Plasma and cerebrospinal fluid pharmacokinetics of nelarabine in nonhuman primates

Incidence and Clinical Presentation of Severe Neurotoxicity from Nelarabine in Patients with T-Cell Acute Lymphoblastic Leukemia

BACKGROUND

Nelarabine is a purine analog with demonstrated efficacy in the treatment of T-cell Lymphoblastic Leukemia and Lymphoma (T-ALL/LBL). Despite its efficacy and excellent blood-brain barrier penetration, it has a significant side effect profile which is namely concerning for neurotoxicity. Reported neurotoxicity has varied from mild peripheral neuropathy to debilitating grade 4 neurologic complications including Guillain-Barre like syndrome and myelopathy.

PATIENTS AND METHODS

We conducted a single centered, retrospective case series to study patients who developed severe neurotoxicity after receiving nelarabine as part of T-ALL treatment. One hundred thirty-five patients were identified. Thirteen patients were reviewed for severe neurotoxicity (defined as ≥grade 3), and of those five patients were deemed to have neurotoxicity secondary to nelarabine exposure.

RESULTS

Five patients (4%) developed severe neurotoxicity as manifested by Guillain-Barre like syndrome or myelopathy within a timeframe of eight to fifty-eight days from last nelarabine dose. Upon diagnosis, patients received formal neurologic evaluation by our neuro-oncology specialists including imaging, cerebrospinal fluid testing, and electromyography. Patients were treated with IVIG, and steroids upon diagnosis, but the majority of neuro-deficits were irreversible.

CONCLUSION

Our study shows that nelarabine is generally well-tolerated, and the incidence of severe neurotoxicity is rare. Given the potential risk of severe neurotoxicity, we propose capped dose of nelarabine 1000 mg/day, neurological assessment before subsequent dosing, and avoidance of simultaneous IT therapy during nelarabine administration.

Drug screen in iPSC-Neurons identifies nucleoside analogs as inhibitors of (G4C2)n expression in C9orf72 ALS/FTD

An intronic (G₄C₂)_n expansion in C9orf72 causes amyotrophic lateral sclerosis and frontotemporal dementia primarily through gain-of-function mechanisms: the accumulation of sense and antisense repeat RNA foci and dipeptide repeat (DPR) proteins (poly-GA/GP/GR/PA/PR) translated from repeat RNA. To therapeutically block this pathway, we screen a library of 1,430 approved drugs and known bioactive compounds in patient-derived induced pluripotent stem cell-derived neurons (iPSC-Neurons) for inhibitors of DPR expression. The clinically used guanosine/cytidine analogs decitabine, entecavir, and nelarabine reduce poly-GA/GP expression, with decitabine being the most potent. Hit compounds nearly abolish sense and antisense RNA foci and reduce expression of the repeat-containing nascent C9orf72 RNA transcript and its mature mRNA with minimal effects on global gene expression, suggesting that they specifically act on repeat transcription. Importantly, decitabine treatment reduces (G₄C₂)_n foci and DPRs in C9orf72 BAC transgenic mice. Our findings suggest that nucleoside analogs are a promising compound class for therapeutic development in C9orf72 repeat-expansion-associated disorders.

Central Nervous System Involvement in Adults with Acute Leukemia: Diagnosis, Prevention, and Management

PURPOSE OF REVIEW

Recent treatment advances in both acute myeloid leukemia and acute lymphoblastic leukemia have drastically improved outcomes for these diseases, but central nervous system (CNS) relapses still occur. Treatment of CNS disease can be challenging due to the impermeability of the blood-brain barrier to many systemic therapies.

RECENT FINDINGS

The diagnosis of CNS leukemia relies on assessment of clinical symptoms, cerebrospinal fluid sampling for conventional cytology and/or flow cytometry, and neuroimaging. While treatment of CNS leukemia with systemic or intrathecal chemotherapy and/or radiation can be curative in some patients, these modalities can also lead to serious toxicities. In the modern era, prophylaxis with intrathecal chemotherapy is the most important strategy to prevent CNS relapses in high risk patients. Accurate risk stratification tools and the use of risk-adapted prophylactic therapy are imperative to improving the outcomes of patients with acute leukemias and preventing the development of CNS leukemia.

Management of CNS Disease in Pediatric Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

The treatment of acute lymphoblastic leukemia (ALL) is one of the success stories of pediatric oncology, but challenges and questions remain, including the optimal approach to the treatment of central nervous system (CNS) leukemia. It is unclear why some children with ALL develop CNS leukemia and others do not, and there remains debate regarding optimal regimens for prophylaxis, upfront treatment, and the treatment of CNS relapses. These topics are especially important since both cranial radiation therapy (CRT) and intensive intrathecal therapy carry risks of both short- and long-term adverse effects. In this review, we aim to identify areas of ongoing debate on this topic, review the biology of CNS leukemia, and summarize clinical trial data that address some of these questions.

RECENT FINDINGS

Both retrospective and meta-analyses have demonstrated that few patients with ALL benefit from CRT as a component of CNS-directed treatment for de novo disease, allowing cooperative groups to greatly limit the number of patients undergoing CRT as part of their initial ALL regimens. More recent efforts are focusing on how best to assay for low levels of CNS disease at the time of diagnosis, as well as the biological drivers that may result in CNS leukemia in certain patients. Progress remains to be made in the identification and treatment of CNS leukemia in pediatric ALL. Advancements have occurred to limit the number of children undergoing CRT, but much has yet to be learned to better understand the biology of and risk factors for CNS leukemia, and novel approaches are required to approach CNS relapse of ALL.

Safety of nelarabine in adults with relapsed or refractory T-cell acute lymphoblastic leukemia/lymphoma

INTRODUCTION

T-cell acute lymphoblastic leukemia (T-ALL) and lymphoma (T-LBL) are aggressive hematological malignancies accounting for 15-20% of adult acute lymphoproliferative diseases. Treatment of relapsed/refractory (R/R) T-ALL/T-LBL is challenging with very few therapeutic options.

AREAS COVERED

This report provides a concise review on the efficacy and safety of nelarabine monotherapy in adults with R/R T-ALL and T-LBL.

EXPERT OPINION

Nelarabine is approved for the treatment of adults with R/R T-ALL/T-LBL in the setting of third or more line of therapy. Hematological and neurological toxicities are the most frequent adverse events. Grade 3 and 4 neutropenia and thrombocytopenia are common, however with treatment-related deaths accounting only for 1-2% of patients. Neurological toxicity is typically characterized by a reversible peripheral neuropathy, usually mild or moderate and without treatment delay. Other neurological (somnolence and depressed level of consciousness) or extra-neurological adverse events are uncommon and rarely severe. In conclusion, nelarabine is a well tolerated and effective salvage therapy in patients with R/R T-ALL/T-LBL and has acquired an important role as a bridge-therapy to allogeneic stem cell transplantation.

Nelarabine neurotoxicity with concurrent intrathecal chemotherapy: Case report and review of literature

Severe nelarabine neurotoxicity in a patient who received concurrent intrathecal (IT) chemotherapy is reported. A 37-year-old Caucasian woman with a history of T-cell lymphoblastic lymphoma was admitted for relapsed disease. She was originally treated with induction chemotherapy followed by an autologous transplant. She developed relapsed disease 10 months later with leukemic involvement. She was re-induced with nelarabine 1500 mg/m2 on days 1, 3, and 5 with 1 dose of IT cytarabine 100 mg on day 2 as central nervous system (CNS) prophylaxis. At the time of treatment, she was on continuous renal replacement therapy due to sequelae of tumor lysis syndrome (TLS). She tolerated therapy well, entered a complete remission, and recovered her renal function. She received a second cycle of nelarabine without additional IT prophylaxis one month later. A week after this second cycle, she noted numbness in her lower extremities. Predominantly sensory, though also motor and autonomic, peripheral neuropathy started in her feet, ascended proximally to the mid-thoracic region, and eventually included her distal upper extremities. A magnetic resonance imaging (MRI) of her spine demonstrated changes from C2 to C6 consistent with subacute combined degeneration. Nelarabine was felt to be the cause of her symptoms. Her neuropathy stabilized and showed slight improvement and ultimately received an unrelated, reduced-intensity allogeneic transplant while in complete remission, but relapsed disease 10 weeks later. She is currently being treated with best supportive care. To our knowledge, this is the first published case report of severe neurotoxicity caused by nelarabine in a patient who received concurrent IT chemotherapy.

High single-drug activity of nelarabine in relapsed T-lymphoblastic leukemia/lymphoma offers curative option with subsequent stem cell transplantation

Nelarabine, a purine analog with T-cell specific action, has been approved for relapsed/refractory T-cell acute lymphoblastic leukemia/lymphoma (ALL/LBL). This is a report of a single-arm phase 2 study conducted in adults (18-81 years of age) with relapsed/refractory T-ALL/LBL. After 1 or 2 cycles, 45 of 126 evaluable patients (36%) achieved complete remission (CR), 12 partial remission (10%), and 66 (52%) were refractory. One treatment-related death was observed, and 2 patients were withdrawn before evaluation. A total of 80% of the CR patients were transferred to stem cell transplantation (SCT). Overall survival was 24% at 1 year (11% at 6 years). After subsequent SCT in CR, survival was 31% and relapse-free survival 37% at 3 years. Transplantation-related mortality was 11%. Neurologic toxicities of grade I-IV/grade III-IV were observed in 13%/4% of the cycles and 16%/7% of the patients. This largest study so far with nelarabine in adults showed impressive single-drug activity in relapsed T-ALL/T-LBL. The drug was well tolerated, even in heavily pretreated patients. A high proportion of CR patients were transferred to SCT with low mortality but a high relapse rate. Exploration of nelarabine in earlier stages of relapse (eg, increasing minimal residual disease), in front-line therapy, and in combination is warranted.