For many patients with lymphoma or multiple myeloma, a stem cell transplant with their own stem cells (an autologous transplant) or CAR T-cell therapy can extend life significantly or even cure the disease. A variety of factors influence which of these two treatments is recommended, including:
- whether a patient is responding to chemotherapy
- whether the patient is likely to relapse after chemotherapy
- whether the patient has health conditions that make them ineligible for a transplant
What is the difference between stem cell transplant and CAR T-cell therapy?
An autologous stem cell transplant involves treatment with high doses of chemotherapy followed by an infusion of the patient’s own hematopoietic stem cells to rebuild their blood supply. It is generally effective only for patients who have responded to cancer therapies like chemotherapy and are in a near or complete remission.
CAR T-cell therapy, by contrast, involves collecting a different set of cells — the patient’s immune system T cells — and genetically modifying them to better recognize cancer cells. The modified cells are then injected back into the patient, where they latch onto and kill tumor cells.
Before the CAR T cells are reinfused, patients may receive chemotherapy for their cancer, which helps create space in their immune system for the cells to expand and proliferate. In contrast to autologous stem cell transplantation, CAR T-cell therapy has been tested only in patients whose cancer has not entered remission from prior therapies.
The decision of which approach to take rests on several considerations:
- Patients whose lymphoma or multiple myeloma is resistant to their most recent chemotherapy regimen are not candidates for an autologous stem cell transplant. This is because an autologous transplant is essentially treatment with high-dose chemotherapy, given in hopes of overcoming the resistance of cancer cells not killed by standard-dose chemotherapy, and thus preventing a relapse. The transplanted stem cells are principally meant to “rescue” patients from the toxic side effects of the high doses of chemotherapy used to kill cancer cells and are not part of the anti-cancer therapy itself.
- Based on the results of several clinical trials, patients with lymphoma that is resistant to chemotherapy are eligible for a CAR T-cell therapy. CAR T-cell therapy was initially approved for patients whose disease had relapsed multiple times, but its success in those patients suggested it could be more effective than some of the standard therapies used in earlier lines of treatment. Two recent trials involved patients with B-cell lymphoma that didn’t respond to first-line treatment or relapsed within 12 months of that treatment. The trials, which compared CAR T-cell therapy to standard second-line therapy followed by an autologous stem cell transplant in responding patients, found CAR T-cell therapy to be more effective for these patients and is now available to them as a second-line therapy.
- For patients with multiple myeloma, CAR T-cell therapy is approved as a fifth-line treatment. That is, it’s offered as standard therapy only if patients haven’t benefited, or no longer benefit, from four previous courses of treatment, which can include an autologous stem cell transplant. However, there are ongoing clinical trials exploring their use in earlier lines of therapy as well.
- Patients who are above age 75 or have heart disease, kidney disease, lung disease, or other health conditions not compatible with high-dose chemotherapy generally are not candidates for an autologous transplant. Many of these patients, however, are likely to be eligible for CAR T-cell therapy, as the toxicities and side effects of, and ability to tolerate, each treatment differs.