Fluorouracil + Leucovorin + Mitoxantrone

The combination of fluorouracil (5-FU), leucovorin, and mitoxantrone is a chemotherapy regimen primarily used in the treatment of metastatic breast cancer. This combination has shown significant efficacy, particularly as a second-line treatment option for patients who have failed previous chemotherapy regimens[1][2]. ## Mechanism of Action Each component of this combination works through different mechanisms: **Fluorouracil (5-FU)** is a chemotherapy drug that destroys rapidly dividing cells by interfering with DNA synthesis. It's a pyrimidine analog that works during the S phase of the cell cycle[5]. **Leucovorin** (also known as folinic acid or calcium folinate) is not a direct cytotoxic agent but enhances the efficacy of 5-FU. It stabilizes the binding of 5-FU to its target enzyme, thymidylate synthase, thereby increasing the cytotoxic effects of 5-FU[5]. **Mitoxantrone** is an anthracenedione agent that works in two primary ways: 1. It inhibits topoisomerase II, an enzyme needed for cell replication and tumor growth 2. It functions similarly to anthracyclines by interfering with DNA replication[10] ## Clinical Efficacy Studies have shown impressive response rates with this combination: - One phase II study reported objective responses in 65% of assessable patients with metastatic breast cancer[1] - Another study demonstrated a 45% partial response rate with a median duration of 6 months[2] - The combination appears particularly effective in patients who haven't previously received doxorubicin treatment, with a 69% response rate in this subgroup compared to 38% in those with prior doxorubicin exposure[2] ## Administration The regimen is typically administered as follows: - Mitoxantrone: 12 mg/m² intravenously on day 1 - Leucovorin: 300 mg intravenously over 1 hour followed by 5-FU - 5-FU: 350 mg/m² intravenous push on days 1, 2, and 3 - Treatment cycles are repeated every 21 days - Responding patients typically receive 6-8 courses of treatment[1] ## Toxicity Profile This combination is generally well-tolerated with relatively mild toxicity compared to other chemotherapy regimens. The most common side effects include: - Mucositis and/or diarrhea (more common than myelosuppression) - Potential cardiac toxicity (particularly in patients with prior high-dose doxorubicin treatment) - Mitoxantrone may cause blue/green discoloration of urine for 1-2 days after administration[10] The combination of mitoxantrone, 5-FU, and high-dose leucovorin represents an effective option for second-line chemotherapy in metastatic breast cancer, offering a favorable balance of efficacy and tolerability.

Other names

5-FU + Leucovorin + MitoxantroneFLUM