Imaging agent aids in resolving nodal status
MELBOURNE — Imagion Biosystems Limited (ASX: IBX), a company dedicated to improving healthcare through the earlier detection of cancer, today presented interim data from the Company’s ongoing Phase I study for its MagSense® HER2 breast cancer imaging agent at the 2022 San Antonio Breast Cancer Symposium, a world-leading forum for scientists and clinicians focused on breast cancer research and patient care.
Previously the Company has reported that the MagSense® HER2 imaging agent has been well tolerated and that there have been no safety issues related to the agent identified. Here the Company reports for the first time the initial findings of the exploratory endpoints related to cancer detection. Analysis of the first cohort of six patients suggests that the molecular signature of the MagSense imaging agent, when used with conventional MRI could help discriminate potentially cancerous nodes from normal nodes. The work was presented by Dr. Yalia Jayalakshmi, Chief Development Officer at Imagion Biosystems, and co-authored by study principal investigators. Together, the authors conclude that when combined with standard morphological assessments, the imaging agent “has the potential to improve radiological evaluation thereby improving the standard of care clinical assessments.” The Company notes that enrolment for the second cohort is ongoing with results consistent with those reported at the meeting and that further studies will be needed to broaden the study population to fully characterize the diagnostic performance of the imaging agent.
Several important findings have emerged from the results to date:
- changes in MR contrast created by the specific binding of the MagSense imaging agent to tumour cells in the nodes aids in resolving nodal status;
- the imaging agent is detectable by magnetic relaxometry, however, more subject samples are needed due to the limited amount of accessible dissected nodal tissue to date; and
- there have been no safety, toxicity or adverse events reported related to the imaging agent.
“We are very excited to be reporting our first clinical data at this important breast cancer meeting”, said Bob Proulx, CEO. “The results presented at the meeting are focused on the study protocol’s first cohort of six patients only, and though the number of patients might seem small, the implications for the Company are large as they provide the first proof-of-principle of our targeted nanoparticle technology in the clinical setting. Evidence in real patients that our nanoparticle technology could improve upon conventional medical imaging methods is a major milestone for the Company. We are very pleased to be sharing these results with our shareholders and we look forward to providing additional updates as we make further progress.”
The Importance for HER2 Breast Cancer
Breast cancer is one of the most commonly diagnosed cancers among women and is the second leading cause of cancer deaths among women overall. Of the four breast cancer subtypes, HER2 represents 10-20 percent and has significant prognostic and predictive implications because the HER2 subtype is considered an aggressive phenotype with a high rate of recurrence and metastasis. The HER2 status is frequently maintained during progression to invasive disease, nodal metastasis, and distant metastasis. Nodal status often determines the course of treatment including systemic therapy, the extent of surgery, reconstruction options, and the need for radiation therapy after mastectomy. Currently, nodal assessment is based on palpation or conventional imaging techniques, predominantly ultrasound. These methods try to identify nodes that appear to be abnormal by size or shape but are not able to confirm if cancer is present. Therefore, the current standard of care still relies on invasive biopsies and follow-up by a pathological confirmation to inform clinical decision-making. Imagion’s noninvasive and molecularly specific approach to cancer detection has the potential to improve the overall diagnostic accuracy of axillary nodal imaging and reduce the need for invasive biopsies.
The poster presented can be found here: REQUEST COPY OF SABCS POSTER
Why only the first six patients?
By the time of the SABCS submission deadline, the available results from the first six subjects had sufficient information to meet the requirements of a scientific presentation at a major conference. This important conference occurs only once a year and we are excited to have had this data available in time to present to this audience. Based on the learnings from the first six subject data, we amended the protocol to improve the data collection. As we noted in the announcement, additional subjects have been enrolled with the amended protocol and the general trend of the data is similar to the prior data set.
What’s the significance of the reported findings?
The poster’s conclusion states: “Comparison of pre-dose vs. post-dose MR images appear to discriminate suspicious nodes from the normal nodes by the molecular signature of the HER2 targeted nanoparticles. These data suggest that combining standard morphological assessments (size and shape) with observable changes in MR contrast has the potential to improve radiological evaluation thereby improving the standard of care clinical assessments.” This is clearly geared to the clinical/scientific community, so here’s a “translation” of the medical speak.
Today most patients after primary diagnosis of breast cancer have an ultrasound exam to look at the lymph nodes. They will look for nodes that are enlarged or misshaped as an indication that there may be metastatic disease. However, ultrasound examination has three limitations: i) it is limited in how many nodes might be visible/detectable, ii) it can’t determine what is in the node just that it is abnormal looking, and iii) it is operator dependent so there is some subjectivity to the exam and analysis.
What we are seeing in the study is that by using the MagSense® nanoparticles the radiologist can still get the standard size/shape assessment but also gets added information that comes from the change in contrast (darkening of the image) resulting from the nanoparticles when they become attached to tumor cells (the “molecular signature”). The amount of contrast is different if the node is “normal” vs when tumor cells are present. The conclusion being that a test with a molecular imaging agent could provide better radiological assessment and improve on the current clinical standard of care.
This is exactly the use we have been aiming for. Rather than use imaging to identify a “region of interest” or “suspicious lesion”, use a molecularly targeted approach to determine if, in fact, cancer cells are present.
The number of subjects is small, how confident can we be?
Unlike therapies where the clinical trials need to assess whether the drug is effective in curing disease or at least deterring disease progression, our imaging agent needs to show detectability and specificity to be clinically useful. The old expression, “we’ve cured a lot of mice of cancer, but not many people” holds true because of the difference in human biology and the complexities of how disease develops and responds to drugs. The goal of our Phase I study has been to bridge the gap between our pre-clinical studies and human biology. The data we have accumulated to-date recapitulates in human subjects what we found in our preclinical workups – that our imaging agent is detectable, and the imaging signature helps differentiate when cancer cells are present.
What does it mean for the magnetic relaxometry technology?
Because we did not want to spend large amounts of money developing a new imaging machine until we knew if the nanoparticle agent would work, we had to design a study that would allow us to test the relaxometry method using our existing prototype system. This is done by obtaining tissue samples from the study subject’s lymph node(s) and measuring the excised tissue sample ex vivo (outside the body). But obtaining enough lymph node tissue can be challenging so we don’t have as much data yet on MRX measurement as we do for MRI. We have reported that for those patients where we have obtained sufficient tissue, there is a measurable MRX signal, indicating detectability, but we feel we need more samples/data before being able to draw any conclusions that would result in commitment of investment in developing the instrument system.
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