Spectrum Pharmaceuticals to Present Data at 2022 ASCO Highlighting the Potential Predictive Capabilities of ctDNA as a Biomarker for Poziotinib Treatment Response

Reduced circulating tumor DNA (ctDNA) and circulating free DNA (cfDNA) levels were associated with tumor shrinkage in patients that responded to poziotinib treatment

Poziotinib has received Fast Track designation from FDA and a Prescription Drug User Fee Act (PDUFA) date of November 24, 2022

Spectrum Pharmaceuticals (NasdaqGS: SPPI), a biopharmaceutical company focused on novel and targeted oncology therapies, today announced additional exploratory data for poziotinib in non-small cell lung cancer (NSCLC) patients harboring HER2 exon 20 insertion mutations at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting being held in Chicago from June 3-7.

In poziotinib treated patients with advanced NSCLC harboring HER2 exon 20 insertion mutations, baseline ctDNA presence was associated with the tumor tissue genotyping with a concordance of 95%. In patients who responded to treatment, reduced ctDNA levels were associated with tumor mass reduction by central imaging. Increases in ctDNA were observed prior to confirmation of tumor escape, or disease progression.

“This early data suggests that a reduction in ctDNA may be a predictor of response to treatment with poziotinib,” said Francois Lebel, M.D., Chief Medical Officer of Spectrum Pharmaceuticals. “We are encouraged by these findings and look forward to further investigate ctDNA as a potential predictive biomarker of poziotinib treatment response.”

Poziotinib is currently under review by the U.S. Food and Drug Administration (FDA) with a PDUFA date of November 24, 2022 and has received Fast Track designation from the agency.

Session title and information for the poster is listed below and is available on the ASCO online itinerary planner.

Circulating tumor DNA (ctDNA) in HER2 exon 20 insertion mutations and responses in NSCLC HER2 exon 20 insertion treated with poziotinib

Session Title: Developmental Therapeutics—Molecularly Targeted Agents and Tumor Biology

Session Date and Time: Sunday, June 5, 2022, 8-11 a.m. CDT, 6-9 a.m. PT

Location: McCormick Place, Chicago IL

Abstract: 3051 / Poster: 43

Copies of the presentation will be available on Spectrum's website at https://investor.sppirx.com/events-and-presentations following presentation at the meeting.

About the ZENITH20 Clinical Trial

The ZENITH20 study is a multicenter, open-label Phase 2 trial, evaluating poziotinib in patients with advanced or metastatic NSCLC patients with EGFR or HER2 exon 20 insertion mutations. The trial is comprised of 7 independent cohorts. Cohorts 1 - 4 were each independently powered for a pre-specified statistical hypothesis with a primary endpoint of ORR, or objective response rate evaluated by independent review committee (RECIST v1.1). Cohorts 5 - 7 are exploratory. Secondary outcome measures are disease control rate, duration of response, progression-free survival, and safety and tolerability. The patients’ quality of life is also measured and assessed throughout. Cohort 4 includes first-line NSCLC patients with HER2 exon 20 mutations and cohort 5 includes previously treated or treatment-naïve NSCLC patients with EGFR or HER2 exon 20 insertion mutations.

About Poziotinib

Poziotinib is a novel, oral epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) that inhibits the tyrosine kinase activity of EGFR as well as HER2 and HER4. Importantly this, in turn, leads to the inhibition of the proliferation of tumor cells that overexpress these receptors. Mutations or overexpression/amplification of EGFR family receptors have been associated with a number of different cancers, including non-small cell lung cancer (NSCLC), breast cancer, and gastric cancer. HER2 exon 20 insertion mutations are a rare subset accounting for approximately 2-4% in NSCLC. There is no approved therapy for either treatment-naïve or previously treated NSCLC with HER2 exon 20 insertion mutations. The company holds an exclusive license from Hanmi Pharmaceutical to develop, manufacture, and commercialize poziotinib worldwide, excluding Korea and China. Poziotinib is currently being investigated by the company and Hanmi in several mid-stage trials in multiple solid tumor indications.

About Spectrum Pharmaceuticals, Inc.

Spectrum Pharmaceuticals is a biopharmaceutical company focused on acquiring, developing, and commercializing novel and targeted oncology therapies. Spectrum has a strong track record of successfully executing across the biopharmaceutical business model, from in-licensing and acquiring differentiated drugs, clinically developing novel assets, successfully gaining regulatory approvals and commercializing in a competitive healthcare marketplace. Spectrum has a late-stage pipeline with novel assets that serve areas of unmet need. This pipeline has the potential to transform the company in the near future. For additional information on Spectrum Pharmaceuticals please visit www.sppirx.com.

Notice Regarding Forward-looking Statements

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