Anterior intratumoural chemotherapy: a newer modality of treatment in advanced solid tumours in children

Click activated protodrugs against cancer increase the therapeutic potential of chemotherapy through local capture and activation

A desired goal of targeted cancer treatments is to achieve high tumor specificity with minimal side effects. Despite recent advances, this remains difficult to achieve in practice as most approaches rely on biomarkers or physiological differences between malignant and healthy tissue, and thus benefit only a subset of patients in need of treatment. To address this unmet need, we introduced a Click Activated Protodrugs Against Cancer (CAPAC) platform that enables targeted activation of drugs at a specific site in the body, i.e., a tumor. In contrast to antibodies (mAbs, ADCs) and other targeted approaches, the mechanism of action is based on in vivo click chemistry, and is thus independent of tumor biomarker expression or factors such as enzymatic activity, pH, or oxygen levels. The CAPAC platform consists of a tetrazine-modified sodium hyaluronate-based biopolymer injected at a tumor site, followed by one or more doses of a trans-cyclooctene (TCO)-modified cytotoxic protodrug with attenuated activity administered systemically. The protodrug is captured locally by the biopolymer through an inverse electron-demand Diels–Alder reaction between tetrazine and TCO, followed by conversion to the active drug directly at the tumor site, thereby overcoming the systemic limitations of conventional chemotherapy or the need for specific biomarkers of traditional targeted therapies. Here, TCO-modified protodrugs of four prominent cytotoxics (doxorubicin, paclitaxel, etoposide and gemcitabine) are used, highlighting the modularity of the CAPAC platform. In vitro evaluation of cytotoxicity, solubility, stability and activation rendered the protodrug of doxorubicin, SQP33, as the most promising candidate for in vivo studies. In mice, the maximum tolerated dose (MTD) of SQP33 in combination with locally injected tetrazine-modified biopolymer (SQL70) was determined to be 19.1-times the MTD of conventional doxorubicin. Pharmacokinetics studies in rats show that a single injection of SQL70 efficiently captures multiple SQP33 protodrug doses given cumulatively at 10.8-times the MTD of conventional doxorubicin with greatly reduced systemic toxicity. Finally, combined treatment with SQL70 and SQP33 (together called SQ3370) showed antitumor activity in a syngeneic tumor model in mice.

The Click Activated Protodrugs Against Cancer (CAPAC) platform uses click chemistry to activate cytotoxic drugs directly at a target site with minimal toxicity, overcoming limitations of conventional chemotherapy and traditional targeted therapies.

Clinico-immunological response to intratumoral versus intravenous neoadjuvant chemotherapy in advanced pediatric solid malignancies

Background:

There is minimal literature on the use of intralesional chemotherapy in the pediatric age group. We undertook this present study to evaluate the two modalities (intratumoral and intravenous) of giving chemotherapy in terms of toxicity of chemotherapy, hematological parameters, efficacy of chemotherapy in reduction in volume of the tumor as well as resectability of tumor with special emphasis on immunological parameters.

Materials and Methods:

Advanced cases of Wilms’ tumor and Neuroblastoma were included in the study. Intratumoral chemotherapy was given through 25 G spinal needle under aseptic precautions and ultrasound guidance in the same dose as in systemic chemotherapy. Intravenous group was given chemotherapy in the usual way. Reassessment was carried out after every course of chemotherapy.

Results:

Group A included 16 cases of Wilms’ tumor and 6 cases of neuroblastoma. In group B, there were 14 cases of Wilms’ tumor and 8 of neuroblastoma. Vomiting, diarrhea, mucositis, and thrombophlebitis were more common in the intravenous group (P<0.05). The fall in Immunoglobulin A, Immunogloblulin G, Immunoglobulin M, and T-cell rosetting was more common in the intravenous group (P<0.05). Seventy percent of patients had completely resectable tumor at the end of 6 doses of intratumoral chemotherapy as compared to 50% resectability in the intravenous group (P<0.05).

Conclusion:

Intratumoral chemotherapy, besides causing less of the adverse effects and increasing the resecability rate, also causes less suppression of the immune system. This may be offered as an alternative safe and effective modality of treatment for advanced solid tumors.