Ann: PAT-DX1 Crosses Blood Brain Barrier to Reduce Tumour Size, page-158

One of PAT-DX1's potential competitors is Ablynx's Nanobodies because

1. Nanobodies are also cell-penetrating antibodies.

“It has been estimated that upwards of four fifths of all potential drug targets are intracellular, but many of these targets are too flat to be targeted with small molecules, and large molecules with the appropriate binding capability can’t get through the cell membrane to get to the target. Cell-penetrating antibody constructs can solve this problem, and arguably unlock multi-billion-dollar drug development opportunities as a result. One of the reason why the Belgian biotech company Ablynx is currently capitalised at >US$1.8bn company is that its nanobodies, derived from camel antibodies, can freely pass across membranes.”
- NDF Research - PAB Initiation of Coverage 19 Dec 2017

2. Almost five years back in 2013 Nanobodies were claimed to be capable of surmounting the BBB.

“Nbs can surmount the blood–brain barrier. One of the Nbs selected from a llama, which was immunized with brain vascular endothelial cells, was found to undergo transcytosis and released on the basolateral side of the endothelial cells. In vivo studies showed that the Nb was efficiently transported across the blood–brain barrier and could even be used to carry any cargo into the brain, including the entire M13 phage particle.”
- International Journal of Nanomedicine - Nanobodies as novel agents for disease diagnosis and therapy 31 Oct 2013
https://pdfs.semanticscholar.org/c601/ce7bb771dbfc89bac8cfb0817e62ee9908fb.pdf

However, Wikipedia seems to have reservation about its ability to cross the BBB.

"Ablynx expects that their Nanobodies might cross the blood–brain barrier and permeate into large solid tumours more easily than whole antibodies, which would allow for the development of drugs against brain cancers."
https://en.wikipedia.org/wiki/Single-domain_antibody

3. Ablynx and its nanobodies platform was snapped up by French pharma giant.

Sanofi beats Novo to buy Ablynx for $4.8 billion in biotech M&A boom 30 Jan 2018
https://www.moneycontrol.com/news/w...4-8-billion-in-biotech-ma-boom-2-2494277.html

Although Nanobodies' benefits and advantages are well recognised in the industry it may be far less superior to Deoxymab 3E10 antibodies which can localise to and directly kill a range of DNA repair-deficient cancer cells of both primary and secondary, so to speak, 3E10 and its variant PAT-DX1 are excellent natural-born anticancer antibodies while Nanobodies are not. As we all know, nowadays, excellent antibodies are a rare and limiting resource in cancer therapy field.

JMO, DYOR