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: Efficacy and safety evaluation of a combination of iguratimod and methotrexate therapy for active rheumatoid arthritis patients: a randomized controlled trial.  This study aimed to investigate the efficacy and safety of iguratimod ( T-614 ) in combination with methotrexate ( MTX ) for active rheumatoid arthritis ( RA ) patients . Sixty active RA patients were enrolled according to the 2010 American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) classification criteria, and were randomized into MTX + T-614 group and MTX group. T-614 was orally administered at a dosage of 50 mg/day (25 mg twice daily) for 24 weeks. MTX was orally administered to RA patients at a stable weekly dosage of 10 mg/week for the first 4 weeks and subsequent 12.5 mg/week for the later 20 weeks. Clinical features at baseline and efficacy endpoints of the ACR 20 % response (ACR20), ACR50, ACR70, and adverse events at 24 weeks were evaluated, respectively. After 24 weeks of treatment, clinical features at baseline, including counts for tender joints and swelling joints, visual analog scale for pain, patient's and physician's global assessment, erythrocyte sedimentation rate, C-reactive protein, disease activity score 28, health assessment questionnaire, simplified disease activity index, and ACR50 in the MTX + T-614 group, showed statistically significant differences comparing with the MTX group (P < 0.05). There was no significant increase in adverse events in the MTX + T-614 group comparing with the MTX group (P > 0.05). The combination of MTX and T-614 therapy appeared to have a good efficacy and safety for active RA and was superior to MTX-alone therapy after 24 weeks of treatment.

sentence: This study aimed to investigate the efficacy and safety of iguratimod ( T-614 ) in combination with methotrexate ( MTX ) for active rheumatoid arthritis ( RA ) patients .
[["iguratimod", "methotrexate", "POS"]]