Editorial: Novel Small-Molecule Agents in Overcoming Multidrug Resistance in Cancers

Overexpression of ABCB1 confers resistance to FLT3 inhibitor FN-1501 in cancer cells: in vitro and in vivo characterization

FN-1501 is a potent FLT3 inhibitor with antitumor activity. A phase 1 trial of FN-1501 monotherapy in patients with advanced solid tumors and R/R AML is in progress. Since one of the primary causes of multidrug resistance (MDR) is the overexpression of ATP-binding cassette superfamily B member 1 (ABCB1), the objective of this study was to investigate the potential relationship between FN-1501 and the ABCB1 transporter. We found ABCB1 overexpressing-cancer cells conferred FN-1501 resistance, which could be reversed by an ABCB1 inhibitor. Molecular docking study revealed that FN-1501 docked the ligand binding site with an affinity score of -9.77 kcal/mol, denoting a strong interaction between FN-1501 and ABCB1. Additionally, the ABCB1 ATPase assay indicated that FN-1501 could significantly stimulate ABCB1 ATPase activity. Furthermore, we observed a similar trend of ABCB1-facilated FN-1501 resistance in tumor-bearing mice model. In sum, we demonstrate that FN-1501 is a substrate of ABCB1 transporter from both in vivo and in vitro studies. Therefore, our findings provide new insight on the mechanism of chemoresistance due to ABCB1 overexpression.

Efficacy and safety of anlotinib plus XELOX regimen as first-line therapy for mCRC: a single-arm, multicenter, phase II study (ALTER-C-001)

Background

Anlotinib showed encouraging anti-tumor activity in metastatic colorectal cancer (mCRC). This study was designed to assess the efficacy and safety of anlotinib plus XELOX as first-line therapy in mCRC patients.

Materials and Methods

Eligible patients aged ≥18 with mCRC were enrolled in this multicenter, single-arm, phase II, exploratory study. Patients received at least 6 cycles of anlotinib, oxaliplatin, and capecitabine as initial therapy. Subsequently, patients received anlotinib monotherapy as maintenance therapy until tumor progression or intolerable toxicity. The primary endpoint was progression-free survival (PFS).

Results

Thirty-one patients were included between December 2019 and March 2022. The median follow-up was 17.5 (95% CI, 3.0-17.5) months. The median PFS was 8.3 (95% CI, 6.3-10.0) months, with 6- and 12-month PFS rates of 82.3% (95% CI, 59.2%-93.0%) and 18.9% (95% CI, 4.8%-40.1%), respectively. Fifteen (48.4%) achieved partial response for an ORR of 48.4% (95% CI, 30.2%-66.9%). The disease control rate was 71.0% (95% CI, 52.0%-85.8%) due to 7 (22.6%) stable diseases. The median duration of response was 6.0 (95% CI, 3.6-8.0) months and 1 patient had the longest ongoing response of 17.3 months. Of 24 patients with evaluable imaging, 23 (74.2%) obtained tumor shrinkage. The median PFS (11.0 vs. 6.9 months) and ORR (66.7% vs. 60.0%) for patients with RAS/BRAF wild-type were numerically better than those with mutation. Three patients are still ongoing treatment. The grade 3 or more treatment-emergent adverse events (TEAEs) were mainly hypertension (12.9%) and decreased neutrophil count (12.9%). Four (12.9%) had serious TEAEs, primarily including abdominal pain and incomplete intestinal obstruction.

Conclusion

Anlotinib plus XELOX as first-line therapy in patients with mCRC showed anti-tumor activity and safety profile, which is worth further investigation.

Clinical Trial Registration

chictr.org.cn, identifier ChiCTR1900028417.

The AKT inhibitor, MK-2206, attenuates ABCG2-mediated drug resistance in lung and colon cancer cells

Introduction: The overexpression of ATP-binding cassette (ABC) transporters, ABCB1 and ABCG2, are two of the major mediators of multidrug resistance (MDR) in cancers. Although multiple ABCB1 and ABCG2 inhibitors have been developed and some have undergone evaluation in clinical trials, none have been clinically approved. The compound, MK-2206, an inhibitor of the protein kinases AKT1/2/3, is undergoing evaluation in multiple clinical trials for the treatment of certain types of cancers, including those resistant to erlotinib. In this in vitro study, we conducted in vitro experiments to determine if MK-2206 attenuates multidrug resistance in cancer cells overexpressing the ABCB1 or ABCG2 transporter. Methodology: The efficacy of MK-2206 (0.03-1 μM), in combination with the ABCB1 transporter sub-strates doxorubicin and paclitaxel, and ABCG2 transporter substrates mitoxantrone, SN-38 and topotecan, were determined in the cancer cell lines, KB-C2 and SW620/Ad300, which overexpress the ABCB1 transporter or H460/MX20 and S1-M1-80, which overexpress the ABCG2 transporter, respectively. The expression level and the localization of ABCG2 transporter on the cancer cells membranes were determined using western blot and immunofluorescence assays, respectively, following the incubation of cells with MK-2206. Finally, the interaction between MK-2206 and human ABCG2 transporter was predicted using computer-aided molecular modeling. Results: MK-2206 significantly increased the efficacy of anticancer compounds that were substrates for the ABCG2 but not the ABCB1 transporter. MK-2206 alone (0.03-1 μM) did not significantly alter the viability of H460/MX20 and S1-M1-80 cancer cells, which overexpress the ABCG2 transporter, compared to cells incubated with vehicle. However, MK-2206 (0.3 and 1 μM) significantly increased the anticancer efficacy of mitoxantrone, SN-38 and topotecan, in H460/MX20 and S1-M1-80 cancer cells, as indicated by a significant decrease in their IC50 values, compared to cells incubated with vehicle. MK-2206 significantly increased the basal activity of the ABCG2 ATPase (EC50 = 0.46 μM) but did not significantly alter its expression level and sub-localization in the membrane. The molecular modeling results suggested that MK-2206 binds to the active pocket of the ABCG2 transporter, by a hydrogen bond, hydrophobic interactions and π-π stacking. Conclusion: These in vitro data indicated that MK-2206 surmounts resistance to mitoxantrone, SN-38 and topotecan in cancer cells overexpressing the ABCG2 transporter. If these results can be translated to humans, it is possible that MK-2206 could be used to surmount MDR in cancer cells overexpressing the ABCG2 transporter.

Biogenic Synthesis of Cu-Mn Bimetallic Nanoparticles Using Pumpkin Seeds Extract and Their Characterization and Anticancer Efficacy

BACKGROUND

Cancer is a chronic, heterogeneous illness that progresses through a spectrum of devastating clinical manifestations and remains the 2nd leading contributor to global mortality. Current cancer therapeutics display various drawbacks that result in inefficient management. The present study is intended to evaluate the anticancer potential of Cu-Mn bimetallic NPs (CMBNPs) synthesized from pumpkin seed extract against colon adenocarcinoma cancer cell line (HT-29).

METHODS

The CMBNPs were biosynthesized by continuously stirring an aqueous solution of pumpkin seed extract with CuSO4 and manganese (II) acetate tetrahydrate until a dark green solution was obtained. The characteristic features of biogenic CMBNPs were assessed by UV-visible spectrophotometry (UV-vis), X-ray powder diffraction (XRD), energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A battery of biological assays, viz. neutral red uptake (NRU) assay, in vitro scratch assay, and comet assay, were performed for anticancer efficacy evaluation.

RESULTS

The formation of spherical monodispersed bimetallic nanoparticles with an average size of 50 nm was recorded using TEM. We observed dose-dependent cytotoxicity of CMBNPs in the HT-29 cell line with an IC₅₀ dose of 115.2 µg/mL. On the other hand, CMBNPs did not show significant cytotoxicity against normal cell lines (Vero cells). Furthermore, the treatment of CMBNPs inhibited the migration of cancer cells and caused DNA damage with a significant increase in comet tail length.

CONCLUSIONS

The results showed substantial anticancer efficacy of CMBNPs against the studied cancer cell line. However, it is advocated that the current work be expanded to different in vitro cancer models so that an in vivo validation could be carried out in the most appropriate cancer model.

A multi-center, single-arm, phase II study of anlotinib plus paclitaxel and cisplatin as the first-line therapy of recurrent/advanced esophageal squamous cell carcinoma

BACKGROUND

Anlotinib, a tyrosine kinase inhibitor, has shown encouraging anti-tumor activity in esophageal squamous cell carcinoma (ESCC). This study was designed to assess the efficacy and safety of anlotinib plus paclitaxel and cisplatin (TP) as first-line therapy for advanced ESCC.

METHODS

In a multi-center, single-arm, phase II clinical trial, patients (aged > 18 years) with ESCC, which was judged to be locally advanced, recurrent, or metastatic, received 10 mg oral anlotinib once daily on days 1-14, 135 mg/m² intravenous paclitaxel on day 1, and 60-75 mg/m² intravenous cisplatin on days 1-3 every 3 weeks for a maximum of 4-6 cycles as the initial therapy in five centers in China. Subsequently, patients received anlotinib monotherapy (10 mg) as maintenance therapy until tumor progression or intolerable toxicity. The primary endpoint was progression-free survival (PFS).

RESULTS

Forty-seven patients were enrolled in this study between October 2019 and March 2021. The median follow-up was 14.04 months (IQR, 9.30-19.38). Of 46 with assessable efficacy, the median PFS and median overall survival were 8.38 months (95% CI, 6.59-10.17) and 18.53 months (95% CI, 13.11-23.95), respectively. The objective response rate was 76.1% (95% CI, 61.2-87.4%), with 4 (8.7%) complete responses and 31 (67.4%) partial responses. The disease control rate was 91.3% (95% CI, 79.2-97.6%). The median duration of response was 6.80 months (95% CI, 4.52-9.08), and 1 patient had an ongoing response for 23 months. Subgroup analysis revealed no association between clinical factors and survival or response. Of the 47 patients with assessable safety, the main grade ≥ 3 treatment-emergent adverse events (TEAEs) were neutropenia (17.0%), bone marrow suppression (12.8%), and vomiting (10.6%). No treatment-related deaths or serious TEAEs were observed. Notably, higher c-Kit levels were an independent factor for superior PFS (HR = 0.032; 95% CI, 0.002-0.606; P = 0.022).

CONCLUSIONS

The study demonstrated a manageable safety profile and durable clinical response of anlotinib plus TP as first-line therapy in advanced ESCC, which suggested a potential therapeutic option for this population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04063683. Registered 21 August 2019.