NO. There is the false notion perpetrated by some websites and then echoed around social media that the Fluoroquinolones were failed chemotherapy drugs (as in anti-tumor or anti-cancer).   The truth is they were derivatives discovered by failed attempts to synthesize anti-malarials.  The Fluoroquinolones were never initially developed to battle cancer, period!..... But please read on.
I have written and still write about the history of the Fluoroquinolones so I will give you an extremely shortened version of the truth. In 1946, researchers C.C. Price and P.M. Roberts were experimenting with the anti-malarial chloroquine in order to seek a synthetic derivative.  One of the compounds they obtained was the compound quinolone-carboxylic acid.  It wasn't until much later that a researcher by the name of G. Lesher working with the Sterling-Winthrop Institute, started working on various analogues of the quinolone-carboxylic acid.  One of these analogues  was nalidixic acid, the grandfather of today's Fluoroquinolones.
Nalidixic acid emerged as a very potent anti-bacterial agent.  Never in G. Lesher's papers does he mention their use for anti-cancer or anti-tumor agents, never! Their penchant for chemotherapeutic or anti-tumor effects were later discovered, much later, after knowledge about the Fluoroquinolones method of action was more fully understood and knowledge about DNA increased.   When quinolone antibiotics emerged on the scene, the science realm didn't know much about DNA, especially mitochondrial DNA, and how these drugs impacted both so negatively.
It is truthful to say that they original Fluoroquinolones would have made poor anti-cancer drugs because they are not metabolically focused enough to target just certain cancer cells (but often neither is traditional chemotherapy as well), but that was not the manufacturer's intent. However, for researchers the Fluoroquinolones do show proven anti-tumor qualities and provide a good platform (scaffold) on which to develop new ones.
Also, their method of action, via topoisomerase inhibition, is the same as certain other anti-cancer (chemotherapy) drugs.   Thus, by default, this qualifies the Fluoroquinolones as anti-cancer or chemotherapeutic agents.   These are strong agents that should never be given out haphazardly.  Also, it is true that new anti-cancer drugs are being developed from the Fluoroquinolones.  The fact is, if you have ever taken an Fluoroquinolones, you were given chemotherapy (anti-cancer), in every sense of the word.
So yes, the Fluoroquinolones are devastatingly harmful drugs.  They are chemotherapeutic agents in the truest sense of the word.  However the term used "failed chemotherapy" is used by websites to garner sensationalism.
I started warning about the re-purposing of the Fluoroquinolones as full-on anti-cancer drugs several years ago (1).  I have discussed in many articles and posts how researchers see them as a powerful scaffold on which to build many more pharmaceuticals (antibiotics, chemotherapy, and antivirals).  Researchers in 2011 said, "... quinolones an endless source of hope and enables further development of new clinically useful drugs." (2).