months * Group 2: Short-duration radiotherapy according to standard practice, lasting one week To receive treatment, patients must come to the hospital where, at each visit, the medical team will carry out medical examinations, prior to administering treatment, to assess the patient's general state of health and tolerance to treatment. A radiological assessment of the disease will be carried out 11 weeks after the end of radiotherapy. Patients whose tumors have not shrunk will undergo surgery to remove them and enter the follow-up phase. Patients whose tumors have shrunk will not undergo surgery, and will enter a surveillance phase. At 21 weeks, patients whose tumors are still present will undergo surgery and enter the follow-up phase. Patients whose tumors have disappeared will remain in a surveillance phase. During the surveillance or follow-up phases, patients will be monitored in hospital every 3 months (if no progression is observed). In the case of surgery, patients will be monitored every 6 months. The maximum duration of treatment is 3 years.

This phase I trial studies the side effects and best dose of papaverine (PPV) when given together with radiation therapy (RT) and tests how well it works in treating patients with rectal cancer that has spread to nearby tissue or lymph nodes (locally advanced). PPV is an enzyme inhibitor, and it may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. RT uses high energy x-rays, particles, or radioactive seeds to kill tumor cells and shrink tumors. Giving PPV with RT may be safe, tolerable, and/or effective in treating patients with locally advanced rectal cancer.