New Data from Stenoparib Phase II Trial

SGO is the world’s premier organization for professionals working to lessen the impact of gynecologic cancers, and the Annual Meeting on Women’s Cancer is the premier educational and scientific event for gynecologic oncologists and others dedicated to advancing gynecologic cancer care.

The poster presentation, titled "A Phase II Trial of Stenoparib (2X-121): A Novel Dual Tankyrase and PARP Inhibitor in Advanced, Recurrent Ovarian Cancer," will be presented by Dr. Fernanda B. Musa, MD, MS, Director of Clinical Trials in Gynecologic Oncology, Providence-Swedish Cancer Institute .Session: Poster Tour Group 14: Clinical Trials Impacting Future TherapiDate/Time: Monday, March 17, 10:30 a.m. PST

The poster presents data from the first Phase II study of stenoparib in advanced ovarian cancer and the first stenoparib study ever to dose twice daily. The study exclusively enrolled patients who had been previously treated with three or more lines of therapy and included patients with especially difficult-to-treat disease. Fourteen of the fifteen enrolled were platinum-resistant, while one patient had primary platinum-refractory disease that did not respond to first-line chemotherapy. There are very few effective treatment options for patients with platinum-resistant and refractory ovarian cancer, who unfortunately tend to have their disease recur within an average of three months. In this study, five patients stayed on therapy longer than four months, with four of these staying on beyond 20 weeks. Importantly, one patient showed a confirmed complete response (i.e., absence of measurable disease) that lasted more than 10 months. The patient with primary platinum-refractory disease remained on therapy beyond 40 weeks. Two patients remain on therapy currently—now more than 17 months.

The data also revealed significant clinical benefit in patients who typically do not get benefit from first-generation PARP inhibitors—those without mutations in the DNA repair gene, BRCA. One of the two patients still on therapy, now more than 17 months, did not have a BRCA mutation or other deficit in homologous DNA repair. Benefit in these BRCA wild-type patients may reflect the unique, dual therapeutic action of stenoparib in inhibiting not only PARP but also the Wnt pathway—a pathway activated in ovarian, colon, and other advanced cancers.

Key Findings:

• i. First study to dose stenoparib twice daily optimizing inhibition of PARP and Tankyrase across every 24-hour period.
• ii. First stenoparib study to show potential durable clinical benefit in platinum-resistant and refractory patients.
• iii. Data continue to show that stenoparib is well-tolerated and does not elicit the bone marrow toxicity typical of first-generation PARP inhibitors.
• iv. Study shows clinical benefit across distinct genetic backgrounds including in both BRCA-mutant patients and in BRCA wild-type (non-mutated) patients, a larger patient group than those with BRCA mutation.
• v. Study supports the unique mechanism of action for stenoparib, which inhibits PARP and the Wnt oncogenic pathway.
• vi. Study sets the stage for the newly announced protocol to evaluate stenoparib monotherapy dosed twice daily in platinum-resistant patients.
   

Dr. Fernanda B. Musa, MD, MS, site investigator for the study, commented, “This remains a challenging disease with limited therapies for patients who have already undergone many prior lines of treatment and who have been declared platinum-resistant or platinum-refractory. The findings from this study suggest that stenoparib may offer a new, well-tolerated therapeutic approach for a broader group of patients, including those with BRCA wild-type disease, who historically have had fewer options. It is a privilege to present these data at SGO 2025 and to share our findings with esteemed colleagues dedicated to advancing gynecologic oncology research.”

Thomas Jensen, Chief Executive Officer of Allarity Therapeutics, stated, “These results are foundational for us as they show stenoparib monotherapy can provide durable clinical benefit to very heavily pre-treated patients, both platinum-resistant and refractory. These data also show clinical benefit in patients both with and without BRCA mutations, or defects in homologous DNA damage repair, and may reflect the unique dual action of stenoparib on both PARP and Tankyrase targets. The data also continue to show that stenoparib is well-tolerated and does not show the bone marrow toxicity of earlier PARP inhibitors. All in all, the results of this exploratory phase 2 study have helped us to craft a new protocol designed with Dr. Fernanda Musa, Dr. Kathleen Moore, and other ovarian cancer thought leaders that will deepen and enrich our understanding of stenoparib’s durable clinical benefit—even in heavily pre-treated patients, enhance our understanding of its unique mechanism of action and accelerate the advance of stenoparib toward regulatory approval.”

Given the relatively heterogeneous patient population in this study, there are no direct comparisons to earlier studies. Importantly, this exploratory trial allowed enrollment of patients with very advanced disease, including massive ascites, following multiple prior lines of therapy. Some of these patients progressed very quickly in the study. The recently announced phase 2 protocol trial was expressly designed to narrow in on patients with platinum-resistant disease who have progressed through only a single, additional line of chemotherapy after the emergence of platinum resistance and who are without active evidence of ascites.