Liposomal Irinotecan Shows a Larger Therapeutic Index than Non-liposomal Irinotecan in Patient-Derived Xenograft Models of Pancreatic Cancer

Integration of liposomal irinotecan in the first-line treatment of metastatic pancreatic cancer: try to do not think about the white bear

The approval of novel therapeutic agents remains widely reliant on evidence derived from large phase III randomized controlled trials. Liposomal irinotecan (ONIVYDE®) stands out as the only drug that has demonstrated improved survival both as a first-line therapy in combination with oxaliplatin and 5-fluorouracil/leucovorin (5FU/LV) (NALIRIFOX) compared to the standard gemcitabine plus nab-paclitaxel in the NAPOLI3 trial, and as a second-line treatment in combination with 5FU/LV compared to the standard 5FU/LV in the NAPOLI1 trial. However, just as the white bear of the Dostoevsky's paradox, the judgment of these results is invariably distracted by the intrusive thought of how different they might be if compared to similar regimens containing standard-free irinotecan as FOLFIRINOX or FOLFIRI, respectively. Here, we present and thoroughly discuss the evidence encompassing the pharmacologic, preclinical, and clinical development of liposomal irinotecan that can dispel any intrusive thoughts and foster a rational and well-considered judgment of this agent and its potential integration into the therapeutic strategies for pancreatic ductal adenocarcinoma.

Could a Long-Acting Prodrug of SN-38 be Efficacious in Sacituzumab Govitecan-Resistant Tumors?

We previously proposed that sacituzumab govitecan (SG, Trodelvy®) likely acts as a simple prodrug of systemic SN-38 as well as an antibody drug conjugate (ADC). In the present commentary, we assess whether a long-acting SN-38 prodrug, such as PLX038, might be efficacious in SG-resistant patients. We first describe possible mechanisms of action of SG, with new insights on pharmacokinetics and TROP2 receptor occupancy. We argue that SG is not an optimal conventional ADC and that the amount of systemic SN-38 spontaneously hydrolyzed from the ADC is so high it must have activity. Then, we describe the concept of time-over-target as related to the pharmacology of SG and PLX038 as SN-38 prodrugs. To be clear, we are not in any way suggesting that PLX038 or any SN-38 prodrug is superior to SG as an anticancer agent. Clearly, SG has the benefit over antigen-independent SN-38 prodrugs in that it targets cells with the TROP2 receptor. However, we surmise that PLX038 should be a more efficacious and less toxic prodrug of systemic SN-38 than SG. Finally, we suggest possible mechanisms of SG resistance and how PLX038 might perform in the context of each. Taken together, we argue that-contrary to many opinions-SG does not exclusively act as a conventional ADC, and propose that PLX038 may be efficacious in some settings of SG-resistance.

Is There Room for Liposomal Irinotecan in Biliary Tract Cancer? A Meta-analysis of Randomised Trials

AIMS

The combination of 5-fluorouracil/leucovorin (5-FU/LV) plus oxaliplatin (FOLFOX) is widely acknowledged as the standard regimen for second-line treatment in patients with advanced biliary tract cancer. Nanoliposomal irinotecan (nal-IRI) has demonstrated its activity in patients with advanced pancreatic cancer. Recent studies have investigated the activity of nal-IRI in combination with 5-FU/LV for biliary tract cancer. However, the results have been contradictory. We conducted a meta-analysis to assess survival outcomes and response rates in randomised trials investigating the activity of nal-IRI in previously treated biliary tract cancer patients.

MATERIALS AND METHODS

We systematically collected potentially relevant findings from PubMed/Medline, the Cochrane library and EMBASE. Abstracts presented at major international oncological meetings were also reviewed. We extracted hazard ratios and 95% confidence intervals for progression-free survival and overall survival, as well as odds ratios and 95% confidence intervals for objective response rate. The outcomes of the accessible randomised studies evaluating the activity of nal-IRI plus 5-FU/LV were analysed.

RESULTS

The combination therapy exhibited a statistically significant decrease in the risk of progression (hazard ratio 0.70; 95% confidence interval 0.50-0.97) when compared with 5-FU/LV alone. Additionally, the dual regimen yielded longer overall survival and a higher objective response rate.

CONCLUSION

Our meta-analysis showed that nal-IRI plus 5-FU/LV had a superior activity in comparison with 5-FU/LV. Further investigations are required to elucidate the role of nal-IRI in this setting and to identify subgroups of patients who could derive the greatest benefit from its administration.