Ado-trastuzumab Emtansine Fails Phase II/III GATSBY trial

Earlier today, in a short statement to the U.S. Securities Exchange Commission (SEC), ImmunoGen, Inc. disclosed that the Phase II/III Gatsby trial, a clinical trial designed to support a new indication for ado-trastuzumab emtansine (Kadcyla®; Roche/Genentech / also known as T-DM1) in second-line treatment of HER2-positive advanced gastric cancer being conducted by the drugs co-developer Roche, did not meet its primary endpoint.[1]

The filing did not provide any details on how the drug trial failed. Detailed clinical findings from the trial are expected to be released during a future medical conference.

Gatsby-trial
The Gatsby-trial is a multicenter, randomized study designed to evaluate the efficacy and safety of ado-trastuzumab emtansine compared to standard treatment with docetaxel or paclitaxel in patients with HER2-positive advanced gastric cancer.  A total of 412 patients already treated with first-line therapy participated in the study.[1]

ADC Bio
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The trial’s primary endpoint was overall survival (OS) over a time frame of approximately 3 years. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), duration of response, safety, response distribution of treatment-related symptoms, time to gastric cancer symptom progression, health related quality of life (hrQoL), and pharmacokinetics.

Image 1.0. The goal of treatment with an antibody-drug conjugate or ADC is to help address the challenge of balancing benefit vs. side effects by delivering  chemotherapy directly to cancer cells, limiting damage to healthy tissues. Click on image to enlarge.

According to the American cancer Society, gastric or stomach cancer is the second most common cause of cancer-related death in the world, leading to around 800,000 deaths each year, yet it is only the fourth most commonly diagnosed cancer, with around one million people diagnosed each year. [2] The incidence of this type of cancer varies geographically, with a higher prevalence in Asian countries (such as Korea) than in the West. Also, men are more prone to gastric cancer than women.

Approved indication
Ado-trastuzumab emtansine is currently approved by the U.S. Food and Drug Administration (FDA) for treatment of metastatic, HER2-positive breast cancer that has grown despite other HER2-targeting treatments. Researchers are investigating if the drug has potential in a number of other indications, including gastric and lung cancer.

Antibody-drug Conjugates or ADCs, including ado-trastuzumab emtansine, combine tumor-specific antibodies with powerful anticancer agents, providing potent cancer treatment while minimizing damage to healthy cells. ADCs are able to recognize and enter cancer cells and release cytotoxic agents once inside the cell, making this kind of drug less harmful to healthy, non-cancerous cells.

Earlier this year, ImmunoGen, Inc. entered into a royalty purchase agreement that monetized the Company’s royalties on sales of ado-trastuzumab emtansine. According to filed statements, the drug is expected to yield about $580.3 million in revenue this year.