Bio-Path is developing RNAi nanoparticle drugs for some of the most lethal blood cancers and solid tumors. The company’s anticancer drug candidates target the expression of proteins that have been implicated in cancer cell growth and resistance to chemotherapy. Inhibition of these proteins may prove to be a low-toxicity approach to treating patients who would not historically be eligible for anticancer therapies because of their age or other comorbidities or whose cancers are unresponsive to standard treatment approaches.
Acute myeloid leukemia (AML) is characterized by the rapid accumulation of immature myeloid cells in the blood, resulting in a drop of the other cell types, such as red blood cells and platelets. Incidence increases with age, with a majority of patients aged 65 or older. AML is the most common acute leukemia in adults. The National Cancer Institute estimates that approximately 20,000 new cases occur each year. Approximately 36% of all leukemias are AML. There is a critically unmet need for non-toxic therapies for older, fragile AML patients who are unfit or ineligible for high-dose chemotherapy or a stem cell transplant. Remission rates for elderly AML patients is between 5-10% and only 5% of patients over the age of 65 will survive more than 5 years after diagnosis.
Prexigebersen (Liposomal Grb2 antisense) is Bio-Path’s lead product candidate, a neutral-charge, liposome-incorporated antisense drug designed to inhibit protein synthesis of Grb2 (growth factor receptor bound protein 2). Grb2 plays an essential role in cancer cell activation via the RAS pathway. Grb2 is an adapter protein that bridges signals between activated and mutated tyrosine kinases, such as Flt3, c-Kit, and Bcr-Abl, and the Ras pathway, leading to activation of the ERK and AKT proteins. Inhibition of Grb2 by prexigebersen represents a significant advance in treating cancers with activated tyrosine kinases using a target not druggable with small molecule inhibitors. Inhibition of Grb2 has been demonstrated to halt cell proliferation and enhance cell killing by chemotherapeutic agents without added toxicity.
Bio-Path has completed a Phase 1 clinical trial on prexigebersen as a monotherapy in relapsed and refractory AML, CML, and MDS patients (cohorts 1-6) and a Phase 2 safety segment for AML in combination with the frontline treatment, low dose Ara C (LDAC) (cohorts 7 and 8). Prexigebersen demonstrates excellent safety profiles with no serious treatment-related adverse events reported, and with data suggesting potential anti-leukemic activity. In the Phase 2 combination trial safety segment, out of a total of six evaluable patients, three patients achieved complete remission, and two achieved partial remission.
Prexigebersen has received orphan drug designation from the FDA for both CML and AML, and from the European Medicines Agency for AML.
Bio-Path is currently conducting a Phase 2 program, which will include two clinical trials of prexigebersen in combination with frontline chemotherapy. The first trial will evaluate the efficacy of prexigebersen in combination with LDAC in de novo AML patients who are elderly and induction therapy ineligible. The second trial will evaluate the efficacy of prexigebersen in combination with LDAC in relapsed and refractory AML patients. More details for these studies may be found on www.clinicaltrials.gov.
Chronic myeloid leukemia (CML) is characterized by expansion in the blood and bone marrow of mature myeloid cells and their precursors. The average age of diagnosis is 64 years old. Untreated or relapsed/refractory CML will progress to an accelerated phase and eventually blast crisis, at which point it becomes an acute leukemia. For the 1.5 percent of patients who go into blast crisis, few treatment options currently exist. Response rate to treatment for blast crisis CML is less than 30% and patients in blast crisis have an average survival of between 7 to 11 months. New therapies for this critical population are essential.
The dose determining segment of the Phase 2 clinical trial for prexigebersen in combination with the CML frontline therapy, dasatinib, is preparing to enroll patients for treatment. More details may be found on www.clinicaltrials.gov.
Prexigebersen (Liposomal Grb2 antisense), Bio-Path’s lead product candidate is a neutral-charge, liposome-incorporated antisense drug designed to inhibit protein synthesis of Grb2 (growth factor receptor bound protein 2) expression, which is critical in bridging tyrosine kinases to Ras activation in cancer cells. A hallmark of CML disease is the Philadelphia chromosome abnormality, a translocation that fuses part of the BCR gene with the ABL gene, resulting in a continuously activated tyrosine kinase leading to cell proliferation. Inhibition of Grb2 by prexigebersen represents a significant advance in treating cancers with activated tyrosine kinases using a target not druggable with small molecule inhibitors. Inhibition of Grb2 has been demonstrated to halt cell proliferation and enhance cell killing by chemotherapeutic agents without added toxicity.
Analyses of solid tumors with activated or mutated tyrosine kinases indicate that BP1001 has high potential for success in treatment of diseases beyond blood cancers. BP1001’s indications include triple negative breast cancer (TNBC), inflammatory breast cancer (IBC), ovarian cancer and autoimmune disease. Preclinical investigation is ongoing to assess the efficacy of BP1001 in treating solid tumors and the autoimmune disease systemic lupus erythematosus.
Follicular lymphoma (FL) is the most common form of low grade or slow-growing non-Hodgkin’s lymphoma (NHL). There are approximately 56,000 new cases of non-Hodgkin’s lymphoma (NHL) per year, with approximately 40% being indolent lymphomas such as follicular lymphoma (FL) and approximately 60% being the more aggressive lymphomas such as diffuse large B cell lymphoma (DLBCL) type. Treatments of varying efficacy exist for FL and DLBCL; however, due to the wide variety of subtypes of this disease, a frontline approach is lacking. FL can arise anywhere in the body within the germinal centers of the lymph nodes. Between 40 to 80 percent of patients will respond to initial therapy, but virtually all will relapse. Ten percent of the relapsed patients will not respond to treatment at all (refractory).
BP1002 (Liposomal Bcl-2) is a neutral-charge, liposome-incorporated antisense drug designed to inhibit protein synthesis of Bcl-2, a protein involved in regulating programmed cell death. Bcl-2 is overexpressed in more than 90 percent of FL and in a wide variety of solid tumors. Amplified expression of Bcl-2 protein in FL is due to the defining genetic hallmark of the disease, the chromosomal translocation t(14;18), which moves the Bcl-2 gene from chromosome 18 into the heavy chain immunoglobin locus on chromosome 14. Overexpression of Bcl-2 stops affected cells from being killed by chemotherapy. We believe that BP1002 overcomes the failures of previous attempts at inhibiting Bcl-2 by specifically interrupting the protein expression of one protein and not a family of necessary proteins and does so without inherent toxicity. With BP1002, more drug substance can reach the circulating lymphocytes so that the cancer cells can be treated with a therapeutically relevant dose. We believe BP1002 provides a new tool for cancer treatment for not just lymphomas, but also many cancers for which Bcl-2 expression is preventing cell death. The introduction of a new, non-toxic, and specific Bcl-2 inhibitor could be a major advance in cancer therapeutics.
Bio-Path is preparing to submit an IND for BP1002 and is planning to initiate a Phase 1 clinical trial for lymphoma in 2018.
Pancreatic adenocarcinoma (PDAC) is a cancer of the exocrine cells of the pancreas. Approximately 50,000 people are diagnosed with PDAC each year while 40,000 die from the disease, placing it 4th for cancer deaths despite being the 12th most common cancer. It is estimated that by 2030, PDAC will be the second most lethal cancer after lung cancer. This is due to rapid advancements that have been made in the treatment of other cancers as well as the rise of type II diabetes, a risk factor for development of PDAC.
Because most people are diagnosed with PDAC late in the disease’s progression, survival rates are very low. Typical survival for a metastatic or advanced patient is only 6-9 months from diagnosis. Treatment of this disease is hampered by the location of the pancreas, which is difficult to reach with conventional therapies and the fibrotic nature of the tumors, which protects them from penetration by chemotherapeutics. A novel and unconventional therapeutic is needed to overcome these barriers to treatment.
BP1003 is an RNAi nanoparticle containing antisense DNA targeting Stat3, a protein associated with increased PDAC severity and poor survival in the majority (80-100%) of pancreatic tumors. Bio-Path intends to initiate IND-enabling studies of BP1003 in 2018.
In addition, expression of Stat3 has been associated with higher disease severity in numerous other cancers including non-small cell lung (NSCLC), prostate, cervical, breast, colon and stage III and IV ovarian cancers. Further, dysregulation of the Jak-Stat pathway is also involved in both autoimmunity and cancer, suggesting that BP1003 may have potential to treat systemic diseases and syndromes for which immunomodulation is needed. Preclinical discovery for BP1003 in additional solid tumors is underway.
A drug that inhibits Stat3 will have significant clinical impact for all solid tumors that express Stat3.