3.BH is an 18-year-old man with osteosarcoma of the right tibia currently being treated with cisplatin, doxorubicin, and high-dose methotrexate. He is 2 days post-methotrexate and 3 weeks post-cisplatin and doxorubicin, reporting dysphagia and nausea that might be related to his methotrexate therapy. CBC and comprehensive metabolic panel (CMP) are within normal limits, including normal creatinine. Urine output is also normal with a rand om urine pH of 7.5. Which of the following is essential to moderate the development of methotrexate-related toxicities?
A. A monthly vitamin B12 injection and daily low-dose folic acid supplementation
B. Immediate IV glucarpidase administration
C. Leucovorin administered starting 24 to 48 hours post-methotrexate
D. Reduction of sodium bicarbonate infusion, titrating to a urine pH of 6 to 7