Investigations in the biotechnology arena have been dramatically transforming the dimensions of healthcare, particularly in the cancer treatment sector. Notably, prominent growth has been witnessed in the field of immune checkpoint therapy, which is revolutionary in treating several forms of cancer.

To understand immune checkpoint therapy, one must comprehend the concept of immune checkpoints. In a normal functioning body, immune checkpoints are imperative for maintaining self-tolerance and thus, preventing the immune system from attacking cells indiscriminately. They serve as "brakes" for the immune system, ensuring it does not act aggressively against normal cells in the body. The most researched immune checkpoints are namely Cytotoxic T-Lymphocyte-associated protein 4 (CTLA-4) and Programmed cell death protein 1 (PD-1).

However, cancer cells are known to exploit these checkpoints, hiding from the immune system by imitating a command found on normal cells and hence, preventing the immune system from destroying them. This is where immune checkpoint inhibitors step into the limelight.

Immune checkpoint inhibitors are drugs - often made of antibodies - that can unleash an immune system attack on cancer cells. By doing so, they disrupt the signals produced by cancer cells that deceive the immune system. In essence, immune checkpoint inhibitors "remove the brakes" and unmask the cancer cells, allowing the immune system to readily recognize and destroy them by utilizing their natural anti-cancer activities.

One of the commonly used immune checkpoint inhibitors is the CTLA-4 inhibitor. CTLA-4 is an immune checkpoint located on T cells (the warriors of our immune system), which when activated, downregulates immune responses. In cancer treatment, CTLA-4 inhibitors work by blocking this checkpoint, thereby enhancing the immune responses against cancer cells. It's worth noting that the first immune checkpoint inhibitor to gain FDA approval was Ipilimumab, a CTLA-4 inhibitor that has shown promising results against melanoma, a type of deadly skin cancer.

With the advent of immune checkpoint therapy, the tides have turned in cancer treatment. Unlike conventional therapies that directly attack the cancer cells, immune checkpoint therapy cleverly enables the body's own immune system to eliminate cancer cells, paving a promising path towards the use of immunotherapies in oncological treatments.

Yet, the complexity lies in the heterogeneous response observed in patients undergoing immune checkpoint therapy. While some patients showcase excellent responses, others appear resistant or develop adverse reactions. Hence, further research is ongoing to elucidate more about the complex biology behind immune checkpoints and the application of their inhibitors, enabling personalized therapy based on individual responses.

In conclusion, the progress and developments in immune checkpoint therapy have undoubtedly reshaped the landscape of cancer treatment and hold immense potential for the future. As the realms of Biotechnology and Immunology continue to interwind, a new era of not only effectively treating but potentially curing cancer seems on the horizon.