With 300,589 projected cases for 2023, breast cancer is anticipated to be the most frequently diagnosed cancer within the United States this year. In 2020 alone, 2.8 million individuals were diagnosed, 685,000 of which proved fatal. Despite incidence increasing, mortality rates have seen a historical decrease. This increase in survivability odds is largely attributed to extended efforts of cutting-edge medical research.
In November 2022, Mary L. Disis, MD and team published an original investigation announcing the success of an experimental vaccine in resisting breast cancer recurrence. The vaccine achieved a strong immune response against key tumor protein ERBB2, formerly known as HER2, in a single arm, phase I clinical trial.
A phase I clinical trial marks the first step in testing a new treatment on humans. The primary goals of a phase I trial are to test the safety, side effects, best dose, and timing of a new treatment. Disis and team found their experimental treatment to be safe at a dosage of 10 to 500 micrograms and noted that the most common side effects associated with their novel injection were flu-like symptoms (33%), and fatigue (36%). Furthermore, the study found that participants who received higher doses demonstrated a higher (better) immune response; however, there were diminishing returns of dosage increase past 100 micrograms.
The term ‘single arm’ for a vaccine study is not what one might expect it to entail. The term does not refer to a vaccine that was injected into one arm, rather, it is a named stage of clinical trial design. In a single arm study, a sample of individuals with a targeted medical condition, in this case, advanced stage ERBB2-positive breast cancer, are dosed with an experimental treatment and followed over a length of time to observe response. Disis’ study observed 66 participants from January 2012 to August 2022. As expected with a single arm study, specific statements regarding efficacy cannot be proven at this time, but results promise a preliminary answer of ‘yes’ on a binary ‘yes’ or ‘no’ scale.
Although not definite proof of efficacy, Disis’ study provides promise of a future where a breast cancer diagnosis is not a terminal one. Unlike preventative vaccines such as the hepatitis B, flu, and human papillomavirus (HPV) shots, which aim to circumvent a diagnosis altogether, Disis’ vaccine hopes to target breast cancer recurrence. Currently, 10.4% of breast cancer survivors will face recurrence in the first five years after remission, with the number peaking at 15.2% in the first two years. This statistic is an ominous gray cloud that hangs over survivors’ heads, leaving many feeling powerless and questioning if/when their tumors will return. The phase II vaccine aims to eradicate the remaining, undetectable breast cancer cells of patients already in remission. Decreased odds of recurrence would provide breast cancer survivors, who already rightfully won their battle against cancer, with emotional relief and a higher quality of life.
A complex disease such as breast cancer requires a cocktail of treatments, consisting of differing ratios depending on an individual cases’ speed of progression and stage. Disis and team’s work signifies one step closer to opening another door a breast cancer patient’s treatment may choose to open. In the upcoming phase II clinical trial, Disis aims to formally test her observations from phase I with randomized administration of the vaccine or immune-stimulating agent, with the end goal of eliminating breast cancer recurrence.
Despite recent progress, the fight remains far from over. Research momentum continues its uphill trek as breast cancer (along with prostate and uterine corpus cancers) continues to bear the largest racial disparities in mortality amongst diagnoses.
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