Radiofrequency ablation before intratumoral injection of (131)I-chTNT improves the tumor-to-normal tissue ratio in solid VX2 tumor

Updated developments on molecular imaging and therapeutic strategies directed against necrosis

Cell death plays important roles in living organisms and is a hallmark of numerous disorders such as cardiovascular diseases, sepsis and acute pancreatitis. Moreover, cell death also plays a pivotal role in the treatment of certain diseases, for example, cancer. Noninvasive visualization of cell death contributes to gained insight into diseases, development of individualized treatment plans, evaluation of treatment responses, and prediction of patient prognosis. On the other hand, cell death can also be targeted for the treatment of diseases. Although there are many ways for a cell to die, only apoptosis and necrosis have been extensively studied in terms of cell death related theranostics. This review mainly focuses on molecular imaging and therapeutic strategies directed against necrosis. Necrosis shares common morphological characteristics including the rupture of cell membrane integrity and release of cellular contents, which provide potential biomarkers for visualization of necrosis and necrosis targeted therapy. In the present review, we summarize the updated joint efforts to develop molecular imaging probes and therapeutic strategies targeting the biomarkers exposed by necrotic cells. Moreover, we also discuss the challenges in developing necrosis imaging probes and propose several biomarkers of necrosis that deserve to be explored in future imaging and therapy research.

Enhanced binding of necrosis-targeting immunocytokine NHS-IL12 after local tumour irradiation in murine xenograft models

PURPOSE

NHS-IL12 is an immunocytokine targeting necrotic tumour areas. IL12 shows anti-tumour activity. As local irradiation might induce additional necrosis in solid tumours, we aimed to evaluate the increase in intratumoural accumulation of NHS-IL12 after irradiation and correlate the findings with diffusion-weighted MRI studies in two xenograft models.

METHODS

Human rhabdomyosarcoma (A204) and prostate cancer (PC3) cells were studied in vitro and as subcutaneous xenografts. Radiation sensitivity of the cell lines was assessed in vitro by colony formation assays. In vivo tumour necrosis was assessed based on apparent diffusion coefficients (ADC). Biodistribution of NHS-IL12 was evaluated with and without tumour irradiation using in vivo small-animal PET and ex vivo biodistribution.

RESULTS

A204 and PC3 differed in their intrinsic radiation sensitivity. Accordingly, radiation-induced tumour necrosis was found only in A204 xenografts. In comparison with control, ADC was significantly increased after irradiation of A204 tumours with 1 × 8.0 Gy and 5 × 2.0 Gy, whereas no change in ADC was observed in PC3 xenografts in all irradiation regimes. ADC correlated with histology. An enhanced uptake of radiolabelled NHS-IL12 in A204 tumours was detected by PET and ex vivo biodistribution after tumour irradiation. In PC3 tumours, no increase in NHS-IL12 uptake was observed.

CONCLUSIONS

In dependence of the tumour model, tumour irradiation enhanced tumour necrosis measured in MRI and histology. In vivo PET and ex vivo biodistribution showed enhanced binding of NHS-IL12 in rhabdomyosarcoma xenografts. Thus, enhanced binding of necrosis-targeting immunocytokines might be a novel mechanism of additive effects in combination with irradiation.

The safety and treatment response of combination therapy of radioimmunotherapy and radiofrequency ablation for solid tumor: a study in vivo

OBJECTION

To investigate the safety and treatment response of radioimmunotherapy (RIT) in combination with radiofrequency ablation (RFA) for the treatment of VX2 tumor on rabbit.

MATERIALS AND METHODS

A total of 36 rabbits bearing VX2 tumor on the thigh were randomly assigned into 3 groups (group I: 1-2 cm; group II: 2-3 cm; group III: 3-4 cm) and 4 subgroups (A: as control, just puncture the tumor using the RFA electrode without power output; B: RFA alone; C: 131I-chTNT intratumoral injection alone; D: RFA+131I-chTNT intratumoral injection 3 days later). The variation of blood assay, weight and survival among different groups and subgroups were used to assess the treatment safety. Ultrasound (US) was used to monitor and assess the tumor response after treatment.

RESULTS

According to the results of the weight and the blood assay among different groups, subgroups, and at two time points (one day before and the 16th day after treatment), no damages to the liver, kidney function and myelosuppression resulting from the treatment were found. No significant differences in survivals among the four subgroups (p = 0.087) were found. In addition, 131I-chTNT did not show significant inhibition effect on VX2 tumor progression according to US measurements.

CONCLUSION

131I-chTNT intratumoral injection alone or in combination with RFA is relatively safe for rabbit without significant toxicity and shows no significant effect on the survival. The treatment response is not as satisfactory as anticipated.