Puma Biotechnology, Inc. (NASDAQ: PBYI), a biopharmaceutical company, announced the presentation of alisertib for the treatment of patients with advanced osimertinib-resistant epidermal growth factor receptor-mutated (EGFR-mutated) non-small cell lung cancer (NCT04085315) at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting currently being held in Chicago. The poster (Abstract #8572, Poster Bd #436), entitled, “A Phase I/Ib study of the aurora kinase A inhibitor alisertib in combination with osimertinib in advanced osimertinib-resistant EGFR-mutated lung cancer,” was presented by Turja Chakrabarti, MD., University of California, San Francisco, at the Lung Cancer – Non-Small Cell Metastatic Poster Session, on June 3 at 1:30 p.m. CDT. A copy of the poster is available on the Puma website.

This open-label, single-center Phase I/Ib study enrolled 21 evaluable patients with stage IV EGFR-mutated NSCLC (EGFR driver mutation: 76.1% exon 19 deletion; 14.3% L858R; 9.5 % L861Q) who had progressed on osimertinib monotherapy. 47.6% of patients had previously received only first-line osimertinib monotherapy, while 52.3% had received two or greater prior lines of therapy. In the Phase I portion of the trial, 10 patients were treated in a 3+3 dose escalation phase with alisertib using an intermittent dosing strategy of 30 mg (n = 6) or 40 mg (n = 4) twice daily (BID) in combination with osimertinib 80 mg daily. Alisertib was added to osimertinib treatment at the time of disease progression on osimertinib. Intermittent alisertib 30 mg BID was identified as the MTD and RP2D in combination with osimertinib 80 mg daily.

In the Phase Ib expansion portion of the trial, 11 additional patients were treated at the 30 mg alisertib BID intermittent dosing schedule in combination with osimertinib 80 mg daily with alisertib being added to osimertinib treatment at the time of disease progression on osimertinib.

The most common treatment-related adverse events (AEs) (any grade) included neutropenia (42.9%), anemia (42.9%), diarrhea (38.1%), and lymphopenia (33.3%). Grade 3 or higher AEs neutropenia (4.8%), anemia (4.8%), diarrhea (14.3%), and lymphopenia (4.8%).

For the 21 evaluable patients, the investigator assessed overall response rate was 9.5% (95% CI: 0 to 22%) and disease control rate was 81% (95% CI: 69% to 93%). The median PFS for all patients was 5.5 months, while the median OS was 23.5 months. For patients with TP53 mutations (n=9), the overall response rate was 0%, and the disease control rate was 66.7%. For patients who were tp53 wild type (n=8), the overall response rate was 25%, and the disease control rate was 87.5%. For patients with TP53 mutations, the progression free survival was 3.7 months, and for patients who were tp53 wild type, the progression free survival was 8.0 months (hazard ratio:0.42, p = 0.05).

Dr. Collin M. Blakely, the lead principal investigator of the study and senior author of the presentation, from the University of California in San Francisco, said, “We are pleased with the initial results of the clinical trial and very interested in the cohort of patients who are tp53 wild type as tp53 is known to be involved in the aurora kinase pathway. We are modifying the protocol to limit further enrollment in the trial to patients who are tp53 wild type and we look forward to further studying this combination in this biomarker directed cohort of patients.”

Alan H. Auerbach, Chief Executive Officer and President of Puma Biotechnology, said, “We are pleased to see the promising efficacy signals in the cohort of patients who are tp53 wild type. As tp53 is well known to be involved in the aurora kinase pathway, we are pleased to see the activity of alisertib when given in combination with osimertinib in this population of patients. We look forward to continuing to enroll this trial in this cohort of patients.”

About Puma Biotechnology

Puma Biotechnology, Inc. is a biopharmaceutical company with a focus on the development and commercialization of innovative products to enhance cancer care. Puma in-licensed the global development and commercialization rights to PB272 (neratinib, oral) in 2011. Neratinib, oral was approved by the U.S. Food and Drug Administration in 2017 for the extended adjuvant treatment of adult patients with early stage HER2-overexpressed/amplified breast cancer, following adjuvant trastuzumab-based therapy, and is marketed in the United States as NERLYNX® (neratinib) tablets. In February 2020, NERLYNX was also approved by the FDA in combination with capecitabine for the treatment of adult patients with advanced or metastatic HER2-positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting. NERLYNX was granted marketing authorization by the European Commission in 2018 for the extended adjuvant treatment of adult patients with early stage hormone receptor-positive HER2-overexpressed/amplified breast cancer and who are less than one year from completion of prior adjuvant trastuzumab-based therapy. NERLYNX® is a registered trademark of Puma Biotechnology, Inc.

In September 2022, Puma entered into an exclusive license agreement for the development and commercialization of the anti-cancer drug alisertib, an investigational, selective, small molecule, orally administered inhibitor of aurora kinase A. Initially, Puma intends to focus the development of alisertib on the treatment of small cell lung cancer and breast cancer. In February 2024, Puma initiated ALISCA-Lung 1, a Phase II clinical trial of alisertib monotherapy for the treatment of patients with extensive-stage small cell lung cancer.

Further information about Puma Biotechnology may be found at https://www.pumabiotechnology.com.

Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding Puma’s anticipated milestones and the development of alisertib. All forward-looking statements involve risks and uncertainties that could cause Puma’s actual results to differ materially from the anticipated results and expectations expressed in these forward-looking statements. These statements are based on current expectations, forecasts and assumptions, and actual outcomes and results could differ materially from these statements due to a number of factors, which include, but are not limited to, the risk factors disclosed in the periodic and current reports filed by Puma with the U.S. Securities and Exchange Commission from time to time, including Puma’s Annual Report on Form 10-K for the year ended December 31, 2023 and subsequent reports. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. Puma assumes no obligation to update these forward-looking statements, except as required by law.

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