Key papers

Dr. Harold F. Dvorak and Angiogenesis

The contribution of Harold F. Dvorak to the study of tumor angiogenesis and stroma generation mechanisms.
Domenico Ribatti. Endothelium. 2007 May-Jun;14(3):131-5.
PMID: 17578706. 

A summary of the contributions of Dr. Hal Dvorak to the field of angiogenesis. Hal and colleagues discovered Vascular Endothelial Growth Factor (VEGF) in 1983, demonstrated that an antibody against VEGF could prevent edema and fluid accumulation in human cancers, and established the parallels between tumor growth and wound healing.

Tumors: wounds that do not heal. Similarities between tumor stroma generation and wound healing.
H F Dvorak. N Engl J Med. 1986 Dec 25;315(26):1650-9.
PMID: 3537791.

The seminal paper in the New England Journal of Medicine in which Hal pointed out that both tumors and wounds release VEGF and induce a similar healing process, but in tumors the process never ends (the wounds do not heal).

Anti-VEGF/VEGFR therapy for cancer: reassessing the target.
Basel Sitohy et al. Cancer Res. 2012 Apr 15;72(8):1909-14.
PMID: 22508695.

Why didn’t VEGF/VEGFR targeted cancer therapies work better? Leading researchers in the field of angiogenesis assess the limitations of the VEGF/VEGFR approach. Their conclusion: “We need to identify new molecular targets on the endothelial cells lining the large tumor blood vessels that supply and drain the tumor microvasculature…. Attacking these large vessels would cut off the blood supply to the entire tumor and, therefore, have a larger effect than pruning the innumerable VEGF-A–sensitive microvessels. As any plumber knows, shutting off the water supply at its source makes more sense than trying to turn off every faucet in the house.”

TM4SF1, Endothelial Biology, and Angiogenesis

The L6 protein TM4SF1 is critical for endothelial cell function and tumor angiogenesis.
Shou-Ching Shih et al. Cancer Res. 2009 Apr 15;69(8):3272-7.
PMID: 19351819.

Angiex co-founder Shou-Ching Shih Jaminet began a series of papers demonstrating the fundamental importance of TM4SF1 in endothelial cell biology and angiogenesis. Here, she and her colleagues demonstrated that TM4SF1 plays essential roles in endothelial cell mobility, proliferation, and cell-cell interactions in vitro and angiogenesis in vivo.

TM4SF1: a tetraspanin-like protein necessary for nanopodia formation and endothelial cell migration.
Andrew Zukauskas et al. Angiogenesis. 2011 Sep;14(3):345-54.
PMID: 21626280.

Continuing their exploration of TM4SF1 biology, Dr. Jaminet and colleagues demonstrate that endothelial cells project long “nanopodia” to find other endothelial cells, form intercellular nanotubes, and coordinate their migration and proliferation in order to form vascular tubes. When TM4SF1 is over-expressed in other cell types, they take on the morphology and behavior of endothelial cells.

TM4SF1 as a Cancer Target

TM4SF1: a new vascular therapeutic target in cancer.
Chi-Iou Lin et al. Angiogenesis. 2014 Oct;17(4):897-907.
PMID: 24986520.

Angiex co-founders Shou-Ching Jaminet and Hal Dvorak, with colleagues at BIDMC, point out important advantages of TM4SF1 as a cancer target, including “its high expression in both tumor cells and on the vascular endothelial cells lining tumor blood vessels”. In this paper, they raised a new TM4SF1-directed antibody, 8G4, and demonstrated its potential to target both angiogenic blood vessels and tumor cells. They also demonstrate that mesenchymal stem cells can express high levels of TM4SF1 and facilitate formation of human vessels when co-implanted with endothelial cells.

Intracellular distribution of TM4SF1 and internalization of TM4SF1-antibody complex in vascular endothelial cells.
Tracey E Sciuto et al. Biochem Biophys Res Commun. 2015 Sep 25;465(3):338-43.
PMID: 26241677.

In further work with the antibody 8G4, Angiex co-founders investigate the suitability of TM4SF1 as a target for antibody-drug conjugate therapy by exploring its internalization biology. In this paper, they demonstrate a novel internalization route from cell surface, along microtubules, through the microtubule organizing center and nuclear pores, to the nucleus. The opportunity to deliver conjugated drug payloads to the nucleus of cells in the tumor environment is a tremendous gift to Angiex and other developers of TM4SF1-directed therapies.

TM4SF1 is a molecular facilitator that distributes cargo proteins intracellularly in endothelial cells in support of blood vessel formation.
Chi-Iou Lin et al. J Cell Commun Signal. 2024 May 7;18(2):e12031.
PMID: 38946725.

In this paper, Dr. Jaminet and colleagues elucidate the functions of the TM4SF1 cell surface to nucleus internalization pathway, by demonstrating that it serves a transport function, and transports a number of growth factor activated proteins, including PLCγ and HDAC6, to the nucleus.

Transmembrane-4 L-Six Family Member-1 Is Essential for Embryonic Blood Vessel Development.
Chi-Iou Lin et al. Curr Issues Mol Biol. 2024 Nov 18;46(11):13105-13118.
PMID: 39590375.

Dr. Jaminet and her co-authors demonstrate that TM4SF1 is essential for blood vessel development. TM4SF1 knockout mice are embryonically lethal by embryonic day 9.5 due to a failure to form blood vessels, while about 50% of heterozygous embryos die by embryonic day 17 due to brain hemorrhage. The surviving heterozygotes live normal lives, but implanted tumors grow one-tenth as fast.

Vascular Injury as a Means of Activating Anti-Tumor Immunity

Tumors vs. Chronic Wounds: An Immune Cell's Perspective.
Yichao Hua, Gabriele Bergers. Front Immunol. 2019 Sep 12:10:2178.
PMID: 31572387.

The wound repair program proceeds from an inflammatory stage in fresh wounds, in which the immune system surveys the wound for foreign cells and tries to kill them, to an immune-suppressed state in later stages of wound healing. The vasculature drives the shift in immune profile, and a vascular injury is a potent means of “re-awakening” the inflammatory state of fresh wounds. The authors propose injuring the tumor vasculature with anti-angiogenic immunotherapies as a means of activating anti-tumor immunity.

The BMS-DeNardo Radioimmunoconjugate Trials, 1990-1997

Phase I trial of murine monoclonal antibody L6 in breast, colon, ovarian, and lung cancer.
G E Goodman et al. J Clin Oncol. 1990 Jun;8(6):1083-92.
PMID: 2161448.

The first TM4SF1-directed antibody, L6, was raised by Karl-Errik Hellstrom and colleagues at the University of Washington, and taken to the clinic with support from Bristol Myers Squibb. In this first Phase-1 trial, the antibody was safe through administration of 77 mg/kg (11 mg/kg q1dx7), and one patient experienced a complete remission of her cancer due to a possible immuno-oncology effect.

The biologic window for chimeric L6 radioimmunotherapy.
S J DeNardo et al. Cancer. 1994 Feb 1;73(3 Suppl):1023-32. 
PMID: 8306244.

With continuing support from Bristol-Myers Squibb, L6 radioimmunoconjugates were generated and tested clinically from 1990 to 1997, with the clinical investigations led by Gerald and Sally DeNardo of the University of California at Davis. In this report from 1994, results of the first four years of clinical investigation are summarized, including the presence of vascular antigen which can be covered by an antibody dose of about 3 mg/kg, and substantial antigen on a variety of human carcinomas, including carcinomas of the lung, breast, colon, and ovary, that could be reached by dosing at higher levels.

Radioimmunotherapy for advanced breast cancer using I-131-ChL6 antibody.
S J Denardo et al. Anticancer Res. 1997 May-Jun;17(3B):1745-51.
PMID: 9179228.

In a further report on their clinical studies of TM4SF1-directed radioimmunoconjugates, the DeNardos and colleagues describe the remarkable tumor homing they were able to achieve at a dose level of 6 mg/kg, and excellent clinical outcomes: a 60% overall response rate, and a 100% response rate in patients treated 3 or more times. Unfortunately, they were limited by off-target toxicities from radioactivity, and by formation of anti-drug antibodies that eliminated efficacy and forced them to stop dosing.

TM4SF1-Directed Antibody-Drug Conjugates

Novel Anti-TM4SF1 Antibody-Drug Conjugates with Activity against Tumor Cells and Tumor Vasculature.
Alberto Visintin et al. Mol Cancer Ther. 2015 Aug;14(8):1868-76.
PMID: 26089370.

Before forming Angiex, and from their positions at Beth Israel Deaconess Medical Center, Angiex co-founders collaborated with Pfizer and its Centers for Therapeutic Innovation to make the first TM4SF1-directed antibody-drug conjugate. Although never taken to the clinic, the drug was tested thoroughly in rodents and monkeys, and established a solid foundation for subsequent development of TM4SF1-directed ADCs. Here, Pfizer’s ADC is described and its preclinical data reported.