Stability of Trivalent Human Papillomavirus (Types 16, 18, 58) Recombinant Vaccine (Escherichia coli)
Cervical cancer remains a significant global health concern, with approximately 530,000 new cases and 270,000 deaths annually. Notably, 85% of these cases occur in developing countries, with China accounting for about 150,000 new cases each year, representing one-third of the global total. Human papillomavirus (HPV) infection, particularly types 16, 18, and 58, is the primary cause of cervical cancer in Chinese women. Vaccination against these high-risk HPV types is the most effective and economical strategy to prevent cervical cancer. Studies have demonstrated that vaccines based on HPV L1 virus-like particles (VLPs) exhibit excellent safety and protective efficacy.
Beijing Health Guard Biotechnology, Inc. has developed a recombinant trivalent HPV vaccine targeting HPV types 16, 18, and 58. This vaccine is expressed in Escherichia coli and adjuvanted with aluminum, presenting as a milky white suspension. The vaccine aims to prevent infections caused by HPV16, HPV18, and HPV58, as well as related diseases such as cervical cancer. The trivalent HPV vaccine received clinical trial approval in October 2017 (approval number: 2017L04835). Cryo-electron microscopy images of the HPV16, HPV18, and HPV58 VLPs are shown in Figure 1.
Stability studies are a critical component of vaccine development, providing the foundation for determining product validity, production process rationality, formulation design, and packaging material selection. These studies typically include real-time stability (long-term stability), accelerated stability, high-temperature, and light condition experiments. Long-term stability studies are essential for establishing vaccine preservation conditions and expiration dates, while accelerated and stress condition tests offer insights into vaccine stability under short-term deviations from preservation conditions and extreme environments.
This article outlines the stability of the trivalent HPV vaccine under various storage conditions, including long-term, accelerated, high-temperature, and light exposure. The study tested three batches of the vaccine stored in prefilled syringes at 2 to 8°C. The stability tests encompassed identity, appearance, fill volume, pH, osmolarity, aluminum content, polysorbate-80 content, sterility, bacterial endotoxin levels, abnormal toxicity, in vitro relative potency analysis, and in vivo potency evaluation.
Long-term stability tests were conducted under actual vaccine storage conditions to establish the vaccine’s effective period. Three batches (batch numbers: 20140501, 20140502, and 20140601) were stored at 2 to 8°C, avoiding light, and tested at 3, 6, 9, 12, 18, 24, 36, 42, 48, and 60 months. The results indicated no significant changes in appearance, fill volume, pH, osmolarity, aluminum content, polysorbate-80 content, or in vivo efficacy. Identity tests confirmed the presence of HPV16, HPV18, and HPV58 VLP antigens. Sterility, bacterial endotoxin, and abnormal toxicity tests were all within acceptable limits. However, in vitro relative potency analysis was qualified at 48 months but exceeded limits at 60 months, suggesting that the trivalent HPV vaccine remains stable for at least 48 months under these conditions.
Accelerated stability tests were performed at 23 to 27°C using the same three batches. Samples were tested at 1, 2, 3, 6, and 12 months. The results showed a slight decrease in aluminum content for batch 20140501 and a reduction in both aluminum and polysorbate-80 content for batch 20140601 at 12 months. The median effective dose (ED50) values for HPV16, HPV18, and HPV58 types were slightly elevated compared to day 0. However, all three batches remained qualified at various time points, indicating stability at 23 to 27°C for up to 12 months. These tests provided valuable information for prescription design, process improvement, quality research, packaging enhancement, and transportation and storage considerations.
High-temperature stability tests involved storing batch 20140501 at 37°C for 7 and 14 days. The results revealed a slight increase in pH, a slow decrease in polysorbate-80 content, and a slight elevation in ED50 values for HPV16, HPV18, and HPV58 compared to day 0. Despite these changes, the vaccine remained qualified after 14 days at 37°C, confirming its stability under high-temperature conditions for at least 14 days.
Light stability tests were conducted at 2 to 8°C under 4000 to 5000 lux illumination. The vaccine was removed from its outer packaging and placed in an open container. The results showed a slow increase in pH, but all other test items remained within acceptable limits, with no significant changes observed over 14 days. These tests validated the rationality of the vaccine’s formulation, production process, and packaging conditions.
Based on the results of these stability tests, the recommended storage condition for the trivalent HPV vaccine is 2 to 8°C, avoiding light. The vaccine remains stable for at least 48 months under these conditions. It can withstand high temperatures and light exposure for up to 14 days and remains stable at 23 to 27°C for up to 12 months. However, exposure to high temperatures and light should be minimized. Conservatively, the vaccine’s validity period is set at 36 months.
The development of a stable and cost-effective trivalent HPV vaccine is of great significance for Chinese women. Currently, HPV vaccines are not covered by China’s Social Medical Insurance System, and the cost of completing the immunization procedure with imported vaccines (Cervarix™, Gardasil®, and Gardasil®9) ranges from RMB 2000 to 4000 Yuan. This high cost poses a barrier for low-income families. By utilizing E. coli as the expression host, the production cost of the trivalent HPV vaccine is significantly reduced, making it a competitive alternative to imported vaccines.
In conclusion, the trivalent HPV vaccine developed by Beijing Health Guard Biotechnology, Inc. demonstrates excellent stability under various storage conditions. Its stability for up to 48 months at 2 to 8°C, along with its resilience to high temperatures and light exposure, underscores its potential as a reliable and affordable option for preventing HPV-related diseases, particularly cervical cancer, in Chinese women.
doi.org/10.1097/CM9.0000000000001659
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