therapeutics / cancer therapies Flashcards
what do u know about AON
Knowledge of DNA sequence of a pathogenic gene allows for the design of complementary oligonucleotides (usually RNA, but can be DNA/chemical analogues), and these bind to targeted mRNA, forming RNA-DNA or dsRNA, resulting in the degradation of targeted mRNA due to normal cellular defence mechanisms. AON binding can also result in exon skipping / inclusion.
what are the 5 AON therapies
fomivirsen (vitravene)
mipomersen
eteplirsen
nusinersin (spinraza)
pegatanib (macugen)
tell me about mipomersen and familial hypercholesteremia
Mipomersen is an antisense oligonucleotide therapy used in familial cholesterolemia. Familial cholesterolemia is an autosomal dominant condition and is one of the major risk factors for atherosclerosis, It is characterised by significantly raised LDL levels in the blood, and there are a few identifiable gene variants: mutation in the LDL receptors (most), mutation in apolipoprotein B and PCSK9 mutations (small proportion). LDL receptors are responsible for the uptake of LDL into hepatocytes, but mutations limit binding capacity / recycling / availability of the LDL receptors. High levels of circulating lipid can precipitate as plaque in arterial walls.
Mipomersen is an anti-cholesterol medication and acts on ApoB levels in the body. Apolipoprotein B-100 is the main component of LDL and VLDL. Mipomersen is a single stranded antisense oligonucleotide, designed to be complementary to the ApoB gene. Upon administration (SQ injection), mipomersen reaches the hepatocyte, penetrates the cell membrane and enters the nucleus and binds to the ApoB mRNA, forming a antisense mRNA duplex (RNA-DNA oligonucleotide hybrid).
Endogenous RNAse H recognises and cleaves the hybrid, and this results in decreased apoB synthesis by the hepatocytes and lowers blood LDL levels.
Originally deemed unsafe by EMA due to links to heart and liver damage, but the hybrid has been made more stable and potent by adding modifications such as methyl group. Modifications also now allow for weekly administration as it is resistant to nuclease degradation.
what does fomivisen (vitravene) do
AON for CMV retinintis in AIDs paitients
targeting the viral nuclei
what does eteplirsen (exondys51) do
DMD (Duchenne muscular dystrophy) is a progressive, irreversible muscle weakness, and it is a X-linked recessive hereditary disease. MDs are due to the mutation in the dystrophin gene, forming an unstable, truncated and nonfunctional protein. Dystrophin is required for anchoring the myofibrils to the sarcolemma, and lack of this bridging impairs muscle contraction.
In MD, the exon 50 is missing, and the patients have a frameshift mutation in exon 51, resulting in the production of an unstable, non-functional and truncated dystrophin. Eteplirsen acts by preventing the incorporation of exon-51 in the pre-mRNA into the mature mRNA (exon skipping) and this removes the frameshift defect (now in frame). This produces a shorter but somewhat (50%) functional dystrophin, improving symptoms of disease greatly.
However, only can treat 16% of patients, and only in the patients specifically in frameshift mutations in exon 51. Other treatments include golodirsen (vyondys53)for those that are amenable to exon 53 skipping, or viltolarsen (8% of patients).
what does nusinersin (spinraza)
helps in the treatment of spinal muscular dystrophy, which affects the nerves (includnig hte ones involed in respiration and swallowing)
autosomal recessive, due to mutation in SMN1 gene
SMN2 gene known as dissease modifying gene, the more the copies of gene the milder the disease phenotypes
SMN2 is same sequence as SMN1, except at exon 7, where there is a critical C –> T transition, which makes its excluded from hte mature mRNA and no functional SMN2 protein made.
nusinersin binds to the second site of exon 7, preventing hte exon 7 from exclusion by the spliceosome (hnRNP) blocking the splice site, allows exon 7 ot be inlcuded and forming a functional SMN2 protein.
Imporves disease symptoms, life expectiany and indiv cna live longer. better otor function, more active. administered once ebery 4 momths hen gui
what does pegaptanib do (macugen)
Pathogenesis: debri (drusen) deposition on the macular, resulting in degeneration in retinal pigmented epithelial cells (DRY), and this can progress to neovascularization, where there is new formation of fragile blood vessels (WET), and the latter can be induced by vascular endothelial growth factor (VEGF) release
Consequence: wet can lead to retinal detachment and haemorrhage, and leading to central blindness
Types: dry and wet
Treatments: main aim is to prevent the progression from DRY → WET
Pegaptanib - VEGF-A aptamer antagonist targeting isoform 165 of VEGF, by adopting a 3D conformation, enabling it to bind VEGF with high affinity and inhibits it from binding to their receptors in the retina, decreasing endothelial cell proliferation and hence neovascularization.
what are aptamers and why do they helpw it h
Aptamer = short, ss oligonucleotides which binds to proteins or other molecules by secondary or tertiary structure (shape), some aptamers composed of short peptides. Shape forming feature of aptamers provides high affinity and specificity for the target.
Can inhibit protein-protein interactions leading to inhibition of target protein function
Chemical modifications to the aptamer make it highly stable, preventing nuclease degradation
Short sequences risk of toxicity / immune response and reduces the cost of manufacturing
what are some treatment for the X-linked haemophilis
- roctavian - haem A (AAV5-delivered F8)
- hemgenix - haem B (AAV5-delivered F9)
what are teh 4 principles of hgenet therapy
- know the basis of thedisease
- safe and efficiency delivery
- animal models of the disease
- phase 1-4
what is regenerative medicine
Regenerative medicine is the process of creating living nad functional tissues to repair and replace tissue or organ function less, due to age, disease, damage or congenital defects. It involves repairing damaged tissues and organs by stimulating previously irreparable tissues and organs to heal themselves.
R3 paradigms of repair:
regeneration, replacement and rejuvenations
iPSC therapy
One example of SC therapy is iPSCs, which are a type of stem cell that can give rise to different cell types in vitro (lab). iPSCs can be induced from mouse embryonic or adult fibroblasts by introducing: Oct 3/4, Sox2, c-Myc, Klf4 under embryonic stem cell conditions.
Human iPSCs express stem cells markers, and are capable of heeranting cell characteristic of all 3 germ layers, and hence can be used to treat certain conditions like heart disease. MI is myocardial tissue necrosis occurring due to O2 insufficiency, secondary to vessel occlusion. iPSC therapy can differentiate into patient specific cardiomyocytes, which are then transplanted back into the patient.
What are stem cells
Stem cells are unspecialised cells that renew themselves for a long period through cell division, and can be induced to become specialised cells. Stem cells can be used in therapy. Stem cells taken from the adult then dedifferentiated into original culture media (72h to 40 days), and depending on the redifferentiation, add the growth specific to the type of cell required, for instance cardiomyocyte. Cells regain functional activity. Then reintroduced into the body. However, the challenges include directing the cells to a proper place, integrating the cels with the patient’s own tissues and overcoming tissue rejection.
what are the features of CARs
Extracellular target binding domain - recognises the specific tumour antigen
Internal activation domain - activating T cells when CAR-T binds to the target
Spacer domain - allowing for flexibility of the extracellular binding domain
Co-stimulatory regions - present in 2nd or 3rd generations CRT-Ts, enhancing the immune response.
