Phase II study of the novel antifolate agent pralatrexate in combination with the histone deacetylase inhibitor romidepsin for the treatment of patients with mature T-cell lymphoma.

Previously, we conducted a Phase I study of the combination of pralatrexate and romidepsin in patients with relapsed/refractory (R/R) lymphomas and subsequently conducted a multicenter Phase II study in patients with untreated or R/R mature T cell lymphomas (MTCL). Patients received pralatrexate 25 mg/m2 and romidepsin 12 mg/m2 every 2 weeks. Fourteen patients were evaluable for efficacy. Overall response rate was 35.7% with CR in 14.3% and disease control in 50%. The mDOR was 8.2 months, mPFS was 3.6 months, and mOS was 20.2 months. Gastrointestinal side effects were most common in up to 33%; there was only one hematologic toxicity of grade 3 anemia. Combining results of MTCL patients from the Phase I and II studies (N = 28), the ORR was 53.5% with CR in 21.4%, disease control in67.8%, and DOR of 7.2 months. The combination was safe however does not out-perform other combination strategies.Trial Registration: www.clinicaltrials.gov (NCT01947140).

Toxicity of pemetrexed during renal impairment explained-Implications for safe treatment.

Pemetrexed is an important component of first line treatment in patients with non-squamous non-small cell lung cancer. However, a limitation is the contraindication in patients with renal impairment due to hematological toxicity. Currently, it is unknown how to safely dose pemetrexed in these patients. The aim of our study was to elucidate the relationship between pemetrexed exposure and toxicity to support the development of a safe dosing regimen in patients with renal impairment. A population pharmacokinetic/pharmacodynamic analysis was performed based on phase II study results in three patients with renal dysfunction, supplemented with data from 106 patients in early clinical studies. Findings were externally validated with data of different pemetrexed dosing regimens. Alternative dosing regimens were evaluated using the developed model. We found that pemetrexed toxicity was driven by the time above a toxicity threshold concentration. The threshold for vitamin-supplemented patients was 0.110 mg/mL (95% CI: 0.092-0.146 mg/mL). It was observed that in patients with renal impairment (estimated glomerular filtration rate [eGFR]: <45 mL/min) the approved dose of 500 mg/m2 would yield a high probability of severe neutropenia in the range of 51.0% to 92.6%. A pemetrexed dose of 20 mg for patients (eGFR: 20 mL/min) is shown to be neutropenic-equivalent to the approved dose in patients with adequate renal function (eGFR: 90 mL/min), but would result in an approximately 13-fold lower area under the concentration-time curve. The pemetrexed exposure-toxicity relationship is explained by a toxicity threshold and substantially different from previously thought. Without prophylaxis for toxicity, it is unlikely that a therapeutic dose can be safely administered to patients with renal impairment.

Pemetrexed - First-Line Therapy for Non-Squamous Non-Small Cell Lung Cancer: A Review of Patent Literature.

BACKGROUND: Pemetrexed is a folate analogue metabolic inhibitor for mammalian cells. Pemetrexed is toxic to several cancer cells by interfering with their new biosynthesis of nucleotides, thus causing cell apoptosis. Presently, Pemetrexed is given to patients with Non-Small Cell Lung Cancer (NSCLC). OBJECTIVE: This review focuses on the recent patents of Pemetrexed. This assessment includes patents grouped in segments like crystalline form patent, composition related patents, product patents, as well as a method of treatment. The aim of this review is to simplify inventors with existing patents in a single place. METHODS: Data were searched from several available databases, including paid databases which include Orbit® and SciFinder®. Free databases include Worldwide Espacenet® (EPO), Patentscope® (WIPO), InPASS (Indian patent database) and Google Patents. RESULTS: Some new polymorph and composition-related inventions of Pemetrexed have been recently patented as its orange-book listed patents will soon expire in May 2022. Further, because of the problem of oxidation through the development and continuing storage of Pemetrexed composition, several excipients are experimented with within these patents to stabilize the same. Nevertheless, there is a need for further development of an improved composition of Pemetrexed with improved characteristics. CONCLUSION: Wide research has been conducted on different processes for preparing Pemetrexed and formulation thereof. Such type of active research may clear the track for the generic companies in the United States, producing the formulation at low prices and providing universal health care at economical prices.

Changes in intracellular folate metabolism during high-dose methotrexate and Leucovorin rescue therapy in children with acute lymphoblastic leukemia.

BACKGROUND: Methotrexate (MTX) is an important anti-folate agent in pediatric acute lymphoblastic leukemia (ALL) treatment. Folinic acid rescue therapy (Leucovorin) is administered after MTX to reduce toxicity. Previous studies hypothesized that Leucovorin could 'rescue' both normal healthy cells and leukemic blasts from cell death. We assessed whether Leucovorin is able to restore red blood cell folate levels after MTX. METHODS: We prospectively determined erythrocyte folate levels (5-methyltetrahydrofolate (THF) and non-methyl THF) and serum folate levels in 67 children with ALL before start (T0) and after stop (T1) of HD-MTX and Leucovorin courses. RESULTS: Erythrocyte folate levels increased between T0 and T1 (mean ± SD: 416.7 ± 145.5 nmol/L and 641.2 ± 196.3 nmol/L respectively, p<0.001). This was due to an increase in 5-methyl THF levels (mean increase: 217.7 ± 209.5 nmol/L, p<0.001), whereas non-methyl THF levels did not change (median increase: 0.6 nmol/L [-9.9-11.1], p = 0.676). Serum folate levels increased between T0 and T1 (median increase: 29.2 nmol/L [32.9-74.0], p<0.001). Results were not significantly affected by age, sex, ALL immunophenotype and MTHFR c.677C>T genotype. CONCLUSION: Intracellular folate levels accumulate after HD-MTX and Leucovorin therapy in children with ALL, suggesting that Leucovorin restores the intracellular folate pool. Future studies are necessary to assess concomitant lower uptake of MTX.

Curcumin ameliorates the targeted delivery of methotrexate intercalated montmorillonite clay to cancer cells.

Montmorillonite Clay (MMT) is aimed to develop as an orally administrable drug delivery vehicle with enhanced efficacy. Aiming to enhance the therapeutic index of methotrexate, curcumin is concomitantly used with methotrexate in the present study. Being folate antagonist in nature, methotrexate is internalized into cells by folate receptor (FR); which is over-expressed in certain human cancer cells such as cervical carcinoma cells (HeLa). Firstly, montmorillonite Clay (MMT) is organically modified (OMMT) with cetyl trimethyl ammonium bromide (CTAB) and used to intercalate curcumin and methotrexate separately, designated as OMMT-Cur and OMMT-MTX, respectively. XRD pattern demonstrated successful intercalation of therapeutics and an increase in clay interlayer distance facilitated by CTAB. The dissolution kinetics of methotrexate follows Higuchi model for both Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF), while the release kinetics for curcumin fitted into Higuchi model for SGF and Hixson-Crowell model for SIF, respectively. OMMT-MTX are able to discriminate FR-positive HeLa cells from FR-negative breast cancer cells (MCF7); irrespective of alike cellular phenotypes. Further, the pre-treatment of HeLa cells with curcumin improves its sensitivity towards methotrexate causing a greater killing of the Hela cells. Together, the results propose the concomitant use of curcumin and methotrexate for successfully targeting highly invasive FR-positive carcinomas by means of folate receptor using MMTs.

A single center retrospective analysis of a protocol for high-dose methotrexate and leucovorin rescue administration.

BACKGROUND: Methotrexate has a wide dosing range. High-dose methotrexate is a dose of 1000 mg/m2 or greater. In the 1970s, the incidence of mortality associated with High-dose methotrexate ranged from 4.6 to 6%. In 2012, the University of Maryland Medical Center implemented a standardized high-dose methotrexate protocol. The purpose of this study was to evaluate whether the institution followed recommendations based on the Bleyer nomogram for the administration of high-dose methotrexate more closely after the implementation of the protocol. METHODS: In this retrospective chart review, 37 patients received 119 cycles of high-dose methotrexate before the protocol implementation (1 January 2009 through 31 December 2010) and 45 patients received 106 cycles of high-dose methotrexate after protocol implementation (1 January 2013 through 31 December 2014). Patient characteristics, protocol data, and complications were analyzed. RESULTS: Protocol implementation significantly reduced the deviation of methotrexate level timing at 24, 48, and 72 h: median 7.47 vs. 1.46 h, 7.23 vs. 1.35 h, and 7.00 vs. 1.52 h before and after implementation, respectively (p < 0.0001 for each). The protocol significantly reduced deviation of the first dose of leucovorin administration: median 5.2 vs. 0.675 h before and after implementation, respectively (p<0.0001). After protocol implementation, there was an increase in the use of leucovorin prescriptions written appropriately for patients discharged before methotrexate levels reached a value of ≤0.05 µmol/L. CONCLUSIONS: Implementation of a protocol for the administration of high-dose methotrexate improved the adherence to consensus recommendations. Further analysis is needed to assess clinical pharmacist involvement and the cost savings implications within this protocol.

Medication Error- A Case Report of Misadventure with Methotrexate.

Methotrexate is an antimetabolite drug with antineoplastic and immunomodulatory properties, useful as an antineoplastic agent in various haematological and solid tumours. MTX toxicity can occur because of accidental ingestion/overdose by the patient or because of prescription error. The toxic effects manifest as severe mucositis or as organ damage (bone marrow depression, renal/hepatic injury). The toxicity usually results from parenteral overdose or repeated chronic drug ingestion. Acute high dose ingestion does not result in MTX toxicity because of saturable absorption kinetics. We present a case of MTX toxicity occurring as a result of prescription error resulting in repeat daily dosing of the drug, and the challenges associated with the management of the same, in a patient with multiple comorbidities. The present case emphasizes on a note of caution on the part of the prescriber and the suggestions regarding the measures which can be taken to avoid MTX toxicity. Keywords: drug overdose; Methotrexate; mucositis; pancytopenia.

The evolving role of pemetrexed disodium for the treatment of non-small cell lung cancer.

INTRODUCTION: Non-small cell lung cancer (NSCLC) remains one of the big cancer killers, despite the introduction of a number of approved therapeutics in recent times. Pemetrexed is a multi-target folate inhibitor, which is currently available to patients affected by advanced non-squamous NSCLC in combination with a platinum derivate in first-line therapy and as a single agent in second-line therapy. Areas covered: This review covers presents the use pemetrexed in the management of NSCLC by exploring the data available from clinical trials and meta-analyses. Data from a phase III trial confirmed its role in the first-line setting in combination with immune checkpoint inhibitors (ICIs). Furthermore, data suggested a role for pemetrexed in local and advanced NSCLC. Expert opinion: To date, in spite of the introduction of novel anti-neoplastic agents, pemetrexed still represents a cornerstone in the management of non-squamous NSCLC. Furthermore, recently published data support its role in innovative combinations including together with chemotherapy and immunotherapy.

Methotrexate causes persistent deficits in memory and executive function in a juvenile animal model.

Methotrexate is a dihydrofolate reductase inhibitor widely employed in curative treatment for children with acute lymphoblastic leukemia (ALL). However, methotrexate administration is also associated with persistent cognitive deficits among long-term childhood cancer survivors. Animal models of methotrexate-induced cognitive deficits have primarily utilized adult animals. The purpose of present study is to investigate the neurotoxicity of methotrexate in juvenile rats and its relevant mechanisms. The doses and schedule of systemic and intrathecal methotrexate, given from post-natal age 3-7 weeks, were chosen to model the effects of repeated methotrexate dosing on the developing brains of young children with ALL. This methotrexate regimen had no visible acute toxicity and no effect on growth. At 15 weeks of age (8 weeks after the last methotrexate dose) both spatial pattern memory and visual recognition memory were impaired. In addition, methotrexate-treated animals demonstrated impaired performance in the set-shifting assay, indicating decreased cognitive flexibility. Histopathological analysis demonstrated decreased cell proliferation in methotrexate-treated animals compared to controls, as well as changes in length and thickness of the corpus callosum. Moreover, methotrexate suppressed microglia activation and RANTES production. In conclusion, our study demonstrated that a clinically relevant regimen of systemic and intrathecal methotrexate induces persistent deficits in spatial pattern memory, visual recognition memory and executive function, lasting at least 8 weeks after the last injection. The mechanisms behind methotrexate-induced deficits are likely multifactorial and may relate to suppression of neurogenesis, alterations in neuroinflammation and microglial activation, and structural changes in the corpus callosum.

Combining Albumin-Binding Properties and Interaction with Pemetrexed to Improve the Tissue Distribution of Radiofolates.

Folic-acid-based radioconjugates have been developed for nuclear imaging of folate receptor (FR)-positive tumors; however, high renal uptake was unfavorable in view of a therapeutic application. Previously, it was shown that pre-injection of pemetrexed (PMX) increased the tumor-to-kidney ratio of radiofolates several-fold. In this study, PMX was combined with the currently best performing radiofolate ([177Lu]cm13), which is outfitted with an albumin-binding entity. Biodistribution studies were carried out in mice bearing KB or IGROV-1 tumor xenografts, both FR-positive tumor types. SPECT/CT was performed with control mice injected with [177Lu]folate only and with mice that received PMX in addition. Control mice showed high uptake of radioactivity in KB and IGROV-1 tumor xenografts, but retention in the kidneys was also high, resulting in tumor-to-kidney ratios of ~0.85 (4 h p.i.) and ~0.60 (24 h p.i.) or ~1.17 (4 h p.i.) and ~1.11 (24 h p.i.) respectively. Pre-injection of PMX improved the tumor-to-kidney ratio to values of ~1.13 (4 h p.i.) and ~0.92 (24 h p.i.) or ~1.79 (4 h p.i.) and ~1.59 (24 h p.i.), respectively, due to reduced uptake in the kidneys. It was found that a second injection of PMX­3 h or 7 h after administration of the radiofolate­improved the tumor-to-kidney ratio further to ~1.03 and ~0.99 or ~1.78 and ~1.62 at 24 h p.i. in KB and IGROV-1 tumor-bearing mice, respectively. SPECT/CT scans readily visualized the tumor xenografts, whereas accumulation of radioactivity in the kidneys was reduced in mice that received PMX. In this study, it was shown that PMX had a positive impact in terms of reducing the kidney uptake of albumin-binding radiofolates; hence, the administration of PMX resulted in ~1.3⁻1.7-fold higher tumor-to-kidney ratios. This is, however, a rather moderate effect in comparison to the previously shown effect of PMX on conventional radiofolates (without albumin binder), which led to 5⁻6-fold increased tumor-to-kidney ratios. An explanation for this result may be the different pharmacokinetic profiles of PMX and long-circulating radiofolates, respectively. Despite the promising potential of this concept, it is believed that a clinical translation would be challenging, particularly when PMX had to be injected more than once.

The promise and challenges of exploiting the proton-coupled folate transporter for selective therapeutic targeting of cancer.

This review considers the "promise" of exploiting the proton-coupled folate transporter (PCFT) for selective therapeutic targeting of cancer. PCFT was discovered in 2006 and was identified as the principal folate transporter involved in the intestinal absorption of dietary folates. The recognition that PCFT was highly expressed in many tumors stimulated substantial interest in using PCFT for cytotoxic drug targeting, taking advantage of its high level transport activity under the acidic pH conditions that characterize many tumors. For pemetrexed, among the best PCFT substrates, transport by PCFT establishes its importance as a clinically important transporter in malignant pleural mesothelioma and non-small cell lung cancer. In recent years, the notion of PCFT-targeting has been extended to a new generation of tumor-targeted 6-substituted pyrrolo[2,3-d]pyrimidine compounds that are structurally and functionally distinct from pemetrexed, and that exhibit near exclusive transport by PCFT and potent inhibition of de novo purine nucleotide biosynthesis. Based on compelling preclinical evidence in a wide range of human tumor models, it is now time to advance the most optimized PCFT-targeted agents with the best balance of PCFT transport specificity and potent antitumor efficacy to the clinic to validate this novel paradigm of highly selective tumor targeting.

A phase 1 study of romidepsin and pralatrexate reveals marked activity in relapsed and refractory T-cell lymphoma.

Peripheral T-cell lymphomas (PTCL) are a group of rare malignancies characterized by chemotherapy resistance and poor prognosis. Romidepsin and pralatrexate were approved by the US Food and Drug Administration for patients with relapsed/refractory PTCL, exhibiting response rates of 25% and 29% respectively. Based on synergy in preclinical models of PTCL, we initiated a phase 1 study of pralatrexate plus romidepsin in patients with relapsed/refractory lymphoma. This was a single institution dose-escalation study of pralatrexate plus romidepsin designed to determine the dose-limiting toxicities (DLTs), maximum tolerated dose, pharmacokinetic profile, and response rates. Patients were treated with pralatrexate (10 to 25 mg/m2) and romidepsin (12 to 14 mg/m2) on 1 of 3 schedules: every week × 3 every 28 days, every week × 2 every 21 days, and every other week every 28 days. Treatment continued until progression, withdrawal of consent, or medical necessity. Twenty-nine patients were enrolled and evaluable for toxicity. Coadministration of pralatrexate and romidepsin was safe, well tolerated, with 3 DLTs across all schedules (grade 3 oral mucositis × 2; grade 4 sepsis × 1). The recommended phase 2 dose was defined as pralatrexate 25 mg/m2 and romidepsin 12 mg/m2 every other week. Twenty-three patients were evaluable for response. The overall response rate was 57% (13/23) across all patients and 71% (10/14) in PTCL. The phase 1 study of pralatrexate plus romidepsin resulted in a high response rate in patients with previously treated PTCL. A phase 2 study in PTCL will determine the efficacy of the combination. This trial was registered at www.clinicaltrials.gov as #NCT01947140.

Protective effect of alpha-lipoic acid in methotrexate-induced ovarian oxidative injury and decreased ovarian reserve in rats.

To determine whether the possible oxidative effect of methotrexate (Mtx) on ovary and to evaluate the effectiveness of alpha lipoic acid (ALA), which may be useful in many oxidative stress models. Thirty-two female Wistar-albino rats were randomly divided into four groups; control group, alpha lipoic acid group (ALA 100 mg/kg, 10 days), multiple dose Mtx group (Mtx 1 mg/kg 1, 3, 5, 7 days) and Mtx and ALA group (Mtx 1 mg/kg 1, 3, 5, 7 days and ALA 100 mg/kg, 10 days). Serum total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI), tumor necrosis factor-alpha (TNF-α), tissue malondialdehyde (MDA) and activities of glutathione peroxidase (GSH-Px) and catalase (CAT) and anti-Mullerian hormone (AMH) and total ovarian follicle count were evaluated. Mtx administration caused a significant decrease in TAS, a significant increase in TOS and OSI, a significant increase in MDA levels and a decrease in GSH-Px and CAT activity. Moreover the proinflammatory cytokine (TNF-α) was increased in the Mtx group. And AMH values and total follicle count were significantly decreased in Mtx group. However, ALA treatment reversed biochemical results and AMH levels and total follicle count. Alpha lipoic acid ameliorates methotrexate induced oxidative damage of ovarian in rats.

Dual Targeting of Epithelial Ovarian Cancer Via Folate Receptor α and the Proton-Coupled Folate Transporter with 6-Substituted Pyrrolo[2,3-d]pyrimidine Antifolates.

Folate uptake in epithelial ovarian cancer (EOC) involves the reduced folate carrier (RFC) and the proton-coupled folate transporter (PCFT), both facilitative transporters and folate receptor (FR) α. Although in primary EOC specimens, FRα is widely expressed and increases with tumor stage, PCFT was expressed independent of tumor stage (by real-time RT-PCR and IHC). EOC cell line models, including cisplatin sensitive (IGROV1 and A2780) and resistant (SKOV3 and TOV112D) cells, expressed a 17-fold range of FRα and similar amounts (within ∼2-fold) of PCFT. Novel 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolates AGF94 and AGF154 exhibited potent antiproliferative activities toward all of the EOC cell lines, reflecting selective cellular uptake by FRα and/or PCFT over RFC. When IGROV1 cells were pretreated with AGF94 at pH 6.8, clonogenicity was potently inhibited, confirming cell killing. FRα was knocked down in IGROV1 cells with lentiviral shRNAs. Two FRα knockdown clones (KD-4 and KD-10) showed markedly reduced binding and uptake of [3H]folic acid and [3H]AGF154 by FRα, but maintained high levels of [3H]AGF154 uptake by PCFT compared to nontargeted control cells. In proliferation assays, KD-4 and KD-10 cells preserved in vitro inhibition by AGF94 and AGF154, compared to a nontargeted control, attributable to residual FRα- and substantial PCFT-mediated uptake. KD-10 tumor xenografts in severe-compromised immune-deficient mice were likewise sensitive to AGF94 Collectively, our results demonstrate the substantial therapeutic potential of novel 6-substituted pyrrolo[2,3-d]pyrimidine antifolates with dual targeting of PCFT and FRα toward EOCs that express a range of FRα, along with PCFT, as well as cisplatin resistance. Mol Cancer Ther; 16(5); 819-30. ©2017 AACR.

Lansoprazole Exacerbates Pemetrexed-Mediated Hematologic Toxicity by Competitive Inhibition of Renal Basolateral Human Organic Anion Transporter 3.

Pemetrexed, a multitargeted antifolate, is eliminated by tubular secretion via human organic anion transporter 3 (hOAT3). Although proton pump inhibitors (PPIs) are frequently used in cancer patients, the drug interaction between PPIs and pemetrexed remains to be clarified. In this study, we examined the drug interaction between pemetrexed and PPIs in hOAT3-expressing cultured cells, and retrospectively analyzed the impact of PPIs on the development of hematologic toxicity in 108 patients who received pemetrexed and carboplatin treatment of nonsquamous non-small cell lung cancer for the first time between January 2011 and June 2015. We established that pemetrexed was transported via hOAT3 (Km = 68.3 ± 11.1 µM). Lansoprazole, rabeprazole, pantoprazole, esomeprazole, omeprazole, and vonoprazan inhibited hOAT3-mediated uptake of pemetrexed in a concentration-dependent manner. The inhibitory effect of lansoprazole was much greater than those of other PPIs and the apparent IC50 value of lansoprazole against pemetrexed transport via hOAT3 was 0.57 ± 0.17 µM. The inhibitory type of lansoprazole was competitive. In a retrospective study, multivariate analysis revealed that coadministration of lansoprazole, but not other PPIs, with pemetrexed and carboplatin was an independent risk factor significantly contributing to the development of hematologic toxicity (odds ratio: 10.004, P = 0.005). These findings demonstrated that coadministration of lansoprazole could exacerbate the hematologic toxicity associated with pemetrexed, at least in part, by competitive inhibition of hOAT3. Our results would aid clinicians to make decisions of coadministration drugs to avoid drug interaction-induced side effects for achievement of safe and appropriate chemotherapy with pemetrexed.

Ulcerations due to methotrexate toxicity in a psoriasis patient

Abstract: Methotrexate is one of the most used drugs in the treatment of psoriasis with indication of systemic therapy. Cutaneous and mucous side effects are described by pharmacological characteristics of the drug itself or due to overdose. We report the case of a patient with ulcerations in oral mucosa and psoriatic plaques after incorrect use of Methotrexate. Prescribed in a weekly dose, it was used continuously for 10 days and without simultaneous intake of folic acid. It is important to ensure correct comprehension of the prescription.

Targeting Nonsquamous Nonsmall Cell Lung Cancer via the Proton-Coupled Folate Transporter with 6-Substituted Pyrrolo[2,3-d]Pyrimidine Thienoyl Antifolates.

Pemetrexed (PMX) is a 5-substituted pyrrolo[2,3-d]pyrimidine antifolate used for therapy of nonsquamous nonsmall cell lung cancer (NS-NSCLC). PMX is transported by the reduced folate carrier (RFC) and proton-coupled folate transporter (PCFT). Unlike RFC, PCFT is active at acidic pH levels characterizing the tumor microenvironment. By real-time reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemistry, PCFT transcripts and proteins were detected in primary NS-NSCLC specimens. In six NS-NSCLC cell lines (A549, H1437, H460, H1299, H1650, and H2030), PCFT transcripts and proteins were detected by real-time RT-PCR and western blots, respectively. 6-Substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolates related to PMX [compound 1 (C1) and compound 2 (C2), respectively] are selective substrates for PCFT over RFC. In the NS-NSCLC cell lines, both [(3)H]PMX and [(3)H]C2 were transported by PCFT. C1 and C2 inhibited proliferation of the NS-NSCLC cell lines; A549, H460, and H2030 cells were more sensitive to C1 than to PMX. C1 and C2 inhibited glycinamide ribonucleotide formyltransferase in de novo purine nucleotide biosynthesis. When treated at pH 6.8, which favors PCFT uptake, C1 and C2 inhibited clonogenicity of H460 cells greater than PMX; PMX inhibited clonogenicity more than C1 or C2 at pH 7.2, which favors RFC transport over PCFT. Knockdown of PCFT in H460 cells resulted in decreased [(3)H]PMX and [(3)H]C2 transport and decreased growth inhibition by C1 and C2, and to a lesser extent by PMX. In vivo efficacy of C1 was seen toward H460 tumor xenografts in severe-combined immunodeficient mice. Our results suggest that 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolates offer significant promise for treating NS-NSCLC by selective uptake by PCFT.

Pralatrexate Monitoring Using a Commercially Available Methotrexate Assay to Avoid Potential Drug Interactions.

Pralatrexate (PDX) is a folate antagonist structurally similar to methotrexate (MTX). Unlike MTX, it is currently not known whether PDX exhibits delayed clearance and heightened toxicity in the setting of fluid overload. A specific serum assay for PDX is not commercially available. To our knowledge, we report the first case using an MTX serum assay as a surrogate for PDX concentrations to avoid a potential drug-drug interaction with pralatrexate. We describe a 76-year-old man with refractory cutaneous T-cell lymphoma who began therapy with weekly PDX 15 mg/m(2) intravenous infusions on days 1, 8, and 15 of a 28-day cycle. He subsequently developed mucositis, a moderate right-sided pleural effusion, and peripheral edema over the next 5 weeks. Aggressive diuresis with furosemide was initiated, which was then withheld the day before his next PDX dose to avoid a potential drug-drug interaction between PDX and furosemide. His baseline MTX/PDX concentration (measured prior to administration of the cycle 2, week 2 PDX dose) was less than 0.20 µmol/L (i.e., undetectable). After PDX administration, his 1-hour peak MTX/PDX concentration increased to 0.58 µmol/L. Aggressive diuresis was withheld until his MTX/PDX concentration was undetectable, 43.5 hours later. PDX is more potent than MTX and displays similar pharmacokinetic properties. PDX concentrations using the serum MTX assay reflect lower values than those reported from PDX-specific assays in clinical studies. Because PDX is approved by the U.S. Food and Drug Administration for the treatment of uncommon malignancies, it is unlikely that a specific assay will be commercially developed. We propose that the MTX serum assay has merit for use in determining when to reinstate possible interacting drug therapies such as loop diuretics.

TAS-102 an Emerging Oral Fluoropyrimidine.

Colon cancer is a common type of cancer with high mortality. The standard therapy for colon cancer is 5-FU-based regimen, although the current response rate to 5-FU is only 10-15%. Various approaches have been used to improve the efficacy of 5-FU including inhibition of its degradation enzyme dihydropyrimidine dehydrogenase (DPD) such as S1, UTF, use of 5-FU pro-drug capecitabine to exploit thymidine phosphorylase (TP) and supplementation of reduced folate acid to increase cytotoxicity. TAS-102 is a newly-developed anti-folate drug containing the 5-FU analogue trifluridine (TFD) and tipiracil hydrochloride (TPI). TPI is an inhibitor of TFD degradation enzyme thymidine phosphorylase and thus increases the bioavailability of TFD. In the present review, we summarize recent progress with regard to TAS-102, including pre-clinical tests and clinical trials. We further propose several approaches to further improve the efficacy of TAS-102 including combination with targeted therapy and immune therapy.

A phase 1 clinical trial of sequential pralatrexate followed by a 48-hour infusion of 5-fluorouracil given every other week in adult patients with solid tumors.

BACKGROUND: Pralatrexate (PDX) is an inhibitor of dihydrofolate reductase that was rationally designed to improve cellular uptake and retention of the drug. Preclinical data have shown synergy with the sequential administration of a dihydrofolate reductase inhibitor followed 24 hours later by 5-fluorouracil (5-FU). METHODS: Twenty-seven patients were enrolled at 1 of 5 PDX dose levels from 75 to 185 mg/m(2) on day 1 followed 24 hours later by 5-FU at a dose of 3000 mg/m(2) /48 hours every 2 weeks with folic acid and vitamin B12 supplementation. Baseline blood was collected for pharmacogenetic analysis of polymorphisms of methylenetetrahydrofolate reductase and thymidylate synthase. RESULTS: Mucositis was the most common dose-limiting toxicity. When the worst toxicities across all cycles were considered, grade 3 to 4 neutropenia, anemia, and thrombocytopenia were found to have occurred in 14.8%, 14.8%, and 0% of patients, respectively. Grade 2 to 3 toxicities included mucositis (66.6%), dehydration (33.3%), fatigue (25.9%), and diarrhea (22.2%). Version 3.0 of the National Cancer Institute Common Toxicity Criteria was used to grade toxicities The median progression-free survival (PFS) was 112 days (range, 28-588 days). Seven patients (26%) had a PFS of >180 days (5 patients with colorectal cancer, 1 patient with pancreatic cancer, and 1 patient with non-small cell lung cancer). Polymorphisms in methylenetetrahydrofolate reductase and thymidylate synthase did not correlate with toxicity. CONCLUSIONS: The recommended dose of PDX was 148 mg/m(2) . A subset of heavily pretreated patients had PFS durations of ≥6 months with this regimen.