Neratinib-Plus-Cetuximab in Quadruple-WT ( KRAS, NRAS, BRAF, PIK3CA) Metastatic Colorectal Cancer Resistant to Cetuximab or Panitumumab: NSABP FC-7, A Phase Ib Study

Abstract

Purpose: In metastatic colorectal cancer (mCRC), HER2 (ERBB2) gene amplification is implicated in anti-EGFR therapy resistance. We sought to determine the recommended phase II dose (RP2D) and efficacy of neratinib, a pan-ERBB kinase inhibitor, combined with cetuximab, in patients with progressive disease (PD) on anti-EGFR treatment.

Patients and methods: Twenty-one patients with quadruple-wild-type, refractory mCRC enrolled in this 3+3 phase Ib study. Standard dosage cetuximab was administered with neratinib at 120 mg, 160 mg, 200 mg, and 240 mg/day orally in 28-day cycles. Samples were collected for molecular and pharmacokinetic studies.

Results: Sixteen patients were evaluable for dose-limiting toxicity (DLT). 240 mg was determined to be the RP2D wherein a single DLT occurred (1/7 patients). Treatment-related DLTs were not seen at lower doses. Best response was stable disease (SD) in 7 of 16 (44%) patients. HER2 amplification (chromogenic in situ IHC) was detected in 2 of 21 (9.5%) treatment-naïve tumors and 4 of 16 (25%) biopsies upon trial enrollment (post-anti-EGFR treatment and progression). Compared with matched enrollment biopsies, 6 of 8 (75%) blood samples showed concordance for HER2 CNV in circulating cell-free DNA. Five SD patients had HER2 amplification in either treatment-naïve or enrollment biopsies. Examination of gene-expression, total protein, and protein phosphorylation levels showed relative upregulation of ≥2 members of the HER-family receptors or ligands upon enrollment versus matched treatment-naïve samples.

Conclusions: The RP2D of neratinib in this combination was 240 mg/day, which was well tolerated with low incidence of G3 AEs. There were no objective responses; SD was seen at all neratinib doses. HER2 amplification, detectable in both tissue and blood, was more frequent post-anti-EGFR therapy.

Trial registration: ClinicalTrials.gov NCT01960023.

Conflict of interest statement

Potential Conflicts of Interest:

Dr. George reports grants pending to his institution for Clinical Research Conduct, as follows: Bristol Myers Squibb, Incyte, Merck, Bayer, AstraZeneca/MedImmune, NewLink Genetics, Ipsen, Seattle Genetics, Lilly, and Tesaro/GSK.

Dr. Sama reports employment and stock options with Bristol Myers Squibb

Ms. Piette reports commercial agreement to perform the statistical analyses, to participate in the writing of the statistical section of the manuscript, and the review.

Dr. Pogue-Geile reports grants from the NCI and the Pennsylvania Dept of Health (PA DoH), during the conduct of the study*, and from Puma Biotechnology, Inc. (Puma).

Mr. Lipchik reports grants to his institution from the PA DoH,* and Puma.

Ms. Finnigan reports grants to her institution from the PA DoH,* and Puma.

Dr. Beumer reports expert testimony from Pfizer, and grants from AbbVie, Spectrum, and NCI P30 CA47904 and R50 CA211241.

Dr. Wolmark reports an institutional business contract with Puma.

Dr. Lucas reports consulting fee paid to spouse from Bayer/Loxo, and stock/options with Amgen.

Dr. Allegra reports fees and payments as an employee of NSABP Foundation.

Dr. Srinivasan reports grants to his institution from the PA DoH, and Puma.

* The Pennsylvania DoH specifically disclaims responsibility for any analysis, interpretations, or conclusions

All other authors have no COIs to declare.

©2020 American Association for Cancer Research.

Figures

Figure 1

A Neratinib trough concentrations on cycle-2, day-1 at 24h (C24) after dosing, plotted as a function of neratinib daily dose. B Total and free trough serum concentrations of cetuximab on cycle-2, day-1. C Cycle-2, day-1 trough concentrations in patients with progressive disease (PD) or stable disease (SD) as best response. Neratinib (C24, ○, Wilcoxon 2-tailed exact rank P=0.694), free cetuximab concentration (◊, Wilcoxon 2-tailed exact rank P=0.779), and total cetuximab concentration (Δ, Wilcoxon 2-tailed exact rank P=0.463), with medians displayed as horizontal bars.

Figure 2

A Expression of ERBB receptor and ligand family members as assayed at the RNA level using HTG EdgeSeq upon enrollment into NSABP FC-7. The heatmap was generated using the normalized(rpm value) HTG data. It shows the expression of HER family transcripts across FC-7 enrollment samples. The expression was normalized across all samples (i.e., column-wise). Red indicates that a transcript has a relatively higher expression in certain samples compared with other samples. B Comparison of gene-expression profiles between the treatment-naïve (pre-anti-EGFR) primary tumor and metastatic enrollment biopsies (post-anti-EGFR) expressed as a ratio (= log2(post-anti-EGFR/pre-anti-EGFR). This heatmap was generated using normalized(rpm value) HTG EdgeSeq data. Red indicates higher expression after anti-EGFR therapy, upon FC-7 enrollment.

Figure 3

A Reverse-phase protein micro-array analysis (RPPA) of post-anti-EGFR, metastatic biopsy samples collected upon enrollment into FC-7. Total protein and specific protein phosphorylation sites were assayed. A total of 41 analytes, as indicated on the x-axis, were examined, covering pathways implicated in HER2 signaling. B Comparison of total protein and protein-phosphorylation status, as assayed by RPPA, between the treatment-naïve (pre-anti-EGFR) primary tumor and metastatic enrollment biopsies (post-anti-EGFR), expressed as a ratio(log2(post-anti-EGFR/pre-anti-EGFR)). Red indicates higher levels of total protein or elevated protein-phosphorylation after anti-EGFR therapy, upon enrollment into FC-7. The two far-left columns indicate HER2 amplification status, in primary (treatment-naïve) and metastatic biopsies collected upon enrollment into FC-7 respectively. Non-amplified (purple), amplified (yellow). C Comparison between the treatment-naïve (pre-anti-EGFR) primary tumor and metastatic biopsies (post-anti-EGFR) collected upon enrollment into FC-7 for the top RPPA signals, focusing on downstream effectors of HER2 signaling. Values expressed as a ratio (log2(post-anti-EGFR/pre-anti-EGFR)) were used to produce the heatmap.