Intranasal drug delivery for brain metastatic breast cancer

Institution: University of Southern California
Investigator(s): Axel  Schonthal , Ph.D. -
Award Cycle: 2013 (Cycle 19) Grant #: 19IB-0141 Award: $242,530
Award Type: IDEA
Research Priorities
Innovative Treatments>Gene therapy and other treatments: new frontiers

Initial Award Abstract (2013)

Non-technical overview of the research topic and relevance to breast cancer:
There is no effective therapy for breast cancer that has spread to the brain. A major roadblock is the fact that the usual breast cancer drugs are not able to penetrate the blood-brain-barrier (BBB) and therefore do not reach metastases in the brain. We are seeking to develop a novel chemotherapeutic agent that enables dosing via nasal inhalation, which will circumvent the BBB and increase brain-targeted activity, while keeping full-body exposure low.

We will take advantage of, but substantially improve upon, certain criteria that have worked well for the treatment of aggressive brain tumors, such as glioblastoma multiforme (GBM). The current gold standard chemotherapy for GBM is temozolomide (TMZ), which is given orally and crosses the BBB reasonably well (although sub-optimally). However, its full-body distribution can cause harmful bone marrow suppression.

Many years ago, the natural product perillyl alcohol (POH), which is found in many plants including fruits, had been tested for anticancer activity. Although it was fairly potent, there were severe intestinal side effects after oral dosing; therefore POH did not enter clinical practice. However, recent studies in Brazil demonstrated that simple inhalation of POH through the nose (with a vaporizer 4 times daily) is effective against brain tumors that have stopped responding to other treatments. Additionally, there were little to no side effects resulting from POH “sniffing”, which favorably impacted quality of life. This gave us the idea that POH might be useful as a vehicle to facilitate delivery of other chemotherapeutic agents into the brain via simple nasal inhalation.

Consequently, the applicant’s long-term collaborator, Dr. Thomas Chen and NeOnc Technologies generated a novel chemical entity where TMZ was fused with POH. Computer modeling predicts that this unique molecule, called T-P, has excellent brain entry, much better than TMZ. We hypothesize that T-P can be given to patients via inhalation and will be effective against breast cancer metastases in the brain, without major side effects.

While our primary intent was to generate a therapeutic molecule that can very effectively enter the brain, we made the surprising discovery that T-P is several-fold more effective at killing cancer cells in a culture dish than either parental compound, TMZ or POH, alone. Moreover, simply mixing TMZ with POH cannot replicate the potency of T-P, showing that stable fusion of the two molecules into a new entity is essential for the greatly improved potency. Administration of T-P to a few mice did not reveal major side effects, and the animals continued to thrive, indicating that the drug is well tolerated. In our proposed study, we intend to investigate whether intranasal T-P exerts therapeutic effects in animals with breast cancer-derived brain metastases.

The question(s) or central hypotheses of the research:
Our hypothesis is the following: (i) T-P is able to circumvent the BBB and enter the brain more effectively than other anticancer drugs. Therefore, in combination with its increased tumor-killing potency, therapeutically effective concentrations can be delivered to intracranial breast metastases. (ii) Intranasal delivery will (a) help concentrate the drug in the brain, and thus reduce systemic (full-body) exposure to the drug, and (b) minimize metabolism/turnover of the drug in the liver. This will enable us to give overall lower drug dosages and thus reduce the chances of unwanted toxic side effects.

The general methodology:
On one hand, we will perform studies in vitro to investigate the molecular mechanisms by which T-P attacks and kills breast cancer cells. With the use of breast cancer cell lines in culture, we will study the known targets of TMZ and POH to find out whether T-P attacks the same molecular targets, and which target(s) is (are) the critical ones to effect tumor cell death. On the other hand, we will use mouse breast tumor models with metastatic spread to the brain. We will apply two methods of drug administration, oral and intranasal, in order to determine which is more effective and has the least side effects.

Innovative elements of the project:
The innovative elements are: (i) The fusion of POH to a chemotherapeutic drug will enable intranasal delivery of the drug and, if therapeutic proof of principle with TMZ indeed can be verified, should be applicable to other drugs as well; (ii) the fusion of POH with TMZ has generated a novel compound that is substantially more potent than its individual parts; (iii) compared to conventional oral or intravenous drug administration, which distributes the drug throughout the entire body, intranasal drug delivery will increase brain targeting but decrease full-body exposure, and thus will minimize the risks of unwanted side effects, such as bone marrow suppression, which is a serious effect of many oral or i.v. chemotherapeutics.

Progress Report 1 (2014)

There is no effective therapy for breast cancer that has spread to the brain. A major roadblock is the blood-brain¬barrier (BBB), which prevents the usual breast cancer drugs from effectively reaching intracranial metastases. The alkylating agent temozolomide (TMZ) is able to penetrate the BBB and has become the gold standard for chemotherapeutic treatment of glioblastoma. However, when it was tested in clinical trials for activity against brain metastases of breast cancer, the results were mixed and ranged from “encouraging activity” to “no objective responses.” In an effort to generate an agent with greater activity against intracranial breast metastases, we synthesized a TMZ analog where the natural product perillyl alcohol (POH) was covalently linked to TMZ, in order allow more effective access to tumor growth located inside the brain. We hypothesized that this novel molecule may overcome the BBB more effectively, and may also allow drug delivery via intranasal administration.

Supported by funding from the CBCRP, we have established that the resulting novel compound, called TMZ¬POH, displayed greatly increased anticancer activity in a variety of breast cancer cell lines, inclusive of TMZ-resistant ones. It caused DNA damage and cell death much more efficiently than its parental compound TMZ, because linkage with POH increased its biological half-life and thus provided greater opportunity for placement of cytotoxic DNA lesions. In an intracranial mouse tumor model with triple-negative breast cancer, TMZ-POH revealed considerably greater therapeutic efficacy than TMZ, where a single cycle of treatment extended median survival benefit from 6 days (in the case of TMZ) to 28 days. This finding indicated that TMZ-POH was quite effective at crossing the BBB, with greater efficacy than TMZ. At the same time, TMZ-POH appeared to be well tolerated by the animals and there were no detectable side effects.

Our work so far has established the veracity of our initial hypothesis, namely that TMZ-POH may have potential as a novel therapy for brain-targeted breast cancer metastases. The important next steps of this project will include testing of TMZ-POH in HER2/neu-positive breast cancer, as this subtype, similar to triple-negative breast cancer, exhibits a propensity to spread to the brain. As well, we will now pursue drug delivery via intranasal administration, in an effort to increase therapeutic outcome even further. Intranasal delivery may support direct brain entry of the drug, which may lead to further concentrated anticancer activity against those difficult-to-treat breast brain metastases.

A novel temozolomide-perillyl alcohol conjugate exhibits superior activity against breast cancer cells in vitro and intracranial triple-negative tumor growth in vivo.
Periodical:Molecular Cancer Therapeutics
Index Medicus: Mol Cancer Ther
Authors: T.C. Chen, H.-Y. Cho, W. Wang, M. Barath, N. Sharma, F.M. Hofman, A.H. Schonthal
Yr: 2014 Vol: 13 Nbr: 5 Abs: Pg:1181-93