The goal of this clinical trial is to see, if addition of chlorophyllin to neoadjuvant Chemo-radiotherapy can reduce the gastro-intestinal/genitourinary/hematological toxicity rates and improve the quality of life in patient's diagnosed with locally advanced rectal cancer.

This is a randomized placebo control trial, wherein participants randomized to Chlorophyllin arm will receive the drug of interest along with the standard treatment. Participants randomized to other arm will receive placebo along with the standard treatment.

Researchers will compare the difference between the outcomes from both the arms and will also observe the non-operative management success rates.

The current standard treatment for locally advanced rectal cancer includes neoadjuvant (treatment given before Surgery) radiotherapy & chemotherapy followed by surgery if needed or wait and watch in patients whom tumour has completely regressed. It has been observed that even after receiving this intensive treatment patients, almost 70% of patients develop acute toxicity (during or within 3 months) of grade 2 or higher (needing medication for toxicity). This affects their treatment tolerance, completion and quality of life.

In this study Researchers are going to see if addition of drug Chlorophyllin (derived from green plant leaves) along with standard treatment would help in reducing the acute toxicity. Chlorophyllin is present in all green leaves of plants giving them green color. The drug is derived from green plant leaves. As it is a plant-based product it is safe for humans and has no known side effects of its own. This is a randomized study which has two arms; Arm 1 is test arm where participants will receive drug of interest (Chlorophyllin) and in other arm participants will receive Placebo. Upon successful completion of study, outcomes from both the study arm will be compared and participants will be followed by standard protocol for 3 years.

Inclusion Criteria:

• Age > 18 years.

• Histologically confirmed diagnosis of adenocarcinoma of the rectum.

• Clinical Stage II/III (T2-3, 4b: adherent to prostate, SV or post vagina but not grossly invading, N0-2) based on MRI.

• Non-circumferential tumours with craniocaudal length <7 cm

• The tumours of the lower rectum, or starting up to 7 cm from the anal verge.

• No evidence of distant metastases on CT Chest and Abdomen.

• No prior pelvic radiation therapy

• No prior chemotherapy or surgery for rectal cancer

• Eastern Cooperative Oncology Group (ECOG) Performance status 0-2

• Patients must read, agree to, and sign a statement of Informed Consent prior to participation in this study.

• Eligible to receive one of the options of standard neoadjuvant chemotherapy as determined by the medical oncologist team.

  • Absolute neutrophil count (ANC) > 1.5 cells/mm3, hemoglobin (HGB) > 8.0 gm/dl, platelet (PLT) > 150,000/mm3.
  • Total bilirubin ≤ 1.5 x ULN (except in patients with Gilbert's Syndrome who must have total bilirubin ≤ 3.0 x ULN), aspartate aminotransferase (AST) ≤ 3 x ULN, alanine transaminase (ALT) ≤ 3 x ULN.

Exclusion Criteria:

• Signet or mucinous histology cancer of rectum
• Recurrent rectal cancer or previous pelvic radiotherapy
• Primary unresectable rectal cancer.
• Creatinine level greater than 1.5 times the upper limit of normal.
• Patients who are unable to undergo an MRI.
• Patients with a history of any arterial thrombotic event within the past 6 months. This includes angina (stable or unstable), MI, TIA, or CVA.
• Ulcerative colitis or any other histologically confirmed inflammatory bowel disease.
• Patients with a history of venous thrombotic episodes such as deep venous thrombosis, and pulmonary embolism occurring more than 6 months prior to enrollment may be considered for protocol participation, provided they are on stable doses of anticoagulant therapy. Similarly, patients who are anticoagulated for a trial fibrillation or other conditions may participate, provided they are on stable doses of anticoagulant therapy.
• Patients with any other concurrent medical or psychiatric condition or disease which, in the investigator's judgment, would make them inappropriate candidates for entry into this study.
• Poor reliability for follow up.
• Ineligible as per eligibility criteria