Abstract 901P
Background
Poorly differentiated neuroendocrine carcinomas (PD NEC) are rare and carry a poor prognosis. Some studies suggest cisplatin (Cis) is more appropriate for younger patients (pts) due to its increased potency and risk of nephrotoxicity compared to carboplatin (Car). We aim to determine whether there is a difference in outcomes for Cis vs Car by retrospectively analyzing treated pts and adjusting for possible confounding factors.
Methods
We identified extrapulmonary PD NEC pts seen at Mayo Clinic between 2000-2022 who received Cis or Car plus etoposide as first line therapy. Kaplan-Meier analysis determined median overall survival (OS) and progression free survival (PFS). Disease control rate (DCR) was the percentage of pts with complete/partial response or stable disease at first assessment. Univariate analysis was conducted with a Cox proportional hazards model.
Results
We identified 25 pts who received Cis/etoposide and 25 pts who received Car/etoposide. Baseline characteristics are in the table. The median follow-up from diagnosis was 20.2 months (m) (95% CI: 6.2-NA) for the entire group. The median PFS was 5.8 m in the Cis group (95% CI: 5.0-NA) vs 4.8 m in the Car group (95% CI: 3.2-11.1; p value 0.69). The median OS was 12.4 m in the Cis group (95% CI 9.6-NA) vs 13.4 m in the Car group (95% CI: 9.1-NA; p value 0.45). DCR was 84% in the Cis group vs 68% in the Car group (p value 0.01). Twelve pts (48%) died in the Cis group and 9 pts (36%) died in the Car group (p value 0.11). In univariate analysis, median OS when accounting for age, creatinine (Cr), and male sex, were not statistically significant between groups. Table: 901P
Baseline characteristics
| Cisplatin Group (n=25) | Carboplatin Group (n=25) | p value | |
| Male, n (%) | 14 (56%) | 19 (76%) | 0.23 |
| Age (years), median (range) | 59 (21-84) | 65 (31-86) | 0.20 |
| Stage 3-4, n (%) | 22 (88%) | 25 (100%) | 0.23 |
| Primary Tumor, n (%) | |||
| Gastrointestinal | 5 (20%) | 6 (24%) | |
| Head & Neck | 4 (16%) | 2 (8%) | |
| Colorectal | 8 (32%) | 5 (20%) | |
| Unknown/Other | 3 (12%) | 6 (24%) | |
| Pancreas | 2 (8%) | 6 (24%) | |
| Genitourinary | 2 (8%) | 0 (0%) | |
| Gynecologic | 1 (4%) | 0 (0%) | |
| Morphology, n (%) | |||
| Large cell | 6 (24%) | 8 (32%) | |
| Small cell | 8 (32%) | 3 (12%) | |
| Nonspecified | 11 (44%) | 14 (56%) | |
| Ki67, median (range) | 80 (30-99) | 70 (35-90) | 0.43 |
| Cr, median (range) | 0.8 (0.6-1.8) | 0.9 (0.6-2.2) | 0.51 |
Conclusions
Extrapulmonary PD NEC remains an aggressive disease with poor outcomes. In this study, Cis was associated with a favorable DCR which was statistically significant. Comparing Cis vs Car, no statistically significant difference was seen in median PFS or OS. With adjustment for age, Cr, and sex, median OS was not significantly different between groups.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
J.S. Starr: Financial Interests, Advisory Role: Tersera, Ipsen, Advanced Accelerated Applications, Taiho, Helsinn Therapeutics, Pfizer, Natera, Tempus. T.R. Halfdanarson: Financial Interests, Advisory Board: Tersera, Lexicon, Terumo, Curium, Ipsen, TM Isotopen Technologien Muenchen, Crinetics, Viewpoint Molecular Targeting; Financial Interests, Other, Research support: Basilea, Turnstone Biologics, Advanced Accelerator Applications, Thermo Fisher Scientific, Agios; Non-Financial Interests, Leadership Role: North American Neuroendocrine Tumor Society (NANETS). All other authors have declared no conflicts of interest.