Status - approved/marketed in China (PRC)

Organizations involved:

Shenzhen SiBiono Gene Technologies Co. – Manuf.; R&D; Tech.; China Mark.

Hubei Tongji Benda Ebei Pharm. Co. – Parent

Benda Phamaceutical, Inc. – Parent

Onyx Pharmaceuticals, Inc. – Tech.

Introgen Therapeutics, Inc. – Patent dispute

Cross ref.: See the entry below for Advexin, a similar p53 adenovirus vector-based gene therapy in the U.S. and European markets.

Description: Gendicine is an intratumor injectable formulation of an E1B-55 gene deleted, oncolytic, replication-selective, serotype 5, adenovirus (Ad5) vector carrying human p53 gene sequence, a cellular transcriptional activator and tumor suppressor gene. This adenovirus vector delivers the p53 gene sequence into cells, but does not integrate into human DNA. Gendicine is manufactured by culture of the transformed adenovirus in infected human embryonic kidney (HEK 293) cells. Gendicine has a purity of more than 97%, and less than one replication-competent adenovirus (RCA) in 3 x 1010 virions. Gendicine is the first gene therapy to receive approval (mainland China; PRC)

[Note, Introgen Therapeutics (Houston, TX) is developing an adenoviral p53 gene therapy, Advexin (see entry below), currently in Phase III trials for treatment of head and neck squamous cell carcinoma. Depending on the source, Introgen’s vector is different and more complex than that of Gendicine, or Gendicine is substantially similar or identical to Advexin].

Nomenclature: p53 Gene Therapy/SciBiono [BIO]; Gendicine [TR China]; Genkaxin [TR former]; Recombinant Human Ad-p53 Injection [SFDA/China proper name]; Ad-p53, recombinant [SY]; adenovirus vector p53 gene therapy [SY]

Biological.: H101 does not replicate in normal cell, and therefore does not damage these cells. The E1B-55kDs gene deletion enables the modified adenovirus to selectively replicate in and lyse p53-mutated tumor cells while leaving normal cells unaffected. New viruses released from the lysed cell can infect and kill more cancer cells

The P53 gene is naturally present in the body and stops cell division when DNA damage occurs. When the P53 gene does not function normally genetic mutations can occur leading to potential cancer growth. The p53 gene, sometimes referred to as the most important antioncogene, expresses the p53 phosphoprotein that induces apoptosis (genetically programmed death of cells) in healthy cells that begin transformation into tumor cells, but has little effect on otherwise healthy cells. Many, if not most, types of tumors arise after the mutation or inactivation of the p53 gene, and restoring the presence of functional p53 protein kills the tumor cells. The p53 gene recognizes damage from mutation, and either stops cell growth to initiates repair, or if damaged beyond repair, initiates apoptosis by inducing cytotoxic T lymphocytes (CTLs) to recognize and attack tumor cells.

p53 is known to be mutated in over 60% of head and neck tumors, a form of cancer particularly common in mainland China. The adenovirus vector is reported to be a much simpler construction than is being used with adenovirus vector-based gene therapies currently in development in the U.S. and other Western countries.

The adenoviral vector-expressed p53 gene appears to exert its antitumor activities by one or more of the following mechanisms:

• Simultaneously triggering apoptotic pathways in tumor cells by a transcription-dependent mechanism in the cell nucleus and by a transcription-independent mechanism in the mitochondria and Golgi apparatus

• Activation of immune response factors such as natural killer (NK) cells to exert “bystander effects” \

• Inhibition of DNA repair and antiapoptosis functions in tumor cells

• Downregulation of the expression of (1) multidrug resistance genes to revert the resistance of tumor cells against radio- and chemotherapies, (2) the vascular endothelial growth factor (VEGF) gene to block the blood supply to tumor tissues, and (3) matrix metalloproteinase (MMP) to suppress tumor cell adhesion, infiltration, and metastasis

• Blockage of the transcription of survival signals in tumor cells, thus inhibiting the growth of tumor cells in any stage of the cell cycle

• Limitation of the uptake of glucose and the production of ATP in tumor cells.

Companies.: Gendicine was developed by Shenzhen SiBiono Gene Technologies, including over five years of clinical trials in China. Gendicine is manufactured in the company’s 16,000 sq. ft. facility (with 42 employees in early 2004). SiBiono was founded by Dr. Peng Zhaohui in 1998 with $300,000 in seed money from the Shenzhen provincial government. Since then, SiBiono has received $5 million from private investors and more than $6 million in government grants. SiBiono is constructing a $20 million facility on the outskirts of Shenzhen with a capacity of 1.5 million doses of Gendicine a year, compared with the current capacity of180,000 doses/year.

In April 2007, Benda Pharmaceutical, Inc., through its 95% owned China-based subsidiary, Hubei Tongji Benda Ebei Pharmaceutical Co., acquired a controlling 57.57% ownership of Shenzhen SiBiono for about $7.7 million.

Manufacture: Gendicine is a recombinant human serotype 5 adenovirus in which the E1 region is replaced by a human wild-type p53 expression cassette. The p53 gene is driven by a Rous sarcoma virus (RSV) promoter with a bovine growth hormone (BGH) poly(A) tail. The recombinant adenovirus is produced in human embryonic kidney (HEK) 293 cells grown in a bioreactor. Virus produced from the bioreactor is further processed and chromatographically purified to produce the recombinant human Ad-p53 injection product.

Clinical trials began in 1998 with vector manufactured in human embryonic kidney (HEK 293) cells using roller bottle culture, then CellCube (Corning Life Sciences) parallel-plate bioreactor system and CelliGen Plus packed-bed perfusion bioreactor(s) from New Brunswick Scientific. Commercial manufacture is now done in suspension, serum-free culture using a "patented large-scale bioreactor system." Shenzhen SiBiono has claimed it can produce titers as high as 2 x 1015 virions in a 14-L vessel loaded with 200 grams of Fibra-Cel disks. Peak viral bursts of approximately 40,000–50,000 virions/cell were attained on days 3 and 5 following infection.

The patented producer cell line, SBN-Cel, is a subclone derived from the HEK293 cell line. The subclone was established at SiBiono through genetic engineering and molecular cloning for the commercialization of Gendicine. The subclone showed stronger attachment to culture surfaces, a faster growth rate (doubling time, approximately 18 hr) than the parental HEK293 cells, and good virus productivity in Shenzhem SiBiono’s cGMP-compliant facility.

"SiBiono has developed and optimized a complete down-stream processing and automated chromatography purification process for the production of Gendicine. Downstream pro- cessing includes tangential flow filtration for harvest clarification and tangential flow ultrafiltration for concentration and diafiltration. The concentrate is further treated with Benzonase (DNase) to break down large cellular DNA. The material is further clarified and chromatographically purified in an automated chromatography system (fast protein liquid chromatography [FPLC]). After a single-step purification, the purity of the Gendicine final product can be greater than 98%. Approximately 4 x 10.sup.15 VP of purified fi- nal product can be produced from a single-batch 14-L bioreactor run. SiBiono has established and qualified both master/working cell banks and master/working virus banks, which are critical raw materials for the commercial production of Gendicine..

Wild-type adenovirus from the American Type Culture Collection (ATCC) is used as a reference standard. Lot release criteria include vector purity, particle concentration, infectivity, gene expression, potency, sterility, adventitious viruses, and level of replication competent adenovirus (RCA)."

"Viral particle titer determination is generally done by the A260 ultraviolet absorption method. In the presence of sodium dodecyl sulfate (SDS), 1 absorption unit at 260 nm equals 1.1 x 10.sup.12 VP/mL."

Infectivity is measured by a median tissue culture infective dose (TCID50) method, using serial dilution. According to the SFDA guideline, the specific activity (IU:VP ratio) of clinical-grade recombinant adenovirus needs to be at least 3.3%. Gendicine generally has an IU:VP ratio of about 4.0% with an infectious titer of 4–5 x 10.sup.10 IU/ml, exceeding the guideline requirement.

"The use of the A260/280 absorbance ratio as a purity indication for rAd is unique and should be in the range of 1.2 to 1.3. HPLC is also used for purity determination. According to HPLC analysis, Gendicine generally has a purity of greater than 98%, exceeding the SFDA guideline specification.

Determination of the replication-competent adenovirus (RCA) level is an important safety criterion. RCA can arise by homologous recombination between adenoviral vector and the host cell genome during the adenovirus production process. Amplification in A549 cells is generally used to detect the pres-ence of RCA. The RCA level for Gendicine meets the less than 1 RCA/3 x 10.sup.10 VP specified in the SFDA guideline.

"Gendicine is produced in accordance with strict GMP regulations as outlined in document ICH Q7A (International Con- ference on Harmonization, Topic Q7A: GMP for Active Phar- maceutical Ingredients). SiBiono has instituted an independent quality assurance function to ensure the consistent production of high-quality Gendicine product."

Status: Gendicine was approved by the State Food and Drug Administration (SFDA), Peoples Republic of China (PRC), on Oct. 16, 2003 for treatment of head and neck squamous cell carcinoma. In April 2004, SiBiono obtained a “Certificate of GMP for Pharmaceutical Product” for Gendicine production facilities. The product was launched in early 2004. Any physician in China may administer Gendicine. As of early 2006, Gendicine has only received approval in the PRC.

Shenzhen SiBiono reportedly drafted the “Points to Consider for the Development of Gene Therapy Products” document published by the SFDA.

This was the first approval anywhere in the world for a gene therapy product. Although approval was based on testing in a relatively small number of patients (by U.S. standards), China apparently saw little downside in approving an exemplary/showcase domestically-developed high-visibility therapeutic for a disease affecting its population with high incidence and mortality, and for which no other effective treatment is available (and with Chinese product approvals and other bureaucratic actions often reported as being associated with political connections or influence, such factor may also have been involved).

Until the recent supplemental approval of Erbitux, there were no FDA approved therapeutics for recurrent head and neck cancer.

Gendicine is expected to be approved for sale in India in 2008 (and it will enter the ~$200 million Indian oncology therapeutics market).

Tech. transfer: Dr. Peng Zhaohui, founder and CEO, SiBono, is recognized as the developer of Gendicine.

Gendicine uses adenovirus vector technology patented in the U.S. and other countries and under development and patented (but not in PRC) by Introgen Therapeutics (Austin, TX). Introgen apparently believes SiBono does not have the capabilities to develop and manufacture Gendicine for North American and European markets.

Shanghai Sunway Biotech Co., Ltd. (Sunway Biotech; PRC) has developed H101 (also reported to delete the E6 gene) in China (PRC), and claims to have licensed related Western patents providing worldwide protection. This includes a series of patents licensed from Onyx Pharmaceuticals (Emeryville, CA), which had been developing and conducting clinical trials in the U.S. with ONYX-015 until abandoning the product in 2003. Although Onyx had no patents on its oncolytic viruses in China, and Sunway was not infringing, it negotiated a license with Onyx in early 2005, with the company planning to eventually seek approval for H101 in the U.S. and other major markets.

Trials: H101 received approval in China in combination with chemotherapy for treatment of nasopharyngeal cancer. Gendicine was tested in China in patients with late-stage head and neck squamous cell carcinoma. Trials started in 1998. The SFDA approval was largely based on a multi-center, randomized, parallel-group study comparing 5-fluorouracil and cisplatin-based chemotherapy with and without H101. The H101 study group demonstrated a 27% increase in the number of patients who had complete or partial tumor size reduction compared to the control group.

In one trial (reported as a Phase II/III trial), 120 patients with late-stage head and neck squamous cell carcinoma (75% having advanced nasopharyngeal cancer) received either Gendicine or radiotherapy alone or the two in combination. After 8 weeks of treatment, 64% of Gendicine recipients’ tumors reportedly showed complete regression and 32% partial regression. In combination with conventional radiotherapy, Gendicine improved efficacy more than three-fold, with no patients relapsing after over 3 years of follow-up. The only reported side effect was grade I or II self-limited fever in about treated one-third of patients.

Results from the pivoal Chinese Phase III study were published in the Chinese Journal of Chemistry, vol. 23, no. 12, p. 1666-70. H1-1 injection combined with cisplatin plus 5-fluorouracil (PF) or adriamycin plus 5-fluorouracil (AF) was compared to PF or AF alone in 160 patients with head and neck or esophagus squamous cell cancer. Patients randomly received H101 (5 x 1011 - 1.5 x 1012 virus particles) daily for five days every three weeks, with all completing at least two cycles. Among accordant patients, overall response for H101 plus PF was 78.8%; for H101 plus AF was 50.0%; for PF alone was 39.6%; and for AF alone was 50.0%. It was concluded that, “Intratumoral H101 injection showed a distinct efficacy in patients with squamous cell cancer of head and neck or esophagus, and was relatively safe.”

Results from a Chinese Phase II study were published in the Chinese Journal of Chemistry, vol. 23, no. 12, p. 1307-12. Among 46 patients, the overall response rate was 30.4% vs. 13.0% for placebo recipients (p < 0.001).

Promising early-phase U.S. trials with a comparable (or equivalent) adenovirus vector construct were reported in J. Natl. Cancer. Inst. 1999 May 5;91(9):763-71.

Disease: There are an estimated 300,000 new cases of head and neck cancer squamous cell carcinoma (HNSCC) annually in China, about 10% of all cancers in China. About 80% of the world’s cased of nasopharyngeal carcinoma occur in China.

Medical: Patients receive intratumor injections of 0.5 mL of solution containing 5 x 1011 viral particles daily for five consecutive days every three weeks, in combination with chemotherapy.

Market: A dose of Gendicine costs about 3,000 yuan (about $360). This cost is beyond what the vast majority of Chinese can afford. To date, most use has been by foreigners, many having failed conventional therapy, who travel to China to receive Gendicine from several authorized clinics. The extent to which the Chinese (government-controlled) health care system will pay for Gendicine treatment vs. requiring patients to pay for Gendicine themselves will affect the product’s sales. For comparison, very few HIV/AIDS patients in China receive antiretroviral drugs costing a comparable amount for annual treatment, with Chinese HIV/AIDS patients having to purchase drugs on their own (with most not doing this). Shenzhen SiBiono plans to expand Gendicine use to other types of cancer and expand marketing into other territories, starting with Southeast Asia.     

The Chinese market for Gendicine is negligible by major market standards. Benda Pharmaceutical's total 2007 revenue was apparently less than or about $20 million.

Ongoing: Shenzhen SiBiono is conducting clinical trials with Gendicine to evaluate its ability to treat other cancers, including skin, lung, stomach, intestinal, esophageal, bladder, ovarian, cervical, and breast cancers, in combination with chemotherapy and radiotherapy.