Overview

While traditional treatments like surgery, chemotherapy, and radiation have been effective, they often come with significant toxicity(side effects) and limited success, particularly in advanced cancers. Cancer immunotherapy has revolutionised oncology in recent years, offering new hope for patients with previously untreatable malignancies. From the early days of cancer vaccines(exposing immune cells to neoantigens) to the current era of immune checkpoint inhibitors(ICI) and CAR-T cell therapies, the field has undergone a remarkable transformation.¹ However, despite significant advances, challenges persist, including treatment resistance, severe side effects, and incomplete responses in many cancer types. To address these limitations, researchers are developing cutting-edge immunotherapy techniques that promise to reshape the landscape(area/surrounding) of cancer treatment and there is still much room for improvement.¹ This article explores some of the most innovative and novel immunotherapy techniques currently in development to address these challenges and potentially offer more effective, targeted treatments for cancer.

Next-Generation Immune Checkpoint Inhibitors

Immune checkpoints are critical regulators of immune responses, and tumours often exploit these checkpoints to evade immune detection. Traditional checkpoint inhibitors like PD-1/PD-L1 inhibitors have shown significant promise, but many tumours either do not respond or eventually develop resistance. To address this, researchers are developing inhibitors that target other immune checkpoints beyond PD-1/PD-L1, such as TIGIT, LAG-3, VISTA, and TIM-3.²

TIGIT Inhibition

TIGIT (T cell immunoreceptor with Ig and ITIM domains) has emerged as a promising target. By blocking TIGIT, researchers aim to enhance both T-cell and natural killer (NK) cell function within tumours, potentially improving outcomes for patients who don't respond to current checkpoint inhibitors or in patients with cancer who have escaped the previous treatment with ICI.²

VISTA and TIM-3 Blockade 

VISTA (V-domain Ig suppressor of T cell activation) and TIM-3 (T-cell immunoglobulin and mucin-domain containing-3) are emerging targets in the immunotherapy field. By blocking these immune checkpoints, researchers hope to restore T-cell activity in the TME and improve outcomes in resistant cancers.²

LAG-3 and Beyond

Lymphocyte-activation gene 3 (LAG-3) inhibitors are being investigated, often combined with PD-1/PD-L1 blockers, to provide a multi-pronged approach to immune activation.² 

CAR-T 2.0: Advancing Cellular Therapies

Chimeric Antigen Receptor T-cell (CAR-T) therapy has shown remarkable efficacy in certain blood cancers, but challenges remain in treating solid tumours. New approaches are being developed to address these limitations:

Targeting Solid tumours

Researchers are engineering CAR-T cells to target antigens commonly expressed in solid tumours, such as mesothelin and HER2. These next-generation CAR-T cells are designed to overcome the hostile tumour microenvironment and improve efficacy against previously resistant cancers.³

Armored CAR-T Cells

To combat the immunosuppressive nature of many tumours, scientists are creating "armoured" CAR-T cells. These enhanced cells are engineered to resist inhibitory signals within the tumour microenvironment, for example, by incorporating PD-1 blocking capabilities directly into the CAR-T cells.³

Dual-Targeting Strategies

Dual CAR-T cells are being developed to reduce the risk of tumour escape through antigen loss. These innovative cells can target two distinct tumour antigens simultaneously, potentially improving long-term efficacy and reducing relapse rates.³

Off-the-Shelf CAR-T Cells: 

Traditional CAR-T cells are patient-specific, requiring an extensive manufacturing process. However, allogeneic or off-the-shelf CAR-T cells, derived from healthy donors, are being developed to address scalability(higher reach to patients) and manufacturing costs.

Oncolytic Virus Therapy

Oncolytic viruses represent a unique and innovative approach to cancer therapy, combining direct tumour cell killing with immune system stimulation. They are genetically engineered or naturally occurring viruses that selectively replicate in and kill cancer cells while sparing normal tissues.⁵ As these viruses infect and lyse tumour cells, they release tumour antigens that can activate a broader immune response against the cancer.⁶

Clinical Progress

The field of oncolytic virus therapy has seen significant advancements in recent years:

• T-Vec (talimogene laherparepvec), a genetically modified herpes simplex virus type 1 (HSV-1) armed with GM-CSF, became the first oncolytic virus approved by the FDA and European regulatory agencies for the treatment of advanced melanoma⁵
• Clinical trials have demonstrated that local injections of oncolytic viruses like T-Vec can not only suppress the growth of injected tumours but also act systemically and prolong overall survival⁵

Engineered Viruses

Researchers are developing increasingly sophisticated oncolytic viruses:

• Viruses are being engineered to express transgenes that enhance their anti-tumor effects or stimulate immune responses⁷
• Some oncolytic viruses are designed to target specific tumour antigens or exploit defects in cancer cell signalling pathways⁶

Combination Strategies

Oncolytic virus therapy is being explored in combination with other cancer treatments:

• Trials combining oncolytic viruses with immune checkpoint inhibitors are ongoing, aiming to enhance overall efficacy⁵
• Researchers are investigating combinations with traditional therapies like chemotherapy and radiation to potentially unlock synergistic effects

Personalised Cancer Vaccines

Cancer vaccines aim to stimulate the immune system to recognise and attack tumour cells. There are two main types: preventive(to prevent cancer) and therapeutic(to treat existing cancer). Leveraging advances in genomic sequencing and bioinformatics, personalised cancer vaccines represent a highly tailored approach to immunotherapy:

Neoantigen-Based Vaccines

These vaccines are designed to target tumour-specific mutations (non-self) unique to each patient's cancer. By training the immune system to recognise these cancer-specific markers, researchers hope to elicit potent and precise anti-tumour responses.⁸

mRNA Vaccine Platforms

Building on the success of mRNA vaccines in infectious diseases(especially viruses), similar platforms are being adapted for cancer immunotherapy. These vaccines can deliver instructions for producing tumour-specific antigens directly to the patient's cells, potentially offering a rapid and adaptable approach to personalised cancer treatment.⁸

Emerging Innovations

Several cutting-edge approaches are pushing the boundaries of cancer immunotherapy:

CRISPR Gene Editing

CRISPR-Cas9 technology is being used to improve T-cell function, creating more potent and targeted cellular therapies. This includes knocking out genes that inhibit immune responses or engineering T-cells to express synthetic receptors against cancer-specific targets. Researchers are using CRISPR to optimise CAR-T and TCR therapies by knocking out genes that inhibit immune cell function or inserting new genes to increase the targeting and persistence of these cells.⁹

Tumour Microenvironment Modulation

Novel strategies aim to reprogram the tumour microenvironment, making it more conducive to anti-tumour immune responses. This includes targeting immunosuppressive cells, altering tumour metabolism, and reducing fibrosis to improve immune cell infiltration. Targeting tumour-associated Macrophages (TAMs) and Myeloid-Derived Suppressor Cells (MDSCs) is an area of intense research, with drugs being developed to convert these immune suppressive cells into tumour-fighting ones. Targeting metabolic pathways that tumours use to evade immune surveillance, such as inhibiting lactic acid production or promoting oxidative stress in the TME.¹⁰

Synthetic Biology

Researchers are applying synthetic biology principles to create "designer" immune cells with enhanced capabilities. These engineered cells can be programmed to respond to specific signals within the tumour environment, offering precise and controllable anti-cancer activity.³

Cytokine-Based Immunotherapy

Cytokines play a central role in regulating the immune response. Cytokine-based therapies** aim to enhance the immune system's ability to attack tumours.

• IL-2 and IL-15 Agonists: Interleukin-2 (IL-2) has been used for decades in cancer immunotherapy, but its clinical use has been limited by severe side effects. Researchers are now developing IL-2 and IL-15 superagonists, which enhance immune cell expansion without the severe toxicities associated with traditional IL-2 therapy¹⁰
• Cytokine/Checkpoint Inhibitor Combinations: Combining cytokines with immune checkpoint inhibitors is a promising strategy to amplify the immune response while mitigating side effects. For example, the combination of IL-15 and anti-PD-1 inhibitors is being explored in clinical trials¹⁰

Many novel therapies are currently undergoing clinical trials, and initial results are promising. Ongoing studies are combining various approaches, such as CAR-T cells with immune checkpoint inhibitors, oncolytic viruses with immune-modulatory cytokines, and personalised vaccines with TCR therapy.⁹

Monoclonal Antibodies and Antibody-Drug Conjugates (ADCs)

Monoclonal Antibodies Targeting tumour Antigens: Antibodies engineered to bind tumour antigens, marking them for immune destruction (e.g., anti-CD47, anti-GD2).

Antibody-Drug Conjugates (ADCs): Conjugating monoclonal antibodies to cytotoxic drugs, enabling targeted delivery of chemotherapy directly to tumour cells.¹¹

Tumour-infiltrating lymphocyte (TIL)Therapy Advancements

TIL therapy is being refined for future:⁹

• Improving TIL selection and expansion techniques
• Combining TIL therapy with checkpoint inhibitors
• Exploring TIL therapy for cancers beyond melanoma

Future Directions and Challenges

The future of cancer immunotherapy lies in precision medicine, where treatments are tailored to the genetic and immune profiles of individual patients. Biomarkers will play a crucial role in identifying which therapies will work best for specific patients, ensuring that treatments are both effective and safe.

While manufacturing challenges for therapies like CAR-T and personalised vaccines remain significant, advances in biotechnology are helping to scale production and make these therapies more accessible. Additionally, integrating immunotherapies with traditional treatments like chemotherapy and radiation may unlock new synergies and improve patient outcomes.

Conclusion

Cancer immunotherapy is evolving rapidly, with novel techniques offering hope for improved outcomes and expanded treatment options. With emerging technologies such as next-generation immune checkpoint inhibitors, CAR-T 2.0, oncolytic viruses, and gene-editing tools like CRISPR, the future holds great promise. The challenges remain, particularly in overcoming the immunosuppressive tumour microenvironment and improving the safety and accessibility of these therapies. As clinical trials progress, these novel approaches may offer more effective, targeted, and personalised treatments for cancer patients worldwide.