Pralatrexate injection combined with CHOP for treatment of PTCL: results from the Fol-CHOP dose-finding phase 1 trial.

ABSTRACT: Pralatrexate is a folate antagonist that selectively enters cells expressing reduced folate carrier type 1 and competitively inhibits dihydrofolate reductase, leading to interruption of RNA synthesis, DNA replication, and apoptosis. This phase 1 study was conducted to evaluate the maximum tolerated dose (MTD) of pralatrexate in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) regimen (part 1) and the response and pharmacokinetics of 6 cycles of this combination (CHOP + Folotyn 30 mg/m2 [Fol-CHOP]) in patients with newly diagnosed peripheral T-cell lymphoma (PTCL). In part 1, on days 1 and 8 of each cycle, patients were treated with 10, 15, 20, 25, or 30 mg/m2 of pralatrexate in combination with CHOP, per dose escalation, in 5 sequential cohorts. No patients experienced DLTs in cohorts 1, 2, 3, 4, and 5. The pralatrexate dose of 30 mg/m2 was selected to be combined with CHOP for part 2 and administered to 33 additional patients in the expansion cohort. At the MTD, the Fol-CHOP regimen was generally well tolerated in patients with PTCL, with an overall response rate (ORR) of 83.9% (20 complete response and 6 partial response), as assessed by treating investigators. Thirty-five patients (67.3%) experienced grade 3/4 treatment-emergent adverse events, the most common of which were anemia (21.2%), neutropenia (19.2%), febrile neutropenia (11.5%), fatigue, mucosal inflammation, nausea, and vomiting (7.7% each). In conclusion, Fol-CHOP was found to be a safe and effective treatment for newly diagnosed PTCL and deemed worthy of further investigation. This trial was registered at www.ClinicalTrials.gov as #NCT02594267.

Pralatrexate inhibited the replication of varicella zoster virus and vesicular stomatitis virus: An old dog with new tricks.

Varicella zoster virus (VZV) is associated with herpes zoster (HZ) or herpes zoster ophthalmicus (HZO). All antiviral agents currently licensed for the management of VZV replication via modulating different mechanisms, and the resistance is on the rise. There is a need to develop new antiviral agents with distinct mechanisms of action and adequate safety profiles. Pralatrexate (PDX) is a fourth-generation anti-folate agent with an inhibitory activity on folate (FA) metabolism and has been used as an anti-tumor drug. We observed that PDX possessed potent inhibitory activity against VZV infection. In this study, we reported the antiviral effects and the underlying mechanism of PDX against VZV infection. The results showed that PDX not only inhibited VZV replication in vitro and in mice corneal tissues but also reduced the inflammatory response and apoptosis induced by viral infection. Furthermore, PDX treatment showed a similar anti-VSV inhibitory effect in both in vitro and in vivo models. Mechanistically, PDX inhibited viral replication by interrupting the substrate supply for de novo purine and thymidine synthesis. In conclusion, this study discovered the potent antiviral activity of PDX with a novel mechanism and presented a new strategy for VZV treatment that targets a cellular metabolic mechanism essential for viral replication. The present study provided a new insight into the development of broad-spectrum antiviral agents.

Pralatrexate Sustainably Released from Polypeptide Thermogel Is Effective for Chondrogenic Differentiation of Mesenchymal Stem Cells.

Folic acid was reported to significantly improve chondrogenic differentiation of mesenchymal stem cells. In a similar mechanism of action, we investigated clinically approved antifolates by the U.S. Food and Drug Administration as chondrogenic-promoting compounds for tonsil-derived mesenchymal stem cells. A poly(ethylene glycol)-poly(l-alanine) thermogelling system was used as a three-dimensional cell culture matrix, where stem cells and antifolates could be incorporated simultaneously during a heat-induced in situ sol-to-gel transition. The antifolates could be supplied over several days by the sustained release of the drug from the thermogel. Initially, seven antifolates were prescreened based on cell viability and expression of a typical chondrogenic biomarker of type II collagen (COL II) at the mRNA level. Then, dapsone, pralatrexate, and trimethoprim were selected as candidate compounds in the second round screening, and detailed studies were carried out on the mRNA and protein expression of various chondrogenic biomarkers including COL II, SRY box transcription factor 9, and aggrecan. Three-dimensional cultures of stem cells in the thermogel in the absence of a chondrogenic promoter compound and in the presence of kartogenin (KGN) were performed as a negative control and positive control, respectively. The chondrogenic biomarkers were significantly increased in the selected antifolate-incorporating systems compared to the negative control system, without an increase in type I collagen (an osteogenic biomarker) expression. Pralatrexate was the best compound for inducing chondrogenic differentiation of the stem cells, even better than the positive control (KGN). Nuclear translocation of the core-binding factor ß subunit (CBFß) and enhanced nuclear runt-related transcription factor 1 (RUNX1) by antifolate treatment suggested that the chondrogenesis-enhancing mechanism is mediated by CBFß and RUNX1. An in silico modeling study confirmed the mechanism by proving the high binding affinity of pralatrexate to a target protein of filamin A compared with other antifolate candidates. To conclude, pralatrexate was rediscovered as a lead compound, and the polypeptide thermogel incorporating pralatrexate and mesenchymal stem cells can be a very effective system in promoting chondrogenic differentiation of stem cells and might be used in injectable tissue engineering for cartilage repair.

Targeting folate receptor beta on monocytes/macrophages renders rapid inflammation resolution independent of root causes.

Provoked by sterile/nonsterile insults, prolonged monocyte mobilization and uncontrolled monocyte/macrophage activation can pose imminent or impending harm to the affected organs. Curiously, folate receptor beta (FRß), with subnanomolar affinity for the vitamin folic acid (FA), is upregulated during immune activation in hematopoietic cells of the myeloid lineage. This phenomenon has inspired a strong interest in exploring FRß-directed diagnostics/therapeutics. Previously, we have reported that FA-targeted aminopterin (AMT) therapy can modulate macrophage function and effectively treat animal models of inflammation. Our current investigation of a lead compound (EC2319) leads to discovery of a highly FR-specific mechanism of action independent of the root causes against inflammatory monocytes. We further show that EC2319 suppresses interleukin-6/interleukin-1ß release by FRß+ monocytes in a triple co-culture leukemic model of cytokine release syndrome with anti-CD19 chimeric antigen receptor T cells. Because of its chemical stability and metabolically activated linker, EC2319 demonstrates favorable pharmacokinetic characteristics and cross-species translatability to support future pre-clinical and clinical development.

Pralatrexate experience in PTCL: A multicenter retrospective study from Turkey.

PURPOSE: Pralatrexate is a new generation antifolate treatment agent used for the treatment of relapsed or refractory peripheral T-cell lymphomas. This study aims to determine the general characteristics of the patients receiving pralatrexate therapy in Turkey, contributing to the literature on the effectiveness of pralatrexate therapy in peripheral T-cell lymphomas by determining the response levels of such patients to the therapy. The study also attempts to clinically examine the major side effects observed in patients during treatment with pralatrexate. METHODS: The study included patients with peripheral T-cell lymphoma followed up in the hematology units of several hospitals in Turkey. Overall, 20 patients aged 18 and over were included in the study. RESULTS: The median age at the time of diagnosis was 58.5 years. PTCL-NOS (Peripheral T-cell lymphoma, not otherwise specified) subtype was in 40% of patients, making the PTCL-NOS the most common subtype in the study. In general, most patients were diagnosed with disease at an advanced stage. Pralatrexate therapy was given to the patients at a median treatment line of 3.5. Pralatrexate dose reduction was required in only 3 patients (15%). Response to pralatrexate therapy with partial remission (PR) and above was observed in 11 (55%) of the patients. CONCLUSION: Pralatrexate seemed to be a promising novel treatment in relapsed refractory PTCL patients. However, patients receiving pralatrexate should be followed up carefully for skin reactions, mucosal side effects, thrombocytopenia and neutropenia.

A Novel Treatment for Glomerular Disease: Targeting the Activated Macrophage Folate Receptor with a Trojan Horse Therapy in Rats.

Since activated macrophages express a functional folate receptor ß (FRß), targeting this macrophage population with folate-linked drugs could increase selectivity to treat inflammatory diseases. Using a macrophage-mediated anti-glomerular basement membrane (anti-GBM) glomerulonephritis (GN) in WKY rats, we investigated the effect of a novel folic acid-aminopterin (AMT) conjugate (EC2319) designed to intracellularly deliver AMT via the FR. We found that treatment with EC2319 significantly attenuated kidney injury and preserved renal function. Kidney protection with EC2319 was blocked by a folate competitor, indicating that its mechanism of action was specifically FRß-mediated. Notably, treatment with methotrexate (MTX), another folic acid antagonist related to AMT, did not protect from kidney damage. EC2319 reduced glomerular and interstitial macrophage infiltration and decreased M1 macrophage recruitment but not M2 macrophages. The expression of CCL2 and the pro-fibrotic cytokine TGF-ß were also reduced in nephritic glomeruli with EC2319 treatment. In EC2319-treated rats, there was a significant decrease in the deposition of collagens. In nephritic kidneys, FRß was expressed on periglomerular macrophages and macrophages present in the crescents, but its expression was not observed in normal kidneys. These data indicate that selectively targeting the activated macrophage population could represent a novel means for treating anti-GBM GN and other acute crescentic glomerulonephritis.

In silico drug repurposing for the treatment of heart diseases using gene expression data and molecular docking techniques.

Heart diseases are known as the most primary causes of mortality worldwide. Although many therapeutic approaches and medications are proposed for these diseases, the identification of novel therapeutics in fatal heart conditions is promptly demanded. Besides, the interplay between gene expression data and molecular docking provides several novel insights to discover more effective and specific drugs for the treatment of the diseases. This study aimed to discover potent therapeutic drugs in the heart diseases based on the expression profile of heart-specific genes exclusively. Initially, the heart-specific and highly expressed genes were identified by comparing the gene expression profile of different body tissues. Subsequently, the druggable-genes were identified using in silico techniques. The interaction between these druggable genes with more than 1600 FDA approved drugs was then investigated using the molecular docking simulation. By comprehensively analyzing RNA-sequencing data obtained from 949 normal tissue samples, 48 heart-specific genes were identified in both the heart development and function. Notably, of these, 24 heart-specific genes were capable to be considered as druggable genes, among which only MYBPC3, MYLK3, and SCN5A genes entered the molecular docking process due to their functions. Afterward, the pharmacokinetics properties of top 10 ligands with the highest binding affinity for these proteins were studied. Accordingly, methylergonovine, fosaprepitant, pralatrexate, daunorubicin, glecaprevir, digoxin, and venetoclax drugs were competent, in order to interact with the target proteins perfectly. It was shown that these medications can be used as specific drugs for the treatment of heart diseases after fulfilling further experiments in this regard.

Characterization of newly established Pralatrexate-resistant cell lines and the mechanisms of resistance.

BACKGROUND: Pralatrexate (PDX) is a novel antifolate approved for the treatment of patients with relapsed/refractory peripheral T-cell lymphoma, but some patients exhibit intrinsic resistance or develop acquired resistance. Here, we evaluated the mechanisms underlying acquired resistance to PDX and explored potential therapeutic strategies to overcome PDX resistance. METHODS: To investigate PDX resistance, we established two PDX-resistant T-lymphoblastic leukemia cell lines (CEM and MOLT4) through continuous exposure to increasing doses of PDX. The resistance mechanisms were evaluated by measuring PDX uptake, apoptosis induction and folate metabolism-related protein expression. We also applied gene expression analysis and methylation profiling to identify the mechanisms of resistance. We then explored rational drug combinations using a spheroid (3D)-culture assay. RESULTS: Compared with their parental cells, PDX-resistant cells exhibited a 30-fold increase in half-maximal inhibitory concentration values. Induction of apoptosis by PDX was significantly decreased in both PDX-resistant cell lines. Intracellular uptake of [14C]-PDX decreased in PDX-resistant CEM cells but not in PDX-resistant MOLT4 cells. There was no significant change in expression of dihydrofolate reductase (DHFR) or folylpolyglutamate synthetase (FPGS). Gene expression array analysis revealed that DNA-methyltransferase 3ß (DNMT3B) expression was significantly elevated in both cell lines. Gene set enrichment analysis revealed that adipogenesis and mTORC1 signaling pathways were commonly upregulated in both resistant cell lines. Moreover, CpG island hypermethylation was observed in both PDX resistant cells lines. In the 3D-culture assay, decitabine (DAC) plus PDX showed synergistic effects in PDX-resistant cell lines compared with parental lines. CONCLUSIONS: The resistance mechanisms of PDX were associated with reduced cellular uptake of PDX and/or overexpression of DNMT3B. Epigenetic alterations were also considered to play a role in the resistance mechanism. The combination of DAC and PDX exhibited synergistic activity, and thus, this approach might improve the clinical efficacy of PDX.

Complete remission of stage IV erythrodermic mycosis fungoides with large cell transformation through combination of pralatrexate and romidepsin followed by allogeneic hematopoietic stem cell transplantation.

We report the case of a 59-year-old woman with stage IV erythrodermic mycosis fungoides (MF) and large cell transformation who, despite failing multiple previous treatments, achieved complete remission through a combination of pralatrexate and romidepsin followed by allogeneic hematopoietic stem cell transplantation (alloSCT). Further studies are needed in focussing on this combined regimen in treating cutaneous T-cell lymphoma (CTCL) and its efficacy as a bridging regimen in facilitating successful alloSCT.

Three efficient chemometrics assisted fluorimetric detection methods for interference-free, rapid, and simultaneous determination of ibrutinib and pralatrexate in various complicated biological fluids.

In this study, a series of green, interference-free fluorimetric detection methods of the excitation-emission matrix coupled with the second-order calibration methods were proposed for the determination of ibrutinib and pralatrexate in various complicated biological fluids. The second-order advantage of the proposed method can overcome the problem of poor selectivity caused by the wide spectra of the fluorescence method. Even in the presence of uncalibrated interferences and severe peak overlap, the signal of pure substance and accurate quantitative results were still obtained. The average recoveries of the three methods were 94.5-104.9% for Alternating Trilinear Decomposition (ATLD) algorithm, 95.5-105.8% for Alternating Normalization Weighted Error (ANWE) algorithm and 94.4-105.7% for Parallel Factor Analysis (PARAFAC) algorithm, respectively. For ATLD, ANWE and PARAFAC, the relative standard deviations (RSD) were lower than 9.2%, 6.8% and 9.2%, and the RMSEPs were less than 8.1, 8.4 and 8.6 ng mL-1, respectively. In addition, the elliptic joint confidence region (EJCR) was adopted to further prove the accuracy of the three methods. The results showed that the three methods can accurately be quantified without significant difference. Good figures of merit parameters were also obtained. Among them, the limit of detection (LOD) and limit of quantification (LOQ) of ibrutinib and pralatrexate were in the range of 0.11-0.76 ng mL-1 and 0.21-1.12 ng mL-1, respectively, which were lower than the corresponding blood concentrations. These results indicate that the proposed method provides a promising, alternative and universal analysis strategy for clinical drug monitoring.

Efficacy and tolerability of folate-aminopterin therapy in a rat focal model of multiple sclerosis.

BACKGROUND: Activated macrophages in the experimental model of multiple sclerosis (MS) express folate receptor-ß (FR-ß), representing a promising target for the treatment of MS. Here, we both evaluated the efficacy of a novel folate-aminopterin construct (EC2319) in a rat focal model of multiple sclerosis (MS) and investigated the utility of 68Ga-labeled 1,4,7-triazacyclononane-1,4,7-triacetic acid-conjugated folate (68Ga-FOL) for assessing inflammatory lesions. In addition, we investigated whether FR-ß is expressed in the brain of patients with MS. METHODS: Focal delayed-type hypersensitivity experimental autoimmune encephalomyelitis (fDTH-EAE) was induced in 40 Lewis rats; 20 healthy Lewis rats were used as controls. Rats were divided into six groups according to the duration of disease (control, acute, or chronic) and intervention (vehicle versus EC2319). 68Ga-FOL analyses, histology, and immunofluorescence of the brain were performed to evaluate the efficacy of subcutaneously administered EC2319 on lesion development. Immunofluorescence was used to assess FR-ß expression in postmortem brain samples from 5 patients with MS and 5 healthy controls. RESULTS: Immunofluorescence and histological analyses revealed significant reductions in FR-ß expression (P < 0.05) and lesion size (P < 0.01), as well as improved inducible nitric oxide synthase/mannose receptor C type 1 ratios (P < 0.01) in macrophages and microglia during the chronic but not acute phase of fDTH-EAE in EC2319-treated rats. The uptake of IV-injected 68Ga-FOL in the brain was low and did not differ between the groups, but the in vitro binding of 68Ga-FOL was significantly lower in EC2319-treated rats (P < 0.01). FR-ß positivity was observed in chronically active lesions and in normal-appearing white matter in MS brain samples. CONCLUSIONS: EC2319 was well tolerated and attenuated inflammation and lesion development in a rat model of a chronic progressive form of MS. Human MS patients have FR-ß-positive cells in chronically active plaques, which suggests that these results may have translational relevance.

Pralatrexate for refractory mycosis fungoides in two Japanese patients.

Pralatrexate has been approved for the treatment of relapsed/refractory peripheral T cell lymphomas. Studies in the U.S. also support the clinical efficacy of pralatrexate to treat advanced-stage cutaneous T-cell lymphomas, but outcomes in Japanese patients have not yet been reported. We herein describe two Japanese patients with heavily-pretreated relapsed/refractory mycosis fungoides that were successfully controlled by pralatrexate.

Pralatrexate in relapsed/refractory T-cell lymphoma: a retrospective multicenter study.

We present a retrospective multicenter study of pralatrexate treatment outcomes in an Australian practice setting for patients with relapsed/refractory T-cell lymphoma who had failed 1+ systemic therapies, treated via a compassionate access program. Endpoints assessed included response rates, toxicities, and subsequent therapies. Progression-free survival (PFS), time to next treatment (TTNT), event-free survival (EFS), overall survival (OS), and time to best response, were assessed by Kaplan-Meier analysis. The study included 31 patients, with median age 69 years. We demonstrated ORR of 35.5% (n = 11), including 4 complete responses (13%) and 7 partial responses (23%). The predicted median OS was 10 months, with EFS of 9 months, and PFS of 9 months. Median TTNT was 8 months. Mucositis was the most commonly observed toxicity. This study - the second largest real-world cohort reported to date - underscores the importance of pralatrexate in relapsed/refractory T-cell lymphoma, as well as its acceptable toxicity profile.

A novel virtual screening procedure identifies Pralatrexate as inhibitor of SARS-CoV-2 RdRp and it reduces viral replication in vitro.

The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus poses serious threats to the global public health and leads to worldwide crisis. No effective drug or vaccine is readily available. The viral RNA-dependent RNA polymerase (RdRp) is a promising therapeutic target. A hybrid drug screening procedure was proposed and applied to identify potential drug candidates targeting RdRp from 1906 approved drugs. Among the four selected market available drug candidates, Pralatrexate and Azithromycin were confirmed to effectively inhibit SARS-CoV-2 replication in vitro with EC50 values of 0.008µM and 9.453 µM, respectively. For the first time, our study discovered that Pralatrexate is able to potently inhibit SARS-CoV-2 replication with a stronger inhibitory activity than Remdesivir within the same experimental conditions. The paper demonstrates the feasibility of fast and accurate anti-viral drug screening for inhibitors of SARS-CoV-2 and provides potential therapeutic agents against COVID-19.

Cost-utility analysis of pralatrexate for relapsed or refractory peripheral T-cell lymphoma based on a case-matched historical control study along with single arm clinical trial.

BACKGROUND: Patients with relapsed or refractory peripheral T-cell lymphoma (R/R PTCL) treated with pralatrexate have previously shown superior overall survival (OS) compared to those who underwent conventional chemotherapy (CC, 15.4 vs. 4.07 months). We conducted an economic evaluation of pralatrexate from a societal perspective in Korea based on data from the PROPEL phase II study. METHODS: Using a Markov model with a weekly cycle, we simulated the experience of patients with R/R PTCL receiving pralatrexate or CC for 15 years. The model consists of five health states; initial treatment, treatment pause, subsequent treatment, stem cell transplantation (SCT) success, and death. Comparative effectiveness was based on PROPEL phase II single-arm study and its matched historical control analysis. Costs included drug, drug administration, monitoring, adverse event management, and SCT costs. RESULTS: The incremental cost-effectiveness ratio of the base case was $39,153 per quality-adjusted life-year (QALY) gained. The results of one-way sensitivity analysis ranged from $33,949 to $51,846 per QALY gained, which remained within an implicit willingness-to-pay (WTP) threshold of anticancer drugs in Korea. CONCLUSIONS: Pralatrexate is a cost-effective intervention with improved OS and incremental costs within the WTP limit. Pralatrexate could function as a new therapeutic option for patients suffering from life-threatening R/R PTCL.

Generation of pralatrexate resistant T-cell lymphoma lines reveals two patterns of acquired drug resistance that is overcome with epigenetic modifiers.

While pralatrexate (PDX) has been successfully developed for the treatment of T-cell lymphoma, the mechanistic basis for its T-cell selectivity and acquired resistance remains elusive. In an effort to potentially identify synergistic combinations that might circumnavigate or delay acquired PDX resistance, we generated resistant cells lines over a broad concentration range. PDX-resistant cell lines H9-12 and H9-200 were developed, each exhibiting an IC50 of 35 and over 1000 nM, respectively. These lines were established in vitro from parental H9 cells. Expression analysis of the proteins known to be important determinants of antifolate pharmacology revealed increase expression of dihydrofolate reductase (DHFR) due to gene amplification, and reduced folate carrier1 downregulation, as the putative mechanisms of resistance in H9-12 and H9-200 cells. Cross resistance was only seen with methotrexate but not with romidepsin, azacitidine (AZA), decitabine, gemcitabine, doxorubicin, or bortezomib. Resistance to PDX was reversed by pretreatment with hypomethylating agents in a concentration-dependent fashion. Comparison of gene expression profiles of parental and resistant cell lines confirmed markedly different patterns of gene expression, and identified the dual specificity phosphatase four (DUSP4) as one of the molecular target of PDX activity. Reduced STAT5 phosphorylation following exposure to PDX was observed in the H9 but not in the H9-12 and H9-200 cells. These data suggest that combination with hypomethylating agents could be potent, and that DUSP4 and STAT5 could represent putative biomarkers of PDX activity.

Efficacy and safety of single-agent pralatrexate for treatment of angioimmunoblastic T-cell lymphoma after failure of first line therapy: a pooled analysis.

Angioimmunoblastic T-cell lymphoma (AITL) is a histological subtype of peripheral T-cell lymphoma associated with a poor prognosis. This post-hoc pooled analysis aims to provide insight about the efficacy of pralatrexate monotherapy in a subset of twenty-nine patients with relapsed or refractory (r/r) AITL drawn from two prospective registration trials completed in China and Japan. After a median of two prior lines of therapy, an overall response rate of 52% (15/29 patients; 95% CI 0.34, 0.70) was demonstrated. The estimated median duration of response, progression free survival (PFS) and overall survival (OS) were 6.4 months (196 days), 5.0 months (151 days), and 18.0 months (548 days), respectively. Grades 1-3 mucositis was observed in twenty-three patients (79.3%); and hemato-toxicity in twenty-six (89.7%) patients. Results of this analysis corroborate with data from two previously reported US retrospective cohorts, supporting the potential benefits of pralatrexate monotherapy in patients with r/r AITL.