You will be shown a paragraph from a biomedical research article. Your task is to extract all drug combinations appearing in a specific sentence within in the paragraph. Each drug combination should be assigned to one of the following three categories:

- POS: Indicates a positive interaction between the drugs in the combination; for instance, drugs that have an additive or synergistic effect.
- NEG: Indicates a negative interaction between the drugs in the combination; for instance, combining these drugs might result in adverse side effects, or might reduce their efficacy.
- COMB: Indicates that the drugs are given in combination, but the type of interaction between the drugs cannot be determined based on the provided context.

Please format your answer as a json array. Each entry in the array should itself be an array formatted as [<drug_1>, <drug_2>, ..., <drug_n>, <category>] where <category> is one of the three categories listed above and <drug_1>, ..., <drug_n> are drug names copied verbatim from the input sentence. Different combinations may involve different numbers of drugs; in other words, the `n` in <drug_n> may vary.

As an example, the following output describes two extracted drug combinations; one between two drugs, and one between three drugs:

[["artesunate", "artemether", "COMB"], ["Nifedipine", "Labetalol", "Prazosin", "POS"]]

The paragraph and specific sentence are below. You should only extract relationships expressed in the specific sentence; the paragraph is provided for context.

In your output, return only the json array and no other text. If no drug combinations appear, return an empty array `[]`.

paragraph: Intestinal perforation in colorectal cancers treated with bevacizumab (Avastin). bevacizumab is a monoclonal antibody that targets vascular endothelial growth factor (VEGF), and it has shown promise as a clinical agent against metastatic colorectal cancer, and particularly in combination with chemotherapy. Bowel perforation is a known risk that's associated with bevacizumab use, but the etiology is unknown. Here we report on two cases of metastatic colorectal cancer in which the patients suffered from intestinal perforation after chemotherapy with bevacizumab. For the first case, a 47 year-old man had rectal cancer with concurrent liver and lung metastasis. He underwent chemotherapy with 5-fluorouracil, irinotecan and bevacizumab. Fever and abdominal pain developed seven days later, and rectal perforation was identified upon exploration 13 days later. For the second case, a 48 year-old woman had sigmoid colon cancer with peritoneal and ovary metastases. After seven days of chemotherapy with 5-fluorouracil , oxaliplatin and bevacizumab , exploratory surgery revealed a perforation at the ileum .

sentence: After seven days of chemotherapy with 5-fluorouracil , oxaliplatin and bevacizumab , exploratory surgery revealed a perforation at the ileum .
[["5-fluorouracil", "oxaliplatin", "bevacizumab", "NEG"]]