Acute myelogenous leukemia (AML) is one of the most lethal cancers, lacking a definitive curative therapy due to essential constraints related to the toxicity and efficacy of conventional treatments. This study explores the co-adjuvant potential of Lippia alba essential oils (EO) for enhancing the effectiveness and selectivity of two chemotherapy agents (cytarabine and clofarabine) against AML cells. EO derived from L. alba citral chemotype were produced using optimized and standardized environmental and extraction protocols. Rational fractionation techniques were employed to yield bioactive terpene-enriched fractions, guided by relative chemical composition and cytotoxic analysis. Pharmacological interactions were established between these fractions and cytarabine and clofarabine. The study comprehensively evaluated the cytotoxic, genotoxic, oxidative stress, and cell death phenotypes induced by therapies across AML (DA-3ER/GM/EVI1+) cells. The fraction rich in citral (F2) exhibited synergistic pharmacological interactions with the studied chemotherapies, intensifying their selective cytotoxic, genotoxic, and pro-oxidant effects. This shift favored transitioning from necrosis to a programmed cell death phenotype (apoptotic). The F2-clofarabine combination demonstrated remarkable synergistic anti-leukemic performance while preserving cell integrity in healthy cells. The observed selective antiproliferative effects may be attributed to the potential dual prooxidant/antioxidant behavior of citral in L. alba EO.

The Japan Children\'s Cancer Group Relapsed Acute Lymphoblastic Leukemia (ALL) Committee conducted a prospective observational study (ALL-R14) to explore promising reinduction therapy regimens for relapsed ALL to investigate in future trials. In Japan, clofarabine- and bortezomib-based regimens were of interest since they were newly introduced for ALL in the study period (2015-2018). Seventy-five pediatric patients were enrolled in total. The 2-year event-free/overall survival rates in patients with first (n = 59) or second (n = 11) relapse were 40.1% (95% confidence interval [CI]: 25.5-52.3%)/66.3% (95% CI 52.3-77.0%) and 34.1% (95% CI 9.1-61.6%)/62.3% (95% CI 27.7-84.0%), respectively. Clofarabine- or bortezomib-based regimens were used only in patients with high-risk disease. The first reinduction therapy used in the 41 patients with early or multiple relapsed B-cell precursor ALL was clofarabine in 7 patients and bortezomib in 9 patients. The odds ratio for reinduction failure risk with a clofarabine- or bortezomib-based regimen compared with other regimens was 9.0 (95% CI 0.9-86.4, P = 0.057) or 1.9 (95% CI 0.4-8.7, P = 0.42), respectively. Thus, clofarabine- or bortezomib-based regimens had no obvious advantage as reinduction therapy for relapsed ALL in children.

OBJECTIVE: ClFdA is a second-generation antineoplastic agent that has demonstrated significant anticancer activity, particularly against acute lymphoblastic leukemia and has been shown to have radiosensitizing activity. The aim of the study was to explore the genotoxic, cytotoxic and radiosensitizing effects of clofarabine (ClFdA) on bone marrow cells (BMCs), normoblasts and leukocytes of mice in vivo.
METHODS: Cytotoxicity was determined by the reduction in reticulocytes (RET), and genotoxicity was determined by the induction of micronucleated reticulocytes (MN-RET) in the peripheral blood and by DNA break induction in leukocytes determined by single-cell gel electrophoresis (SCGE). The radiosensitizing capacity of ClFdA was determined in leukocytes and BMCs by SCGE.
RESULTS: Two mechanisms of MN-RET induction were identified according to the antecedents, that could be due to inhibition of DNA synthesis and demethylation of G-C regions, and subsequent chromosome fragility. ClFdA cytotoxicity causes two contiguous peaks, an early peak that seems to inhibit MN-RET induction and a second peak that seems to be caused by ribonucleotide reductase (RR) and/or DNA synthesis inhibitions. ClFdA induced early DNA damage in noncycling leukocytes, and also radiosensitizes leukocytes immediately after treatment. ClFdA-ionizing radiation (IR) causes two time-dependent episodes of DNA damage, the latest after 80 min triggers a major breakage of DNA. In terms of the number of damaged cells, leukocytes and BMCs are similarly sensitive to ionizing radiation; BMCs are slightly more sensitive than leukocytes to ClFdA, but BMCs are doubly sensitive to combined treatment.
CONCLUSIONS: ClFdA causes early DNA damage and radiosensitivity in non-proliferating leukocytes, which rules out the most favored hypotheses of the participation of RR and DNA polymerase inhibition.

The oncogenesis and development of glioblastoma multiforme have been linked to glycosylation modifications, which are common post-translational protein modifications. Abnormal glycosyltransferase development leads to irregular glycosylation patterns, which hold clinical significance for GB prognosis. By utilizing both single-cell and bulk data, we developed a scoring system to assess glycosylation levels in GB. Moreover, a glycosylation-based signature was created to predict GB outcomes and therapy responsiveness. The study led to the development of an glyco-model incorporating nine key genes. This risk assessment tool effectively stratified GB patients into two distinct groups. Extensive validation through ROC analysis, RMST, and Kaplan-Meier (KM) survival analysis emphasized the model\'s robust predictive capabilities. Additionally, a nomogram was constructed to predict survival rates at specific time intervals. The research revealed substantial disparities in immune cell infiltration between low-risk and high-risk groups, characterized by differences in immune cell abundance and elevated immune scores. Notably, the glyco-model predicted diverse responses to immune checkpoint inhibitors and drug therapies, with high-risk groups exhibiting a preference for immune checkpoint inhibitors and demonstrated superior responses to drug treatments. Furthermore, the study identified two potential drug targets and utilized Connectivity Map analysis to pinpoint promising therapeutic agents. Clofarabine and YM155 were identified as potent candidates for the treatment of high-risk GB. Our well-crafted glyco-model effectively discriminates patients by calculating the risk score, accurately predicting GB outcomes, and significantly enhancing prognostic assessment while identifying novel immunotherapeutic and chemotherapeutic strategies for GB treatment.

Current standard-of-care systemic therapy options for locally advanced and metastatic bladder cancer (BC), which are predominantly based on cisplatin-gemcitabine combinations, are limited by significant treatment failure rates and frailty-based patient ineligibility. We previously addressed the urgent clinical need for better-tolerated BC therapeutic strategies using a drug screening approach, which identified outstanding antineoplastic activity of clofarabine in preclinical models of BC. To further assess clofarabine as a potential BC therapy component, we conducted head-to-head comparisons of responses to clofarabine versus gemcitabine in preclinical in vitro and in vivo models of BC, complemented by in silico analyses. In vitro data suggest a distinct correlation between the two antimetabolites, with higher cytotoxicity of gemcitabine, especially against several nonmalignant cell types, including keratinocytes and endothelial cells. Accordingly, tolerance of clofarabine (oral or intraperitoneal application) was distinctly better than for gemcitabine (intraperitoneal) in patient-derived xenograft models of BC. Clofarabine also exhibited distinctly superior anticancer efficacy, even at dosing regimens optimized for gemcitabine. Neither complete remission nor cure, both of which were observed with clofarabine, were achieved with any tolerable gemcitabine regimen. Taken together, our findings demonstrate that clofarabine has a better therapeutic window than gemcitabine, further emphasizing its potential as a candidate for drug repurposing in BC. PATIENT SUMMARY: We compared the anticancer activity of clofarabine, a drug used for treatment of leukemia but not bladder cancer, and gemcitabine, a drug currently used for chemotherapy against bladder cancer. Using cell cultures and mouse models, we found that clofarabine was better tolerated and more efficacious than gemcitabine, and even cured implanted tumors in mouse models. Our results suggest that clofarabine, alone or in combination schemes, might be superior to gemcitabine for the treatment of bladder cancer.

BACKGROUND: We recently reported results of the prospective, open-label HOVON-100 trial in 334 adult patients with acute lymphoblastic leukemia (ALL) randomized to first-line treatment with or without clofarabine (CLO). No improvement of event-free survival (EFS) was observed, while a higher proportion of patients receiving CLO obtained minimal residual disease (MRD) negativity.
OBJECTIVE: In order to investigate the effects of CLO in more depth, two multi-state models were developed to identify why CLO did not show a long-term survival benefit despite more MRD-negativity.
METHODS: The first model evaluated the effect of CLO on going off-protocol (not due to refractory disease/relapse, completion or death) as a proxy of severe treatment-related toxicity, while the second model evaluated the effect of CLO on obtaining MRD negativity. The subsequent impact of these intermediate events on death or relapsed/refractory disease was assessed in both models.
RESULTS: Overall, patients receiving CLO went off-protocol more frequently than control patients (35/168 [21%] vs. 18/166 [11%], p = 0.019; HR 2.00 [1.13-3.52], p = 0.02), especially during maintenance (13/44 [30%] vs. 6/56 [11%]; HR 2.85 [95%CI 1.08-7.50], p = 0.035). Going off-protocol was, however, not associated with more relapse or death. Patients in the CLO arm showed a trend towards an increased rate of MRD-negativity compared with control patients (HR MRD-negativity: 1.35 [0.95-1.91], p = 0.10), which did not translate into a significant survival benefit.
CONCLUSIONS: We conclude that the intermediate states, i.e., going off-protocol and MRD-negativity, were affected by adding CLO, but these transitions were not associated with subsequent survival estimates, suggesting relatively modest antileukemic activity in ALL.

OBJECTIVE: Clofarabine is used to treat acute lymphoblastic leukaemia, but evidence of its safety and effectiveness in Japanese patients is limited. We evaluated the safety and effectiveness of clofarabine in patients with relapsed/refractory acute lymphoblastic leukaemia in real-world clinical practice in Japan.
METHODS: An observational, multicenter, post-marketing, all-case surveillance was conducted for safety. Effectiveness analyses were conducted in patients aged ≤21 years and those treated with clofarabine monotherapy and combination therapy (clofarabine plus etoposide and cyclophosphamide).
RESULTS: In the all-case survey, 260 of 264 registered patients were eligible for safety analysis. Among the 225 patients eligible for effectiveness analysis, 139 were aged ≤21 years. For monotherapy and combination therapy, 20/31 and 34/88 patients were eligible, respectively. In the all-case survey, the median age was 16.0 years, and 47.7% of patients were <15 years old. Adverse drug reaction incidence was 83.5% and the most common were hematologic toxicities. The best overall response rates in the population aged ≤21 years were complete remission, 29.7%; complete remission without platelet recovery, 7.3% and partial remission, 10.9%. The rest (52.2%) were classified as ineffective. The sum of complete remission, complete remission without platelet recovery and partial remission rates (effectiveness rate) was 47.8% (66/138 patients). The effectiveness rates in the monotherapy and combination therapy surveys were 10.0% (2/20 patients) and 58.8% (20/34 patients), respectively.
CONCLUSIONS: These post-marketing surveys provide real-world evidence of the safety and effectiveness of clofarabine regimens, including monotherapy and combination therapy in Japanese patients with relapsed/refractory acute lymphoblastic leukaemia. The safety and effectiveness profiles were comparable with those of previous prospective studies.

Over 50% of patients with systemic LCH are not cured with front-line therapies, and data to guide salvage options are limited. We describe 58 patients with LCH who were treated with clofarabine. Clofarabine monotherapy was active against LCH in this cohort, including heavily pretreated patients with a systemic objective response rate of 92.6%, higher in children (93.8%) than adults (83.3%). BRAFV600E+ variant allele frequency in peripheral blood is correlated with clinical responses. Prospective multicentre trials are warranted to determine optimal dosing, long-term efficacy, late toxicities, relative cost and patient-reported outcomes of clofarabine compared to alternative LCH salvage therapy strategies.

Acute myeloid leukemia patients with induction failure or relapsed refractory disease have minimal chance of achieving remission with subsequent treatments. Several trials have shown the feasibility of clofarabine-based conditioning in allogeneic stem cell transplants (allo-HSCT) for non-remission AML patients. Pre-transplant conditioning with clofarabine followed by reduced-intensity allo-HSCT has also demonstrated a potential benefit in those patients with human leukocyte antigen (HLA)-identical donors, but it is not commonly used in haploidentical and mismatched transplants. In this case report, we describe our experience of seven cases of non-remission AML who received clofarabine preconditioning followed by an allo-HSCT with PTCy. The 2-year overall survival and disease-free survival was 83.3% (95% confidence interval (CI): 27.3-97.9%) and 85.7% (95% CI: 33.4-97.9%). Median days of neutrophil and platelet recovery were 16 (range of 13-23) and 28 (range of 17-75), respectively. The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) at day 100 and chronic GVHD at 1-year showed 28.6% (95% CI: 8-74.2%) and 28.6% (95% CI: 3-63.9%), respectively. The two-year relapse rate was 14.3% (95% CI: 2.14-66.6%). One-year GVHD-free relapse-free survival (GFRS) at 1-year was 71.4% (95% CI: 25.8-92%). Our patients showed successful outcomes with clofarabine preconditioning to reduce the leukemic burden at the pre-transplant period followed by PTCy to reduce GVHD resulting in lower relapsed rate and better GFRS in these patients.

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapeutic treatment for many patients with high-risk hematologic malignancies and bone marrow failure syndromes. While allo-HCT can be highly effective, it is met with significant bone marrow conditioning regimen-related toxicities and complications such as infections related to poor immune reconstitution. This chapter describes the measurement of clofarabine and fludarabine concentrations to support clinical trials whose goal is to determine the optimal therapeutic ranges in order to maximize effectiveness while minimizing variability and regimen-related adverse events and toxicities. Moreover, the same holds true for patients receiving fludarabine as part of their lymphodepleting chemotherapy for chimeric antigen receptor T-cells (CAR T-cells). It is believed that one of the causes of variable outcomes after CAR T-cell therapy is lymphodepletion due to the variable fludarabine concentrations.This chapter describes a HPLC-MS/MS method to measure both compounds simultaneously. Clofarabine and fludarabine are extracted with solvent from plasma by the addition of deuterated internal standards prepared in methanol. Chromatographic separation is attained using a reversed-phase column followed by mass spectrometry which is performed in the positive ion mode. Herein, the described method to quantify both compounds in plasma is fast, accurate, and sensitive and allows for rapid drug concentration monitoring and timely dose adjustments.