BriaCell (BCTX) is a clinical stage immuno-oncology company with their lead drug candidate (Bria-IMT™) being studied for the treatment of advanced metastatic breast cancer.  Breast cancer has been a difficult indication for immuno-oncology (IO) and so there is both a high unmet medical need and also a significant unmet need for an IO approach specifically. 

BriaCell has recently announced an agreement with the FDA for their pivotal, registration trial in advanced metastatic breast cancer.  The trial will use Bria-IMT™ in combination with a checkpoint inhibitor.  The combination arm will be compared to a physicians’ choice control arm.  There will be a smaller third arm of Bria-IMT™ monotherapy, but the key will be the combination arm compared to the physicians’ choice.  Upon successful completion (statistically significant benefit of treatment) of the trial BriaCell will be able to apply for full commercial approval. 

What is Bria-IMT™ and why is the combination with a checkpoint inhibitor the preferred choice?

Bria-IMT™ is a cellular immunotherapy based on a well-established breast cancer cell line.  The goal is to stimulate a patient’s immune system to both recognize and successfully attack the tumor.  Bria-IMT™ produces breast cancer antigens and it also makes GM-CSF which stimulates the immune response.  It also can directly stimulate cancer-fighting T cells. This dual direct and indirect mechanism of action ultimately increases CD4+ and CD8+ T-cells, which are critical in making a tumor susceptible to immunotherapy.

BriaCell has already observed in its Phase IIa, that Bria-IMT™ has synergistic effects with checkpoint inhibitors. The is important as the stimulation of the CD4+ and CD8+ T-cells unleash the power of the immune system, but you also need to lessen the immune-dampening effect of tumor cells.  BriaCell had previously reported data on 11 patients treated with Bria-IMT™ and Keytruda (the anti-PD1 checkpoint inhibitor marketed by Merck).

The most recent data, even more compelling, are the 12 patients treated with Bria-IMT™ and Zynyz (the Incyte Therapeutics anti-PD1 checkpoint inhibitor).  The patients were heavily pretreated with an average of 5 previous treatments – meaning these women were very sick with advanced-stage cancer.  While disease control rates are a signal of efficacy, progression free survival (PFS) is critical when looking at efficacy.  BriaCell not only looked at progression free survival but most importantly how it compared to each patient’s previous treatments.  It is important to note that as patients advance through various treatment options, the progression free survival of each subsequent treatment tends to decrease.  In other words, treatments become less effective over time, which makes perfect sense.

Medications that can limit those diminishing returns are clearly desirable, and especially treatments that can generate a better effect.  Treatment with Bria-IMT™ not only avoids those diminished returns but actually increases the PFS effect.  The data are clear as patients treated with BriaCell’s combination have a longer PFS than their previous treatment. In fact, 70% of patients demonstrated an increase in PFS as compared to the most recent drug regimen or disease control based on imaging (x-rays, CT scan, etc.).  That is quite good to say the least.

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Not only does treatment extend the PFS from the previous treatment regimen but there also appears to be a benefit in overall survival.  The median overall survival with Bria-IMT™ + CPI pre-COVID was 13.1 months compared to the overall survival in similar metastatic breast cancer patients who have failed 2+ prior therapy attempts is 6.7-9.8 months. In addition, 15 of 18 patients who started on the study since 2022 remained alive (as of AACR presentation April 2023). The longer than expected patient survival data highlights tolerability and clinical effectiveness of BriaCell’s combination treatment.

Overall, the data with Bria-IMT™ has a consistency of effect across a number of trials that speaks well to the mechanism of action as well as overall efficacy.  Clearly, registrational trial data that confirms efficacy and demonstrates survival benefits will fundamentally revalue BriaCell.  The registrational trial remains on track to commence in 2023.

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