Plasma Exchange Can Be an Alternative Therapeutic Modality for Severe Cytokine Release Syndrome after Chimeric Antigen Receptor-T Cell Infusion: A Case Report

In recent years, there has been rapid progress in tumor immunotherapy. The goal of tumor immunotherapy has been to harness the antitumor potential of the immune system and translate these capabilities into effective therapies for patients. Chimeric antigen receptor (CAR)-T cell therapy, an emerging tumor immunotherapy, has produced exciting results, especially in the treatment of B-cell malignancies (1–5). CAR-T cells engineered to target CD19 have been successfully used in the treatment of patients with relapsed and refractory (r/r) acute lymphocytic leukemia (ALL; refs. 1–5). Promisingly, unprecedented remission rates of 67% to 90% have been observed in adult and pediatric patients with r/r ALL treated with second-generation anti-CD19 CAR-T cells (3–5).

However, in association with activation of the immune system, which is critical to the efficacy of CAR-T cell therapy, certain types of treatment-related toxicity, such as CRS and neurologic toxicity, have emerged as new challenges (6–8). CRS is the most serious of these toxicities and can even be life-threatening. CRS, which is characterized by fever, hypotension, coagulopathy, respiratory distress, nervous system symptoms, and end-organ dysfunction, appears to be driven by the supraphysiologic secretion of proinflammatory cytokines, including interleukin (IL)-1β, IL2, IL6, IL8, IL10, tumor necrosis factor α (TNFα) and interferon γ (IFNγ; refs. 6, 9). The National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE v4.0) includes a grading system for assessing CRS related to antibody therapeutics. Lee and colleagues summarized their clinical experience with CAR-T cell therapy and proposed a new CRS grading system to minimize toxic reactions while maximizing the benefits of treatment for patients (9).

Based on the different degrees of toxic reactions generated after CAR-T cell therapy, CRS has been divided into four grades, and corresponding treatment measures have been recommended. However, therapeutic plasma exchange (TPE), which could remove autoantibodies and cytokines and may be beneficial for CRS therapy, has not been proposed as a treatment for CRS and has rarely been reported in the literature. Here, we report a case involving a patient with r/r ALL who developed life-threatening CRS after receiving an infusion of anti-CD19 CAR-T cells. Therefore, in combination with glucocorticoid therapy, TPE was performed daily for 3 consecutive days. Over the course of treatment, the patient's inflammatory factors nearly returned to baseline levels, and his CRS-related symptoms were relieved. The patient was eventually discharged in a normal condition.

A 23-year-old male Pakistani patient who had been diagnosed with B-cell ALL was treated with chemotherapy and achieved complete remission 7 years ago. Unfortunately, the tumor recurred in October 2017. The patient underwent two courses of conventional chemotherapy at a hospital in Pakistan, but the effects of this chemotherapy were poor, and the disease was not controlled. He developed r/r B-cell ALL and was admitted to the Department of Hematology at Tianjin First Center Hospital on December 24, 2017. The patient complained of fatigue and poor appetite. The results of his laboratory examinations were as follows: (i) His white blood cell (WBC), hemoglobin (Hb), and platelet (Plt) levels were 0.74 × 10⁹/L, 77 g/L, and 65 × 10⁹/L, respectively; (ii) A bone marrow (BM) smear showed that lymphoblast cells accounted for 91.5% of nonerythroid cells (NEC; Fig. 1A); (iii) Immunophenotyping via flow cytometry indicated that malignant cells accounted for approximately 91.79% of all examined cells and exhibited the expression pattern CD19⁺CD34⁺CD10⁺CD13^dimCD33^dimCD22^dimCD20⁻CD38⁻CD3⁻ (Fig. 1E); (iv) Genotyping via second-generation sequencing revealed IKZF1 and TERT mutations; (v) Conventional cytogenetic analysis demonstrated a normal 46, XY karyotype [20]; (vi) A liver function test performed on December 24, 2017, suggested liver damage (Table 1); (vii) Abdominal computed tomography (CT) showed hepatic edema with the possibility of infiltration by leukemic cells. Based on all of these findings, the patient was diagnosed with r/r B-cell ALL with liver damage and a high tumor burden and was treated with the VICP chemotherapy regimen (vindesine 4 mg, days 1 and 8; idarubicin 10 mg, days 1–3; cyclophosphamide 1,200 mg, day 1; prednisone 55 mg, days 1–14). After the patient had completed this course of chemotherapy, his liver function returned to normal, but there was no reduction in lymphoblast cells in the BM (Fig. 1B and F). Therefore, the patient was recruited into our CAR-T clinical trial for r/r ALL (ChiCTR-ONN-16009862).

Cruz and colleagues have reported the infusion of donor-derived CD19 CAR-T for B-cell malignancies relapsed after allogeneic stem cell transplant (10). Due to consanguineous marriage between his parents, the patient's HLA antigens completely matched his mother's. Due to his low T-cell counts, his mother's cells were used to construct allogeneic CAR-T cells after approval by the ethics committee of our hospital. Briefly, T lymphocytes from peripheral blood were sorted and amplified in vitro and were then transduced with lentivirus to generate CAR-T cells. The structural features of our CAR-T products include anti-CD19 scFv, a transmembrane domain, and a 4-1BB/CD3ζ signaling domain. The patient was pretreated with the FC chemotherapy regimen (fludarabine 50 mg, days 1–3; cyclophosphamide 400 mg, days 1–3) starting on January 6, 2018. An infusion of 1 × 10⁶/kg of engineered anti-CD19 CAR-T cells was then administered on January 10, 2018 (day 0). Six hours after this infusion of CAR-T cells, the patient developed fever with a body temperature of up to 39.8°C, which was accompanied by chills, muscle soreness, and knee joint pain. Antiallergic and antipyretic drugs were administered to control the fever. However, good improvement in the patient's condition was not achieved. Fever onset occurred 3 to 4 times a day, with a peak body temperature that reached 40.0°C; significant deterioration in the patient's general health condition and markedly increased levels of inflammatory cytokines were also observed (Fig. 2). Forty-eight hours after the CAR-T infusion, 40 mg of methylprednisolone was administered because the patient's peak body temperature remained high. Routine blood tests revealed low levels of WBC, Hb, Plt (Table 2), and globulin. Therefore, the patient received anti-infection therapy with meropenem, teicoplanin, and voriconazole and an intravenous infusion of immunoglobulin. Among peripheral blood cells, CAR-T cells accounted for 3.58% of T lymphocytes. In addition, the BM showed many damaged cells with cell enlargement, irregular shape, or no nucleus and significantly reduced numbers of immature lymphocytes (Fig. 1C and G). However, peak body temperature and fever onset frequency were not improved. The patient underwent a typical CRS reaction, with increases in fever, muscle soreness, and inflammatory cytokines. Referring to the report by Hay and colleagues (11), 4 mg/kg of IL6 antibody (tocilizumab) was administered on days 3 and 5, and 40 mg q12h of methylprednisolone was administered to control the severe CRS. To our disappointment, the patient's condition rapidly deteriorated on day 6. He developed apathy accompanied by muscle tremor, hypoxemia, and a body temperature of up to 40.8°C. His heart rate increased to 152/minute, his blood pressure (BP) dropped to 80/40 mmHg, his Plt count decreased to 45 × 10⁹/L, several petechiae appeared on his back and lower limbs, and he developed systemic edema. Laboratory results showed that the patient's inflammatory cytokine levels were extremely elevated and had peaked on day 5 (Fig. 2), accompanied by coagulation abnormalities (Table 2).The level of CAR-T cells in the patient's peripheral blood was reexamined and had reached 57.5%. Head CT ruled out the possibility of a cerebrovascular accident, whereas chest and abdomen CT showed large quantities of effusion. Given all of these findings, the patient was diagnosed with grade 3 CRS based on the aforementioned CRS grading system (9). He was treated with high-flow oxygen inhalation and continuous intravenous infusion of dopamine and norepinephrine to increase BP. The patient was then transferred to the intensive care unit and was administered dexamethasone 10 mg q6h and plasma exchange. The plasma exchange program has been approved by the ethics committee of our hospital. It was initiated with approximately 1 times the predicted plasma volume (estimated by the following formula: [0.065 × body weight (kg)] × [1 − hematocrit]) per session, using fresh frozen plasma as the replacement solution at the flow rate of 50 mL/minute. During the first exchange, the replaced plasma was dark yellow, turbid, and viscous. After 12 hours of plasma exchange, the patient regained consciousness; this development was accompanied by significantly decreased levels of inflammatory cytokines (Fig. 2). In this patient, plasma exchange was performed once a day for 3 consecutive days, and blood samples were obtained 12 hours after each plasma exchange to measure inflammatory cytokine levels. During the third exchange, the replaced plasma was clear and yellow. On the day after the third plasma exchange, the patient's symptoms gradually improved, his body temperature returned to normal, and his levels of inflammatory indicators markedly decreased; he was then transferred back to the general ward. In addition, the patient's WBC, Hb, and Plt levels began to increase, eventually returning to normal on day 18. Excitingly, a BM smear showed no lymphoblast cells (Fig. 1D). Although there was a small population of CD19⁺ suspicious cells, accounting for approximately 0.50% in the BM on day 28 (Fig. 1H), they were considered to be impurities, rather than cells after further analysis (Fig. 1I–L). Because there is no such kind of cell that can express all these markers. Therefore, minimal residual disease was considered to be negative on day 28. Moreover, CAR-T cells in the PB continued to be sustained at a high level of 25.3%. Trichosporon asahii was isolated from initial blood samples, but negative results for this organism were obtained when blood culture was reexamined after the administration of voriconazole. Multiple cytomegalovirus and Epstein–Barr virus tests were negative after the infusion of CAR-T cells.

Due to the infusion of allogeneic CAR-T cells, we have to differentiate between CRS and graft-versus-host disease (GVHD). GVHD is a specific immune reaction that results from the interaction between immunocompetent cells from the donor and immune-suppressed tissues in the recipients (12). Generally, acute GVHD occurs within 3 months after BM transplantation and is more common 3 to 4 weeks after transplantation. The main pathologic changes of acute GVHD are necrosis in the skin, liver, and digestive tract. In severe cases, it can cause extensive intestinal mucosal and skin shedding. The typical clinical manifestations of acute GVHD are rash, diarrhea, liver dysfunction, and fever. However, this patient's toxic reaction occurred on that day after the infusion with no rash, diarrhea, liver damage, or other related symptoms. The laboratory tests showed elevated lymphocytes, which were mainly CAR-T cells. In addition, because of the all-matched HLA antigens, the risk of GVHD was low. Taken together, the patient's toxic effect was considered to be CRS rather than GVHD.

As a promising treatment for malignancies, CAR-T therapy has gained increasing attention. However, accompanying toxicities and side effects have remained a concern. A better understanding of the unique toxicities associated with CAR-T therapy and optimal management approaches to maintain high levels of efficacy and safety can help advance this treatment modality.

CRS, a common and severe complication of CAR-T therapy, is associated with high levels of inflammatory markers and the release of various cytokines, including IL1β, IL2, IL6, IL8, IL10, TNFα, and IFNγ (6, 9, 13). Clinical features of CRS are manifold and can include high fever, chills, low BP, decreased cardiac output, hypoxia, pulmonary edema, liver and kidney dysfunction, abnormal coagulation, and/or neurologic disorders (3–5, 9, 14). Generally, CRS-related adverse events caused by immunotherapy are defined using CTCAE v4.0 criteria (15). With the development of relevant clinical trials, evaluation criteria for CRS after CAR-T therapy have been proposed by various research centers in recent years (4, 5, 9). Appropriate treatments have also been suggested based on CRS grade. For instance, mild CRS may be self-limiting, and antipyretic and supportive treatment may be required. However, severe CRS may require treatment based on anticytokine therapy, such as tocilizumab or etanercept and glucocorticoids (4, 5, 9). The intensity and duration of CRS are variable and may be associated with tumor burden and individual differences (5, 16). A series of trials involving treatment with second-generation anti-CD19 CAR-T cells for r/r ALL showed that 60% to 100% of patients developed different levels of CRS, with a severe condition observed for 2% to 43% of these patients (8). CRS can be well controlled via medication and supportive treatment in most patients. However, a few patients died of brain edema or multiple organ failure caused by CRS despite receiving routine treatment (7).

CRS can produce an excessive inflammatory response that leads to associated clinical symptoms that may be life-threatening. Excessive inflammatory factors may be controlled using extracorporeal blood purification techniques, such as high-volume hemofiltration, cascade hemofiltration, plasma exchange, and coupled plasma filtration adsorption. The main objective of these techniques is to selectively eliminate molecules of medium molecular weight, such as cytokines (17). The use of TPE to treat thyroid storm and pancreatitis has also been reported (18, 19). In this paper, we have described a patient with r/r ALL who developed severe, life-threatening CRS after an infusion of anti-CD19 CAR-T cells. After conventional treatment, the patient remained in extremely poor condition, with high levels of inflammatory factors. Therefore, he underwent TPE combined with glucocorticoid therapy. After completing three TPE cycles, the patient's levels of inflammatory factors were nearly normal, and his CRS-related symptoms were relieved. At 28 days after CAR-T cell infusion, no malignant cells were found in his BM. Currently, the patient is in complete remission (CR) and is preparing for allogeneic hematopoietic stem cell transplantation.

Although TPE is not included in CRS management guidelines, this case shows that plasma exchange is feasible in at least some patients with severe CRS. This type of TPE must be performed by experienced medical personnel because of the potential for challenging complications. Fortunately, no severe complications were observed in our patient. TPE is performed to clear cytokines in the plasma. Once threatening CRS arises, TPE can be an alternative therapeutic modality after CAR-T cell infusion.

No potential conflicts of interest were disclosed.

Conception and design: M. Zhao

Development of methodology: X. Xiao

Acquisition of data (provided animals, acquired and managed patients, provided facilities, etc.): X. Xiao, Q. Li, H. Zhang, J. Meng

Analysis and interpretation of data (e.g., statistical analysis, biostatistics, computational analysis): X. He

Writing, review, and/or revision of the manuscript: X. Xiao, X. He

Administrative, technical, or material support (i.e., reporting or organizing data, constructing databases): J. Meng, Y. Jiang

Study supervision: Q. Deng, J. Meng

This work was supported by grants from the National Natural Sciences Foundation of China (81400092; to M. Zhao), the Tianjin Key Natural Science Foundation (17JCZDJC35800 and 15JCQNJC45500; to M. Zhao), and the Tianjin Key Science and Technology Program (2015K215, 15KG134, and 16KG110; to M. Zhao), as well as Tianjin First Central Hospital. This work was also supported by the Ph.D. Candidate Research Innovation Fund of Nankai University (X. He).

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.