Bioreducible cross-linked polymer coated mesoporous silica nanoparticles for targeted delivery of siRNA to

HER2+ breast cancer

Nanotek & Expo, San Francisco, CA

December 2, 2014

Moataz RedaBiomedical Engineering (BME),

Oregon Heath & Science University

siRNA (Small interfering RNA)

- First reported in 1998, leading to the 2006 Nobel Prize for Andrew Fire/Craig Mello- Used extensively for knocking down genes of cells in vitro - Since genes/proteins are responsible for metastasis, angiogenesis, anti-apoptosis, and drug-resistance, siRNA holds great promise for cancer therapy

- >85% of cancer genes are not druggable by small molecule inhibitors or antibodies.- siRNA can knock-down target genes in very specific manner

1. siRNA incorporates into RISC

2. RISC uses this siRNA strand as a template to recognize target mRNA

3. RISC then cleaves mRNA with perfect complementarity to the guide strand

4. Stop the production of that specific gene/protein (e.g., HER2).

History: 2004: First human trial for local siRNA injection to treat eye disease (Age-related macular degeneration); 2009: First human trial for treating cancer using siRNA-NPs (Davis et al, Cal Tech)

Abcam

Our target: HER2 in HER2+ breast cancer

- HER2 is overexpressed in 20% of all breast cancer but treatment cost ~ 50% of all BC market- HER2+ BCs have initial or acquired resistance to drugs within a year - HER2+ BC which acquired resistance to Tykerb and Herceptin still respond to siRNA against HER2 (‘siHER2’) siHER2 can serve as a great therapeutic if the delivery barrier can be overcome

0.001 0.01 0.1 1 10 1000

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Herceptin

Herceptin concentration (g/ml)

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ol) BT474 BT474-TR

BT474-TR developed from long termTreating BT474 cells with TykerbCells become resistant to both Herceptin and Tykerb

However, the resistant BT474-TR cells responded to siHER2-NPs in the same manner with parental BT474

Cationic polymer (PEI-PEG) coated mesoporous silica nanoparticles (MSNP) conjugated with antibody for targeted delivery

Core size (TEM) = 50 nmSize in water = 100 nm

Our nanoparticle is designed to address the delivery barriers of siRNA (e.g., short half-life due to kidney clearance, poor cellular uptake, and siRNA degradation by blood enzyme).

siRNA protection from blood enzymes

- Two versions of NPs (modified with 1.8kDa and 10kDa PEI) had been developed

- NP with 10KDa PEI was found to be optimal; it could protect 100% of siRNA for at least 24hrs in 50% human serum

- Naked siRNA had half-life of only 1 hr.

Nanoparticles conjugated with HER2-antibody impart delivery specificity to HER2+ cells and not HER2- cells

• >90% of HER2+ cells, (SKBR3), were internalized with NP-HER2-Ab in 2 hrs, but only ~5% with NP-CD20-Ab (negative control antibody)

• HER2- cells (MCF7) did not uptake the NP (<10%)

NanoparticlessiRNANuclei

Flow cytometry of dye-tagged siRNA-NP-antibody inside 10,000 cells

In vitro Efficacy: NP can knock down > 80% of HER2, leading to apoptotic death of HER2+ cells and not HER2- cells

> 80% HER2knockdown vs. siX

Death is specific to HER2+ cells, and not

HER2- or normal organ cells

All with 60 nM of siRNA

Yantasee, confidential

In vivo Efficacy: siHER2-NP-H knocks down 60% of HER2 in HCC1954 tumors

siHER2-NP-H could inhibit growth of drug-resistant HCC1954 tumors (1.25 mg siRNA/kg, i.v. once a week for 5 weeks)

HCC1954 tumors grown in MFP of mice to 200 mm3 before treatment

siHER2-NP conjugated with HER2-antibody (H)

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siRNA-NP-antibody has very favorable safety profile

High treatment specificity: previous slide.

Blood safety (in vitro): - No hemolysis vs. PBS control- No platelet aggregation- Normal blood coagulation time

Immune responses (in vitro):-Not trigger cytokine (IL-6, IL-1b, IFN-a, TNF-a) production of in blood immune cells (PBMC) compared to abraxane and feraheme

Acknowledgement

• Dr. Wassana Yantasee’s Lab– Worapol Ngamcherdtrakul– Jingga Morry– Shenda Gu– Thanapon Sangvanich– David Castro– Samuel Mihelic– Brandon Beckman– Xinran Li

• Joe Gray (cancer genomics)• Zhi Hu (HER2-siRNA)• Rosie Sears (breast cancer model)

Sponsors◦ Prospect Creek foundation◦ R01 from NIGMS◦ Fast track SBIR contract from NCI

(PDX Pharmaceuticals, LLC)◦ VPR Nanomedicine Startup