Objective Response Rate Primary Endpoint Research Articles

Abstract CT081: Poziotinib activity and durability of responses in previously treated EGFR exon 20 NSCLC patients - a Phase 2 study

Abstract Introduction and Purpose of Study: Effective and approved therapy for treating non-small cell lung cancer (NSCLC) with EGFR exon 20 mutations is an unmet medical need. Poziotinib is a potent tyrosine kinase inhibitor (TKI) of EGFR and HER2 exon 20 insertion mutants. We evaluated the efficacy and safety of poziotinib in previously treated NSCLC patients with EGFR exon 20 insertion mutations (ZENITH20-1) in an independent cohort of a multi-cohort, multi-center Phase 2 study. Methods: Poziotinib (16 mg) was administered orally QD, allowing dose reductions for AEs, with follow up for 24 months. The primary endpoint was objective response rate (ORR), evaluated by central radiographic review using RECIST v1.1. The ORR endpoint was to be met if the lower bound of 95% CI>17% in the As-Treated Population. The secondary endpoints included disease control rate (DCR), duration of response (DOR), progression-free survival (PFS) and safety. Safety monitoring was conducted throughout the study. Results: A total of 115 patients with a median age of 61 years (33-83) were enrolled. Patients had received and failed prior therapy (median of 2 [1-9]) with majority receiving both chemo and immunotherapy. The median relative dose intensity was 72% (7-100%) with 65% having dose reductions. 10% of patients discontinued due to related AEs. The ORR was 14.8% (95% CI 8.9%-22.6%), and the DCR was 68.7% (95% CI 59.4%-77.0%). Seventeen patients had a confirmed partial response (PR), 5 patients had unconfirmed PR and 62 (53.9%) patients had stable disease (SD). Overall, 75 (65%) patients had tumor size reductions. The median DoR was 7.4 months (95% CI 3.7-9.7) and the median PFS was 4.2 months (95% CI 3.7-6.6). Safety profile was mechanism related and similar to other 2nd generation tyrosine kinase inhibitors with the most common treatment-related Grade ≥3 AEs (preferred term) being rash (28%), diarrhea (26%), stomatitis (9%) and paronychia (6%). The incidence of treatment-related pneumonitis, an important AE associated with TKIs, was 4%. Conclusion: Although the ORR primary endpoint was not met, poziotinib induced tumor size reduction in the majority (65%) of patients. The tumor size reduction combined with long duration of response demonstrated the clinical activity of poziotinib in treating this patient population. We are further optimizing dosing and AE management. Citation Format: Xiuning Le, Jonathan Goldman, Jeffrey Clarke, Nishan Techekmedyian, Zofia Piotrowska, David Chu, Gajanan Bhat, Francois Lebel, Mark Socinski. Poziotinib activity and durability of responses in previously treated EGFR exon 20 NSCLC patients - a Phase 2 study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT081.

Poziotinib shows activity and durability of responses in subgroups of previously treated EGFR exon 20 NSCLC patients.

9514 Background: Treatment of non-small cell lung cancer (NSCLC) with EGFR exon 20 mutations is an unmet medical need. Poziotinib is a potent tyrosine kinase inhibitor (TKI) of EGFR and HER2 exon 20 insertion mutants. We evaluated the efficacy and safety of poziotinib in previously treated NSCLC patients with EGFR exon 20 insertion mutations in an independent cohort of a multi-cohort, multi-center Phase 2 study ( ZENITH20-1). Methods: ZENITH20-1 study enrolled pts with advanced NSCLC with an EGFR exon 20 insertion identified on local tissue testing who had received at least one prior line of therapy. Poziotinib (16 mg) was administered orally QD, allowing dose reductions for AEs, with follow up for 24 months. The primary endpoint was objective response rate (ORR), evaluated centrally by RECIST v1.1. Secondary endpoints included disease control rate (DCR), duration of response (DOR), progression-free survival (PFS) and safety. Efficacy was also evaluated by specific exon 20 insertions and prior lines of therapy. Results: 115 patients with a median age of 61 years (33-83) were enrolled. Patients had a median of 2 prior lines of therapy (range, 1-9.) The median relative dose intensity was 72% (7-100%) with 65% having dose reductions. The ORR in the as-treated population was 14.8% (95% CI 8.9 - 22.6%), and the DCR was 68.7% (95% CI 59.4 - 77.0%) with a median DoR of 7.4 months. 65% patients had tumor size reductions and the median PFS was 4.2 months. In the evaluable population (n = 88), the ORR was 19.3% and the unconfirmed ORR was 25%. Responses were predominantly observed in insertions between residues M766 to D770 of exon 20 (8/44; 18.2%). Responses were observed in patients with 2 lines (14%); ≥3 lines of therapy (16.2%). The most common treatment-related Grade ≥3 AEs were rash (28%), diarrhea (26%), stomatitis (9%) and paronychia (6%). The incidence of treatment-related pneumonitis was 4%, however some cases may have been confounded by prior checkpoint inhibitors as first line treatment. Conclusions: Although the ORR primary endpoint was not met, poziotinib induced tumor reduction in the majority of patients with durable responses, including the heavily pre-treated population. Responses were more common in patients with insertions between M766 to D770 of EGFR exon 20. The safety profile was overall consistent with other 2nd generation EGFR TKIs. Evaluation of these subgroups with refined dosing and improved toxicity management to maintain continuous treatment is warranted to assess the potential of poziotinib in Exon20 related tumors. Clinical trial information: NCT03318939 .

ACTR-34. SINGLE AGENT ONC201 IN PREVIOUSLY-TREATED, PROGRESSIVE ADULT H3 K27M-MUTANT GLIOMA

Abstract H3 K27M-mutant gliomas often manifest as midline gliomas, have a dismal prognosis, and have no established or effective treatments at recurrence. ONC201 is the first clinical bitopic DRD2 antagonist/ClpP agonist and is under evaluation in Phase II trials for gliomas and other cancers. We previously reported in vitro studies suggesting dysregulated dopamine receptor expression and enhanced ONC201 sensitivity among H3 K27M-mutant gliomas. Following these observations, adults with midline H3 K27M-mutant glioma patients were enrolled to a dedicated Phase II clinical trial (NCT03295396), a multi-arm Phase II trial (NCT0252569), and expanded access protocols under the Sponsor’s IND. An integrated radiographic analysis with an objective response rate primary endpoint in patients who received ONC201 monotherapy with confirmed H3 K27M-mutant glioma (not primarily in the pons or spinal cord and without leptomeningeal spread) that was progressive and measurable disease by RANO criteria, >90 days from completion of prior radiation, and had KPS >60. As of December 15, 2018, 15 patients have received single agent ONC201 who meet these criteria (n=9 NCT03295396; n=5 NCT0252569; n=1 expanded access). ONC201 was orally administered at 625 mg weekly, except for one patient dosed once every 3 weeks. As midline gliomas can exhibit a mixture of contrast-enhancing and non-contrast-enhancing disease, objective response was assessed by blinded independent central review using RANO-HGG and RANO-LGG criteria for each patient. Best response to date by RANO-HGG criteria is at least 27%: 1 CR, 3 PR, 7 SD, and 4 PD; by RANO-LGG is at least 36%: 1 CR, 1 PR, 3 minor response (MR), 4 SD, 5 PD, 1 unevaluable. By RANO-HGG, median onset of response is 2.6 months (range 1.3–3.4); median duration of response has not been reached with a median follow-up of 7.7 months (range 1.8–29.8). Updated radiographic response, pharmacodynamics, safety, and other clinical outcomes will be reported.