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SNGX: SGX942: Cancer Control is an “Added Bonus” for OM Treatment

By Grant Zeng, CFA


Soligenix (NASDAQ:SNGX) is a late stage biopharmaceutical company focused on cancer/cancer supportive care, GI disorders and biodefense. Based on three platform technologies, SNGX has built a diversified pipeline targeting multiple indications. We are optimistic about its lead candidates SGX301for CTLC and SGX942 for the treatment of oral mucositis. The Company’s oral BDP is in various development stages for a variety of indications, most notably, in pediatric Crohn’s disease, where they will be initiating a Phase III study soon for SGX203. SNGX also is developing vaccines using its ThermoVax technology for biodefense. 

Recently, Soligenix announced the positive data from its Phase II clinical trial of SGX942 (dusquetide) in the treatment of oral mucositis (OM) in head and neck cancer patients undergoing chemoradiation therapy (CRT).  The company is engaging the FDA and the European Medicines Agency (EMA) on the design of a pivotal Phase IIb/III clinical program. 

With the biologic activity of the IDR technology now confirmed in humans, Soligenix is also look to expand its potential utility in other disease space. In addition to tissue damage and infection, another potential area for SGX942 is for the treatment of cancer.

Recently we interviewed the company’s Sr. VP and CSO Dr. Oreola Donini about SGX942’s potential as a cancer treatment agent. Here are the highlights of the interview. 

Would you please update us on the recent development of the company’s key asset SGX942?

Dr. Donini: We have recently announced the clearance of the Phase III protocol for SGX942 (dusquetide) to treat oral mucositis (OM) in head and neck cancer patients which came directly on the heels of the completion of the Phase II follow-up visits and study report in late 2016. As we move forward with our Phase III study this year we plan to evaluate the OM treatment response in the high risk population we identified in the exploratory Phase II study, where the median duration of OM was 30 days in the placebo group compared to only 10 days in the SGX942 1.5 mg/kg dose group (67% treatment effect; p=0.04). The phase 2 efficacy data was published in 2016 (see ) while the long term follow-up data publication is anticipated this year. The cleared Phase III study will evaluate the same endpoints as the Phase II study, including safety endpoints related to infection control and the rapidity of tumor resolution. 

Soligenix continues to explore avenues to move the SGX94 (dusquetide) technology platform forward in the infectious disease space as well, given the positive proof of concept data generated in the Phase II OM trial with respect to infection control as well as the extensive nonclinical database - some of which has been published (see North et al 2016 at ). 

In addition to tissue damages and infections, I have noticed that SGX942 may have the potential to treat cancers, can you discuss the mechanism of action?
As we know, the immune system is one of the most potent protections and treatment options for cancer. In particular, where cancer occurs there is a local accommodation of the tissue and the immune tolerance of that tissue. Immune modulation has the potential to alter this local "tolerance" for the cancer cells / growth, making the environment for the tumor less favorable and potentially controlling growth and clearance of the tumor.   

The target protein for Innate Defense Regulators (of which SGX942 is the lead clinical candidate) is p62 and it has been implicated in precisely this role in the context of multiple myeloma - where p62 and downstream IL-6 signaling of the stromal cells is important to the control of myeloma. 

In addition, some tumor cells are also directly susceptible to p62 modulation due to their internal mechanisms for uncontrolled proliferation (tumorigenesis). An example of this is some breast cancer cell lines. 

Mechanistically then there is a rationale for potentially expecting a direct anti-tumor effect of SGX942.

Do you have any preclinical or clinical data of SGX942 for the treatment of cancers?

Clearly the impact of SGX942 on tumor control is a very important safety issue for OM treatment. In fact, the fear of negatively impacting tumor control is the reason why other products have been limited to treating OM in specific tumor contexts only, despite the fact that the pathogenesis of OM is considered the same in all cancer settings. 

With this is mind, we have looked at the impact of SGX942 on tumor growth in nonclinical animal studies - one of which we have discussed in our publication last year. In this case we see SGX942 does not support tumor growth. In fact, in this study we saw that there was a decrease in tumor growth with SGX942 treatment.  This suggests we may have a direct anti-tumor effect, consistent with the known activity of the target protein p62. 

In our Phase II study - we evaluated the tumor resolution in head and neck cancer, again as a safety endpoint only. Here we saw faster resolution of the tumor (see our December webcast on our website for more details on this).  That is, at the 1-month follow-up visit, more patients with the most effective SGX942 treatment (1.5 mg/kg) had a "complete resolution" of their underlying head and neck cancer than in the placebo group.
What’s your development plan for SGX942 in the cancer indications?
Soligenix is focused on oral mucositis as our primary indication.  It is crucial to regulators, clinicians and patients that any treatment for OM does not negatively impact the ability to treat the underlying cancer. The fact that SGX942 may have a direct anti-tumor effect is an "added bonus" of the therapy but is not a treatment claim we are pursuing. Cancer treatment trials require significantly more follow up (3-5 years), making approval timelines much longer. 

Anything else should investors pay attention to for SGX942 cancer treatment?
As I noted above, we view any potential anti-tumor activity as an ancillary benefit or "added bonus" to the use of SGX942 for OM treatment. Given the problems with other treatments for OM - which have been specifically contraindicated in some patient populations due to the risk of promoting tumor growth - this has the potential to be a significant product advantage relative to potential competitors. 
The mechanism of Innate Defense Regulators really positions them across a broad range of indications that relate to innate immunity. Because innate immune modulation is a new approach to disease treatment, the constellation of available indications is not grouped by disease site or other commonly used paradigms.  Innate Defense Regulators can work across infectious disease, oral mucositis, acute inflammatory ailments (eg, macrophage activation syndrome) and acute radiation exposure, for example.  And as the disease pathogenesis of other diseases are found to involve innate immunity, a not unlikely event given how our understanding of the contribution of innate immunity to disease is still emerging, more indications will likely be added to this list with time. 

Given the broad range of potential indications, Soligenix has elected to focus initially on oral mucositis, where the regulatory path is very well defined, and secondarily on infectious disease, where Innate Defense Regulators can treat antibiotic resistant infections, a rising concern with the development of resistance to antibiotics. 

Other indications may be explored in future, but are not an immediate priority.

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