Theoretically required urinary flow during high-dose methotrexate infusion

Onconephrology: mitigation of renal injury in chemotherapy administration

PURPOSE OF REVIEW

Onconephrology was first coined as a name for the intersection of cancer medicine and nephrology in the early 2010s. It was recognized then that beyond and understanding of kidney physiology, a new generation of nephrologists skilled in both molecular biology and precision medicine were needed to deal with the challenges of emerging cancer therapies. Stem cell transplants, biologic agents, adjuvants blocking basic cellular signaling pathways, immunotherapy were found to promote novel anticancer outcomes, but also to pose new risks to the kidneys. The field rapidly overlapped with emerging expertise in vascular glomerular disease, glomerular disease, and the same biologic agents now applied to auto immune systemic and kidney diseases.

RECENT FINDINGS

Many categories of chemotherapeutic agents have been discovered to have adverse renal side effects. In this review, we address classic chemotherapeutic nephrotoxicity and oncologic clinical situations leading to acute kidney injury. We also review the frontiers of nephrotoxicity reported with cell cycle inhibitors, diverse classes of tyrosine kinase inhibitors, immune checkpoint inhibitors, chimeric antigen receptor T-cell therapy, anticancer vaccines, and thrombotic microangiopathies triggered by malignancy and chemotherapy. The aim will be to focus on published strategies to mitigate nephrotoxicity.

SUMMARY

As onconephrology expands into its own field, it gives birth to new subdisciplines. An understanding that patient populations want the benefits of chemotherapy without the renal (and other) systemic toxicities is emerging. A need to develop a new class of molecular and genetic experts in onconephrology to mitigate nephrotoxicity from chemotherapy is apparent and urgent.

Risk factors for delayed elimination of high-dose methotrexate in childhood acute lymphoblastic leukemia and lymphoma

High-dose methotrexate (HD-MTX) therapy is widely used in patients with acute lymphoblastic leukemia (ALL) and lymphoma. However, some patients experience delayed MTX elimination, which requires treatment suspension or dose reduction to avoid organ damage. This single-center retrospective analysis reviewed the clinical data of 88 children with ALL or non-Hodgkin lymphoma who received a total of 269 courses of HD-MTX therapy between April 2008 and April 2019. HD-MTX was defined as MTX administration at 2.0, 3.0, or 5.0 g/m² over a 24-h period, and delayed MTX elimination was defined as a serum MTX concentration ≥ 1.0 µmol/L at 48 h after the start of HD-MTX. Clinical factors were compared between courses with and without delayed MTX elimination. MTX elimination was delayed in 21 of the 269 courses (7.8%). Multivariate analysis showed that first HD-MTX course (OR 4.04), lower urine volume per BSA on the first day of HD-MTX administration (< 2,675 mL/m², OR 5.10), higher total bilirubin (> 0.5 mg/dL, OR 5.11), lower eGFR (< 136 mL/min/1.73 m², OR 3.90), higher dose of MTX(> 3.0 g/m², OR 10.8), and lower urine volume per BSA on the next day of starting HD-MTX (< 2,107 mL/m², OR 3.43) were independent risk factors for delayed MTX elimination.

Consensus Guideline for Use of Glucarpidase in Patients with High-Dose Methotrexate Induced Acute Kidney Injury and Delayed Methotrexate Clearance

An expert panel was convened to provide specific, expert consensus guidelines for the use of glucarpidase in patients who develop high‐dose methotrexate (HDMTX)‐induced nephrotoxicity and delayed methotrexate excretion. This guideline provides recommendations to identify the population of patients who would benefit from glucarpidase rescue by more precisely defining the absolute methotrexate concentrations associated with risk for severe or life‐threatening toxicity at several time points after the start of a HDMTX infusion.

Acute kidney injury due to high‐dose methotrexate (HDMTX) is a serious, life‐threatening toxicity that can occur in pediatric and adult patients. Glucarpidase is a treatment approved by the Food and Drug Administration for high methotrexate concentrations in the context of kidney dysfunction, but the guidelines for when to use it are unclear. An expert panel was convened to provide specific, expert consensus guidelines for the use of glucarpidase in patients who develop HDMTX‐induced nephrotoxicity and delayed methotrexate excretion. The guideline provides recommendations to identify the population of patients who would benefit from glucarpidase rescue by more precisely defining the absolute methotrexate concentrations associated with risk for severe or life‐threatening toxicity at several time points after the start of an HDMTX infusion. For an HDMTX infusion ≤24 hours, if the 36‐hour concentration is above 30 µM, 42‐hour concentration is above 10 µM, or 48‐hour concentration is above 5 µM and the serum creatinine is significantly elevated relative to the baseline measurement (indicative of HDMTX‐induced acute kidney injury), glucarpidase may be indicated. After a 36‐ to 42‐hour HDMTX infusion, glucarpidase may be indicated when the 48‐hour methotrexate concentration is above 5 µM. Administration of glucarpidase should optimally occur within 48–60 hours from the start of the HDMTX infusion, because life‐threatening toxicities may not be preventable beyond this time point.

Implications for Practice.

Glucarpidase is a rarely used medication that is less effective when given after more than 60 hours of exposure to high‐dose methotrexate, so predicting early which patients will need it is imperative. There are no currently available consensus guidelines for the use of this medication. The indication on the label does not give specific methotrexate concentrations above which it should be used. An international group of experts was convened to develop a consensus guideline that was specific and evidence‐based to identify the population of patients who would benefit from glucarpidase.

Extended duration of prehydration does not prevent nephrotoxicity or delayed drug elimination in high-dose methotrexate infusions: a prospectively randomized cross-over study

BACKGROUND

Alkalized hydration is used as supportive care to prevent renal toxicity during infusions with high-dose methotrexate (HDMTX). In children with acute lymphoblastic leukemia (ALL), the hydration is commonly initiated 4 hours before start of the methotrexate (MTX) infusion. To test if longer duration of prehydration would prevent MTX-induced renal toxicity, we preformed a randomized cross-over study comparing 12-4 hours of hydration before the infusion of HDMTX.

PROCEDURES

Children with ALL and non-Hodgkin lymphoma that were treated with infusions of HDMTX 5 or 8 g/m(2) were randomized to receive intravenous prehydration 12 or 4 hours before the first HDMTX infusion. Patients alternated between 12 and 4 hours of prehydration in the subsequent HDMTX infusions. Renal toxicity was defined as 50% increase in plasma creatinine after the HDMTX infusion. The plasma MTX concentration was measured during and after the HDMTX infusion to determine if the duration of prehydration would influence the systemic MTX clearance.

RESULTS

A total of 47 patients (224 HDMTX infusions) with a median age of 4.9 years were included in the study. The duration of prehydration had no effect on MTX induced renal toxicity that occurred in 18.5% of all HDMTX 5 g/m(2) infusions and in 40.0% of all HDMTX 8 g/m(2) infusions. Similar the duration of prehydration had no impact on the systemic clearance of MTX.

CONCLUSION

Extending prehydration beyond 4 hours does not reduce the risk of renal toxicity or delayed MTX clearance after infusions with HDMTX 5-8 g/m(2).

Rational administration schedule for high-dose methotrexate in patients with primary central nervous system lymphoma

Methotrexate (MTX) at a dose of ≥1 g/m(2) remains the most efficient treatment against primary central nervous system lymphoma (PCNSL), and is the most widely used drug in prospective clinical trials. MTX is a folate analog that inhibits dihydrofolate reductase, thereby blocking de novo purine synthesis. MTX as well as 7-hydroxy-MTX, its main metabolite in serum, are both eliminated by the kidneys. The elimination of MTX is prolonged in patients with renal impairment and third-space fluid collections, and in patients receiving concurrent non-steroidal antirheumatic drugs, benzimidazoles and sulfonamides, among others. Main adverse events with high-dose MTX include severe myelosuppression, renal dysfunction and stomatitis. Supportive measures such as rigorous hydration, urine alkalinization and careful drug monitoring with supplemental leucovorin rescue are crucial to avoid significant toxicity. Strategies to optimize clinical efficacy of high-dose MTX in patients with PCNSL include administration of 3 h instead of longer infusions, potentially supplemented with an additional intravenous MTX bolus, and maintaining MTX dose intensity over the course of four treatment cycles. Some pharmacological studies suggest that achieving an MTX area under the plasma concentration-time curve (AUC(MTX)) of between 1000 and 1100 μmol.h/L may improve clinical outcome, but clinical data are not conclusive at present. In this review, we analyze the impact of patient, lymphoma and pharmacokinetic variables on the antitumor activity of high-dose MTX in patients with PCNSL, summarize recommendations for daily clinical practice and give some suggestions for future trials.

Drugs and pharmaceuticals: management of intoxication and antidotes

The treatment of patients poisoned with drugs and pharmaceuticals can be quite challenging. Diverse exposure circumstances, varied clinical presentations, unique patient-specific factors, and inconsistent diagnostic and therapeutic infrastructure support, coupled with relatively few definitive antidotes, may complicate evaluation and management. The historical approach to poisoned patients (patient arousal, toxin elimination, and toxin identification) has given way to rigorous attention to the fundamental aspects of basic life support--airway management, oxygenation and ventilation, circulatory competence, thermoregulation, and substrate availability. Selected patients may benefit from methods to alter toxin pharmacokinetics to minimize systemic, target organ, or tissue compartment exposure (either by decreasing absorption or increasing elimination). These may include syrup of ipecac, orogastric lavage, activated single- or multi-dose charcoal, whole bowel irrigation, endoscopy and surgery, urinary alkalinization, saline diuresis, or extracorporeal methods (hemodialysis, charcoal hemoperfusion, continuous venovenous hemofiltration, and exchange transfusion). Pharmaceutical adjuncts and antidotes may be useful in toxicant-induced hyperthermias. In the context of analgesic, anti-inflammatory, anticholinergic, anticonvulsant, antihyperglycemic, antimicrobial, antineoplastic, cardiovascular, opioid, or sedative-hypnotic agents overdose, N-acetylcysteine, physostigmine, L-carnitine, dextrose, octreotide, pyridoxine, dexrazoxane, leucovorin, glucarpidase, atropine, calcium, digoxin-specific antibody fragments, glucagon, high-dose insulin euglycemia therapy, lipid emulsion, magnesium, sodium bicarbonate, naloxone, and flumazenil are specifically reviewed. In summary, patients generally benefit from aggressive support of vital functions, careful history and physical examination, specific laboratory analyses, a thoughtful consideration of the risks and benefits of decontamination and enhanced elimination, and the use of specific antidotes where warranted. Data supporting antidotes effectiveness vary considerably. Clinicians are encouraged to utilize consultation with regional poison centers or those with toxicology training to assist with diagnosis, management, and administration of antidotes, particularly in unfamiliar cases.

Resumption of high-dose methotrexate after methotrexate-induced nephrotoxicity and carboxypeptidase G2 use

PURPOSE

The successful resumption of high-dose methotrexate in a 13-year-old boy with recurrent anaplastic large-cell lymphoma (ALCL) who suffered renal dysfunction after a 24-hour infusion of high-dose methotrexate and required treatment with carboxypeptidase G(2) (CPDG(2) ) is described.

SUMMARY

A 13-year-old boy who had been diagnosed in 2001 with stage I ALCL was admitted to the hospital in February 2005 after he developed a smaller left axillary mass in the area of his original mass. Recurrent ALCL was diagnosed, and treatments were initiated based on branch K3 of the protocol published in the non-Hodgkin's lymphoma-Berlin-Frankfurt-Münster (NHL-BFM) trial 90. In the NHL-BFM 90 protocol, all AA and BB courses include high-dose methotrexate therapy, which consists of aggressive alkalinized hydration, methotrexate 5 g/m(2) given as an i.v. infusion over 24 hours, and leucovorin rescue. During course BB2, the boy's serum methotrexate values exceeded NHL-BFM goals at 36, 42, and 48 hours. Because the patient's elimination of methotrexate remained slow and his serum creatinine level remained above normal limits, CPDG(2) was obtained for the treatment of methotrexate toxicity. The patient tolerated the CPDG(2) without adverse effects, and the patient's serum methotrexate concentration decreased from 14.47 to 0.66 microM. The patient went on to complete six courses based on the protocol. High-dose methotrexate was resumed at 50% then 100% of the original dose. He is currently in remission on maintenance therapy.

CONCLUSION

A 13-year-old boy with recurrent ALCL had methotrexate-induced nephrotoxicity following high-dose methotrexate. The resultant delayed methotrexate clearance required the standard therapies as well as use of investigational CPDG(2). High-dose methotrexate was successfully resumed.

Occurrence and impact of unanticipated variation in intravenous methotrexate dosing

BACKGROUND

Studies using direct measurement suggest that the doses of up to 65% of drug infusions are outside industry standards. These preparation-associated errors occur despite routine safety procedures. As of April 5, 2006, the clinical impact of these errors had not been evaluated.

OBJECTIVE

To measure the occurrence and associated clinical outcomes of variations in intravenous methotrexate dosing.

METHODS

A prospective observational study was performed on 47 methotrexate infusions of 800 mg/m2 that were administered to 19 children with acute lymphoblastic leukemia. Serum methotrexate concentrations were measured at the end of the infusions, which were administered over 24 hours. The total methotrexate dose was determined by direct measurement of the concentration and the volume of each infusion.

RESULTS

Dosing errors greater than or equal to 10% occurred in 11 (23%) infusions and ranged from -61% to 55% of the ideal dose. Repeated measures regression analysis found the measured total methotrexate dose was not significantly associated with the serum methotrexate concentration (p = 0.58) or with clinical toxicities. The methotrexate dose administered over the last hours of infusion (p = 0.006) and the serum creatinine level at diagnosis (p = 0.05) were the most significant predictors of the methotrexate concentration. High methotrexate concentrations were significantly associated with increased hepatic aminotransferase levels; however, the degree of elevation was of limited clinical relevance.

CONCLUSIONS

While unexpected errors in drug dosing are more common than is suggested by other methods, the clinical impact observed in this model of methotrexate infusion was not demonstrably greater than medication errors described by other methods. Subsequent studies in this model of dosing error will require larger sample sizes, and other drugs should be evaluated.

Flow cytometric analysis of marrow cell kinetics in children treated with high-dose MTX and CF rescue

Normal marrow cell kinetics were studied by flow cytometry with computer analysis in 11 children with malignancies who received high-dose MTX followed by CF rescue. Nine children with hematological tumors in remission each received an infusion of MTX over 24 h, followed by delayed CF rescue. In 8 of the 9, an accumulation of cells in early to mid-S phase and a decrease of cells in G2/M phase were observed at 24-48 h after the beginning of the MTX infusion. At 144 h after MTX infusion this kinetic perturbation disappeared and the DNA histogram returned to the same state as before therapy. Two children who had malignant bone tumors without marrow infiltration each received an infusion of MTX over 6 h with early CF rescue following an initial IV injection of vincristine. They did not have any prominent perturbation of marrow cell kinetics after MTX exposure, except for a transient increase of cells in G2/M phase. These results confirm that with the high-dose MTX therapy described above for hematological malignancies the impairment of marrow cell kinetics was much more severe and was soon followed by complete recovery, whereas with the therapy for solid tumors the impairment was much slighter.