In short
OBI-821 is being investigated in clinical trials as an innovative immunotherapy approach for various advanced cancers. This drug works as an adjuvant combined with OBI-833 (also known as Globo H-CRM197), creating a carbohydrate-conjugate vaccine that targets Globo H, a tumor-associated carbohydrate antigen found in many cancer types. Current trials are examining this combination's effectiveness as maintenance therapy for biliary tract cancer and as a treatment for advanced gastric, lung, colorectal, and breast cancers. The treatment aims to stimulate the immune system to recognize and attack cancer cells, potentially offering new hope for patients with limited treatment options.
Key points
- OBI-821 is being investigated in clinical trials as an immunotherapy component paired with OBI-833 (Globo H-CRM197) for treating various advanced cancers. This combination forms a carbohydrate-conjugate vaccine that targets Globo H, a tumor-associated antigen present in many epithelial cancers. Current trials include a Phase 2 study evaluating its use as maintenance therapy for biliary tract cancer patients who haven't progressed on standard chemotherapy, and studies in metastatic gastric, lung, colorectal, and breast cancers. The treatment is administered through subcutaneous injections on a gradually decreasing schedule. Researchers are measuring progression-free survival, overall survival, tumor response, and immune activation to determine the therapy's effectiveness in addressing the significant unmet needs in these difficult-to-treat cancers.
At a glance
- Drug Combination
- OBI-833 (Globo H-CRM197) and OBI-821 (saponin-based adjuvant)
- Mechanism of Action
- Carbohydrate-conjugate vaccine that targets Globo H (tumor-associated carbohydrate antigen) combined with an immune adjuvant
- Administration
- Subcutaneous injections on a gradually decreasing frequency schedule
- Cancer Types in Trials
- Biliary tract cancer (cholangiocarcinoma), gastric cancer, lung cancer, colorectal cancer, breast cancer
- Phase 2 Biliary Tract Cancer Trial
- Single-arm study with 30 patients who have Globo H-positive advanced disease and haven't progressed on first-line gemcitabine/cisplatin
- Other Trial
- Open-label study in advanced/metastatic gastric, lung, colorectal, or breast cancer with dose escalation and cohort expansion
- Primary Outcomes
- Progression-free survival, safety (number of participants with treatment-emergent adverse events)
- Secondary Outcomes
- Overall survival, tumor response, safety profile, immune response (anti-Globo H antibodies), biomarker correlations
- Treatment Duration
- Up to 80 weeks in the biliary tract cancer trial; various schedules in other trials
- Target Population
- Patients with Globo H-positive tumors (Globo H is expressed in approximately 41% of intrahepatic cholangiocarcinoma specimens)
What is OBI-821?
OBI-821 is a medical treatment being studied for various types of cancer. It's not used alone but is combined with another medication called OBI-833 (also known as Globo H-CRM197) to create a special type of cancer treatment called an immunotherapy vaccine. This combination is designed to help your immune system fight cancer cells.
OBI-821 is specifically a saponin-based adjuvant derived from the bark of the Quillaja saponaria Molina tree. In simple terms, it's a substance that helps boost the effectiveness of the vaccine. It's structurally similar to another adjuvant called QS-21 and is used to enhance your body's immune response to the treatment.
How Does OBI-821 Work?
The OBI-833/OBI-821 combination works as an active cancer immunotherapy. This means it trains your immune system to recognize and attack cancer cells. Here's how it works:
- OBI-833 contains a substance called Globo H, which is a type of marker (called a tumor-associated carbohydrate antigen or TACA) found on many cancer cells but not normally found on healthy cells.
- This Globo H is attached to a carrier protein called CRM197, which is a harmless form of diphtheria toxin.
- OBI-821 is added as an adjuvant to strengthen your immune system's response to the vaccine.
When given to patients, this combination helps the immune system recognize the Globo H marker on cancer cells and attack them. It's like training your immune system to spot and fight the cancer on its own.
What Conditions Does OBI-821 Treat?
Based on the current clinical trials, OBI-833/OBI-821 is being studied for treating several types of advanced or metastatic cancers (cancers that have spread from where they started). These include:
- Biliary tract cancer (including cholangiocarcinoma) - these are cancers that form in the bile ducts, which carry digestive fluid bile from the liver to the small intestine
- Gastric cancer (stomach cancer)
- Lung cancer
- Colorectal cancer (cancer of the colon or rectum)
- Breast cancer
The treatment appears to be specifically targeted at cancers that are Globo H-positive, meaning the cancer cells have the Globo H marker on their surface. For example, about 41% of intrahepatic cholangiocarcinoma (a type of bile duct cancer) specimens have been found to express Globo H.
Current Clinical Research
OBI-833/OBI-821 is currently being studied in clinical trials, which are research studies that test how well new medical approaches work in people. Two important studies are:
- Phase 2 study for advanced biliary tract cancer: This trial is evaluating OBI-833/OBI-821 as a maintenance therapy for patients with Globo H-positive advanced biliary tract cancer who have responded to initial chemotherapy with gemcitabine and cisplatin. The study aims to see if adding this treatment can help maintain and extend the benefits of first-line chemotherapy.
- Open-label study for various advanced/metastatic cancers: This trial is assessing the safety, tolerability, and effectiveness of OBI-833/OBI-821 in patients with advanced or metastatic gastric, lung, colorectal, or breast cancer.
These clinical trials are crucial to understanding how well this treatment works and for which patients it might be most beneficial.
How is OBI-821 Administered?
OBI-833/OBI-821 is given as a subcutaneous injection, which means it's injected just under the skin. The treatment schedule varies depending on the specific clinical trial, but generally follows a pattern of more frequent injections at the beginning, then gradually decreasing in frequency.
For example, in the biliary tract cancer study, injections are given on a schedule of:
- Weekly for the first 4 weeks (Weeks 1, 2, 3, 4)
- Every 2 weeks for the next 4 weeks (Weeks 6, 8)
- Every 4 weeks for the next 16 weeks (Weeks 12, 16, 20, 24)
- Every 8 weeks thereafter (Weeks 32, 40, 48, 56, 64, 72, 80)
The total treatment period can last up to 80 weeks in some cases. Throughout this time, patients are regularly monitored for both safety and treatment response.
Effectiveness of OBI-821
Since OBI-833/OBI-821 is still in clinical trials, comprehensive data on its effectiveness isn't yet available. However, the research is looking at several important outcomes to measure how well it works:
- Progression-free survival: This measures how long patients live without their cancer getting worse. This is the primary goal of the biliary tract cancer study.
- Overall survival: This measures how long patients live after starting the treatment.
- Tumor response: This looks at whether tumors shrink or stop growing in response to the treatment.
- Immune response: Researchers are measuring antibody responses against Globo H to see if there's a correlation between immune response and survival.
Previous studies have shown that OBI-833/OBI-821 can trigger immune responses and help stabilize disease in some cancer patients, which is promising for future research.
Safety Profile
As with any medical treatment, especially one still in clinical trials, monitoring for side effects is important. The current trials are carefully tracking any adverse reactions that patients might experience.
Researchers are specifically monitoring:
- General adverse events and serious adverse events
- Local injection site reactions (such as redness, swelling, or pain where the injection was given)
- Changes in laboratory tests, including blood counts and chemistry
- Changes in vital signs
- Changes in physical examination findings
In the biliary tract cancer study, there's a specific "lead-in safety cohort" of 6 patients that will be evaluated first before moving to full enrollment, which shows the careful approach being taken to ensure patient safety.
It's important to remember that the safety and effectiveness of OBI-833/OBI-821 are still being evaluated through these clinical trials, and the treatment is not yet approved for general use outside of research studies.