GCSF

GCSF (Granulocyte Colony Stimulating Factor)

Generic Name: Filgrastim

Other Names: G-CSF, granulocyte-colony stimulating factor

Chemical Formula: C₈₄₅H₁₃₄₃N₂₂₃O₂₄₃S₉               
Mol. Wt.: 
                 GCSF: 18799Da
                 PEG-GCSF: 38800Da

Half life in Human body, 
                                          GCSF: 3 to 4 hours
                                          Peg GCSF: 15 to 80 hours 

Amino acid sequence:

MTPLGPASSLPQSFLLKCLEQVRKIQGDGAALQEKLCATYKLCHPEELVLLGHSLGIPWA
PLSSCPSQALQLAGCLSQLHSGLFLYQGLLQALEGISPELGPTLDTLQLDVADFATTIWQ
QMEELGMAPALQPTQGAMPAFASAFQRRAGGVLVASHLQSFLEVSYRVLRHLAQP

GCSF is belongs to CSF (colony stimulating family). There are three protein in this family CSF-1 is macrophage colony stimulating factor (M-CSF), CSF-2 is granulocyte macrophage colony stimulating factor (GM-CSF), CSF-3 is granulocyte colony stimulating factor (G-CSF).

That's why GCSF also known as CSF3 (Colony Stimulating Factor 3). GCSF naturally produced by Endothelial, Macrophages and other immune cells. GCSF receptor present on precursor cells on the bone marrow and on response to GCSF it goes to proliferation and differentiation to mature granulocytes. This glycoprotein naturally occurs in two forms 174 and 177 amino acid, the 174 amino acid glycoprotein is more abundant and more active form which is used for development of pharmaceutical products by recombinant DNA technology. Active GCSF contains a free cysteine at position 17 and two intramolecular disulfide bonds between positions 36/42 and 64/74.

While genetically it can produce by recombination DNA technology.  Generally E.Coli bacterial host cells used for recombination techniques as it is non glycosylated protein. 

As per Indian Pharmacopoeia following tests are carried out on each batch prior to release,

1)    Impurities regards to molecular mases shall be determined by electrophoresis (SDS PAGE).

2)    Impurities regards to charges shall be determined by isoelectric focusing.

3)    Impurities regards to related proteins shall be determined by Liquid chromatography.

4)    Impurities of dimers and related substance of higher molecular mass shall be determined by size exclusion  chromatography.

5)    Potency- Biological activity (In Vitro) shall be determined based on the stimulation of NFS-60 cells (murine myeloblastic cell line), HL-60 (Human leukemia cell line) or any other suitable myeloblastic cell line by recombinant G-CSF.

GCSF/PEG-GCSF Manufacturing company and their Brand name:

Company	Brand
Abbott Laboratories	Imumax
Amgen	Neupogen
Biocon	Nufil
Cadila Pharmaceuticals	Filcad
Zydus Cadila	Colstim
Dr. Reddy’s Laboratories	Grafeel
Emcure Pharmaceuticals	Emgrast
Intas iopharmaceuticals	Neukine
Novartis/Sandoz	Zarzio and Zarxio
Pfizer	Nivestim and Nivestym
Reliance Life Science	Religrast
USV	Grasustek

USFDA approval
●First GCSF analog "Neupogen" was developed and got USFDA approval by Amgen in 1991 to treat cancer patient receiving myelosuppressive chemotherapy and subsequently approved for several oncology  related indication and severe chronic neutropenic condition.  
Amgen developed pegylated filgrastim (pegfilgrastm) as a long acting formulation under the brand name "Neulasta" and got the USFDA approval on 2002.
●Granix (Tbo-figrastim) marketed by SICOR Biotech (Teva  pharmaceutical Ltd.) got FDA approve on Aug 2012, it contain same active ingredients and biologically similar but formulated to be short acting. 
●Zarxio is marketed by Sandoz got FDA approved on March 2015 and is indicated for the same condition as Neupogen hence considered as a first biosimilar.
●Nivestym is marketed by Pfizer got the FDA approval on 2018.
● Fulphila (pegfilgrastim jmdb) was developed and got the USFDA approval in 2018 by Mylan and Biocon.

PEG-GCSF:

• The PEG-GCSF produces by attaching a 20kDa methoxypolyethylene glycol propionaldehyde (mPEG-ALD) to the N- terminal amino acid of G-CSF giving molecular mass 38.8 kDa.
• Udenyca (Pegfilgrastim-cbqv) was developed and got the USFDA approval in 2018 by Coherus Bioscience, inc.

PEG-GCSF Vs GCSF:

• PEG-GCSF has longer half-life compare to GCSF.
• For the treatment GCSF is administered intravenous or subcutaneous daily for up to maximum of 14 days, while PEG-GCSF need a single subcutaneous dose per chemotherapy cycle with no restrictions of 14 day cycle only.
• Still no study prove that PEG-GCSF is superior than GCSF and clinically assume both are equivalent in treatment, safety and efficacy. However some non control study shows PEG-GCSF is superior compare to GCSF.

USES

• Used in Neutropenia and Oncological chemotherapy : Filgrastim basically used along with chemotherapy as chemotherapy affects the constantly growing cells like hair cells, blood cells produces by bone marrow. Thus patient abide to chemotherapy suffer from infection and neutropenic (Low White Blood Cells) fever. Thus Filgrastim stimulates bone marrow to produce granulocytes and stem cells and release them into the blood stream.
• Stem cell transplant : It can also be used before and after stem cell transplant.
• GCSF should be used after 24 hours of chemotherapy.

Side Effects:
All patients are not suffered with all side effects but some reported side effects are:

1. Allergic reaction: Rarely its happen, Signs include rash, swallowing or breathing problem, swelling of lips, face, throat or tongue.
2. Spleen rupture
3. Thrombocytopenia
4. Red/itchy skin around injection site,
5. Bone pain : very common
6. Bruishing and bleeding : It happen as GCSF reduces the platelet cells, This includes nose bleeding, bleeding gums, tiny red or purple spots on skin
7. Headache,
8. Fever and Chills,
9. Sickness or reduce appetite,
10. Bowel and Liver changes
11. Acute respiratory distress syndrome
12. Glomerulonephritis, kidney failure