Development of a Pemetrexed/Folic Acid Nanoformulation: Synthesis, Characterization, and Efficacy in a Murine Colorectal Cancer Model

Our plain-English summary of Development of a Pemetrexed/Folic Acid Nanoformulation: Synthesis, Characterization, and Efficacy in a Murine Colorectal Cancer Model, by J.G. Rosch, A.N. DuRoss, M.R. Landry, et al (ACS Omega, 2020).

The study

• Authors: J.G. Rosch, A.N. DuRoss, M.R. Landry, C. Sun
• Journal: ACS Omega
• Published: 2020;5(25):15424-15432
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The folate analogue pemetrexed (PEM) is an approved therapeutic for non-small cell lung cancer and malignant pleural mesothelioma with the potential for broader application in combination therapies. Here, we report the development of a nanoformulation of PEM and its efficacy against the CT26 murine colorectal cancer cell line in vitro and in vivo. Utilizing layer-by-layer deposition, we integrate PEM, along with folic acid (FA), onto a fluorescent polystyrene nanoparticle (NP) substrate. The final nanoformulation (PEM/FA-NP) has a size of ∼40 nm and a zeta potential of approximately -20 mV. Cell uptake studies indicated increased uptake in vitro for the PEM/FA-NP compared to the uncoated NP, likely due to the presence of PEM and FA. Viability studies were performed to determine the potency of the PEM/FA-NP formulation against CT26 cells. Syngeneic CT26 tumors in BALB/c mice showed reduced growth when treated once daily (2.1 mg/kg PEM) for 3 days with PEM/FA-NP versus the vehicle (uncoated) control, with no observable signs of systemic toxicity associated with the nanoformulation. Although the current study size is limited (n = 4 animals for each group), the overall performance and biocompatibility of the PEM/FA-NP observed suggest that further optimization and larger-scale studies may be warranted for this novel formulation.

Copyright © 2020 American Chemical Society.

In plain English

This cell and mouse study did not involve people or asbestos. The authors coated polystyrene nanoparticles with folic acid and pemetrexed, approved for non-small cell lung cancer and malignant pleural mesothelioma, and tested them against CT26 mouse colorectal cancer cells. Cells given coated particles showed two to three times the average fluorescence of cells given uncoated ones, the authors' measure of uptake. The coated particles reduced cell viability by half at 0.33 micrograms of pemetrexed per milliliter; free pemetrexed did so at 0.013 micrograms per milliliter. Four treated mice received three daily injections of coated particles carrying 2.1 mg/kg pemetrexed; four control mice received uncoated particles. Three of four treated tumors were smaller than control tumors. This difference was not significant on day 8. It became significant on day 10, after one animal was removed from each group, including the treated mouse that had not responded. Survival differences were not statistically significant. Treated mice showed no significant weight loss, and examined organs showed no discernible tissue differences. The authors concluded that larger animal studies are warranted.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study: the authors made and characterized a drug-coated nanoparticle, then ran cell-culture experiments and a small-scale mouse tumor experiment
• Who was studied: CT26 mouse colorectal cancer cells in culture, and BALB/c mice with CT26 tumors grown in the hind flank (n = 4 per group)
• Exposure: No asbestos exposure was studied. The treated mice received intravenous injections of pemetrexed/folic acid-coated nanoparticles (2.1 mg/kg pemetrexed) once daily for 3 days. The control mice received uncoated (bare) nanoparticles.
• Main results:
  • The final particles had an average size of 42.77 plus or minus 2.29 nm and a surface charge (zeta potential) of minus 21.27 plus or minus 0.49 mV
  • The formulation contained 213.5 micrograms of pemetrexed per mL, an encapsulation efficiency of 51.3%
  • CT26 cells given coated particles showed an average fluorescence signal about two to three times that of cells given uncoated particles. The authors used fluorescence as their measure of particle uptake.
  • In cells, the concentration that reduced viability by half was 0.33 micrograms of pemetrexed per mL for the coated particles and 0.013 micrograms per mL for free pemetrexed
  • In the mice, the difference in tumor size between the treated group and the uncoated-particle group was not significant on day 8, although three of the four treated tumors were smaller
  • The difference became significant on day 10, after one animal was removed from each group
  • Differences in survival were not statistically significant, although three of the four treated animals reached their endpoints later than most control animals
  • Particles coated with pemetrexed alone did not seem to produce a therapeutic response; only a single animal showed tumor inhibition
  • The treated mice showed no significant reduction in average weight
  • No discernible differences in organ histology were seen between the control groups and the treatment group. The authors interpreted this as indicating the treatment was likely not causing short-term toxicity in the clearance organs.
• The authors' conclusion: The authors concluded that the formulation seemed to show a moderate increase in tumor growth inhibition without short-term systemic toxicity, and that larger studies are warranted.
• Limitations the authors state:
  • The number of animals was small, and larger studies are needed to establish significance
  • The significant day-10 result reflects the dropout of the one treated animal that did not respond
  • Drug loading was measured indirectly and may be overstated
  • Tumor staining showed no differences between groups, likely because the tumors had large areas of dead (necrotic) tissue

Topics

Medical terms in this study, explained in our Lexicon: Pemetrexed (Alimta), Colorectal Cancer, Non-Small Cell Lung Cancer, Pleural Mesothelioma, Deposition.

Related studies

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• Folic acid phenotype (FAP) is a superior biomarker predicting response to pemetrexed-based chemotherapy in malignant pleural mesothelioma — F.D. Mairinger, C. Vollbrecht, et al. (2017)
• Efficacy of repeated adenoviral suicide gene therapy in a localized murine tumor model — E.S. Lambright, S.D. Force, et al. (2000)
• Development and characterization of a rapid-onset rodent inhalation model of asbestosis for disease prevention — B.T. Mossman, Y.M. Janssen, et al. (1991)
• Near-infrared photoimmunotherapy targeting GPR87: Development of a humanised anti-GPR87 mAb and therapeutic efficacy on a lung cancer mouse model — H. Yasui, Y. Nishinaga, et al. (2021)
• An unblinded, randomised phase II study of platinum-based chemotherapy with vitamin B12 and folic acid supplementation in the treatment of lung cancer with plasma homocysteine blood levels as a biomarker of severe neutropenic toxicity — A.R. Minchom, K. Saksornchai, et al. (2014)

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