Pralatrexate

Synthetic Routes and Reaction Conditions: The synthesis of Pralatrexate involves several key steps. One method starts with 10-propargyl-10-methoxycarbonyl-4-deoxy-4-amino-10-deaza pteroic acid methyl ester as the starting material. This compound undergoes a saponification reaction to yield 4-(2-carboxy-1-(2,4-diaminopteridine-6-yl)pent-4-yn-2-yl)benzoic acid. This intermediate is then decarboxylated to produce 4-(1-(2,4-diaminopteridine-6-yl)pent-4-yn-2-yl)benzoic acid, which reacts with L-diethyl glutamate to form 10-propargyl-10-deaza aminopterin diethyl ester. Finally, a saponification reaction is performed to obtain this compound .

Industrial Production Methods: The industrial production of this compound follows similar synthetic routes but is optimized for higher yields and purity. The process involves the use of polar solvents like dehydrated alcohol and basic solutions such as sodium hydroxide to facilitate the reactions .

Types of Reactions: Pralatrexate undergoes various chemical reactions, including:

Oxidation: this compound can be oxidized under specific conditions to form different derivatives.

Reduction: Reduction reactions can modify the pteridine ring system.

Substitution: Substitution reactions can occur at the amino groups or the pteridine ring.

Common Reagents and Conditions:

Oxidation: Common oxidizing agents include hydrogen peroxide and potassium permanganate.

Reduction: Reducing agents like sodium borohydride are used.

Substitution: Reagents such as alkyl halides and acyl chlorides are employed.

Major Products: The major products formed from these reactions include various derivatives of this compound that can have different pharmacological properties .

Pralatrexate has a wide range of scientific research applications:

Chemistry: Used as a model compound to study antifolate mechanisms and develop new antifolate drugs.

Biology: Helps in understanding folate metabolism and transport in cells.

Medicine: Primarily used in the treatment of peripheral T-cell lymphoma. .

Industry: this compound’s synthesis and production methods are studied to improve industrial processes and reduce costs

Pralatrexate is a folate analog metabolic inhibitor that competitively inhibits dihydrofolate reductase (DHFR). This inhibition prevents the reduction of dihydrofolate to tetrahydrofolate, a critical step in the synthesis of thymidylate, purine nucleotides, and certain amino acids. By inhibiting DHFR, this compound disrupts DNA, RNA, and protein synthesis, leading to cell death. The compound selectively targets cancer cells overexpressing the reduced folate carrier protein-1 (RFC-1), enhancing its therapeutic window .

Methotrexate: An older antifolate used in various cancers and autoimmune diseases.

Pemetrexed: Another antifolate used in the treatment of non-small-cell lung cancer and mesothelioma.

Raltitrexed: Used in the treatment of colorectal cancer.

Lometrexol: An investigational antifolate with potential anticancer properties.

Uniqueness of Pralatrexate: this compound is unique due to its high affinity for the reduced folate carrier, which allows for efficient internalization and retention in tumor cells. This property makes it more effective in targeting cancer cells compared to other antifolates .

Pralatrexate, a novel antifolate drug, has emerged as a significant therapeutic agent in the treatment of various malignancies, particularly peripheral T-cell lymphoma (PTCL). Its mechanism of action, efficacy, and safety profile have been extensively studied, providing insights into its biological activity.

This compound acts primarily as an inhibitor of dihydrofolate reductase (DHFR) and is known to interfere with folate metabolism. This inhibition leads to a reduction in the synthesis of nucleotides necessary for DNA replication and cell division. The drug is transported into cells via the Reduced Folate Carrier (RFC), and its efficacy is closely linked to the expression levels of RFC in different cancer cell lines .

Overview of Clinical Trials

This compound has been evaluated in several clinical trials, notably the PROPEL study, which focused on patients with relapsed or refractory PTCL. This study enrolled 115 patients and reported a response rate of 29%, with 11% achieving complete responses and 18% partial responses. The median duration of response was 10.1 months, and the median progression-free survival (PFS) was 3.5 months .

Case Studies

• PROPEL Study :
  • Population : 115 patients with relapsed/refractory PTCL.
  • Dosage : this compound administered at 30 mg/m² weekly for six weeks.
  • Results :
    • Overall response rate: 29% (32 out of 109 evaluable patients).
    • Complete responses: 11% (12 patients).
    • Median overall survival (OS): 14.5 months.
    • Common adverse events included thrombocytopenia (32%) and mucositis (22%) .
• Combination Therapy with Romidepsin :
  • A phase 1 study combining this compound with romidepsin showed a higher overall response rate of 57% in previously treated PTCL patients. This combination was well-tolerated with manageable toxicity profiles .

Biological Activity in Preclinical Models

This compound has demonstrated potent anti-tumor activity in various preclinical models. Studies have shown that it exhibits concentration- and time-dependent cytotoxicity against T-cell lymphoma lines, often showing synergistic effects when combined with other agents such as bortezomib. In vitro studies indicated that this compound induced apoptosis through caspase activation pathways, particularly in sensitive cell lines .

Table: Summary of Key Findings from Preclinical Studies

Safety Profile

The safety profile of this compound has been characterized by common adverse effects including myelosuppression, mucositis, and fatigue. In the PROPEL study, severe adverse events were reported but were generally manageable . The addition of vitamin B12 and folic acid has been recommended to mitigate some side effects associated with antifolate therapy .

Basic Research Questions

Q. What is the mechanism of action of pralatrexate, and how does it differ from other antifolate agents?

this compound is a folate analogue metabolic inhibitor that selectively targets dihydrofolate reductase (DHFR), a critical enzyme in nucleotide synthesis. Unlike methotrexate, this compound exhibits higher affinity for the reduced folate carrier type 1 (RFC-1), enhancing cellular uptake in tumors with overexpressed RFC-1 receptors. This selectivity improves cytotoxicity in malignant cells while potentially sparing normal tissues . Methodologically, its efficacy is validated via in vitro assays measuring DHFR inhibition and competitive binding studies comparing RFC-1 affinity across antifolates.

Q. What clinical trial designs have been used to evaluate this compound’s efficacy in relapsed/refractory lymphomas?

The pivotal PROPEL study (PDX-008) was a non-randomized, single-arm, open-label Phase II trial that established this compound’s monotherapy efficacy in peripheral T-cell lymphoma (PTCL). Key endpoints included overall response rate (ORR: 29% per central review) and duration of response (median 10.1 months). Limitations of this design (e.g., lack of comparator arm) were addressed in follow-up studies like PDX-009, a Phase I/II trial combining this compound with gemcitabine, which used a 3+3 dose-escalation model to determine maximum tolerated dose (MTD) .

Q. How is this compound’s safety profile characterized in clinical settings?

Common adverse events (Grade ≥3) include mucositis (22%), thrombocytopenia (22%), and neutropenia (14%). Safety assessments in trials like PROPEL relied on CTCAE criteria, with dose adjustments (e.g., vitamin B12/folate supplementation) to mitigate toxicity. Real-world retrospective analyses corroborate these findings but note variability in tolerability based on patient comorbidities .

Advanced Research Questions

Q. How can preclinical data on this compound’s synergy with other agents inform clinical trial design?

Preclinical studies in NHL cell lines demonstrated schedule-dependent synergy between this compound and gemcitabine, attributed to sequential inhibition of nucleotide synthesis pathways. This informed PDX-009’s Phase I design, where this compound was administered 24 hours before gemcitabine to maximize synergy. However, clinical translation showed limited efficacy (ORR: 15% in Phase IIa), highlighting the need for pharmacodynamic biomarkers to optimize scheduling .

Q. What methodological challenges arise when repurposing this compound for COVID-19 treatment?

Computational screening identified this compound as a potent SARS-CoV-2 inhibitor (EC50: 0.008 µM vs. remdesivir’s EC50: 1.65 µM). In vitro validation used Vero E6 cells infected with SARS-CoV-2, with viral load quantified via RT-PCR. Challenges include reconciling its high cytotoxicity (peak plasma concentration = 10.5 µM) with therapeutic index requirements and designing adaptive clinical trials to assess antiviral vs. toxic effects .

Q. How do real-world efficacy data for this compound compare with controlled trial outcomes?

A multicenter retrospective analysis of relapsed/refractory PTCL patients (n=109) reported lower ORR (15%) vs. PROPEL (29%), attributed to heterogeneous prior therapies and poorer baseline performance status. Methodologically, such studies use propensity scoring to adjust for confounding variables but remain limited by selection bias, underscoring the need for registry-based prospective cohorts .

Q. What strategies address contradictions between preclinical and clinical data for this compound combinations?

Despite preclinical synergy with carboplatin in ovarian cancer models, Phase I/II trials (e.g., carboplatin AUC5 + this compound) achieved only modest efficacy (median PFS: 7.2 months). Discrepancies may stem from tumor microenvironment factors or folate pathway redundancy. Current strategies include integrating patient-derived xenografts (PDXs) to model resistance mechanisms and using functional imaging (e.g., FDG-PET) to assess early metabolic response .

Q. How are pharmacogenomic factors incorporated into this compound research?

RFC-1 expression and polymorphisms in DHFR and thymidylate synthase (TYMS) are explored as predictive biomarkers. For example, RNA-seq profiling in PTCL patients correlates RFC-1 mRNA levels with response duration. However, validation requires multicenter consortia to aggregate sufficient samples, given PTCL’s rarity .

Q. Methodological Recommendations

• For combination trials : Prioritize sequential dosing guided by preclinical synergy studies and incorporate biomarker-driven patient stratification.
• For repurposing studies : Use physiologically based pharmacokinetic (PBPK) modeling to balance antiviral efficacy and toxicity .
• For real-world data : Apply standardized RECIST criteria across retrospective cohorts to reduce heterogeneity in response assessment .