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: Biweekly doxorubicin/ketoconazole as second-line treatment in docetaxel-resistant, hormone-refractory prostate cancer. docetaxel is an effective first-line treatment for hormone-refractory prostate cancer. Nevertheless, the prognosis subsequent to progression after first-line therapy is poor and no second-line treatment has been established. ### methods A total of 34 patients with androgen-independent prostate cancer received doxorubicin , 30 mg/m(2 ) , every 2 weeks and ketoconazole daily , 400 mg orally every 8 hours . All patients had been treated with docetaxel and had disease progression within 6 months after completion of first-line treatment. ### results Of the 32 evaluable patients, 13 (43.7%, 95% confidence interval [CI] 26.3% to 62.3%) had a prostate-specific antigen (PSA) response, and 4 (28%, 95% CI 8.4% to 58.1%) of 14 patients with measurable disease had a response to therapy. The median time to progression (TTP) was 3.9 months (95% CI 2.0 to 5.9), and the median overall survival (OS) was 13 months (95% CI 8.7 to 17.3). Toxicity was mild, with only 4 cases of nonhematologic grade 3 or 4 toxicity. The most frequent toxicity was nail changes (33 of 34 patients), which was mainly grade 1 (30 cases). ### conclusions The combination of biweekly doxorubicin and ketoconazole is an effective, well-tolerated, second-line therapy for hormone-refractory prostate cancer.

sentence: A total of 34 patients with androgen-independent prostate cancer received doxorubicin , 30 mg/m(2 ) , every 2 weeks and ketoconazole daily , 400 mg orally every 8 hours .
[["doxorubicin", "ketoconazole", "POS"]]