A team of researchers from the University of the Philippines Marine Science Institute (UP MSI) has identified a potential breakthrough in the fight against metastatic breast cancer.
Led by marine scientist Dr. Gisela P. Concepcion, the all-female team found that a compound derived from the Philippine blue sponge (Xestospongia sp.), called renieramycin M (RM), when combined with the chemotherapy drug doxorubicin (Dox), significantly reduced tumor size in mice while also minimizing the toxic side effects typically associated with chemotherapy.
The study was conducted with Dr. Lilibeth Salvador-Reyes, Zildjian Acyatan, Shalice Susana-Guevarra, Myra Ruth Picart, and Eliza Belen.
According to a post published on the UP website, the World Health Organization reported that breast cancer remains one of the leading causes of cancer-related deaths worldwide, with 2.3 million people diagnosed in 2022.
The Philippines, in particular, has one of the highest breast cancer incidence rates in Asia.
In a 2023 forum, Philippine Cancer Society President Dr. Corazon Ngelangel noted that around 65 percent of breast cancer cases in the country are diagnosed at an advanced or metastatic stage, significantly lowering the survival rate.
For metastatic breast cancer, the five-year survival rate is just 44 percent.
Concepcion, a biochemist specializing in marine-derived natural products, explained that metastatic cancer cells spread throughout the body, consuming resources and forming new tumors.
Her research team focuses on compounds from marine organisms, such as invertebrates, to develop new treatments for aggressive diseases like metastatic breast cancer.
Challenges with current therapies
Concepcion emphasized that current therapies for metastatic breast cancer are often insufficient, as cancer cells spread rapidly and form secondary tumors in various organs.
Existing treatments, like cyclophosphamide, are non-specific and can harm healthy cells, leading to significant side effects.
Likewise, Taxol, though effective, is expensive and may be rendered ineffective by drug-resistant cancer cells.
In contrast, Dox, while more affordable, is associated with serious side effects such as heart damage and leukemia.
Moreover, Dox alone is not very potent at low doses, often requiring high doses that increase the risk of harmful side effects.
Promising results
In their study, the team demonstrated that RM, when combined with Dox, significantly improved treatment outcomes for metastatic breast cancer in mice.
The researchers tested different doses of RM and Dox, including a combination of 5 mg/kg of Dox and 1 mg/kg of RM, and found that the combination resulted in a 46.53 percent reduction in tumor size by day 21 of the experiment.
This was a significant result compared to the groups treated with Dox or RM alone.
Furthermore, the combination treatment also showed promising results in reducing liver metastases, with an 86.36 percent reduction in metastasis compared to a 76.04 percent reduction for RM alone.
In addition to its effectiveness, the combination of RM and Dox helped minimize chemotherapy's typical side effects.
Mice treated with high doses of Dox or RM alone suffered higher mortality rates, but those receiving the combination treatment showed reduced toxicity.
The study showed that a low-dose combination of Dox and RM (5 mg/kg + 0.2 mg/kg) had no fatalities and showed a more favorable safety profile.
According to the researchers, the combination of RM and Dox could offer a promising treatment for metastatic breast cancer by improving efficacy while minimizing toxicity.
While the results are encouraging, the researchers stressed the need for further studies, including clinical trials, before RM-based treatments can be used in humans.