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ORAL 10 - SCLC (ID 98)
- Event: WCLC 2015
- Type: Oral Session
- Track: Small Cell Lung Cancer
- Presentations: 1
ORAL10.01 - A DLL3-Targeted ADC, Rovalpituzumab Tesirine, Demonstrates Substantial Activity in a Phase I Study in Relapsed and Refractory SCLC (ID 1598)
10:45 - 12:15 | Author(s): T. Bauer
Rovalpituzumab tesirine (i.e. SC16LD6.5) is a Delta-like protein 3 (DLL3) targeted antibody-drug conjugate (ADC) comprised of a humanized monoclonal antibody, dipeptide linker, and pyrrolobenzodiazepine (PBD) dimer toxin with a drug-to-antibody ratio of 2. DLL3 is highly expressed in human neuroendocrine tumors and their tumor-initiating cells, including approximately two-thirds of small cell lung cancer (SCLC). DLL3 is not expressed at detectable levels in normal tissues. Rovalpituzumab tesirine induced tumor regression and prolonged time to progression significantly outperforming cisplatin/etoposide in DLL3-expressing SCLC patient-derived xenograft tumor models. Based on this promising activity, a first-in-human phase I trial in patients (pts) with recurrent SCLC was initiated and preliminary results are reported below.
SCLC pts with progressive disease after 1 or 2 previous lines of therapy received escalating doses of rovalpituzumab tesirine as a single agent once every 3 weeks (Q3W) in 1-3 pt cohorts until dose limiting toxicities (DLTs) were observed. The doses were 0.05, 0.1, 0.2, 0.4 and 0.8 mg/kg Q3W. Midway through accrual, pharmacokinetic data revealed a longer than expected ADC half-life of ~11 days, prompting evaluation of a Q6W schedule. A DLL3 antibody was developed and utilized to assess antigen expression in archived tumor specimens. Biomarker positive (BM+) tumors were defined by IHC membrane-associated H-Scores ≥ 120.
52 pts were treated: 34 Q3W and 18 Q6W; 24F/28M; median age, 61 years (44-82). Acute and chronic DLTs of thrombocytopenia and capillary leak syndrome (CLS) were observed at 0.8 and 0.4 mg/kg Q3W, respectively. Maximum tolerated doses (MTD) of 0.2 mg/kg Q3Wx3 cycles and 0.3 mg/kg Q6Wx2 cycles were further evaluated in expansion cohorts. The most common treatment emergent adverse events of any grade among all pts were fatigue (40%), rash (39%), nausea (29%), dyspnea (23%), decreased appetite (21%) and vomiting (21%). Grade 3+ CLS and thrombocytopenia were seen in 7 (14%) and 3 (6%) pts, respectively, with no reported Grade 5 toxicity. Of 38 archived tumor specimens received from enrolled pts, 23 (61%) were DLL3 BM+. Among the 16 confirmed DLL3 BM+ pts treated at the MTDs, 7 pts (44%) had partial response (PR) and 8 pts (50%) achieved stable disease (SD) for a combined clinical benefit rate (CBR) of 94%. In all evaluable pts treated at the MTD without regard for DLL3 biomarker status (n=32), the ORR was 22% (n=7 PR) and SD 53% (n=17), for a CBR of 75%. Notably, all pts with PRs that were treated at the MTD, and those having the most durable clinical benefit (up to 569 days OS), were BM+. Similar response rates were observed among pts sensitive and refractory to first-line therapy, and in the third-line setting where no standard-of-care currently exists.
Rovalpituzumab tesirine, a first-in-class DLL3-targeted ADC, has manageable toxicity and demonstrated significant anti-tumor activity (44% ORR and 95% CBR) as a single agent in second- and third-line pts with recurrent DLL3 BM+ SCLC. A pivotal study is being planned.
ORAL 33 - ALK (ID 145)
- Event: WCLC 2015
- Type: Oral Session
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
ORAL33.07 - Clinical Activity and Safety of the ALK/ROS1 TK Inhibitor PF-06463922 in Advanced NSCLC (ID 295)
16:45 - 18:15 | Author(s): T. Bauer
Overcoming acquired resistance in ALK+ and ROS1+ non-small-cell lung cancer (NSCLC) patients (pts) is key to optimizing therapy. PF-06463922 is a selective, brain-penetrant tyrosine kinase inhibitor (TKI) with demonstrated clinical activity against de novo fusions as well as resistance mutations, including ALK G1202R, that arise during treatment with other TKIs.
In this ongoing phase I study, eligible pts had ALK+ or ROS1+ NSCLC, with or without brain metastases, and were treatment naïve or had disease progression after at least 1 prior TKIs. Pts with central nervous system (CNS) metastases, including untreated asymptomatic metastases, were eligible. Tumor tissue (archival sample or de novo biopsy) was required for enrollment. A modified continual reassessment method was used to estimate the maximum tolerated dose (MTD) and select a recommended phase II dose (RP2D). Once- (QD) or twice-daily (BID) dosing in 21-day cycles was explored. Secondary objectives included efficacy, safety, tolerability, pharmacokinetics (PK), effect on cognitive function, patient-reported outcomes, potential to induce/inhibit CYP3A4, biomarkers of drug response and resistance, and intracranial antitumor activity.
25 ALK+ pts (20 with CNS metastases, 23 previously treated with at least 1 ALK TKIs) and 5 ROS1+ pts (3 with CNS metastases, 3 previously treated with crizotinib) have been enrolled across 7 QD dose levels and 2 BID dose levels. Of 21 patients evaluable for intracranial response, 16 had stable disease or confirmed complete/partial response. The most common treatment-related adverse events (AEs) were hypercholesterolemia, peripheral neuropathy, and peripheral edema, occurring in 47%, 27% and 23% of pts, respectively. Peripheral neuropathy was reversible following treatment delay or dose reduction. The most common grade 3 and higher treatment-related AE was hypercholesterolemia, occurring in 10% of pts, which was well managed with statins. One DLT was reported for a pt at 200 mg QD, who received less than 16 of the 21 planned doses of study drug due to grade 2 CNS effects. To date, 20 pts remain on treatment. Preliminary PK analyses suggest that exposure increased linearly from 10 to 75 mg QD, with a terminal half-life of 20-28 hrs. At doses beyond 75 mg QD, the increase in exposure appeared to be non-proportional. PF-06463922 is considered a moderate inducer of CYP3A4.
PF-06463922 is a potent ALK/ROS1 TKI that has demonstrated clinical activity in ALK+ and ROS1+ NSCLC pts, most of whom had CNS metastases and had received at least 1 prior TKI. The RP2D has not yet been established.