What is the dosing regimen and usage of Gemtasa (gemcitabine) in cancer treatment?

Gemcitabine (Gemtasa) Dosing Regimen and Usage in Cancer Treatment

The standard dosing regimen for gemcitabine in pancreatic cancer is 1000 mg/m² administered intravenously over 30 minutes once weekly for the first 7 weeks followed by one week of rest, then once weekly for 3 weeks of each 28-day cycle. 1

Dosing Regimens by Cancer Type

Pancreatic Cancer

• 1000 mg/m² IV over 30 minutes once weekly for 7 weeks, followed by 1 week rest, then weekly for 3 weeks of each 28-day cycle 1
• For patients with poor performance status: 1000 mg/m² over 30 minutes, weekly for 3 weeks every 28 days (category 1) 2
• Fixed-dose-rate gemcitabine (10 mg/m²/min) may substitute for standard infusion (category 2B) 2

Non-Small Cell Lung Cancer

• 28-day schedule: 1000 mg/m² IV over 30 minutes on days 1,8, and 15 of each 28-day cycle in combination with cisplatin 1
• 21-day schedule: 1250 mg/m² IV over 30 minutes on days 1 and 8 of each 21-day cycle in combination with cisplatin 1

Breast Cancer

• 1250 mg/m² IV over 30 minutes on days 1 and 8 of each 21-day cycle in combination with paclitaxel 1

Ovarian Cancer

• 1000 mg/m² IV over 30 minutes on days 1 and 8 of each 21-day cycle in combination with carboplatin 1

Combination Regimens

Preferred Combinations for Pancreatic Cancer

• Gemcitabine monotherapy (category 1) 2
• Gemcitabine + albumin-bound paclitaxel (category 1, preferred for metastatic disease) 2
• Gemcitabine + erlotinib (category 1) 2
• Gemcitabine + capecitabine 2
• Gemcitabine + cisplatin (especially for patients with BRCA1/BRCA2 or other DNA repair mutations) 2

Dose Modifications

For Myelosuppression in Pancreatic Cancer

• ANC ≥1000/μL and platelets ≥100,000/μL: No modification 1
• ANC 500-999/μL or platelets 50,000-99,999/μL: 75% of full dose 1
• ANC <500/μL or platelets <50,000/μL: Hold treatment 1

For Non-Hematologic Adverse Reactions

• Permanently discontinue gemcitabine for:
  • Unexplained dyspnea or severe pulmonary toxicity 1
  • Hemolytic uremic syndrome or severe renal impairment 1
  • Severe hepatic toxicity 1
  • Capillary leak syndrome 1
  • Posterior reversible encephalopathy syndrome 1
• Withhold or reduce dose by 50% for other Grade 3 or 4 non-hematological adverse reactions until resolved 1

Administration Considerations

• Gemcitabine is for intravenous infusion use only 1
• Standard administration is over 30 minutes 1
• Fixed-dose-rate administration (10 mg/m²/min) may maximize intracellular concentrations of the phosphorylated forms of gemcitabine 2
• Dilute with 0.9% Sodium Chloride Injection to a minimum final concentration of at least 0.1 mg/mL 1
• Discard diluted solution after 24 hours 1

Common Adverse Effects

• Hematologic: Neutropenia (most common dose-limiting toxicity), thrombocytopenia, anemia 3
• Non-hematologic: Nausea/vomiting, increased liver enzymes (AST, ALT, alkaline phosphatase), proteinuria, fever, rash, dyspnea, edema 1, 3
• Flu-like symptoms occur in approximately 19% of patients 3
• Myelosuppression is generally short-lived and rarely of clinical significance 3

Clinical Pearls

• Gemcitabine provides clinical benefit and modest survival advantage in pancreatic cancer 2
• For patients with poor performance status, gemcitabine monotherapy is recommended due to its favorable toxicity profile 2
• Combination therapy with albumin-bound paclitaxel significantly improves survival in metastatic pancreatic cancer compared to gemcitabine alone 2
• Monitor complete blood counts prior to each dose to guide dose modifications 1
• Assess renal and hepatic function before and during treatment 1

Gemcitabine has demonstrated efficacy across multiple solid tumors with a generally favorable toxicity profile, making it a cornerstone of treatment for pancreatic cancer and an important component of combination regimens for several other malignancies 4, 3.