Antitumor effect of antitissue factor antibody-MMAE conjugate in human pancreatic tumor xenografts.

Tissue factor (TF) triggers the extrinsic blood coagulation cascade and is highly expressed in various types of cancer. In this study, we investigated the antitumor effect of an antibody-drug conjugate (ADC) consisting of an anti-TF monoclonal antibody and monomethyl auristatin E (MMAE). MMAE was conjugated to an anti-human TF or anti-mouse TF antibody using a valine-citrulline linker that could be potentially hydrolyzed by cathepsin B in the acidic environment of the lysosome. The cytotoxic and antitumor effects of the ADCs against four pancreatic cancer cell lines were analyzed. Both the ADC with the anti-human TF antibody and that with the anti-mouse TF antibody were stable under physiological conditions. The anti-human ADC was internalized in TF-expressing human tumor cell lines, followed by effective MMAE release. The half maximal inhibitory concentration (IC50 ) of MMAE was approximately 1 nM for all of the cell lines used. Meanwhile, the IC50 of anti-human ADC was 1.15 nM in the cell lines showing high TF expression, while exceeding 100 nM in the cells showing low TF expression levels. Anti-human ADC with passive and active targeting ability exerted significant suppression of tumor growth as compared to that observed in the saline group (p < 0.01). Also significant tumor growth suppressions were seen at the anti-mouse ADC and control ADC groups compared to the saline group (p < 0.01) due to EPR effect. Because various clinical human cancers express highly amount of TF, this new anti-TF ADC may deserve a clinical evaluation.

Koga Y ，Manabe S ，Aihara Y ，Sato R ，Tsumura R ，Iwafuji H ，Furuya F ，Fuchigami H ，Fujiwara Y ，Hisada Y ，Yamamoto Y ，Yasunaga M ，Matsumura Y ... -  《-》

An antibody-drug conjugate that targets tissue factor exhibits potent therapeutic activity against a broad range of solid tumors.

Tissue factor (TF) is aberrantly expressed in solid cancers and is thought to contribute to disease progression through its procoagulant activity and its capacity to induce intracellular signaling in complex with factor VIIa (FVIIa). To explore the possibility of using tissue factor as a target for an antibody-drug conjugate (ADC), a panel of human tissue factor-specific antibodies (TF HuMab) was generated. Three tissue factor HuMab, that induced efficient inhibition of TF:FVIIa-dependent intracellular signaling, antibody-dependent cell-mediated cytotoxicity, and rapid target internalization, but had minimal impact on tissue factor procoagulant activity in vitro, were conjugated with the cytotoxic agents monomethyl auristatin E (MMAE) or monomethyl auristatin F (MMAF). Tissue factor-specific ADCs showed potent cytotoxicity in vitro and in vivo, which was dependent on tissue factor expression. TF-011-MMAE (HuMax-TF-ADC) was the most potent ADC, and the dominant mechanism of action in vivo was auristatin-mediated tumor cell killing. Importantly, TF-011-MMAE showed excellent antitumor activity in patient-derived xenograft (PDX) models with variable levels of tissue factor expression, derived from seven different solid cancers. Complete tumor regression was observed in all PDX models, including models that showed tissue factor expression in only 25% to 50% of the tumor cells. In conclusion, TF-011-MMAE is a promising novel antitumor agent with potent activity in xenograft models that represent the heterogeneity of human tumors, including heterogeneous target expression.

Breij EC ，de Goeij BE ，Verploegen S ，Schuurhuis DH ，Amirkhosravi A ，Francis J ，Miller VB ，Houtkamp M ，Bleeker WK ，Satijn D ，Parren PW ... -  《-》

A Novel Anti-CD22 Anthracycline-Based Antibody-Drug Conjugate (ADC) That Overcomes Resistance to Auristatin-Based ADCs.

We are interested in identifying mechanisms of resistance to the current generation of antibody-drug conjugates (ADC) and developing ADCs that can overcome this resistance. Pinatuzumab vedotin (anti-CD22-vc-MMAE) and polatuzumab vedotin (anti-CD79b-vc-MMAE) are ADCs that contain the microtubule inhibitor monomethyl auristatin E (MMAE) attached to the antibody by the protease-cleavable linker maleimidocaproyl-valine-citrulline-p-aminobenzoyloxycarbonyl (MC-vc-PAB). Early clinical trial data suggest that these ADCs have promising efficacy for the treatment of non-Hodgkin lymphoma (NHL); however, some patients do not respond or become resistant to the ADCs. Anthracyclines are very effective in NHL, but ADCs containing the anthracycline doxorubicin were not clinically efficacious probably due to the low drug potency and inadequate linker technology. The anthracycline analogue PNU-159682 is thousands of times more cytotoxic than doxorubicin, so we used it to develop a new class of ADCs. We used the same MC-vc-PAB linker and antibody in pinatuzumab vedotin but replaced the MMAE with a derivative of PNU-159682 to make anti-CD22-NMS249 and tested it for in vivo efficacy in xenograft tumors resistant to MMAE-based ADCs. We derived cell lines from in vivo xenograft tumors that were made resistant to anti-CD22-vc-MMAE and anti-CD79b-vc-MMAE. We identified P-gp (ABCB1/MDR1) as the major driver of resistance to the vc-MMAE-based conjugates. Anti-CD22-NMS249 was at least as effective as anti-CD22-vc-MMAE in xenograft models of the parental cell lines and maintained its efficacy in the resistant cell lines. These studies provide proof of concept for an anthracycline-based ADC that could be used to treat B-cell malignancies that are resistant to vc-MMAE conjugates.

Yu SF ，Zheng B ，Go M ，Lau J ，Spencer S ，Raab H ，Soriano R ，Jhunjhunwala S ，Cohen R ，Caruso M ，Polakis P ，Flygare J ，Polson AG ... -  《-》

An EGFR-targeting antibody-drug conjugate LR004-VC-MMAE: potential in esophageal squamous cell carcinoma and other malignancies.

Epidermal growth factor receptor (EGFR) is a rational target for cancer therapy, because its overexpression plays an important oncogenic role in a variety of solid tumors; however, EGFR-targeted antibody-drug conjugate (ADC) therapy for esophageal squamous cell carcinoma (ESCC) is exceedingly rare. LR004 is a novel anti-EGFR antibody with the advantages of improved safety and fewer hypersensitivity reactions. It may be of great value as a carrier in ADCs with high binding affinity and internalization ability. Here, we prepared an EGFR-targeting ADC, LR004-VC-MMAE, and evaluated its antitumor activities against ESCC and EGFR-positive cells. LR004 was covalently conjugated with monomethyl auristatin E (MMAE) via a VC linker by antibody interchain disulfide bond reduction. VC-MMAE was conjugated with LR004 with approximately 4.0 MMAE molecules per ADC. LR004-VC-MMAE showed a potent antitumor effect against ESCC and other EGFR-positive cells with IC50 values of nM concentrations in vitro. The in vivo antitumor effects of LR004-VC-MMAE were investigated in ESCC KYSE520 and A431 xenograft nude mice models. Significant activity was seen at 5 mg·kg-1 , and complete tumor regression was observed at 15 mg·kg-1 in the KYSE520 xenograft nude mice after four injections, while the naked antibody LR004 had little effect on inhibiting tumor growth. Similar promising results were obtained in the A431 models. In addition, the tumors also remained responsive to LR004-VC-MMAE for large tumor experiments (tumor volume 400-500 mm3 ). The study results demonstrated that LR004-VC-MMAE could be a potential therapeutic agent for ESCC and other EGFR-expressing malignancies. We also evaluated PK profile of LR004-VC-MMAE ADC in the mice model, which would provide qualitative guiding significance for the further research.

Hu XY ，Wang R ，Jin J ，Liu XJ ，Cui AL ，Sun LQ ，Li YP ，Li Y ，Wang YC ，Zhen YS ，Miao QF ，Li ZR ... -  《-》

Enhanced antitumor effect of anti-tissue factor antibody-conjugated epirubicin-incorporating micelles in xenograft models.

For the creation of a successful antibody-drug conjugate (ADC), both scientific and clinical evidence has indicated that highly toxic anticancer agents (ACA) should be conjugated to a monoclonal antibody (mAb) to administer a reasonable amount of ADC to patients without compromising the affinity of the mAb. For ordinary ACA, the conjugation of a mAb to ACA-loaded micellar nanoparticles is clinically applicable. Tissue factor (TF) is often overexpressed in various cancer cells and tumor vascular endothelium. Accordingly, anti-TF-NC-6300, consisting of epirubicin-incorporating micelles (NC-6300) conjugated with the F(ab')2 of anti-TF mAb was developed. The in vitro and in vivo efficacy and pharmacokinetics of anti-TF-NC-6300 were compared to NC-6300 using two human pancreatic cancer cell lines, BxPC3 (high TF expression) and SUIT2 (low TF expression), and a gastric cancer cell line, 44As3 (high TF expression). The intracellular uptake of epirubicin was faster and greater in BxPC3 cells treated with anti-TF-NC-6300, compared with NC-6300. Anti-TF-NC-6300 showed a superior antitumor activity in BxPC3 and 44As3 xenografts, compared with NC-6300, while the activities of both micelles were similar in the SUIT2 xenograft. A higher tumor accumulation of anti-TF-NC-6300 compared to NC-6300 was seen, regardless of the TF expression levels. However, anti-TF-NC-6300 appeared to be localized to the tumor cells with high TF expression. These results indicated that the enhanced antitumor effect of anti-TF-NC6300 may be independent of the tumor accumulation but may depend on the selective intratumor localization and the preferential internalization of anti-TF-NC-6300 into high TF tumor cells.

Yamamoto Y ，Hyodo I ，Koga Y ，Tsumura R ，Sato R ，Obonai T ，Fuchigami H ，Furuya F ，Yasunaga M ，Harada M ，Kato Y ，Ohtsu A ，Matsumura Y ... -  《-》