First Line Metastatic Pancreatic Cancer : 5FU/LV+Nal-IRI, Gemcitabine+Nab-paclitaxel or a Sequential Regimen of 2 Months 5FU/LV+Nal-IRI

Pancreatic cancer (PC) is the seventh cause from cancer and the fifth cause from cancer-related death in Europe. Nearly as many deaths occur from PC than the number of new cases diagnosed each year, reflecting the poor prognosis typically associated with this disease. PC is insidious in onset and is often diagnosed late at the stage of metastatic spread. In spite of advances made in the management of other more common gastrointestinal cancers, the treatment of PC did take only a small advantage of recent progresses in gastrointestinal oncology and targeted therapies did not significantly modify its prognosis to date.

Thus, for more than 10 years, gemcitabine has been the standard of care to treat metastatic PC. Recently, two positive phase III trials in metastatic PC were reported.

First, the gemcitabine with nab-paclitaxel combination therapy was compared to gemcitabine alone in 861 randomized patients with metastatic PC. Results showed a significant improvement in response rate (RR), progression free survival (PFS) and overall survival (OS). Second, the results of the PRODIGE 4/ACCORD 11 trial testing the FOLFIRINOX regimen in metastatic PC patients, finally gave a hope showing a major improvement in PFS and OS as compared to gemcitabine. However, though manageable, the safety profiles of FOLFIRINOX and of gemcitabine plus nab-paclitaxel were less favourable than that of gemcitabine. These regimens were associated with a higher incidence of grade 3-4 neutropenia, febrile neutropenia, thrombocytopenia, diarrhoea, and grade 2-3 sensory neuropathy.

Irinotecan has a stronger growth-inhibiting effect than cisplatin, mitomycin C and fluorouracil on cultured pancreatic adenocarcinoma cells. In most trials testing this molecule in PC patients, however, the response rates were low (<10%) and survivals were poor. Intensive regimens with irinotecan and 5-FU have been developed in colorectal cancer patients to increase the anti-tumor effects of this combination therapy. From those, the FOLFIRI.3, in which the irinotecan is administered before and after a 5-FU 46h continuous infusion gave promising results. The investigator has tested this regimen in a phase II trial in advanced PC patients, with an objective RR of 37.5%, a median OS time of 12 months and acceptable tolerability. Considering these encouraging results the investigator has proposed a new approach to improve outcomes for patients with metastatic PC, using FOLFIRI.3 and gemcitabine alone, sequentially, to increase patient survival with a preserved quality of life (QOL). Indeed, some authors have reported that the administration of different patterns of sequential polychemotherapy was independently associated with OS in patients with PC and other gastrointestinal tumors such as metastatic colorectal cancer. Such strategies using drugs without cross-resistance sequentially may increase anti-tumor effects and limit cumulative and non-cumulative toxicities.

The investigator thus performed a randomized multicentre phase II trial to assess this sequential treatment strategy using FOLFIRI.3 and gemcitabine alternately in one arm and gemcitabine alone in the other arm, in patients with metastatic non pre-treated pancreatic adenocarcinoma. In this study the FIRGEM strategy seems to be an effective first line treatment option in good condition patients with metastatic PC. The primary endpoint was reached with a rate of PFS at 6 months of 44.9% in the FIRGEM arm while gemcitabine alone failed (25.7%). This good PFS rate at 6 months was maintained at 12 and 18 months (26.2% and 18% respectively) though median PFS was 5.0 months. Moreover, an impressive objective response rate was observed in the FIRGEM arm (40%) as compared to the gemcitabine arm (11.4%). These results confirm those of the initial phase II trial evaluating the FOLFIRI.3 regimen (37.5% objective response rate)(15) in PC patients and compare favourably with the 31.6% and 23% reported in the two trials evaluating FOLFIRINOX and gemcitabine + nab-paclitaxel, respectively.

Median overall survival was 11 months with FIRGEM versus 8.2 months with gemcitabine (HR:0.710 95% CI: 0.457-1.103). Here again the experimental arm gave good results, with median OS in the range of those reported with FOLFIRINOX (11.1 months). The safety profile of the FIRGEM strategy showed that hematological and GI toxicities were more important than with gemcitabine alone. Interestingly no limiting sensory neuropathy was observed with our treatment schedule and a significant increase in the time to definitive deterioration of the QoL was observed in the FIRGEM group as compared with the gemcitabine group. This effect was observed for all domains.

Considering that nab-paclitaxel improves significantly patients outcome in metastatic PC when combined to gemcitabine, the addition of this drug to the FIRGEM strategy may be of particular interest. And the PRODIGE 37 trial tested this combination in a randomized phase II trial recently closed for inclusions. This trial allowed to fight the cancer with 4 different drugs, without any cross resistance described between them, given sequentially in the first 4 months of treatment. Moreover, the "resting period" without nab-paclitaxel may delay significantly the occurrence of the cumulative neuropathy induced by this molecule and optimised its used with such a "stop and go" like strategy. Results are awaited for early 2018.

More recently a liposomal irinotecan has been developed and tested in pancreatic cancer patients, it comprises irinotecan free base encapsulated in liposome nanoparticles, which keep irinotecan into the circulation sheltered from conversion to its active metabolite (SN-38) longer and use local macrophage-mediated activation, which would increase and prolong intratumoral levels of both irinotecan and SN-38. In a phase II study of 40 patients with MPA previously treated with gemcitabine-based therapy, monotherapy with nal-IRI resulted in a median overall survival of 5.2 months, and a manageable toxicity profile. The NAPOLI-1 phase III trial was then conducted, comparing three arms of chemotherapy in patients previously treated with gemcitabine-based therapy: liposomal irinotecan (MM-398 or nal-IRI) alone or combined with 5FU and folinic acid, and 5FU and folinic acid alone. Combination of nal-IRI and 5FU/LV was more effective than 5FU alone or Nal-IRI alone (median OS of 6.1 vs. 4.2 and 4.9 months respectively (HR: 0.67; p=0.012). Increased hematologic and GI toxicities were also seen in the Nal-IRI arms but were manageable. Nal-IRI plus 5FU and folinic acid extends survival in patients with metastatic pancreatic ductal adenocarcinoma who previously received gemcitabine-based therapy. In a setting where there is a paucity of second line treatment option, this combination is an important emerging treatment option for metastatic adenocarcinoma of the pancreas.

Considering all these data, the investigator proposes to run a randomized phase II trial testing the standard continuous Gemcitabine + Nab-paclitaxel schedule vs Nal-IRI+5FU/LV vs Nal-IRI+5FU/LV for two months followed by Gemcitabine + Nab-paclitaxel for two months before starting again Nal-IRI. This will allow i) to generate efficacy and tolerability data on the Nal-IRI/5FU combination in the first line setting, ii) to test a new sequential strategy with Nal-IRI , in regards of the interesting results obtained in second and third line pancreatic cancer treatment, iii) to control our results in the experimental arms with one of the two first line worldwide standard regimen: Gemcitabine + Nab-paclitaxel.