Development of potent antibody drug conjugates against ICAM1+ cancer cells in preclinical models of cholangiocarcinoma

As a highly lethal adenocarcinoma of the hepatobiliary system, outcomes for cholangiocarcinoma (CCA) patients remain prominently poor with a 5-year survival of <10% due to the lack of effective treatment modalities. Targeted therapeutics for CCA are limited and surgical resection of CCA frequently suffers from a high recurrence rate. Here we report two effective targeted therapeutics in this preclinical study for CCA. We first performed a quantitative and unbiased screening of cancer-related antigens using comparative flow cytometry in a panel of human CCA cell lines, and identified intercellular adhesion molecule-1 (ICAM1) as a therapeutic target for CCA. After determining that ICAM1 has the ability to efficiently mediate antibody internalization, we constructed two ICAM1 antibody-drug conjugates (ADCs) by conjugating ICAM1 antibodies to different cytotoxic payloads through cleavable chemical linkers. The efficacies of two ICAM1 ADCs have been evaluated in comparison with the first-line chemodrug Gemcitabine in vitro and in vivo, and ICAM1 antibodies coupled with warhead DX-8951 derivative (DXd) or monomethyl auristatin E (MMAE) elicit a potent and consistent tumor attenuation. In summary, this study paves the road for developing a promising targeted therapeutic candidate for clinical treatment of CCA.

A Randomized, Open-Label, Multicenter, Phase 3 Study of High-Dose Vitamin C Plus FOLFOX ± Bevacizumab versus FOLFOX ± Bevacizumab in Unresectable Untreated Metastatic Colorectal Cancer (VITALITY Study)

PURPOSE

To compare the efficacy and safety of high-dose vitamin C plus FOLFOX ± bevacizumab versus FOLFOX ± bevacizumab as first-line treatment in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Between 2017 and 2019, histologically confirmed patients with mCRC (n = 442) with normal glucose-6-phosphate dehydrogenase status and no prior treatment for metastatic disease were randomized (1:1) into a control (FOLFOX ± bevacizumab) and an experimental [high-dose vitamin C (1.5 g/kg/d, intravenously for 3 hours from D1 to D3) plus FOLFOX ± bevacizumab] group. Randomization was based on the primary tumor location and bevacizumab prescription.

RESULTS

The progression-free survival (PFS) of the experimental group was not superior to the control group [median PFS, 8.6 vs. 8.3 months; HR, 0.86; 95% confidence interval (CI), 0.70-1.05; P = 0.1]. The objective response rate (ORR) and overall survival (OS) of the experimental and control groups were similar (ORR, 44.3% vs. 42.1%; P = 0.9; median OS, 20.7 vs. 19.7 months; P = 0.7). Grade 3 or higher treatment-related adverse events occurred in 33.5% and 30.3% of patients in the experimental and control groups, respectively. In prespecified subgroup analyses, patients with RAS mutation had significantly longer PFS (median PFS, 9.2 vs. 7.8 months; HR, 0.67; 95% CI, 0.50-0.91; P = 0.01) with vitamin C added to chemotherapy than with chemotherapy only.

CONCLUSIONS

High-dose vitamin C plus chemotherapy failed to show superior PFS compared with chemotherapy in patients with mCRC as first-line treatment but may be beneficial in patients with mCRC harboring RAS mutation.

Abstract 6175: Developing antibody-drug conjugates against cholangiocarcinoma using a novel molecular target

As a rare malignancy, cholangiocarcinoma (CCA) is a lethal disease with a 5-year overall survival rate of merely 5%. Highly invasive and asymptomatic characteristics of CCA cause most patients diagnosed at advanced stages, severely deteriorating their clinical outcomes. The drug treatment options for CCA are limited and surgical resection of CCA frequently suffers from a high recurrence rate of 66%. Albeit Pemigatinib, a FGFR2 inhibitor, has recently been approved by FDA as the first CCA-targeted therapeutic, only less than 10% of patients with CCA carry FGFR2 fusion mutations that can benefit from this drug. Ivosidenib, another targeted drug against IDH1 mutation, only works for 13% CCA patients carrying this mutation. Therefore, discovering new molecular targets and developing associated targeted drugs remain a significant and unmet medical need in CCA therapy. In this study, we first screened potential molecular targets for CCA by comparing the expression levels of a panel of cancer-related cell membrane antigens between human CCA cells and normal human intrahepatic biliary epithelial cells through flow cytometry. CD54 was identified as a remarkable molecular target of CCA with strong binding force to its antibodies and high endocytosis efficiency by flow cytometry and confocal fluorescent microscopy. Meanwhile, we confirmed that CD54 was absent in most normal human tissues but was highly upregulated in CCA tumor tissues through immunohistochemical (IHC) staining. Based on this newly discovered CCA target, we constructed a series of CD54 antibody-drug conjugates (ADCs) using different chemical linkers and payloads. We next evaluated and compared the half maximum inhibitory concentrations (IC50s) of each ADC in ablating human CCA cells in vitro in order to identify an optimized ADC formulation. Furthermore, we validated its anti-tumor efficacy against primary and peritoneal metastatic CCA tumors in vivo in comparison with conventional chemotherapy. Eventually, we determined the biodistribution and safety profile of this CD54 ADC in order to ensure that it is well-tolerated under the effective dose. In general, we identified CD54 as a novel molecular target for CCA through antibody library screening, and explored its potential in the development of CCA-targeted ADCs, providing a promising targeted therapeutic for clinical treatment of CCA.

Citation Format: Bing Zhu, Shi-Li Yao, Xin-Yan Wang, Rui Xu, Peng Guo, Jie-Er Ying. Developing antibody-drug conjugates against cholangiocarcinoma using a novel molecular target [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6175.

Trametes robiniophila Murr Sensitizes Gastric Cancer Cells to 5-Fluorouracil by Modulating Tumor Microenvironment

Trametes robiniophila Murr (TRM) is a traditional Chinese medicine which has been used in clinics for enhancing immunity and improving the efficacy of chemotherapy. However, the mechanisms of action of TRM are unknown. In the previous study, we found that the Trametes robiniophila Murr n-butanol extract (TRMBE) comprises the major bioactive components of TRM. In the present study, we aimed to assess the combinational effects of TRMBE and 5-fluorouracil (5-FU) on the treatment of gastric cancer (GC) and explore its mechanism of action. It was found that TRMBE significantly potentiated the anticancer activity of 5-FU and prolonged the survival time of mice bearing Mouse Forestomach Carcinoma (MFC) xenograft tumors. We observed that the combination of TRMBE and 5-FU decreased the risk of liver metastasis in vivo. Furthermore, the combination of TRMBE and 5-FU reduced the levels of immune cytokines IL-6, IL-10, and TGF-β and increased the level of IFN-γ in peripheral blood. This combination therapy also significantly decreased the levels of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and PD-1-positive CD8⁺ T cells and increased the levels of NK cells in tumor microenvironment (TME). However, TRMBE treatment was unable to enhance the chemosensitivity of GC to 5-FU in vivo after the depletion of CD8⁺ T and NK cells. Taken together, our results demonstrate that TRMBE can reshape the TME of GC by regulating PMN-MDSCs, CD8⁺ T cells, and NK cells, therefore improving the therapeutic effects of 5-FU. This study suggests that the combination of TRMBE and 5-FU could enhance immunity and could be a promising approach for GC treatment.

A multicenter clinical study: personalized medication for advanced gastrointestinal carcinomas with the guidance of patient-derived tumor xenograft (PDTX)

BACKGROUND

Establish patient-derived tumor xenograft (PDTX) from advanced GICs and assess the clinical value and applicability of PDTX for the treatment of advanced gastrointestinal cancers.

METHODS

Patients with advanced GICs were enrolled in a registered multi-center clinical study (ChiCTR-OOC-17012731). The performance of PDTX was evaluated by analyzing factors that affect the engraftment rate, comparing the histological consistency between primary tumors and tumorgrafts, examining the concordance between the drug effectiveness in PDTXs and clinical responses, and identifying genetic variants and other factors associated with prognosis.

RESULTS

Thirty-three patients were enrolled in the study with the engraftment rate of 75.8% (25/33). The success of engraftment was independent of age, cancer types, pathological stages of tumors, and particularly sampling methods. Tumorgrafts retained the same histopathological characteristics as primary tumors. Forty-nine regimens involving 28 drugs were tested in seventeen tumorgrafts. The median time for drug testing was 134.5 days. Follow-up information was obtained about 10 regimens from 9 patients. The concordance of drug effectiveness between PDTXs and clinical responses was 100%. The tumor mutation burden (TMB) was correlated with the effectiveness of single drug regimens, while the outgrowth time of tumorgrafts was associated with the effectiveness of combined regimens.

CONCLUSION

The engraftment rate in advanced GICs was higher than that of other cancers and meets the acceptable standard for applying personalized therapeutic strategies. Tumorgrafts from PDTX kept attributes of the primary tumor. Predictions from PDTX modeling closely agreed with clinical drug responses. PDTX may already be clinically applicable for personalized medication in advanced GICs.

XELOX doublet regimen versus EOX triplet regimen as first-line treatment for advanced gastric cancer: An open-labeled, multicenter, randomized, prospective phase III trial (EXELOX)

Background

There is no consensus on whether triplet regimen is better than doublet regimen in the first‐line treatment of advanced gastric cancer (AGC). We aimed to compare the efficacy and safety of oxaliplatin plus capecitabine (XELOX) and epirubicin, oxaliplatin, plus capecitabine (EOX) regimens in treating AGC.

Methods

This phase III trial enrolled previously untreated patients with AGC who were randomly assigned to receive the XELOX or EOX regimen. The primary endpoint was non‐inferiority in progression‐free survival (PFS) for XELOX as compared with EOX on an intention‐to‐treat basis.

Results

Between April 10, 2015 and August 20, 2020, 448 AGC patients were randomized to receive XELOX (n = 222) or EOX (n = 226). The median PFS (mPFS) was 5.0 months (95% confidence interval [CI] = 4.5‐6.0 months) in the XELOX arm and 5.5 months (95% CI = 5.0‐6.0 months) in the EOX arm (hazard ratio [HR] = 0.989, 95% CI = 0.812‐1.203; P_{non‐inferiority} = 0.003). There was no significant difference in median overall survival (mOS) (12.0 vs. 12.0 months, P = 0.384) or objective response rate (37.4% vs. 45.1%, P = 0.291) between the two groups. In patients with poorly differentiated adenocarcinoma and liver metastasis, the EOX arm had a significantly longer mOS (P = 0.021) and a trend of longer mPFS (P = 0.073) than the XELOX arm. The rate of grade 3/4 adverse events (AEs) was 42.2% (90/213) in the XELOX arm and 72.5% (156/215) in the EOX arm (P = 0.001). The global health‐related quality of life (QoL) score was significantly higher in the XELOX arm than in the EOX arm during chemotherapy.

Conclusions

This non‐inferiority trial demonstrated that the doublet regimen was as effective as the triplet regimen and had a better safety profile and QoL as a first‐line treatment for AGC patients. However, the triplet regimen might have a survival advantage in patients with poorly differentiated adenocarcinoma and liver metastasis.

Immunological impact of chemotherapy on the tumor microenvironment in gastric cancer

OBJECTIVE

This study aimed to investigate alterations in pre- and post-neoadjuvant chemotherapy (NACT) tumor-infiltrating immune cells and subsequent evaluation of the predictive and prognostic value of these changes in gastric cancer (GC).

METHODS

Fifty patients with GC underwent three cycles of S-1 and oxaliplatin (SOX regimen)-NACT. Paired samples from tumor lesions before and after NACT were available for all patients participating in the study. Immunohistochemistry was performed for T cell subsets (CD3⁺ and CD8⁺ ) and macrophages (CD68⁺ and CD163⁺ ).

RESULTS

After NACT, the average expression levels of CD3, CD8, CD68, and CD163 were significantly increased (p < .001). However, neither expression levels pre- nor post-chemotherapy correlated with treatment response. Multivariate Cox regression analysis demonstrated that upregulation of CD8/CD3 levels (hazard ratio [HR] = 0.117; 95% confidence interval [CI] = 0.031-0.446; p = 0.002) and CD163 levels after chemotherapy (HR = 2.258; 95% CI = 1.047-4.867; p = 0.038) were independent prognostic factors of overall survival.

CONCLUSION

Chemotherapy in GC is useful to induce CD3⁺ and CD8⁺ T lymphocytes as well as CD68⁺ and CD163⁺ macrophages in the tumor microenvironment in combination with its direct cytotoxic effects. These results indicate that chemotherapy may play a role in tumor immune microenvironment remodeling.

Developments in metastatic pancreatic cancer: is gemcitabine still the standard?

In the past 15 years, we have seen few therapeutic advances for patients with pancreatic cancer, which is the fourth leading cause of cancer-related death in the United States. Currently, only about 6% of patients with advanced disease respond to standard gemcitabine therapy, and median survival is only about 6 mo. Moreover, phase III trials have shown that adding various cytotoxic and targeted chemotherapeutic agents to gemcitabine has failed to improve overall survival, except in cases in which gemcitabine combined with erlotinib show minimal survival benefit. Several meta-analyses have shown that the combination of gemcitabine with either a platinum analog or capecitabine may lead to clinically relevant survival prolongation, especially for patients with good performance status. Meanwhile, many studies have focused on the pharmacokinetic modulation of gemcitabine by fixed-dose administration, and metabolic or transport enzymes related to the response and toxicity of gemcitabine. Strikingly, a phase III trial in 2010 showed that, in comparison to gemcitabine alone, the FOLFIRINOX regimen in patients with advanced disease and good performance status, produced better median overall survival, median progression-free survival, and objective response rates. This regimen also resulted in greater, albeit manageable toxicity.