Gene Therapy Primer for Pharmacists

When people hear the term 'gene therapy' many think of a futuristic technology to treat disease, while others may have questions about the ethics of the application for nonmedical uses. Survey data, meanwhile, shows that public perception of gene therapy has been increasing over the years¹, a trend which is likely to increase as more gene therapy medications are approved as potentially curative treatment.

Pharmacists should know about gene therapy medications, from current approved products to near and long-term pipeline information.

Gene Therapy Overview

The FDA defines gene therapy as a medical technique that works to modify a person’s genes to treat or cure disease. Gene therapies can work through several mechanisms:

• Replacing a disease-causing gene with a new, functioning copy of the gene
• Inactivating a disease-causing gene that is not functioning properly
• Introducing a new or modified gene into the body to help treat a disease²

Currently Approved Products^3-5

As of January 2019, there are 3 FDA-approved gene therapy products on the market:

Product

Approval Date

Indication

Administration

Estimated Cost

Kymriah^© (tisagenlecleucel)

August 2017

Relapsed or refractory large B-cell lymphoma or leukemia

Intravenous infusion (one time)

$373,000 ^- $475,000^*

Yescarta^© (axicabtagene ciloleucel)

October 2017

Relapsed or refractory large B-cell lymphoma

Intravenous infusion (one time)

$373,000^*

Luxturna^© (voretigene neparvovec-rzyl)

December 2017

Inherited form of vision loss that may result in blindness

Subretinal injection (one time per eye)

$425,000 per eye

* Kymriah’s cost is indication-specific. Note, price listed includes only the acquisition cost of the medication. Before receiving medication, patient must receive 3 days of conditioning chemotherapy. Product must be infused in the hospital setting and patient typically remains inpatient for a minimum of 7 days, all of which will increase total cost of care.

Safety Considerations^3-5

From clinical studies, the most concerning safety issues with Kymriah and Yescarta are cytokine release syndrome (CRS) and neurotoxicity. Up to 94% of participants in clinical trials experienced some degree of CRS with symptoms ranging from fever, malaise, and myalgia, to more serious symptoms of hypoxia, hypotension, and organ damage. Grade 2 or higher CRS can be managed through administration of Actemra (tocilizumab), to block inflammatory cytokines, with or without corticosteroids.

Neurotoxicity adverse reactions ranged in 58-87% of participants in studies with symptoms including encephalopathy, headache, tremor, dizziness, aphasia, delirium, insomnia, and anxiety.

In comparison, Luxturna has a much milder adverse event profile. In studies, 66% of subjects that received Luxturna had ocular adverse reactions including conjunctival hyperemia, cataracts, increased intraocular pressure and retinal tear.

Place of Administration

Each of the 3 gene therapy products are available only at an authorized treatment center. Specialized healthcare teams at each center are trained to store, handle, and infuse these medications and how to properly monitor and care for patients.

As of January 2018, Kymriah^© and Yescarta^© can be administered at 97 hospitals in 31 states while Luxturna^© can be administered at 10 hospital and/or ambulatory care centers in 9 states.

A Robust Pipeline

To date, nearly 2600 gene therapy clinical trials have been completed, are ongoing or have been approved worldwide in a variety of diseases including hemophilia, Fabry disease, Huntington’s disease, sickle cell disease, and various types of cancer.⁶

An analysis from Massachusetts Institute of Technology, projects that by 2030 we could see 40-60 cell and gene therapy launches. They also estimated that approximately 500,000 patients will have been treated with gene therapy products by 2030.⁷

Near-term pipeline^8-11

Anticipated Approval

Drug Name

Indication

Disease Prevalence

Administration

Estimated Cost

May 2019

Zolgensma (AVXS-101)

Spinal muscular atrophy (SMA) type 1

500 in U.S.

IV infusion

(one-time)

$1-4M

Mid/Late 2019

Toca-511

Recurrent high grade glioma

8000 in U.S.

One-time, followed by ER 5-fluorocytosine

TBD

Mid/Late 2019

Lisocabtagene

Large B-cell lymphoma

1-3 per 10,000

IV infusion

(one-time)

TBD

Late 2019

Valoctocogene roxaparvovec

Hemophilia A

1 per 12,000

IV infusion

(one-time)

TBD

Late 2019

LentiGlobin

Transfusion-dependent beta-thalassemia

1000 in U.S.

IV infusion

(one-time)

TBD

Conclusion

Gene therapy represents a paradigm shift in the United States healthcare system, transitioning from chronic, often lifelong treatments, to the potential for cure with as little as 1 dose of medication. As more products are approved, gene therapy will offer treatments for diseases that previously had high rates of morbidity and mortality.

The majority of pharmacists will likely never dispense or even see a prescription for a gene therapy product due to the rigorous restrictions around their administration. However, due to a robust pipeline and large number of gene therapies currently being studied, it’s important for pharmacists to be up to date on these products.

References

• Robillard JM, Roskams-Edris D, Kuzeljevic B, Illes J. Prevailing public perceptions of the ethics of gene therapy. Hum Gene Ther. 2014 Aug;25(8):740-6. doi: 10.1089/hum.2014.030. Epub 2014 Jun 17.
• What is Gene Therapy? U.S. Food & Drug Administration. https://www.fda.gov/biologicsbloodvaccines/cellulargenetherapyproducts/ucm573960.htm?rel=0" ?rel=0" . Accessed December 27, 2018.
• Kymriah [Prescribing Information]. Novartis. East Hanover, New Jersey. May 2018.
• Yescarta [Prescribing Information]. Kite Pharma, Inc. Santa Monica, California. October 2017.
• Luxturna [Prescribing Information]. Spark Therapeutics. Philadelphia, Pennsylvania. December 2017.
• Ginn SL, Amaya AK, Alexander IE, Edelstein M, Abedi MR. Gene therapy clinical trials worldwide to 2017: An update. J Gene Med. 2018 May; 20(5):e3015. doi: 10.1002/jgm.3015.
• MIT NEWDIGS Research Brief 2018F210-v027-Launches. Massachusetts Institute of Technlogy. October 29 2018. https://newdigs.mit.edu/sites/default/files/FoCUS%20Research%20Brief%202018F210v027.pdf?rel=0"
• Gene Therapies: Promising, Costly, Complex. Insight Feature—CVS Health. January 23, 2018. https://payorsolutions.cvshealth.com/sites/default/files/cvs-health-payor-solutions-gene-therapies-promising-costly-complex-feature-january-2018.pdf?rel=0" ?rel=0"
• Our Products. Tocagen. https://tocagen.com/product-candidates/?rel=0" ?rel=0" . Accessed December 27, 2018.
• Taylor P. BioMarin eyes 2019 FDA filing for haemophilia A gene therapy. PMLive. November 8, 2018. www.pmlive.com/pharma_news/biomarin_eyes_2019_fda_filing_for_haemophilia_a_gene_therapy_1259266
• Terry M. Bluebird Bio One Step Closer to its First Approved Drug. Biospace. April 20, 2018. https://www.biospace.com/article/bluebird-bio-one-step-closer-to-its-first-approved-drug?rel=0"