Rechallenge With High-Dose Methotrexate After Treatment With Glucarpidase in Adult Patients With Lymphoma.

PURPOSE: Limited evidence exists regarding methotrexate (MTX) resumption after patients with lymphoma receive glucarpidase for toxic MTX levels and acute kidney injury (AKI). METHODS: This retrospective review included adults with lymphoma treated with glucarpidase after MTX at Mayo Clinic between January 31, 2020, and October 10, 2022. Descriptive statistics summarize patient characteristics and clinical outcomes. RESULTS: Of 11 patients treated with glucarpidase after MTX, seven (64%) were rechallenged with MTX. Indications for MTX rechallenge included confirmed CNS disease (n = 6, 86%) and intravascular lymphoma (n = 1, 14%). Compared with the nonrechallenged subgroup, before receiving MTX that required glucarpidase rescue, the rechallenged patients had lower median pretreatment serum creatinine (Scr; 0.7 v 1.2 mg/dL), and none had AKI with previous MTX doses, n = 0 (0%) versus n = 2 (50%). During the MTX dose requiring glucarpidase rescue, the rechallenged group had lower median peak Scr (1.26 v 3.32 mg/dL) and lower incidence of AKI stage III (n = 1 [14%] v n = 3 [75%]), and none of the rechallenged patients required renal replacement therapy (RRT; n = 0 [0%] v n = 1 [25%]). At the first rechallenge after glucarpidase administration, the median MTX dose reduction was 56% (range, 46%-75%), and the lowest used dose when prescribed according to each treatment protocol schedule was 1.5 g/m2. Two (29%) patients experienced AKI (n = 1 stage I, n = 1 stage II) after MTX rechallenge. Zero patients required RRT, and zero required another glucarpidase administration. Six (86%) patients completed all recommended MTX doses. CONCLUSION: In selected adults with lymphoma who required glucarpidase for toxic MTX levels after administration of high-dose MTX, resumption of MTX therapy at lower doses is safe. Patients selected for MTX resumption had experienced less severe AKI during the previous cycle compared with those not selected for MTX resumption.

Routine use of low-dose glucarpidase following high-dose methotrexate in adult patients with CNS lymphoma: an open-label, multi-center phase I study.

BACKGROUND: High-dose methotrexate (HD-MTX) has broad use in the treatment of central nervous system (CNS) malignancies but confers significant toxicity without inpatient hydration and monitoring. Glucarpidase is a bacterial recombinant enzyme dosed at 50 units (u)/kg, resulting in rapid systemic MTX clearance. The aim of this study was to demonstrate feasibility of low-dose glucarpidase to facilitate MTX clearance in patients with CNS lymphoma (CNSL). METHODS: Eight CNSL patients received HD-MTX 3 or 6 g/m2 and glucarpidase 2000 or 1000u 24 h later. Treatments repeated every 2 weeks up to 8 cycles. RESULTS: Fifty-five treatments were administered. Glucarpidase 2000u yielded > 95% reduction in plasma MTX within 15 min following 33/34 doses (97.1%) and glucarpidase 1000u yielded > 95% reduction following 15/20 doses (75%). Anti-glucarpidase antibodies developed in 4 patients and were associated with MTX rebound. In CSF, glucarpidase was not detected and MTX levels remained cytotoxic after 1 (3299.5 nmol/L, n = 8) and 6 h (1254.7 nmol/L, n = 7). Treatment was safe and well-tolerated. Radiographic responses in 6 of 8 patients (75%) were as expected following MTX-based therapy. CONCLUSIONS: This study demonstrates feasibility of planned-use low-dose glucarpidase for MTX clearance and supports the hypothesis that glucarpidase does not impact MTX efficacy in the CNS. CLINICAL TRIAL REGISTRATION: NCT03684980 (Registration date 26/09/2018).

Half-dose glucarpidase as efficient rescue for toxic methotrexate levels in patients with acute kidney injury.

PURPOSE: High-dose methotrexate (HDMTX)-associated acute kidney injury with delayed MTX clearance has been linked to an excess in MTX-induced toxicities. Glucarpidase is a recombinant enzyme that rapidly hydrolyzes MTX into non-toxic metabolites. The recommended dose of glucarpidase is 50 U/kg, which has never been formally established in a dose finding study in humans. Few case reports, mostly in children, suggest that lower doses of glucarpidase might be equally effective in lowering MTX levels. METHODS: Seven patients with toxic MTX plasma concentrations following HDMTX therapy were treated with half-dose glucarpidase (mean 25 U/kg, range 17-32 U/kg). MTX levels were measured immunologically as well as by liquid chromatography-mass spectrometry (LC-MS). Toxicities were assessed according to National Cancer Institute-Common Terminology Criteria for Adverse Events (CTCAE) v5.0. RESULTS: All patients experienced HDMTX-associated kidney injury (median increase in creatinine levels within 48 h after HDMTX initiation compared to baseline of 251%, range 80-455%) and showed toxic MTX plasma concentrations (range 3.1-182.4 µmol/L) before glucarpidase injection. The drug was administered 42-70 h after HDMTX initiation. Within one day after glucarpidase injection, MTX plasma concentrations decreased by ≥ 97.7% translating into levels of 0.02-2.03 µmol/L. MTX rebound was detected in plasma 42-73 h after glucarpidase initiation, but concentrations remained consistent at < 10 µmol/L. CONCLUSION: Half-dose glucarpidase seems to be effective in lowering MTX levels to concentrations manageable with continued intensified folinic acid rescue.

A second administration of glucarpidase in a different cycle of high-dose methotrexate: Is it safe and effective in adults?

INTRODUCTION: Methotrexate intoxication following high-dose methotrexate-induced acute kidney injury is a life-threatening complication. Glucarpidase can quickly reduce extracellular methotrexate to safe levels, but the effectiveness and safety of its use in different episodes of nephrotoxicity remain an unknown area. CASE REPORT: A 30-year-old male diagnosed with acute lymphoblastic T-cell lymphoma received methotrexate 5 g/m2 intravenous (IV) as part of the first consolidation cycle. On Consolidation 3, he restarted methotrexate at a dose of 3 g/m2 IV showing slow methotrexate elimination, associated myelosuppression, and hepatic toxicity. Glucarpidase was administered (total dose of 2000 International Units (IU)). No adverse events were observed, and his renal function returned to normal. One hundred and six days later, he was diagnosed with leptomeningeal and cerebellar relapse and treatment with methotrexate 3,5 g/m2 IV day 1 and cytosine arabinoside (Ara-C) 2 g/m2 IV twice per day days 1, 3, and 5 was started. At 36 h from methotrexate infusion, serum creatinine increased up to 1.89 mg/dL and methotrexate concentration was 100 µmol/L.Management and Outcome: Ara-C was suspended, and a second administration of glucarpidase (2000 IU) was dispensed. No adverse events were noticed, methotrexate levels decreased and renal function progressively improved, recovering completely three weeks later. DISCUSSION: The effectiveness and safety of the use of glucarpidase in different episodes of nephrotoxicity remain an unknown area, and the rate and consequences of antiglucarpidase antibody formation remain poorly understood. This case report is, to our knowledge, the first case of a second administration of glucarpidase in a different cycle of high-dose methotrexate in an adult patient.

Successful Treatment of Delayed Methotrexate Clearance Using Glucarpidase Dosed on Ideal Body Weight in Obese Patients.

Delayed methotrexate (MTX) elimination after treatment with high-dose (HD) MTX may result in life-threatening toxicities as well as acute kidney injury (AKI). Treatment includes administration of glucarpidase, an enzyme that rapidly inactivates MTX. Dosing of glucarpidase is based on body weight; however, recommendations for dosage adjustments in obese patients are lacking. We describe three obese adult patients (body mass index [BMI] range 31-43 kg/m2 ) who received HD-MTX following all precautions for its treatment. Although peak MTX concentrations were within the expected range (308-368 µmol/L), MTX concentrations after 24 hours or later were markedly increased (97, 52, and 19 µmol/L, respectively). Two patients experienced AKI. After a single intravenous dose of glucarpidase 4000 units (50 units/kg on the basis of ideal body weight [IBW]) was administered to each patient 38, 46, and 60 hours, respectively, after the start of MTX, MTX concentrations dropped quickly to 1.37, 0.07, and 0.03 µmol/L, respectively, and further decreased steadily. Over time, clinical status and renal function improved in all patients. Glucarpidase is a highly hydrophilic molecule with a volume of distribution of 3.6 L, representing the intravascular volume of an adult. Therefore, we used IBW for glucarpidase dose calculations, allowing us to reduce the dose that would have been determined by using total body weight. This approach resulted in a rapid decrease of MTX serum concentrations and may reduce treatment costs of this highly expensive drug.

Production of "biobetter" glucarpidase variants to improve drug detoxification and antibody directed enzyme prodrug therapy for cancer treatment.

Recombinant glucarpidase (formerly: Carboxypeptidase G2, CPG2) is used in Antibody Directed Enzyme Prodrug Therapy (ADEPT) for the treatment of cancer. In common with many protein therapeutics, glucarpidase has a relatively short half-life in serum and, due to the need for the repeated cycles of the ADEPT, its bioavailability may be further diminished by neutralizing antibodies produced by patients. PEGylation and fusion with human serum albumin (HSA) are two approaches that are commonly employed to increase the residency time of protein therapeutics in blood, and also to increase the half-lives of the proteins in vivo. To address this stability and the immunogenicity problems, 'biobetter' glucarpidase variants, mono-PEGylated glucarpidase, and HSA fused glucarpidase by genetic fusion with albumin, were produced. Biochemical and bioactivity analyses, including anti-proliferation, bioassays, circular dichroism, and in vitro stability using human blood serum and immunoassays, demonstrated that the functional activities of the designed glucarpidase conjugates were maintained. The immunotoxicity studies indicated that the PEGylated glucarpidase did not significantly induce T-cell proliferation, suggesting that glucarpidase epitopes were masked by the PEG moiety. However, free glucarpidase and HSA-glucarpidase significantly increased T-cell proliferation compared with the negative control. In the latter case, this might be due to the type of expression system used or due to trace impurities associated with the highly purified (99.99%) recombinant HSA-glucarpidase. Both PEGylated glucarpidase and HAS-glucarpidase exhibit more stability in human serum and were more resistant to key human proteases relative to native glucarpidase. To our knowledge, this study is the first to report stable and less immunogenic glucarpidase variants produced by PEGylation and fusion with HSA. The results suggest that they may have better efficacy in drug detoxification and ADEPT, thereby improving this cancer treatment strategy.

Therapeutic Drug Monitoring of Methotrexate in Plasma Using Ultra High-Performance Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry: Necessary After Administration of Glucarpidase in Methotrexate Intoxications.

High-dose methotrexate (HD-MTX) is used to treat a variety of cancers. In all patients receiving HD-MTX, plasma MTX levels are monitored mainly to anticipate rescue therapy to prevent adverse events. We present 2 children treated with HD-MTX and afterward treated with glucarpidase at different time-points after their HD-MTX infusions. After the administration of glucarpidase, a nontoxic metabolite of MTX cross-reacts with MTX in the standard immunoassay (Abbott Diagnostics, Hoofddorp, the Netherlands) resulting in an artificially elevated MTX level. An artificially elevated MTX level results in unnecessarily long folinic acid administration, which decreases the effectivity of MTX. This grand round highlights the importance of measuring plasma MTX levels after the administration of glucarpidase with an ultra high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry method instead of with an immunoassay.

Treatment of two cases on the same day of intrathecal methotrexate overdose using cerebrospinal fluid exchange and intrathecal instillation of carboxypeptidase-G2.

BACKGROUND: Two 14-year old boys with acute lymphocytic leukemia were treated according to the NOPHO-ALL-08 protocol with intrathecal methotrexate (MTX) on the same day. Due to a preparation error in the hospital pharmacy, they were both given 240 mg of MTX instead of the prescribed 12 mg. Treatment (or methods): Both patients developed acute neurotoxicity with confusion, pain and seizures. Intravenous dexamethasone and folinic acid (leucovorin) was given. Exchange of cerebrospinal fluid was performed. Intrathecal glucarpidase (carboxypeptidase-G2) was administered after 11 h. RESULTS: One patient developed a toxic arachnoiditis. Three years after the incident, one patient has no neurological or neuropsychological sequelae after the overdose, while the other reports some loss of short-term memory. CONCLUSION: Fast recognition and treatment of intrathecal MTX overdose is critical to survival and outcome. Efforts to prevent such overdoses are of vital importance.

Comparable efficacy with varying dosages of glucarpidase in pediatric oncology patients.

BACKGROUND: Glucarpidase rapidly reduces methotrexate plasma concentrations in patients experiencing methotrexate-induced renal dysfunction. Debate exists regarding the role of glucarpidase in therapy given its high cost. The use of reduced-dose glucarpidase has been reported, and may allow more institutions to supply this drug to their patients. This report explores the relationship between glucarpidase dosage and patient outcomes in pediatric oncology patients. METHODS: The authors evaluated data from 26 patients who received glucarpidase after high-dose methotrexate. Decrease in plasma methotrexate concentrations and time to renal recovery were evaluated for an association with glucarpidase dosage, which ranged from 13 to 90 units/kg. RESULTS: No significant relationship was found between glucarpidase dosage (units/kg) and percent decrease in methotrexate plasma concentrations measured by TDx (P > 0.1) or HPLC (P > 0.5). Patients who received glucarpidase dosages <50 units/kg had a median percent reduction in methotrexate plasma concentration of 99.4% (range, 98-100) measured by HPLC compared to a median percent reduction of 99.4% (range, 77.2-100) in patients who received ≥50 units/kg. Time to SCr recovery was not related to glucarpidase dosage (P > 0.8). CONCLUSIONS: The efficacy of glucarpidase in the treatment of HDMTX-induced kidney injury was not dosage-dependent in this retrospective analysis of pediatric oncology patients.

Efficacy of glucarpidase (carboxypeptidase g2) in patients with acute kidney injury after high-dose methotrexate therapy.

STUDY OBJECTIVE: Because the incidence rate of renal impairment is 2-10% for patients treated with high-dose methotrexate and renal impairment develops in 0-12.4% of patients treated for osteosarcoma, we sought to evaluate the efficacy of glucarpidase, a recently approved drug that rapidly hydrolyzes methotrexate to inactive metabolites, which allows for nonrenal clearance in patients with delayed renal methotrexate elimination. DESIGN: Pooled analysis of efficacy data from four multicenter single-arm compassionate-use clinical trials using protocols from 1993 to 2007. PATIENTS: Of 476 patients with renal toxicity and delayed methotrexate elimination who were treated with intravenous glucarpidase for rescue after high-dose methotrexate, 169 patients had at least one preglucarpidase (baseline) plasma methotrexate concentration greater than 1 µmol/L and one postglucarpidase methotrexate concentration measurement by high-performance liquid chromatography and were included in the efficacy analysis; renal recovery was assessed in 436 patients who had at least one recorded preglucarpidase and postglucarpidase serum creatinine concentration measurement. MEASUREMENTS AND MAIN RESULTS: Efficacy was defined as rapid and sustained clinically important reduction (RSCIR) in plasma methotrexate concentration, with a concentration of 1 µmol/L or lower at all postglucarpidase determinations. Median age of efficacy-evaluable patients was 20 years (range 5 weeks-84 years). Osteosarcoma (36%), non-Hodgkin lymphoma (27%), and acute lymphoblastic leukemia (20%) were the most frequent underlying diagnoses. Median preglucarpidase serum methotrexate was 11.7 µmol/L. At the first (median 15 minutes) through the last (median 40 hours) postglucarpidase measurement, plasma methotrexate concentrations demonstrated consistent 99% median reduction. RSCIR was achieved by 83 (59%) of 140 patients. A total of 64% of patients with renal impairment greater than or equal to Common Terminology Criteria for Adverse Events grade 2 recovered to grade 0 or 1 at a median of 12.5 days after glucarpidase administration. CONCLUSION: Glucarpidase caused a clinically important 99% or greater sustained reduction of serum methotrexate levels and provided noninvasive rescue from methotrexate toxicity in renally impaired patients.