Written by Karen Selby, RN | Medically Reviewed By Dr. Jeffrey Velotta | Edited By Walter Pacheco | Last Update: July 12, 2024

What Is Cyclophosphamide?

Researchers have already proven the safety and efficacy of cyclophosphamide in other diseases. The U.S. Food and Drug Administration (FDA) approved it for use in several cancers and diseases, including breast cancer and leukemia. Doctors have seen mixed results in clinical trials but remain hopeful that the drug can be implemented successfully in mesothelioma treatment regimens.

Cyclophosphamide Information
Name Cytoxan
Related Drug Ifosfamide
Manufacturer Bristol-Myers Squibb
Dosage 40-50 mg/kg over 2-5 days
Administration Route Intravenous or oral
Active Ingredient Cyclophosphamide
Drug Class Antineoplastic alkylating agent
Medical Code J9097, J8530
Alternate Names Lyophilized Cytoxan, Endoxan, Cytophosphane, Neosar, Procytox, Revimmune, Cycloblastin
Interacting Drug Grapefruit, grapefruit juice, alcohol, live vaccines, carbamazepine, idarubicin, natalizumab, entanercept, palifermin, phenobarbital
Medical Studies Tumor-Infiltrating Lymphocytes and Low-Dose Interleukin-2 Therapy Following Cyclophosphamide and Fludarabine in Patients with Pleural Mesothelioma
FDA Warning Immune suppression, bone marrow toxicity, myelosuppression, kidney and urinary toxicity, heart toxicity, pulmonary toxicity, liver disease, secondary cancer, fetal toxicity, reproductive harm

Now, researchers are studying its effects in combination with other chemotherapy drugs and in combination with immunotherapy on mesothelioma patients. The goal is to find drugs that surpass the survival rates seen in pemetrexed and platinum-based chemotherapy regimens.

How Is It Used?

Unlike traditional chemotherapy drugs that must be administered intravenously, cyclophosphamide may also be administered in tablet form, once or twice daily. Mesothelioma patients in clinical trials usually receive the drug in the traditional intravenous manner, typically once every two weeks.

In general, chemotherapy drugs disrupt the division of cells that divide quickly, preventing cancer cells from replicating and growing.

Jennifer Suga
Dr. Jennifer Marie Suga, Oncologist at Kaiser Permanente Vallejo Medical Center

Cyclophosphamide is an alkylating agent, which means it is designed to inhibit tumor growth by interfering with the DNA of cancer cells. It can bind with DNA in mesothelioma cells. Once it does so, it prevents cell division and prompts the death of cancer cells.

In clinical trials, it is being studied in combination with other chemotherapy drugs or immunotherapy agents such as SS1P and certain vaccines.

What Are the Side Effects?

Cyclophosphamide comes with the general side effects of chemotherapy, such as fatigue, weight loss, nausea and hair loss. It may cause additional side effects of abdominal pain, chest pain or shortness of breath, which usually are not severe.

Common Side Effects
  • Abdominal pain
  • Anemia
  • Blood in urine
  • Bruising or bleeding
  • Change in nails
  • Chest pain or shortness of breath
  • Diarrhea
  • Fatigue
  • Hair loss
  • Infection
  • Nausea, vomiting and loss of appetite
  • Pain in belly
  • Rash
  • Skin changes
  • Weight loss

However, doctors have noted one significant potential side effect: an increased risk of other types of cancer. Long-term use and high doses create the most risk. Bladder cancer is the most common resulting cancer, which may develop years after use. Acute leukemia is also associated with the use of cyclophosphamide.

Karen Selby, RN and Patient Advocate at The Mesothelioma Center

The goal of chemotherapy is to actually slow down or kill the rapidly growing cancer cells that are growing in the patient. However, those agents that are used can sometimes also kill rapid growing healthy cells. So, I always encourage patients to understand that there may be side effects to the agent that they’re going to be prescribed but not all the time.

Karen Selby, RN and Patient Advocate

Study Results

Researchers have had mixed results when testing cyclophosphamide in mesothelioma patients. In 2021, a research study involving cyclophosphamide with dendritic cell therapy showed promising results. The overall survival at two years for mesothelioma patients was 55.2% and over 20% of patients lived for 5 years or more.

A 2017 study combined cyclophosphamide with an immunotherapy approach called T-cell therapy in six pleural mesothelioma patients. Of the four patients evaluated at publication, one showed tumor shrinkage, another patient’s tumor stopped growing, and the other two did not respond (their cancer progressed).

Chemotherapy is a weird thing to describe to people who never lived it. At times you just don’t feel right, but it’s hard to always pinpoint why. Your body just gets out of sorts.

Al Schwartz, wife Rebecca and Olivia
Albert Schwartz, pleural mesothelioma survivor

One study had positive results when patients underwent radiation therapy followed by a chemotherapy regimen of cyclophosphamide and doxorubicin. Adding the chemotherapy regimen caused tumors to decrease in size by about 25%. Overall, patients who received radiation therapy and chemotherapy survived a median of 13 months, compared to only six months in patients who received radiotherapy alone. However, these results may be slightly skewed since chemotherapy was only given to those patients who were 70 or younger and responded well to initial radiation therapy.

Doctors see promise in cyclophosphamide for treating mesothelioma cancer, and clinical trials continue to test the drug on mesothelioma patients. Ongoing studies test the chemotherapy agent with immunotherapy or other chemotherapy drugs to treat mesothelioma patients.

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