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: Neoadjuvant chemotherapy (MVAC) in locally invasive bladder cancer. In order to evaluate the efficacy of neoadjuvant chemotherapy in invasive urothelial carcinoma of the bladder a retrospective analysis was performed. 54 patients without distant metastases ( T2-T3b , N0-X , M0 ) received 3 cycles of neoadjuvant chemotherapy according to the MVAC protocol ( methotrexate , vinblastine , doxorubicin and cisplatin ) after transurethral resection ( TUR ) followed by cystectomy . 52 patients had previously undergone cystectomy immediately after TUR. Complete histopathological remission was observed in 9 patients (17.3%) after TUR and in 17 patients (31.5%) after TUR+MVAC. Neoadjuvant MVAC resulted, therefore, in a 14% higher rate of complete remissions. The overall response to TUR was significantly improved by MVAC therapy. Downstaging by neoadjuvant chemotherapy was more readily achieved in initially low-stage tumours (T2: 44.4% and 30.8%, T3a: 47.1% and 19%, T3b: 5.3% and 5.5% in patients receiving TUR+MVAC and TUR alone, respectively). Overall survival did not differ significantly between both groups. Patients who were successfully downstaged to pT0 had a significantly better prognosis, and patients resistant to chemotherapy had the poorest prognosis, showing the shortest survival. In conclusion, histopathological response at cystectomy was improved by neoadjuvant MVAC chemotherapy after TUR and can be expected to be prognostically relevant in those patients who can be downstaged to T0, although overall survival failed to be significantly increased in this relatively small patient sample.

sentence: 54 patients without distant metastases ( T2-T3b , N0-X , M0 ) received 3 cycles of neoadjuvant chemotherapy according to the MVAC protocol ( methotrexate , vinblastine , doxorubicin and cisplatin ) after transurethral resection ( TUR ) followed by cystectomy .
[["methotrexate", "vinblastine", "doxorubicin", "cisplatin", "POS"]]