5-FU-induced acute leukoencephalopathy

Leukoencephalopathy with transient splenial lesions related to 5-fluorouracil or capecitabine

BACKGROUND

5-Fluorouracil (5-FU) and its oral prodrug capecitabine have been rarely but consistently associated with acute central nervous system toxicity, including transient leukoencephalopathies involving the splenium of the corpus callosum.

METHODS

We performed a retrospective search in the French Pharmacovigilance database (FPDB) (January 1985-July 2020) for adult patients affected by solid cancers who developed acute toxic leukoencephalopathies with splenial lesions following treatment with 5-FU or capecitabine. A comprehensive review of the literature helped to circumstantiate our findings.

RESULTS

Our research in the FPDB identified six patients who, within 3 days from their first cycle of 5-FU or capecitabine, developed acute neurological symptoms, including gait ataxia (n = 4), dysarthria (n = 3), dysmetria (n = 2), headache (n = 2), and confusion (n = 2). Brain magnetic resonance imaging (MRI) showed T2/FLAIR (fluid-attenuated inversion recovery) hyperintensities in the corpus callosum, with diffusion restriction and no contrast enhancement, generally accompanied by additional alterations in the bilateral supratentorial white matter (n = 5). All patients discontinued the agent supposedly responsible for the toxicity and experienced full recovery after a median of 8.5 days from symptom onset. Control MRI showed a progressive normalization of acute MRI abnormalities. Literature review identified 26 cases with similar clinical and paraclinical characteristics. A single patient from the literature resumed 5-FU at a lower dose, with no recurrent toxicity.

CONCLUSIONS

5-FU and capecitabine might be responsible for acute leukoencephalopathies with transient splenial lesions that are generally reversible upon drug discontinuation. Resuming the agent responsible for toxicity might be feasible in selected cases, after having excluded dihydropyrimidine dehydrogenase deficiency, if expected benefits outweigh the risks.

Disturbance of consciousness due to hyperammonemia and lactic acidosis during mFOLFOX6 regimen: Case report

INTRODUCTION

FOLFOX therapy is the main chemotherapy regimen for colorectal cancer. Peripheral neuropathy, hematotoxicity, and digestive symptoms are known to be the most frequent adverse events. Hyperammonemia and lactic acidosis rarely occur simultaneously during treatment with FOLFOX therapy; the number of case reports is limited worldwide. We report a case of disturbance of consciousness, considered to be caused by hyperammonemia and lactic acidosis that occurred during treatment with mFOLFOX6 therapy that was administered as postoperative adjuvant treatment for rectal cancer.

PATIENT CONCERNS

This case was of a 71-year-old man who had been receiving oral treatment for chronic kidney disease and diabetes mellitus. Laparoscopic low anterior resection and artificial anal construction surgery were performed for stage III rectal cancer. As adjuvant postoperative therapy, mFOLFOX6 therapy was started but was followed by a disturbance of consciousness.

DIAGNOSES

Results of the blood tests revealed notable hyperammonemia (ammonia level, 1,163 μg/dl) and lactic acidosis (pH 7.207; lactate, 17.56 mmol/L); however, imaging diagnosis did not reveal intracranial lesions that could cause disturbance of consciousness.

INTERVENTIONS

For hyperammonemia, branched-chain amino acid agents and Ringers solution supplementation were administered. For acidosis, 7% sodium hydrogen carbonate was administered as treatment.

OUTCOMES

The disturbance of consciousness improved within 12 hours of initiating the treatment, and the patient was discharged with no sequelae on 7th day after hospitalization.

CONCLUSION

In patients with chronic kidney disease, FOLFOX regimen may confer risks of hyperammonemia and lactic acidosis.

[A case of acute leukoencephalopathy induced by a combination of 5-fluorouracil and metronidazole]

We describe a 66-year-old woman who received folinic acid, leucovorin, fluorouracil and oxaliplatin for advanced rectal carcinoma. These drugs were initiated on day 1, and a pelvic abscess was identified on day 7. Piperacillin-tazobactam was initially administered, but was changed to ceftriaxone and metronidazole on day 14 on the basis of antimicrobial susceptibility testing. On the following day, the patient reported blindness, and MRI of the brain showed signal abnormalities in the splenium of the corpus callosum on DWI, suggestive of metronidazole encephalopathy. Although the total body exposure was 2 g, metronidazole was discontinued. The patient developed coma a few days later, and MRI of the brain on day 26 showed high signal intensity extensively involving the white matter in the cerebrum as well as the brainstem and cerebellum. She died 37 days after the initial administration of the chemotherapy. Pathological studies demonstrated decreased staining intensity in the myelin sheath and multiple vacuolar alterations, consistent with toxicity induced by metronidazole and fluorouracil. Care should be taken when administering a combination of these drugs, even if the total body exposure to each drug is limited.

Redox biology in normal cells and cancer: restoring function of the redox/Fyn/c-Cbl pathway in cancer cells offers new approaches to cancer treatment

This review discusses a unique discovery path starting with novel findings on redox regulation of precursor cell and signaling pathway function and identification of a new mechanism by which relatively small changes in redox status can control entire signaling networks that regulate self-renewal, differentiation, and survival. The pathway central to this work, the redox/Fyn/c-Cbl (RFC) pathway, converts small increases in oxidative status to pan-activation of the c-Cbl ubiquitin ligase, which controls multiple receptors and other proteins of central importance in precursor cell and cancer cell function. Integration of work on the RFC pathway with attempts to understand how treatment with systemic chemotherapy causes neurological problems led to the discovery that glioblastomas (GBMs) and basal-like breast cancers (BLBCs) inhibit c-Cbl function through altered utilization of the cytoskeletal regulators Cool-1/βpix and Cdc42, respectively. Inhibition of these proteins to restore normal c-Cbl function suppresses cancer cell division, increases sensitivity to chemotherapy, disrupts tumor-initiating cell (TIC) activity in GBMs and BLBCs, controls multiple critical TIC regulators, and also allows targeting of non-TICs. Moreover, these manipulations do not increase chemosensitivity or suppress division of nontransformed cells. Restoration of normal c-Cbl function also allows more effective harnessing of estrogen receptor-α (ERα)-independent activities of tamoxifen to activate the RFC pathway and target ERα-negative cancer cells. Our work thus provides a discovery strategy that reveals mechanisms and therapeutic targets that cannot be deduced by standard genetics analyses, which fail to reveal the metabolic information, isoform shifts, protein activation, protein complexes, and protein degradation critical to our discoveries.

TCF7L2 activation is required for myelin regeneration in 5-FU-induced demyelinating mice

Previous studies have shown that 5-FU (5-fluorouracil) could cause delayed myelin degeneration by inducing oligodendrocyte death.

5-Fluorouracil causes severe CNS demyelination by disruption of TCF7L2/HDAC1/HDAC2 complex in adolescent mice

Several studies have showed the anti-cancer efficacy of 5-FU (5-fluorouracil) on pediatric tumors. Although the delayed demyelination induced by 5-FU in adult patients has been reported, the effect of 5-FU on oligodendrocyte myelination in adolescence is still unknown. Here, we demonstrate that systemic administration with 5-FU leads to immediate demyelination in the central nervous system (CNS) of adolescent mice, which is mainly attributed to the death of OLs. Gene-chip microarray transcriptome analysis identifies that oligodendrocyte-specific factor TCF7L2 may be a toxic target of 5-FU-impaired myelination. 5-FU-decreased TCF7L2 results in disruption of the interaction between TCF7L2 and HDAC1/2. Inhibition of crucial myelination-promoting factors by 5-FU is more significantly antagonized by co-transfection of TCF7L2, HDAC1 and HDAC2 than TCF7L2 alone. Our findings reveal that 5-FU could acutely induce the severe myelin degeneration in adolescence and disruption of TCF7L2/HDAC1/HDAC2 complex is at least partially involved in 5-FU-induced demyelination.

Systemic 5-fluorouracil treatment causes a syndrome of delayed myelin destruction in the central nervous system

BACKGROUND

Cancer treatment with a variety of chemotherapeutic agents often is associated with delayed adverse neurological consequences. Despite their clinical importance, almost nothing is known about the basis for such effects. It is not even known whether the occurrence of delayed adverse effects requires exposure to multiple chemotherapeutic agents, the presence of both chemotherapeutic agents and the body's own response to cancer, prolonged damage to the blood-brain barrier, inflammation or other such changes. Nor are there any animal models that could enable the study of this important problem.

RESULTS

We found that clinically relevant concentrations of 5-fluorouracil (5-FU; a widely used chemotherapeutic agent) were toxic for both central nervous system (CNS) progenitor cells and non-dividing oligodendrocytes in vitro and in vivo. Short-term systemic administration of 5-FU caused both acute CNS damage and a syndrome of progressively worsening delayed damage to myelinated tracts of the CNS associated with altered transcriptional regulation in oligodendrocytes and extensive myelin pathology. Functional analysis also provided the first demonstration of delayed effects of chemotherapy on the latency of impulse conduction in the auditory system, offering the possibility of non-invasive analysis of myelin damage associated with cancer treatment.

CONCLUSIONS

Our studies demonstrate that systemic treatment with a single chemotherapeutic agent, 5-FU, is sufficient to cause a syndrome of delayed CNS damage and provide the first animal model of delayed damage to white-matter tracts of individuals treated with systemic chemotherapy. Unlike that caused by local irradiation, the degeneration caused by 5-FU treatment did not correlate with either chronic inflammation or extensive vascular damage and appears to represent a new class of delayed degenerative damage in the CNS.

Hyperammonemia encephalopathy: an important cause of neurological deterioration following chemotherapy

Idiopathic hyperammonemic encephalopathy is an uncommon but frequently fatal complication of chemotherapy. It is characterised by abrupt alteration in mental status with markedly elevated plasma ammonia levels in the absence of obvious liver disease or any other identifiable cause, and frequently results in intractable coma and death. It usually occurs in patients with haematologic malignancies during the period of neutropenia following cytoreductive therapy or bone marrow transplantation, and in solid organ malignancies treated with 5-fluorouracil. Although the aetiology of this syndrome is yet to be determined, it appears to be multi-factorial in nature. Optimal management remains to be formally established, and the critical step is increased awareness of the syndrome by measurement of plasma ammonium levels in patients with neurological symptoms, leading to early diagnosis and the prompt implementation of therapy.