1. Questions 1–9 refer to this CASE:
JT is a 42-year-old man with recurrent diffuse-type tenosynovial giant cell tumor (TGCT) of the left knee. The knee is slightly swollen upon examination. He has chronic pain that ranges from 3 to 7 on a 10-point scale, depending on his activity level. The patient complains of pain with extremes of motion at the knee, both flexion and extension. He has undergone 2 arthroscopies in the past 6 years, the last surgery being 16 months ago. His most recent imaging demonstrates proliferative thickened synovium with effusions. He has decided that he would like to start pexidartinib. Baseline laboratory results: white blood cell (WBC) count, 3.8 K/µL (normal range, 2.1–6.8 K/µL), absolute neutrophil count (ANC) 2200 cells/µL (1500–8000 cells/µL), aspartate aminotransferase (AST) 34 (7–52 U/L), alanine aminotransferase (ALT) 28 (9–30 U/L), alkaline phosphatase (ALP) 158 (35–104 U/L), total bilirubin (Tbili) 0.8 (0.9–1.2 g/dL), direct bilirubin (Dbili) 0 (0–0.3 g/dL), gamma-glutamyl transferase (GGT) 18 (10–56 U/L).

Of the three most common characteristic presentation symptoms that patients with TGCT consider important, which one does JT have?

2. JT should return to the clinic for laboratory tests in how many days after the start of pexidartinib?

3. Which laboratory tests are required to be monitored at each time point after starting pexidartinib?

4. JT should be counseled that the following adverse effects occur most commonly?

5. Which of the following actions is required of JT's doctor to begin pexidartinib therapy if the doctor is already certified through the Risk Evaluation and Mitigation Strategy (REMS) program?

6. JT calls the clinic to inquire about taking omeprazole and ibuprofen as needed while on pexidartinib. What recommendations can be made?

7. JT comes in for a follow-up visit after being on pexidartinib for 2 months. His pain feels a little better, but the swelling around the knee seems to be about the same. The patient has some swelling around the eyes, and his hair is much more gray than the dark brown color he had previously. What adverse effects is the patient experiencing from pexidartinib?

8. At this visit, JT's labs come back with the following values: ALT 102 U/L, AST 182 U/L, ALP 282 U/L, GGT 22 U/L, Tbili 1.1 g/dL. How should his dose be adjusted?

9. JT comes in for a follow-up visit after having been on therapy for 16 months. He has had an excellent response to pexidartinib, and the surgeon believes it would be a good time for him to undergo knee replacement surgery due to the degenerative damage in the joint secondary to the previous surgeries and the tumor itself. His therapy is held while he undergoes surgery, and he returns 6 weeks after surgery. He is undergoing physical therapy and is improving his range of motion every week. He will resume pexidartinib to try to prevent another recurrence of his disease. Since he has been on the drug before, how often do his laboratory tests need to be monitored?

10. SA is a 49-year-old woman diagnosed with diffuse-type TGCT in her right elbow that was diagnosed 2.5 years ago. She underwent a surgical resection, but tumors have recurred twice with partial resections each time. Laboratory results before beginning therapy with pexidartinib were as follows: AST 34 (9–30 U/L), ALT 45 (7–52 U/L), ALP 121 (35–104 U/L), Tbili 0.4 (0.2–1.2 mg/dL), Dbili 0.1 (0–0.3 mg/dL), GGT 38 (10–56 U/L), serum creatinine 2.1 mg/dL (0.6–1.4 mg/dL), WBC 3.8 (2.1–6.8 K/µL) , ANC 3242 (1500–8000 cells/µL), and estimated creatinine clearance 67 (90–120 mL/min). The patient's weight is 131 kg, height 167 cm, and body surface area, 2.33 m2. On what dose of pexidartinib should SA be started?

Evaluation Questions

11. How confident are in your treatment choices for JT?

12. How confident are in your treatment choice for SA?

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