Reducing the size of a tumor for six to eight weeks (especially via a new method) could actually be an important result. Many cancer drugs only result in temporary remission when used in isolation, before the cancer out-evolves the drug and comes back. However, using multiple drugs simultaneously (combination chemotherapy) and using the drugs after surgery to kill remnant cells can have a far larger impact. Many of the drugs that can now 'cure' certain cancers in combination only provide brief remission by themselves. (Disclaimer: my only knowledge of this comes from the book The Emperor of All Maladies)