Differential Protein Expression in Response to Varlitinib Treatment in Oral Cancer Cell Line: an In Vitro Therapeutic Approach

Epidermal growth factor receptor (EGFR) is the most frequently overexpressed receptor histologically exhibited by oral squamous cell carcinoma (OSCC) patients. Aberrated EGFR signaling may lead to recurrence and metastasis, thus laying the foundation of targeted therapy. Deactivating EGFR is likely to prevent downstream signaling thus resulting in apoptosis. Tyrosine kinase inhibitors (TKIs) have come into play to revert aggressiveness of OSCC. We exploited comparative proteomic analyses based on anti-EGFR potential of varlitinib, using cellular proteomes from treated and untreated groups of oral cancer cells to identify protein players functional during oral carcinogenesis. Following separation by two-dimensional electrophoresis, differentially expressed cellular proteins (varlitinib-treated and untreated cells) were analyzed and later identified using QTOF mass spectrometer. In silico analysis for protein-protein interaction was carried out using STRING. Six differentially expressed proteins were identified as binding immunoglobulin protein (BiP), heat shock protein 7 C (HSP7C), protein disulfide isomerase 1 A (PDIA1), vimentin (VIME), keratin type I cytoskeletal 14 (K1C14), and β-Actin (ACTB). Relative expression of five proteins was found to be downregulated upon varlitinib treatment, whereas only K1C14 was upregulated in treated cells compared to control. Protein network analysis depicts the interaction between BiP, PDIA1, VIME, etc. indicating their role in oral carcinogenesis. Oral cancer cells show proteome shift based on varlitinib treatment compared to corresponding controls. Our data suggest candidature of varlitinib as a potent therapeutic agent and BiP, PDIA1, HSP7C, VIME, and β-Actin as complementary/prognostic markers of OSCC.

Phase Ib Dose-Finding Study of Varlitinib Combined with Weekly Paclitaxel With or Without Carboplatin ± Trastuzumab in Advanced Solid Tumors

Background

Varlitinib is a highly potent, small-molecule, pan-HER inhibitor targeting HER1, HER2, and HER4. It has demonstrated activity in gastric, biliary tract, and breast cancers.

Objective

We conducted a phase Ib dose confirmation study to determine safety and early efficacy signals of varlitinib in combination with chemotherapy (paclitaxel ± carboplatin) ± subcutaneous trastuzumab.

Methods

Eligible patients had advanced or metastatic solid tumors. A 3+3 dose de-escalation study design was used and pharmacokinetic analyses of varlitinib and paclitaxel were performed.

Results

Thirty-seven patients were enrolled into eight cohorts with median 4 (0–14) prior lines of palliative systemic therapies. Carboplatin area under the curve 1.5 and paclitaxel 80 mg/m² weekly with varlitinib 500 mg twice daily continuously was de-escalated over four dose levels to 300 mg twice daily intermittently (4 days on, 3 days off) due to dose-limiting toxicities, most commonly neutropenia, febrile neutropenia, and electrolyte disturbances, with the triplet combination deemed intolerable and unable to be developed further. Varlitinib was then combined with paclitaxel alone; the recommended phase II dose of varlitinib was 300 mg twice daily intermittently. The addition of subcutaneous trastuzumab 600 mg was safe with no dose-limiting toxicities. Thirty-one patients were evaluable for response: 35.5% partial response, 41.9% stable disease. Twenty patients had HER2+ metastatic breast cancer with a median of 4 (0–14) treatment lines, 8/20 continued on single-agent varlitinib after completing chemotherapy for a median of 5.1 (range 2.0–13.3) months. A pharmacokinetic analysis showed that plasma exposure of varlitinib was dose dependent. Varlitinib administration did not significantly affect the maximum concentration or area under the curve of paclitaxel.

Conclusions

The recommended phase II dose of varlitinib with paclitaxel is 300 mg twice daily intermittently dosed. This is active in HER2+ metastatic breast cancer. Subcutaneous trastuzumab can be added safely to varlitinib and paclitaxel. This combination is currently being evaluated as neoadjuvant therapy in HER2+ breast cancer (NCT02396108).

Clinical Trial Registration: NCT02396108, date of registration: 25 March, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11523-022-00867-0.

Varlitinib Downregulates HER/ERK Signaling and Induces Apoptosis in Triple Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is a complex disease associated with the aggressive phenotype and poor prognosis. TNBC harbors heterogeneous molecular subtypes with no approved specific targeted therapy. It has been reported that HER receptors are overexpressed in breast cancer including TNBC. In this study, we evaluated the efficacy of varlitinib, a reversible small molecule pan-HER inhibitor in TNBC. Our results showed that varlitinib reduced cell viability and induced cell apoptosis in most TNBC cell lines but not in MDA-MB-231 cells. MEK and ERK inhibition overcame resistance to varlitinib in MDA-MB-231 cells. Varlitinib inhibited HER signaling which led to inhibition of migration, invasion and mammosphere formation of TNBC cells as well as significant suppression of tumor growth of MDA-MB-468 xenograft mouse model. In summary, these results suggest that HER signaling plays an important role in TNBC progression and that pan-HER inhibition is potentially an effective treatment for TNBC patients.