The U.S. Food and Drug Administration (FDA) has issued a press release making the first even gene therapy available for treatment of children with a form of acute lymphoblastic leukemia (ALL). The drug Kymriah (tisagenlecleucel) is the first of its kind that uses gene therapy to treat patients with this condition. The release was updated yesterday identifying the designantions that were granted to Kymriah.
FDA Commissioner Scott Gottlieb, in a statement called this a new “frontier in medical innovation” that would be able to reprogram the patient’s cells in such a way that they would be able to attack the cancer. Gene and cell therapies can “transform” medicine not only with their ability to cure and treat several intractable and incurable diseases but also tailor make the therapies. Gottleib emphasized that these therapies are potentially lifesaving and this their development would be accelerated and expedited.
Kymriah, also called CTL019, is a cell-based gene therapy that is now approved in the United States for the treatment of patients under 25 with B-cell precursor ALL that is refractory to treatment or has come back with a second or later relapse. An estimated 15-20 percent of patients do not respond to treatment with traditional therapies and come in with a relapse.
The drug works by genetically-modifying the T cells of the body and thus is called autologous T-cell immunotherapy. T cells are a particular type of white blood cells in the body that act as soldiers against infections and foreign cells. Kymriah is customized or tailor made to the particular patient’s own T cells. For the treatment, the patient’s T cells are first collected and sent to the manufacturing center. These cells are modified here so that they carry a new gene within them. The gene carries a specific protein called the chimeric antigen receptor or CAR. Additions of this protein make the newly altered T cells target and kill leukemia cells. This is because the CAR recognizes the specific antigen (CD19) that is present over the cancer cells. Once the T cells are prepared with the new gene in place, they are infused back into the patient where they get to work.
Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research (CBER) also said that this drug is a “first-of-its-kind treatment” in an area that has limited treatment options. It has shown good efficacy in terms of achievement of remission or disease-free states and improves survival. The newly approved agent was tried in a multicenter clinical trial of 63 pediatric and young adult patients who had relapsed or refractory B-cell precursor ALL. The overall remission rate within three months of treatment was 83 percent. It was tried in a single-arm Phase II ELIANA trial in 25 centers in the US, EU, Canada, Australia and Japan.
The drug is not without the risk of side effects and the FDA has mandated that the box label carries a warning. There is a potential risk for life threatening cytokine release syndrome (CRS). In this condition body responds to the activation and multiplication of the altered T cells with the CAR. This results in flu like symptoms, high fever, and neurological events. This can be life threatening.
In addition, Kymriah may also cause low blood pressure, serious infections, kidney damage, low oxygen levels etc. Kyriah causes serious infections because normal B cells also possess the CD-19 marker that is targeted by the altered T cells. This means the body is devoid of its fighters and there is an increased risk of infections for a long period of time. These side effects appear within the first 22 days of treatment.
In order to handle CAR T-cell-induced severe or life-threatening CRS in patients 2 years of age or older, FDA also approved of another drug called Actemra (tocilizumab). Results from the clinical trial showed that 69 percent of clinical trial patients had complete resolution of CRS within two weeks after one or two doses of Actemra.
The FDA has approved a Risk Evaluation and Mitigation Strategy (REMS) for Kymriah. This means that physicians who would be using this agent would be informed and educated regarding the risks that may be associated with Kymriah treatment.
The FDA granted approval of Kymriah to Novartis Pharmaceuticals Corp. The FDA granted the expanded approval of Actemra to Genentech Inc. Novartis is set to file applications to both the FDA and the European Medicines Agency (EMA) for the approval of Kymriah for the treatment of adult patients with r/r diffuse large B-cell lymphoma (DLBCL).
Acute Lymphoblastic Leukemia
ALL or acute lymphoblastic leukemia is a cancer of the lymphocytes or a specific type of white blood cells. The abnormal lymphocytes crowd other types of cells in the bone marrow and thus reduce the number of healthy cells. ALL comprises approximately 25% of all cancers that are diagnosed in children less than 15 years. It is the most common childhood cancer in the US. The National Cancer Institute estimates that approximately 3,100 patients aged 20 and younger are diagnosed with ALL each year. Both T cell or B cells can be involved in different types of ALL but B-cell ALL is the most common.