Puma Biotechnology Presents Updated Findings from the Phase II SUMMIT Basket Trial of Neratinib for HER2-Mutant, Recurrent/Metastatic Cervical Cancer at the ESMO Congress 2022

Puma Biotechnology, Inc. (NASDAQ: PBYI), a biopharmaceutical company, announced the presentation of updated findings from the Phase II SUMMIT basket trial of neratinib for HER2 (ERBB2)-mutant, metastatic cervical cancer at the 2022 European Society for Medical Oncology (ESMO) Congress, currently taking place in Paris, France. The poster (#559P) entitled, "Neratinib in HER2-mutant, recurrent/metastatic cervical cancer: updated findings from the phase 2 SUMMIT basket trial,” was presented by Claire F. Friedman, M.D., Melanoma and Immunotherapy Service, Memorial Sloan Kettering Cancer Center, on September 11 at 11:10 a.m. CEST.

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The Phase II SUMMIT ‘basket’ trial is an open-label, multicenter, multi-national study evaluating the safety and efficacy of neratinib administered daily to patients who have solid tumors with activating, somatic HER2 mutations. The cervical cancer cohort was comprised of 22 patients with persistent, recurrent, or metastatic cervical cancer and a HER2 mutation, as documented by institutional testing at a CLIA/CAP- (or regionally equivalent) certified laboratory. Patients were treated with neratinib monotherapy (240 mg/day); 22 patients (100%) had previously received platinum-based chemotherapy, 16 patients (73%) had prior bevacizumab, and 4 patients (18%) received prior pembrolizumab. Overall, the objective response rate was 18.2% (95% CI: 5.2–40.3%) and the clinical benefit rate was 45.5% (95% CI: 24.4–67.8%), which included 1 patient with a confirmed complete response, 3 patients with confirmed partial responses, and 6 patients with stable disease at equal or greater than 16 weeks. The median progression-free survival was 5.1 months (95% CI: 1.7–7.2 months). Among the 13 patients (59.1%) who had tumors with a highly activating HER2 S310F/Y mutation, 4 had confirmed responses.

The safety profile observed in the neratinib-treated cervical cancer patients was consistent with that reported for neratinib monotherapy in HER2-amplified breast cancer. The most frequently observed treatment-related adverse event was any-grade diarrhea (n=18; 81.8%), which included 5 (22.7%) Grade 3 or higher diarrhea events. Diarrhea was manageable with anti-diarrheal prophylaxis and none of the diarrhea events resulted in dose reduction or treatment discontinuation.

“HER2 mutations are present in 5% of cervical cancers, most commonly in endocervical adenocarcinomas, and HER2 targeted therapy is a potential treatment option for patients whose cancer has grown after standard first lines of treatment, including platinum-based chemotherapy,” said Dr. Friedman, an investigator of the study from Memorial Sloan Kettering Cancer Center. “Neratinib treatment has been effective against several HER2-mutant cancers and the observed durable responses and disease control in metastatic patients with HER2-mutant cervical cancer are extremely promising for patients.”

Alan H. Auerbach, CEO and President of Puma Biotechnology, added, “We are very pleased to observe that treatment with neratinib led to durable response and effective disease control in patients with aggressive HER2-mutant cervical cancer and that the adverse event of diarrhea could be managed with prophylaxis. Improving the lives of our cancer patients is our foremost goal, and we are pleased to see the benefit that was provided to these patients in the SUMMIT trial.”

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-licenses the global development and commercialization rights to PB272 (neratinib, oral), PB272 (neratinib, intravenous) and PB357. 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.

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

To help ensure patients have access to NERLYNX, Puma has implemented the Puma Patient Lynx support program to assist patients and healthcare providers with reimbursement support and referrals to resources that can help with financial assistance. More information on the Puma Patient Lynx program can be found at https://www.NERLYNX.com or 1-855-816-5421.

INDICATIONS:

NERLYNX^® (neratinib) tablets, for oral use, is a kinase inhibitor indicated:

• As a single agent, for the extended adjuvant treatment of adult patients with early stage HER2-positive breast cancer, to follow adjuvant trastuzumab-based therapy.
• 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.

IMPORTANT SAFETY INFORMATION Regarding NERLYNX® (neratinib) U.S. Indication:

CONTRAINDICATIONS: None

WARNINGS AND PRECAUTIONS:

• Diarrhea: Manage diarrhea through either NERLYNX dose escalation or loperamide prophylaxis. If diarrhea occurs despite recommended prophylaxis, treat with additional antidiarrheals, fluids, and electrolytes as clinically indicated. Withhold NERLYNX in patients experiencing severe and/or persistent diarrhea. Permanently discontinue NERLYNX in patients experiencing Grade 4 diarrhea or Grade ≥ 2 diarrhea that occurs after maximal dose reduction.
• Hepatotoxicity: Monitor liver function tests monthly for the first 3 months of treatment, then every 3 months while on treatment and as clinically indicated. Withhold NERLYNX in patients experiencing Grade 3 liver abnormalities and permanently discontinue NERLYNX in patients experiencing Grade 4 liver abnormalities.
• Embryo-Fetal Toxicity: NERLYNX can cause fetal harm. Advise patients of potential risk to a fetus and to use effective contraception.

ADVERSE REACTIONS: The most common adverse reactions (reported in ≥ 5% of patients) were as follows:

• NERLYNX as a single agent: Diarrhea, nausea, abdominal pain, fatigue, vomiting, rash, stomatitis, decreased appetite, muscle spasms, dyspepsia, AST or ALT increased, nail disorder, dry skin, abdominal distention, epistaxis, weight decreased, and urinary tract infection.
• NERLYNX in combination with capecitabine: Diarrhea, nausea, vomiting, decreased appetite, constipation, fatigue/asthenia, weight decreased, dizziness, back pain, arthralgia, urinary tract infection, upper respiratory tract infection, abdominal distention, renal impairment, and muscle spasms.

To report SUSPECTED ADVERSE REACTIONS, contact Puma Biotechnology, Inc. at 1-844-NERLYNX (1-844-637-5969) or FDA at 1-800-FDA-1088 or https://www.fda.gov/medwatch.

DRUG INTERACTIONS:

• Gastric acid reducing agents: Avoid concomitant use with proton pump inhibitors. Separate NERLYNX by at least 2 hours before or 10 hours after H₂-receptor antagonists. Or separate NERLYNX by at least 3 hours with antacids.
• Strong CYP3A4 inhibitors: Avoid concomitant use.
• P-gp and moderate CYP3A4 dual inhibitors: Avoid concomitant use.
• Strong or moderate CYP3A4 inducers: Avoid concomitant use.
• Certain P-gp substrates: Monitor for adverse reactions of P-gp substrates for which minimal concentration change may lead to serious adverse reactions when used concomitantly with NERLYNX.

USE IN SPECIFIC POPULATIONS:

• Lactation: Advise women not to breastfeed.

Please see Full Prescribing Information for additional safety information.

Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding the development of Puma’s product candidates. 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 Securities and Exchange Commission from time to time, including Puma’s Annual Report on Form 10-K for the year ended December 31, 2021 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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