Nowadays, the importance of metal-based drugs (MBD) in medical applications and commercial markets is increased by the advancement of nanotechnology [
1,
2]. The antiquity MBD, which is composed of elements such as iron, lithium, vanadium, gold, magnesium, and bismuth, has long been used to treat ailments such as anemia, bipolar disorder, diabetes, rheumatoid arthritis, stroke, and ulcers, respectively [
3]. Among them, the most well-known is platinum-based drugs (PBD) such as cisplatin, carboplatin, and oxaliplatin, which are the most commonly used to treat cancer [
4]. PBD in general or cisplatin in particular was approved in 1978, and it is the most preferable drug candidate [
5] for a wide range of human diseases in chemotherapeutic applications [
6,
7]. As a result, this triumph has had a large impact on cancer treatment regimens [
8] and influenced the discovery of a new MBD [
9]. In this perspective, the current clinical trials are limited to several putative compounds and mechanisms of action in the development of cancer drugs [
10] and diagnostic agents [
1]. This is not a good sign for drug development [
11]. Alternative potencies, such as copper and zinc (CuZn) compounds, should be explored to bring new action mechanisms and chemotherapeutic approaches [
12,
13]. Without doubt, copper-based drugs (CBD) [
14] and zinc-based drugs (ZBD) [
15] have active metabolic and physiological functions to develop into the most promising pharmacological non-steroidal anti-inflammatory drugs (NSAID) [
12,
16]. In addition, zinc stimulates bone formation and mineralization and improves osteoblast differentiation [
17]. Combining copper with zinc will avoid genetic disorders and release oncogenic enzymes to regulate and restore homeostasis [
18] [
19]. A better understanding of their combination and how they play important roles in physiological functions will enhance OS drug development [
20]. This will alter MBD’s perspectives and generate new drug discovery insight maps [
21]. In modern medicine, the understanding of metal-ion functions [
22] and diagnosis at the molecular level [
23] have become inevitable consequences of delivering new MBD in medicinal bioinorganic chemistry [
24,
25]. There is still inadequate effort devoted at mechanistic levels [
26] towards providing an alternative, targeted, and rational approach [
27] to supplement screening of novel chemical entities for biological activity [
21].
Chemoresistance in OS immunotherapy [
28] is the main problem in MBD in general and PBD in particular [
29]. This problem increases after long-term treatments due to its acquired and accumulated nature [
30,
31]. It becomes more complicated after including tumorigenesis, metastasis, and immune evasion, as stated in our previous paper [
32]. Chemoresistance develops over time, limiting clinical application and raising concerns about efficacy and systemic toxicity [
33,
34]. Many attempts intend to solve this problem, but none combines CuZn into a biosensor to stimulate drug release for OS therapy [
30,
35]. In our previous paper, we presented some evidence of combinational and targeted biosensors to trigger and stimulate drug release [
36]. Our efforts to develop a multifunctional biosensor for OS therapy (OST), however, will be insufficient unless we investigate the physiological functions of CuZn [
37]. On the contrary, not much research on CuZn has successfully provided details of multifunctional biosensors for balancing and controlling drug release during cancer invasion [
34]. Despite this, their chelation structures [
38], aromatic organic solvents [
39], and donor atoms of ligands [
18] remain unclear, making structural strength [
40] the primary barrier to therapeutic efficacy. Thus, more recent approaches are needed to elucidate them and further intensify their degradation factors and functions [
41,
42].
In this review, the therapeutic efficacy and anti-chemoresistance of OS are discussed but not the OS pathology [
36]. It is prudent to discuss the physiological functions of copper and zinc elements in OST but not their general chemotherapeutic potencies. Notably, there are too many papers discussing them; therefore, this paper will reconstruct their combination to elaborate on anti-chemoresistance and OST precisely. First of all, their ions serve as chelators for their structures, such as chelating and metal–organic frameworks (MOF), which influence their anti-chemoresistance. Secondly, the structures of the main organic solvents, such as planar aromatic, Schiff-based, and Schiff-paired, also influence their anti-chemoresistance. Thirdly, their ligand degradation factors are discussed individually to enrich our understanding. The basic functions of their ligands are expected to serve as biosensors, which are clearly elucidated through this review. That is to say, the key biosensor functions, such as redox and photo, serve as guidance for the next-generation OST biosensors [
43]. In fact, it is important to design an enzymatic stimulation biosensor for OST. The reality is that this and other functions of biosensors could not be elaborated due to space limitations. As a result, those interested can find more information in our papers [
36,
37]. This is the rationale for developing a biosensor with sustained efficacy and minimal adverse effects. There are some remaining unclear problems resulting in a major obstacle towards clinical translation, which will be discussed later.