I am not a doctor, but my neighbors dad had cancer, ane when he had his chemo, he lost his hair, but hje beat the disease, and I have heard that its a good sign, that it shows that it is working.
Fortunately or unfortunately, losing your hair is neither a good nor a bad sign. Certain types of chemotherapy cause hair loss; those types will cause hair loss regardless of whether or not the chemo is working to defeat the cancer. Other types of chemotherapy do not cause hair loss, and even if those types of chemo are working fine, you still will not lose your hair.
Hair loss from chemo has nothing to do with whether or not the chemo is working.