Adstiladrin Vs Vicinium: Treatment Options for Bladder Cancer
Bladder cancer patients now have innovative treatment alternatives with Adstiladrin and Vicinium. These novel therapies represent significant advancements for patients who haven't responded to conventional BCG immunotherapy. Let's explore how these treatments compare and what they offer to patients seeking non-surgical options.
What Are Adstiladrin and Vicinium?
Adstiladrin (nadofaragene firadenovec) is a gene therapy developed for non-muscle invasive bladder cancer (NMIBC). It works by delivering the interferon alfa-2b gene directly to the bladder wall cells, causing them to produce this protein that helps fight cancer. The treatment is administered via catheter every three months, making it a periodic intervention rather than a daily treatment.
Vicinium (oportuzumab monatox) represents a different approach as a recombinant fusion protein. It specifically targets EpCAM (epithelial cell adhesion molecule) which is often overexpressed in bladder cancer cells. By binding to these cancer cells, Vicinium delivers a cytotoxic protein that triggers cell death. The administration schedule begins with twice-weekly treatments for six weeks, followed by weekly treatments for another six weeks, then maintenance therapy.
How These Treatments Work
The mechanism of action for Adstiladrin involves genetic modification at the cellular level. Once administered into the bladder, the viral vector delivers the interferon alfa-2b gene to the cells lining the bladder. These cells then begin producing interferon, a protein with anti-cancer properties that helps stimulate the immune system to fight the cancer cells while also directly inhibiting tumor growth.
Vicinium works through a targeted approach. The fusion protein consists of an antibody fragment that specifically recognizes and binds to EpCAM on cancer cells, coupled with a bacterial toxin (Pseudomonas exotoxin A). When Vicinium attaches to cancer cells, the toxin enters the cell and disrupts protein synthesis, leading to cell death. This targeted mechanism aims to minimize damage to healthy tissue while maximizing impact on cancer cells.
Clinical Efficacy Comparison
Clinical trials have provided valuable insights into the effectiveness of both treatments. In Phase III trials, Adstiladrin demonstrated a complete response rate of approximately 53.4% at three months, with 24.3% of patients maintaining this response at 12 months. The therapy showed particular promise in patients with carcinoma in situ (CIS), a high-risk form of bladder cancer.
Vicinium's Phase III VISTA trial showed a complete response rate of 40% at three months in patients with CIS with or without papillary disease. The durability of response was notable, with 17% of patients maintaining complete response at 12 months. Both treatments have shown efficacy in patients who previously failed BCG therapy, a population with limited treatment options.
It's important to note that these treatments haven't been compared head-to-head in the same clinical trial, making direct comparisons challenging. Patient-specific factors, including cancer subtype, previous treatments, and comorbidities, play significant roles in determining which treatment might be more suitable for individual cases.
Provider Comparison and Availability
Adstiladrin is developed by Ferring Pharmaceuticals, which acquired the rights from FKD Therapeutics. The FDA granted approval for Adstiladrin in December 2022, making it available to patients with BCG-unresponsive high-risk NMIBC. The company has invested in manufacturing capabilities to ensure supply meets demand.
Vicinium was developed by Seagen (formerly Seattle Genetics), which acquired the rights from Sesen Bio. Despite promising results, Vicinium faced regulatory challenges when the FDA issued a Complete Response Letter in 2021, requesting additional clinical data. This has impacted its availability compared to Adstiladrin.
The following table compares key aspects of both treatments:
Treatment Comparison Table
| Feature | Adstiladrin | Vicinium |
|---|---|---|
| Mechanism | Gene therapy (interferon alfa-2b) | Fusion protein targeting EpCAM |
| Administration | Every 3 months | Twice weekly, then weekly, then maintenance |
| Complete Response Rate (3 months) | ~53.4% | ~40% |
| Durability (12 months) | 24.3% | 17% |
| FDA Status | Approved (2022) | Not yet approved |
| Developer | Ferring Pharmaceuticals | Seagen |
Benefits and Side Effects
Adstiladrin offers several advantages, including a less frequent administration schedule (quarterly vs. weekly/biweekly for Vicinium), which can improve patient compliance and quality of life. The treatment has shown good tolerability, with most adverse events being mild to moderate. Common side effects include bladder discharge, fatigue, bladder spasm, and micturition urgency.
Vicinium's targeted approach potentially offers precision in attacking cancer cells while sparing healthy tissue. Its side effect profile includes dysuria, hematuria, urinary tract infection, and fatigue. Some patients experience a systemic inflammatory response, though this is generally manageable with supportive care.
Both treatments represent significant advances over radical cystectomy (bladder removal surgery) for appropriate patients, potentially preserving bladder function and avoiding major surgery. However, neither treatment completely eliminates the need for ongoing surveillance, as regular cystoscopy examinations remain necessary to monitor for cancer recurrence.
Patient selection plays a crucial role in maximizing benefits while minimizing risks. Factors such as tumor characteristics, previous treatment history, and patient preferences should guide treatment decisions. Consultation with healthcare providers specializing in urologic oncology, such as those at Memorial Sloan Kettering Cancer Center or MD Anderson Cancer Center, can help determine the most appropriate treatment approach.
Conclusion
Both Adstiladrin and Vicinium represent promising advancements in treating non-muscle invasive bladder cancer, particularly for patients who haven't responded to BCG therapy. While Adstiladrin has gained FDA approval and offers a convenient quarterly administration schedule, Vicinium's targeted mechanism shows potential despite regulatory hurdles. The choice between these treatments should be personalized, considering factors such as cancer characteristics, treatment goals, and patient preferences. As research continues and clinical experience grows, these therapies may significantly improve outcomes for bladder cancer patients while preserving quality of life. Patients should discuss these options with their healthcare providers to determine the most appropriate treatment approach for their specific situation.
Citations
This content was written by AI and reviewed by a human for quality and compliance.