Gastrointestinal Stromal Tumor Drug Summary

Last updated: 21 January 2025

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Targeted Cancer Therapy


Drug Dosage Remarks
Avapritinib PDGFRA exon 18 mutation including D842V tumors: 300 mg PO 24 hourly until disease progression or unacceptable toxicity
Adverse Reactions
  • Hematologic effects (anemia, decreased WBC, decreased neutrophil count); GI effects (abdominal pain, nausea and vomiting, diarrhea, GERD, decreased appetite); Hepatic effects (hyperbilirubinemia, increased transaminases); CNS effects (dizziness, cognitive disorder, memory impairment); Other effects (increased lacrimation, hair color changes, rash, edema, fatigue)

Special Instructions

  • Should be taken on an empty stomach, at least 1 hour before or 2 hours after a meal
  • Avoid in patients with severe hepatic or renal impairment
  • Use with caution in patients with known or at risk of QT interval prolongation
  • Avoid exposure to direct sunlight
  • Monitor CBC and LFTs periodically during treatment
Entrectinib NRTK gene fusion-positive solid tumors: 600 mg PO 24 hourly until disease progression or unacceptable toxicity
Adverse Reactions
  • GI effects (nausea and vomiting, constipation, dysgeusia); CNS effects (dizziness, cognitive impairment, dysesthesia); Resp effects (cough, dyspnea); Musculoskeletal effects (myalgia, arthralgia); Other effects (fatigue, edema, increased weight, pyrexia, vision disorders)
Special Instructions
  • Use with caution in patients with CHF, severe renal impairment, and moderate to severe hepatic impairment
  • Assess LV ejection fraction before initiation
  • Monitor LFTs every 2 weeks during the first month of treatment then monthly or as clinically indicated thereafter, serum uric acid levels before and periodically during treatment, and for signs and symptoms of CHF hyperuricemia
 Imatinib 400 mg PO 24 hourly
As indicated, may increase to 800 mg/day PO

Adverse Reactions

  • CNS effect (headache) GI effects (nausea and vomiting, diarrhea, abdominal pain); Musculoskeletal effects (arthralgia, muscle spasms and cramps); Dermatologic effects (dermatitis, eczema, rash); Hematologic effects (thrombosytopenia, neutropenia, anemia, fatigue); Other effects (peripheral edema, fluid retention)

Special Instructions

  • Use with caution in patients with renal or hepatic impairment, history of CV disease, severe fluid retention
  • Weight, LFT, CBC should be monitored
 Larotrectinib NTRK gene fusion-positive solid tumors: 100 mg PO 12 hourly until disease progression or unacceptable toxicity

Adverse Reactions

  • GI effects (nausea and vomiting, diarrhea, constipation); Other effects (fatigue, dizziness, anemia, increased ALT and AST, cough)

Special Instructions

  • Use with caution in patients with moderate to severe hepatic impairment
  • May impair the ability to drive or operate machinery
  • Monitor LFTs every 2 weeks during the first month of treatment then monthly or as clinically indicated thereafter
 Regorafenib 160 mg PO 24 hourly for the first 21 days of a 28-day cycle

Adverse Reactions

  • GI effects (nausea and vomiting, diarrhea, mucositis, decreased appetite); Dermatologic effects (palmar-plantar erythrodysesthesia, rash, alopecia); Hematologic effects (anemia, thrombocytopenia, hemorrhage); Other effects (hypertension, fatigue, dysphonia, hypocalcemia, hypophosphatemia

Special Instructions

  • Use with caution in patients with renal or hepatic impairment
  • Monitor abnormal biochemical and metabolic lab tests, hepatic effects, hemorrhage, myocardial ischemia, GI perforation, wound healing complications, dermatological toxicity
 Sunitinib 50 mg PO 24 hourly for 4 weeks followed by a 2-week off period to comprise a complete 6-week cycle

Adverse Reactions

  • GI effects (nausea and vomiting, dyspepsia, stomatitis); Dermatologic effects (palmar-plantar erythrodysesthesia, rash, dry skin, changes in hair color, skin discoloration); Other effects (hypertension, fatigue, anorexia, pulmonary embolism, thrombocytopenia, tumor hemorrhage, febrile neutropenia)

Special Instructions

  • Use with caution in patients with osteonecrosis of the jaw, surgical procedures, skin discoloration, GI disturbances, hemorrhagic and hematological effects, CV effects, hypertension, hypothyroidism, increased serum lipases and amylase, seizures, tumor lysis syndrome
  • May cause dizziness during treatment

Atypical/2ND Generation Antipsychotic


Drug Dosage Remarks
Other Antipsychotic
Brexpiprazole Treatment of agitation associated with dementia due to AD:
Initial dose:
Day 1-7: 0.5 mg PO 24 hourly
Day 8-14: 1 mg PO 24 hourly
Day 15 onwards: 2 mg PO 24 hourly
Target dose: 2 mg PO 24 hourly
May increase to 3 mg PO 24 hourly after at least 2 weeks
Max dose: 3 mg/day
Adverse Reactions
  • Psychiatric effects (suicidal thoughts/behavior, agitation, compulsive disorders); CNS effects (insomnia, anxiety, headache, lightheadedness, drowsiness, sedation, tremor); GI effects (constipation, nausea and vomiting); CV effects (tachycardia, orthostatic hypotension); Endocrine effect (hyperprolactinemia); Other effects (weight gain, dyslipidemia, blurred vision, fatigue)
  • Potentially fatal: Neuroleptic malignant syndrome (NMS), blood dyscrasias, ketoacidosis/hyeperosmolar coma
  • Incidence of extrapyramidal symptoms is low with akathisia being the most commonly reported; tardive dyskinesia is infrequent
Special Instructions
  • Use with caution in patients with known CV disease, cerebrovascular disease, Parkinson's disease or diseases that would predispose patients to hypotension, patients with a history of seizure, dementia-related psychosis
  • Use with caution in patients taking strong CYP34A or CYP2D6 inhibitors and inducers
  • CBC, fasting lipid profile, and fasting blood glucose/HbA1c should be tested prior to therapy then monitored periodically
  • Perform annual eye examination
  • Monitor for suicidal ideation or clinical worsening
  • Avoid abrupt withdrawal