Selective Internal Radiation Therapy in the Multidisciplinary Management of Liver Metastases From Colorectal Carcinoma

Advancements in colorectal cancer treatment: The role of metal-based and inorganic nanoparticles in modern therapeutic approaches

Recent advances in the treatment of colorectal cancer (CRC) have highlighted the integration of metal-based nanoparticles into sophisticated therapeutic strategies. This examination delves into the potential applications of these nanoparticles, particularly in augmenting the effectiveness of photodynamic therapy (PDT) and targeted drug delivery systems. Metal nanoparticles, such as gold (Au), silver (Ag), and copper (Cu), possess distinctive characteristics that make them valuable in cancer treatment. Beyond their role as drug carriers, these nanoparticles actively engage in therapeutic processes like apoptosis induction, enhancement of photothermal effects, and generation of reactive oxygen species (ROS) crucial for tumor cell eradication. The utilization of metal nanoparticles in CRC therapy addresses significant challenges encountered with conventional treatments, such as drug resistance and systemic toxicity. For example, engineered Au nanoparticles enable targeted drug delivery, reducing off-target effects and maximizing therapeutic efficacy against cancerous cells. Their capacity to absorb near-infrared light allows for localized hyperthermia, effectively eliminating cancerous tissues. Similarly, Cu nanoparticles exhibit potential in overcoming drug resistance by enhancing the efficacy of traditional chemotherapeutic agents through ROS production and improved drug stability. This review underscores the significance of precision medicine in CRC care. Through the integration of metal nanoparticles alongside complementary biomarkers and personalized treatment strategies, a more efficient and tailored therapeutic approach can be achieved. The synergistic effect of PDT in combination with metal nanoparticles introduces a novel methodology to CRC treatment, offering a dual-action mechanism that enhances tumor targeting while minimizing undesirable effects. In conclusion, the integration of metal-based nanoparticles in CRC therapy marks a significant progress in oncological treatments. Continued research is imperative to comprehensively grasp their mechanisms, optimize their clinical utility, and address potential safety considerations. This thorough assessment aims to pave the way for future advancements in CRC treatment through the application of nanotechnology and personalized medicine strategies.

90Y-/166Ho- 'Radiation lobectomy' for liver tumors induces abnormal morphology and impaired drainage of peritumor lymphatics

Background & Aims

High-dose unilobar radioembolization, or 'radiation lobectomy' (RL), is an induction therapy that achieves contralateral future liver remnant hypertrophy while simultaneously irradiating the tumor. As such, it may prevent further growth, but it is unknown whether RL affects intrahepatic lymphatics, a major route via which liver tumors disseminate.

Methods

This was a case-control study conducted at University Medical Center Utrecht. The study compared lymph vessels in livers that had undergone RL (cases) with those in livers that had not undergone RL (controls). Histological samples were acquired from patients diagnosed with hepatocellular carcinoma (HCC) or colorectal liver metastases (CRLM) between 2017 and 2022. Lymph vessel morphology was analyzed by two researchers using podoplanin, a protein that is expressed in lymphatic endothelium. In vivo liver lymph drainage of radioembolized livers was assessed using intraoperative liver lymphangiography (ILL): during liver surgery, patent blue dye was injected into the liver parenchyma, followed by inspection for staining of perihepatic lymph structures. ILL results were compared to a previously published cohort.

Results

Immunohistochemical analysis on post-RL tumor tissues from ten patients with CRLM and nine patients with HCC revealed aberrant morphology of irradiated liver lymphatics when compared to controls (n = 3 per group). Irradiated lymphatics were tortuous (p <0.05), thickened (p <0.05) and discontinuous (p <0.05). Moreover, post-RL lymphatics had larger lumens (1.5-1.7x, p <0.0001), indicating lymph stasis. ILL revealed diminished lymphatic drainage to perihepatic lymph nodes and vessels in irradiated livers when compared to non-radioembolized controls (p = 1.0x10-4).

Conclusions

Radioembolization impairs peritumoral lymph vessel function. Further research is needed to evaluate if radioembolization impairs tumor dissemination via this route.

Impact and implications

Unilobar radioembolization can serve as an alternative to portal venous embolization for patients who are considered unresectable due to an insufficient future liver remnant. This research suggests that radioembolization impairs the function of peritumoral liver lymph vessels, potentially hindering dissemination via this route. These findings provide support for considering unilobar radioembolization over standard portal venous embolization.

Colorectal liver metastases that survive radioembolization display features of aggressive tumor behavior

BACKGROUND

Radiation lobectomy is a therapeutic approach that involves targeted radiation delivery to induce future liver remnant hypertrophy and tumor control. In patients with colorectal liver metastases, only 30-40% have complete tumor regression. The importance of tumor biology in treatment response remains elusive.

METHODS

Patients with colorectal liver metastases who received radiation lobectomy were selected from surgical pathology files. Using a machine learning scoring protocol, pathological response was correlated to tumor absorbed dose and expression of markers of radioresistance Ki-67 (proliferation), CAIX (hypoxia), Olfm4 (cancer stem cells) and CD45 (leukocytes).

RESULTS

No linear association was found between tumor dose and response (ρ < 0.1, P = 0.73 (90Y), P = 0.92 (166Ho)). Response did correlate with proliferation (ρ = 0.56, P = 0.012), and non-responsive lesions had large pools (>15%) of Olfm4 positive cancer stem cells (Fisher's exact test, P = 0.0037). Responding lesions (regression grade ≤2) were highly hypoxic compared to moderate and non-responding lesions (P = 0.011). Non-responsive lesions had more tumor-infiltrating leukocytes (3240 cells/mm2 versus 650 cells/mm2), although this difference was not significant (P = 0.08).

CONCLUSION

The aggressive phenotype of a subset of surviving cancer cells emphasizes the importance of prompt resection after radiation lobectomy.

[Interventional Radiology in Oncology - Update 2021]

Interventional radiology plays a crucial role in oncology. The most common interventional treatments are transarterial embolisation as well as percutaneous thermal ablations. Transarterial embolisation, such as transarterial chemoembolization (TACE) or selective internal radiation therapy (SIRT) are well established, usually palliatively intended treatment options for primary and secondary hepatic malignancies. Embolisation is usually well tolerated under conscious sedation and can be repeated several times. Percutaneous thermoablation is a local ablative, usually curatively intended treatment for hepatic, renal and pulmonary tumors. As a minimally invasive technique, it competes against surgery and radiation therapy. There are different types of thermoablation, most commonly used are radiofrequency ablation (RFA), microwave ablation (MWA) and cryo-ablation. Ablation is usually performed in general anesthesia, less common in conscious sedation. New interventional treatments are high intensity focused ultrasound (HIFU) and irreversible electroporation (IRE). HIFU allows a non-invasive, imaging-guided thermoablation that is currently certified for uterine myoma, prostate cancer and bone tumors. IRE is a minimal invasive non-thermal ablation that is especially established for locally advanced tumors that show a close relationship to large vessels, for example pancreatic cancer.

Basics to advances in nanotherapy of colorectal cancer

Colorectal cancer (CRC) is the third most common cancer existing across the globe. It begins with the formation of polyps leading to the development of metastasis, especially in advanced stage patients, who necessitate intensive chemotherapy that usually results in a poor response and high morbidity owing to multidrug resistance and severe untoward effects to the non-cancerous cells. Advancements in the targeted drug delivery permit the targeting of tumor cells without affecting the non-tumor cells. Various nanocarriers such as liposomes, polymeric nanoparticles, carbon nanotubes, micelles, and nanogels, etc. are being developed and explored for effective delivery of cytotoxic drugs to the target site thereby enhancing the drug distribution and bioavailability, simultaneously subduing the side effects. Moreover, immunotherapy for CRC is being explored for last few decades. Few clinical trials have even potentially benefited patients suffering from CRC, still immunotherapy persists merely an experimental alternative. Assessment of the ongoing and completed trials is to be warranted for effective treatment of CRC. Scientists are paying efforts to develop novel carrier systems that may enhance the targeting potential of low therapeutic index chemo- and immune-therapeutics. Several preclinical studies have revealed the superior efficacy of nanotherapy in CRC as compared to conventional approaches. Clinical trials are being recruited to ascertain the safety and efficacy of CRC therapies. The present review discourses in a nutshell the molecular interventions including the genetics, signaling pathways involved in CRC, and advances in various strategies explored for the treatment of CRC with a special emphasis on nanocarriers based drug targeting.