Intrathecal tocilizumab for immune-mediated central nervous system complication after haploidentical hematopoietic stem cell transplantation in children: Two case reports

Abstract

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective measure for the treatment of hematological disease. With the progress and wide use of allo-HSCT, post-transplant central nervous system complications (CNSC) have gotten more and more attention because of its poor prognosis and high mortality. Since there is no standard treatment for patients with immune-mediated CNSC currently, new treatments are needed to be developed urgently. Here, we attempted a novel therapy regimen of intrathecal tocilizumab injection in two pediatric patients with immune-mediated CNSC manifested as cytokine release syndrome (CRS) after haploidentical hematopoietic stem cell transplantation (halpo-HSCT). In the two patients, persistent seizure symptoms could not be resolved 7 h after intravenous tocilizumab, while the symptoms were controlled rapidly only 2 hours or 1 hour after the first intrathecal injection of tocilizumab. Moreover, the level of interleukin 6 in the cerebrospinal fluid returned to normal after the fifth intrathecal injection. Even more appealing, no acute or chronic adverse reactions were observed during injection and subsequent follow-up. In conclusion, intrathecal tocilizumab seems to be more rapid and effective than intravenous administration for immune-mediated CNSC manifested as CRS in haplo-HSCT recipients. We recommend this treatment modality for further investigation.

1. Introduction

Central nervous system complications (CNSC) are one of the most serious complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT), with an incidence rate of 8 %–42 % [1]. The most important triggers and risk factors are drug-, radiation-, and metabolic-related toxicity, infections (especially due to immunodeficiency), cerebrovascular and immune-mediated events [2]. Immune-mediated CNSC after allo-HSCT are rare, with a fatal overall mortality of 40 %–70 % [1]. In a large retrospective study with 1484 patients after allo-HSCT detected only 7 patients (0.5 %) developed an immune-mediated neuropathy following allo-HSCT [3]. Immune-mediated CNSC after allo-HSCT mediated by immune mechanisms, mainly manifests as the pathological infiltration of immune cells or humoral factors in the central nervous system (CNS) tissues, resulting in functional deficits of the nervous system [[3], [4], [5], [6]]. There is no optimal treatment for immune-mediated CNSC which mainly relies on immunosuppressive therapies based on a high-dose of glucocorticoid which is likely to result in a fatal infection. We are committed to finding another safe and effective way for the treatment of such patients.

CASE/CASE SERIES PRESENTATIONA: The clinical data and characteristics of the two pediatric patients were summarized in Table 1. This research was approved by the Institutional Ethics Committee and written consents were obtained from guardians. The treatment regimen was intrathecal (IT) injection of 10mg tocilizumab (TCZ, Chugai Pharma Manufacturing Co., Ltd.) diluted to 2 ml with normal saline over 10 min daily, until the symptoms of CNS were controlled and the level of cytokines interleukin-6 (IL-6) in Cerebrospinal fluid (CSF) returned to nomal. The vital signs were closely monitored induring and after the lumbar puncture. Each patient was diagnosed by a team of experts (a hematologist, neurologist, and pediatrist).

Table 1.

The basic information and clinical data of 2 patients.

	Case 1	Case 2
Gender	Female	Male
Age	9	4
Original disease	SAA	AML (MDS transformed)
The donor of the first haplo-HSCT	Old brother	Father
Type of transplantation	Haplo-HSCT (5/10)	Haplo-HSCT (5/10)
Preparative regimen	FLU 30 mg/m2·d −6∼-2d CTX 30 mg/kg·d −5∼-2d ATG 2.5 mg/kg·d −4∼-1d	Chidamide 10 mg Biw, for 3 weeks FLU 50 mg/m2·d −5∼-2d Bu 3.2 mg/kg·d −5∼-2d Ara-C 1.0 g/m2·d −5∼-2d
The dose of MNC and CD34+ cell	9.8 × 108/kg and 6.3 × 106/kg	9.60 × 108/kg and 9.4 × 106/kg
GvHD prophylaxis	PT/Cy	PT/Cy
The donor of the second haplo-HSCT	Father	Younger brother
Preparative regimen	TBI 2.5 Gy -1d FLU 40 mg/m2·d 4∼-2d CTX 40 mg/kg·d −4∼-2d BU 3.2 mg/kg·d −6∼-5d ALG 4 mg/kg·d −4∼-1d	TBI 4 Gy d −2∼-1d FLU 50 mg/m2 q12h −4∼-3d CTX 800 mg/m2 q12h −4∼-3d
The dose of MNC and CD34+ cell	15.55 × 108/kg and 8.99 × 106/kg	15.48 × 108/kg and 8.33 × 106/kg
GvHD prophylaxis	PT/Cy	PT/Cy
Information at the onset of CNS symptoms
WBC, neutrophil count ( × 109/L)	0.81; 0.64	1.18; 0.71
Hb (g/L)	116	115
Plt ( × 109/L)	46	79
Flow cytometry of CSF	Negative	Negative
Biochemistry of CSF: protein (g/L); glucose (mmol/L); chlorine (mmol/L);	0.49; 4.32; 125	0,31; 4.0; 129
Cerebrospinal fluid routine: Cell count ( × 106/L)	20	10
The level of IL-6 (pg/ml): CSF; serum	1680.16; 2276.25	576.25; 327.43
The concentration of CsA in the serum (ng/ml)	203	207
systemic acute GvHD	Skin II°, Liver II°	Skin II°, Liver I°
Additional treatment	Intravenous tocilizumab, methylprednisolone, and CTX; plasmapheresis	intrathecal dexamethasone; intravenous 25mg of rabbit anti-human thymocyte immunoglobulin
The information at the end of intrathecal tocilizumab
WBC, neutrophil count ( × 109/L)	3.88; 3.25	2.22; 1.66
Hb (g/L)	90	101
Plt ( × 109/L)	49	26
Biochemistry of CSF: protein (g/L); glucose (mmol/L); chlorine (mmol/L)	0.45; 3.15; 117	0.25; 2.9; 130
Cerebrospinal fluid routine: Cell count ( × 106/L);	8	5
The level of IL-6 in CSF (pg/ml)	0	0
systemic acute GvHD	Negative	Negative
Time of observation (month)	48	48

SAA, severe aplastic anaemia; AML, acute myeloid leukaemia; MDS, myelodysplastic syndromes; haplo-HSCT, haploidentical stem cell transplantation; GvHD, graft-versus-host disease; CNS, central nervous system; CSF, cerebrospinal fluid; FLU, fludarabine; CTX, cyclophosphamide; BU, busulfan; Ara-C, cytarabine; ALG, antilymphocyte immunoglobulin; ATG, antithymocyte globulin; TBI, total-body irradiation; PT/Cy, post transplantation cyclophosphamide; MNC, mononuclear cells; CsA, cyclosporine; WBC, white blood cell; Hb, hemoglobin; Plt, platelet.

Case 1 became febrile to 39.2 °C on day +8 after transplantation, the level of IL-6 in the serum was significantly increased from 354.95 pg/ml (day +8) to 581.09 pg/ml (day +10) (normal values: 0–7 pg/ml). The patient underwent blood cultures, urine cultures, chest X-ray, and other appropriate examination to rule out infectious etiology. After considering a diagnosis of acute graft-versus-host disease (aGvHD), she was treated with methylprednisolone (MP), TCZ and plasmapheresis. Neutrophil engraftment occurred on day +11, the body temperature returned to normal and the level of IL-6 had decreased to 80.46 pg/ml.

Seizures and coma occurred at 6 a.m. on day +12. The concentration of cyclosporine (CsA) and the level of IL-6 in the serum were 203 ng/ml (normal values: 100–200 ng/ml) and 2276.25 pg/ml, respectively. Brain magnetic resonance imaging (MRI) was not feasible because the patient couldn't cooperate. We performed a lumbar puncture under sedation for the diagnosis. The CSF pressure was as high as 160 mmH₂O (normal values: 40–100 mmH₂O). The level of IL-6 in CSF was 1680.16 pg/ml (normal values: 0–7 pg/ml). The white blood cell (WBC) count, glucose and chlorine in CSF were normal, while the protein level was slightly higher. 1, 3-β-D-glucan test (G experiments), Galactomannan antigen detection (GM experiments), ink staining, acid-fast staining, bacterial and fungal cultures, the quantitative real-time polymerase chain reaction measurement and metagenomic next-generation sequencing for CSF pathogenic microorganisms were negative, such as bacteria, viruses and fungi. After excluding other causes such as infection, drugs like cyclosporine, etc., we considered a diagnosis of immune-mediated CNSC manifested as cytokine release syndrome (CRS) based on the history (systemic aGvHD) and CSF analysis (significantly high level of IL-6 in CSF).

Despite the continuous infusion of diazepam, and intravenous 200 mg of TCZ at 10 a.m., seizures and the coma could not be resolved until 17 p.m. In consideration of the critical condition, we decided to administrate intrathecal 10mg of TCZ immediately in the absence of other better options in the afternoon. The level of IL-6 in CSF was rechecked again before intrathecal TCZ, and it had increased to 2353.89 pg/ml. Two hours after the intrathecal injection, the coma had recovered and seizures were controlled. Then we performed brain MRI which showed no abnormalities. The level of IL-6 in the serum significantly decreased on day +13 (63.99 pg/ml), but a grade II aGvHD in the patient's liver and skin appeared on the day, so MP (0.5mg/kg/d) and 200mg of cyclophosphamide were given intravenously for the systemic aGvHD. Considering the high level of IL-6 in CSF, 10mg of TCZ was given intrathecally daily for the immune-mediated CNSC. On day +16, the clinical symptoms were controlled, and the level of IL-6 in CSF had returned to normal, intrathecal TCZ was stopped. The liver aGvHD was completely controlled on day +22, and the dose of MP was gradually reduced and was eventually discontinued on day +30 (Fig. 1). The patient had another epileptic seizure on day +53, and was diagnosed with posterior reversible encephalopathy syndrome (PRES) according to the brain MRI, the CSF examination and the concentration of CsA in the serum. The CsA was immediately discontinued, and sirolimus was used to prevent GvHD. The epileptic seizure symptoms were gradually controlled. To date, the patient has been followed up for 48 months and does not show any CNS symptoms. During intrathecal tocilizumab and the subsequent follow-up, no early or late, CNS or systemic, and otherwise adverse reactions were observed.

Fig. 1.

Representation of laboratory parameters and treatment strategies in case 1.

Despite intravenous 140 mg of tocilizumab at 10 a.m. on day +12, epileptic seizures and coma could not be controlled until 17 p.m., and the level of IL-6 in CSF was still increasing. Nevertheless, 2 h after intrathecal 10mg of tocilizumab and 2.5 mg of dexamethasone, the coma had recovered and epileptic seizures were controlled. Then the lumbar puncture was given daily, the level of IL-6 in CSF significantly decreased. On day +16, the level of IL-6 in CSF had returned to normal, and intrathecal tocilizumab was stopped.

Case 2 developed liver and skin aGvHD on day +11 after allo-HSCT, and neutrophil engraftment occurred on the day. Seizures and coma appeared at 3 a.m. on day +12. Brain MRI was not feasible because the patient couldn't cooperate. The CSF pressure had increased slightly by 140 mmH₂O. The level of IL-6 in CSF was 576.25 pg/ml, the concentration of CsA in the serum was 207 ng/ml. After excluding other causes such as infection, drugs like cyclosporine, etc., we considered a diagnosis of immune-mediated CNSC manifested as CRS based on the symptoms of systemic aGvHD and CSF analysis. Seizures couldn't be controlled by intravenous diazepam and intravenous 160 mg of TCZ. Considering the critical condition, we decided to administrate intrathecal 10 mg of TCZ to control the symptom, and a systemic application of rabbit anti-human thymocyte immunoglobulin 25 mg to control the systemic aGvHD at the same time. Thankfully, his seizures were gradually controlled 1 h after intrathecal TCZ. Then 10 mg of TCZ was given intrathecally daily. On day +16, the level of IL-6 in CSF had returned to normal, and the liver and skin aGvHD were completely controlled, intrathecal TCZ was stopped. To date, the patient has been followed up for 48 months and is still in a clinical and imaging remission status.

DISCUSSION: Immune-mediated CNSC after allo-HSCT is mediated by immunological mechanisms. The main clinical manifestations are mental behavior abnormalities, seizures, immediate memory impairment, etc. In a few cases, brain MRI shows diffuse or focal white matter abnormalities, and CSF examination shows inflammatory infiltration [7]. Even so, immune-mediated CNSC is difficult for early recognition and diagnosis. The important measure for diagnosis remains a biopsy of the brain tissue. Due to the low platelet count and immunosuppressive status after transplantation, the pathological diagnosis based on a biopsy is difficult to make. When we consider immune-mediated CNSC, brain MRI and CSF should be examined, and other CNS complications should be excluded, such as infection, drug toxicity, disease infiltration, microvascular thrombosis, etc. At present, there are very few researches on the immune-mediated CNSC after allo-HSCT, mostly are the case reports [4,5,8].

Haplo‐HSCT with use of post‐transplant cyclophosphamide (PT/Cy) avoid the use of immunosuppressive drugs for approximately 72 hours, allowing for a potentially CRS. Severe CRS (>grade 3) is a life-threatening toxicity after haplo-HSCT [9]. In this report, after the failure of the first haplo-HSCT, both pediatric patients received a second haplo-HSCT from changing donors. They developed seizures at the time of neutrophil reconstruction. Because of the low platelets and high-dose of immunosuppressants given within a short period of time, the risk of a tissue biopsy was very high. Therefore, we chose the CSF examination and brain MRI with less trauma to define the diagnosis. We made the diagnose of immune-mediated CNSC for the following reasons: 1. The symptoms of epileptic seizures and coma; 2. The imperfect development of the blood-brain barrier in children leading to the high IL-6 level in peripheral easily entering into CNS, combined with IL-6 produced by CNS, resulted in significantly high level of IL-6 in CSF. 3. The history of systemic aGvHD; 4. Other possible reasons (such as infection, drug toxicity, disease infiltration, microvascular thrombosis, etc.) were excluded. Based on the above reasons, the seizures may be caused by the immunological mechanism called a cytokine storm. Although there was no evidence confirmed by the brain biopsy, the condition could still be diagnosed as immune-mediated CNSC manifested as CRS. Unfortunately, we didn't-test the lymphocyte subsets in CSF and peripheral blood in two children.

Immune-mediated CNSC after allo-HSCT mainly relies on immunosuppressive therapy. However, the two patients received haplo-HSCT twice in a short time combined with fatal damage to the immune system by immunosuppresssants, so the immunosuppressive therapy couldn't be the top priority. Intravenous TCZ has been shown to have a favorable impact on neuroinflammation (such as amyotrophic lateral sclerosis) [10,11], CNS toxicity caused by chimeric antigen receptor T-cell immunotherapy (CAR-T) cell induced CRS [12], refractory seizures or possible immunological reactions due to coronavirus disease 2019 (COVID-19) infection [13] and CRS subsequent to allo-HSCT [14], in which CSF barrier is disrupted. In our report, seizures couldn't be resolved rapidly after intravenous TCZ, considering the high IL-6 level, after abtaining written consents from guardians, we administrate intrathecal 10mg of TCZ in the absence of other better options. Seizures were well controlled after 2 h after intrathecal TCZ in case 1, while it only needs 1 h in case 2. Regrettably, so far, we haven't tried to administer intrathecal TCZ to treat the complication again because of no similar cases. However, it suggests that intrathecal TCZ may be more rapid and effective than intravenous administration for immune-mediated CNSC manifested as CRS after allo-HCST.

2. Conclusion

As we've seen, this is the first report of the application of intrathecal tocilizumab in the treatment of immune-mediated CNSC manifested as CRS after allo-HSCT. Both two children were cured and no adverse events were observed during injection and subsequent follow-up, indicating the convincing effectiveness and safety of this method. Even more compelling, the data was also presented at ASH 2018, which is the best proof of the innovation of this idea. However, the efficacy of tocilizumab may depend on the level of IL-6 in CSF, and the optimal intrathecal dose require further exploration.

CRediT authorship contribution statement

Ruirui Gui: Writing – review & editing, Writing – original draft, Methodology, Investigation, Formal analysis, Data curation. Zhen Li: Visualization, Software. Juan Wang: Validation, Software, Resources. Yingling Zu: Validation, Software. Binglei Zhang: Visualization, Software. Juanjuan Zhao: Software, Funding acquisition. Yongping Song: Validation, Investigation, Conceptualization. Jian Zhou: Writing – review & editing, Validation, Project administration, Conceptualization.

Ethics statement

Ethical approval was not required for the publication of this manuscript. The authors obtained informed consent from the patient.

Data availability statement

Data will be made available on request.

Funding

This study received no specific grants from any funding agency in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.