Subgroup analyses in randomized phase III trials of systemic treatments in patients with advanced solid tumours: a systematic review of trials published between 2017 and 2020

BACKGROUND

Subgroup analyses of randomized controlled trials are very common in oncology; nevertheless, the methodological approach has not been systematically evaluated. The present analysis was conducted with the aim of describing the prevalence and methodological characteristics of the subgroup analyses in randomized controlled trials in patients with advanced cancer.

METHODS

A systematic literature search using PubMed was carried out to identify all phase III randomized controlled trials conducted in adult patients affected by locally advanced or metastatic solid tumours, published between 2017 and 2020.

RESULTS

Overall, 253 publications were identified. Subgroup analyses were reported in 217 (86%) publications. A statistically significant association of presence of subgroup analysis with study sponsor was observed: subgroup analyses were reported in 157 (94%) for-profit trials compared with 60 (70%) non-profit trials (P < 0.001). Description of the methodology of subgroup analysis was completely lacking in 82 trials (38%), only cited without methodological details in 100 trials (46%) and fully described in 35 trials (16%). Forest plot of subgroup analyses for the primary endpoint was available in 195 publications (77%). Among publications with reported forest plots, the median number of subgroups for primary endpoint was 19 (range 6-78). Out of the 217 publications with subgroup analyses, authors discuss the heterogeneity of treatment effect among different subgroups in 173 publications (80%), although a formal test for interaction for subgroup analysis of primary endpoint was reported for at least one variable only in 60 publications (28%). Correction for multiplicity was explicitly carried out only in nine trials (4%).

CONCLUSIONS

The very high prevalence of subgroup analyses in published papers, together with their methodological weaknesses, makes advisable an adequate education about their correct presentation and correct reading. More attention about proper planning and conduction of subgroup analysis should be paid not only by readers, but also by authors, journal editors and reviewers.

Chemotherapy toxicity and activity in patients with pancreatic ductal adenocarcinoma and germline BRCA1-2 pathogenic variants (gBRCA1-2pv): a multicenter survey

BACKGROUND

Germline BRCA1-2 pathogenic variants (gBRCA1-2pv)-related pancreatic ductal adenocarcinoma (PDAC) showed increased sensitivity to DNA cross-linking agents. This study aimed at exploring safety profile, dose intensity, and activity of different chemotherapy regimens in this setting.

PATIENTS AND METHODS

gBRCA1-2pv PDAC patients of any age and clinical tumor stage who completed a first course of chemotherapy were eligible. A descriptive analysis of chemotherapy toxicity, dose intensity, response, and survival outcomes was performed.

RESULTS

A total of 85 gBRCA1-2pv PDAC patients treated in 21 Italian centers between December 2008 and March 2021were enrolled. Seventy-four patients were assessable for toxicity and dose intensity, 83 for outcome. Dose intensity was as follows: nab-paclitaxel 72%, gemcitabine 76% (AG); cisplatin 75%, nab-paclitaxel 73%, capecitabine 73%, and gemcitabine 65% (PAXG); fluorouracil 35%, irinotecan 58%, and oxaliplatin 64% (FOLFIRINOX). When compared with the literature, grade 3-4 neutropenia, thrombocytopenia, and diarrhea were increased with PAXG, and unmodified with AG and FOLFIRINOX. RECIST responses were numerically higher with the three- (81%) or four-drug (73%) platinum-containing regimens that outperformed AG (41%) and oxaliplatin-based doublets (56%). Carbohydrate antigen 19.9 (CA19.9) reduction >89% at nadir was reported in two-third of metastatic patients treated with triplets and quadruplets, as opposed to 33% and 45% of patients receiving oxaliplatin-based doublets or AG, respectively. All patients receiving AG experienced disease progression, with a median progression-free survival (mPFS) of 6.4 months, while patients treated with platinum-containing triplets or quadruplets had an mPFS >10.8 months. Albeit still immature, data on overall survival seemed to parallel those on PFS.

CONCLUSIONS

Our data, as opposed to figures expected from the literature, highlighted that platinum-based regimens provoked an increased toxicity on proliferating cells, when dose intensity was maintained, or an as-expected toxicity, when dose intensity was reduced, while no change in toxicity and dose intensity was evident with AG. Furthermore, an apparently improved outcome of platinum-based triplets or quadruplets over other regimens was observed.

Germinal BRCA1-2 pathogenic variants (gBRCA1-2pv) and pancreatic cancer: epidemiology of an Italian patient cohort

OBJECTIVE

Germline BRCA1-2 pathogenic variants (gBRCApv) increase the risk of pancreatic cancer and predict for response to platinating agents and poly(ADP-ribose) polymerase inhibitors. Data on worldwide gBRCApv incidence among pancreatic ductal adenocarcinoma (PDAC) patients are sparse and describe a remarkable geographic heterogeneity. The aim of this study is to analyze the epidemiology of gBRCApv in Italian patients.

MATERIALS AND METHODS

Patients of any age with pancreatic adenocarcinoma, screened within 3 months from diagnosis for gBRCApv in Italian oncologic centers systematically performing tests without any selection. For the purposes of our analysis, breast, ovarian, pancreas, and prostate cancer in a patient's family history was considered as potentially BRCA-associated. Patients or disease characteristics were examined using the χ2 test or Fisher's exact test for qualitative variables and the Student's t-test or Mann-Whitney test for continuous variables, as appropriate.

RESULTS

Between June 2015 and May 2020, 939 patients were tested by 14 Italian centers; 492 (52%) males, median age 62 years (range 28-87), 569 (61%) metastatic, 273 (29%) with a family history of potentially BRCA-associated cancers. gBRCA1-2pv were found in 76 patients (8.1%; 9.1% in metastatic; 6.4% in non-metastatic). The gBRCA2/gBRCA1 ratio was 5.4 : 1. Patients with gBRCApv were younger compared with wild-type (59 versus 62 years, P = 0.01). The gBRCApv rate was 17.1% among patients <40 years old, 10.4% among patients 41-50 years old, 9.2% among patients 51-60 years old, 6.7% among patients aged 61-70 years, and 6.2% among patients >70 years old (none out of 94 patients >73 years old). gBRCApv frequency in 845 patients <74 years old was 9%. Patients with/without a family history of potentially BRCA-associated tumors had 14%/6% mutations.

CONCLUSION

Based on our findings of a gBRCApv incidence higher than expected in a real-life series of Italian patients with incident PDAC, we recommend screening all PDAC patients <74 years old, regardless of family history and stage, due to the therapeutic implications and cancer risk prevention in patients' relatives.

Survival and glial fate acquisition of neural crest cells are regulated by an interplay between the transcription factor Sox10 and extrinsic combinatorial signaling

The transcription factor Sox10 is required for proper development of various neural crest-derived cell types. Several lineages including melanocytes, autonomic and enteric neurons, and all subtypes of peripheral glia are missing in mice homozygous for Sox10 mutations. Moreover, haploinsufficiency of Sox10 results in neural crest defects that cause Waardenburg/Hirschsprung disease in humans. We provide evidence that the cellular basis to these phenotypes is likely to be a requirement for Sox10 by neural crest stem cells before lineage segregation. Cell death is increased in undifferentiated, postmigratory neural crest cells that lack Sox10, suggesting a role of Sox10 in the survival of neural crest cells. This function is mediated by neuregulin, which acts as a survival signal for postmigratory neural crest cells in a Sox10-dependent manner. Furthermore, Sox10 is required for glial fate acquisition, as the surviving mutant neural crest cells are unable to adopt a glial fate when challenged with different gliogenic conditions. In Sox10 heterozygous mutant neural crest cells, survival appears to be normal, while fate specifications are drastically affected. Thereby, the fate chosen by a mutant neural crest cell is context dependent. Our data indicate that combinatorial signaling by Sox10, extracellular factors such as neuregulin 1, and local cell-cell interactions is involved in fine-tuning lineage decisions by neural crest stem cells. Failures in fate decision processes might thus contribute to the etiology of Waardenburg/Hirschsprung disease.

The Ets domain transcription factor Erm distinguishes rat satellite glia from Schwann cells and is regulated in satellite cells by neuregulin signaling

Distinct glial cell types of the vertebrate peripheral nervous system (PNS) are derived from the neural crest. Here we show that the expression of the Ets domain transcription factor Erm distinguishes satellite glia from Schwann cells beginning early in rat PNS development. In developing dorsal root ganglia (DRG), Erm is present both in presumptive satellite glia and in neurons. In contrast, Erm is not detectable at any developmental stage in Schwann cells in peripheral nerves. In addition, Erm is downregulated in DRG-derived glia adopting Schwann cell traits in culture. Thus, Erm is the first described transcription factor expressed in satellite glia but not in Schwann cells. In culture, the Neuregulin1 (NRG1) isoform GGF2 maintains Erm expression in presumptive satellite cells and reinduces Erm expression in DRG-derived glia but not in Schwann cells from sciatic nerve. These data demonstrate that there are intrinsic differences between these glial subtypes in their response to NRG1 signaling. In neural crest cultures, Erm-positive progenitor cells give rise to two distinct glial subtypes: Erm-positive, Oct-6-negative satellite glia in response to GGF2, and Erm-negative, Oct-6-positive Schwann cells in the presence of serum and the adenylate cyclase activator forskolin. Thus, Erm-positive neural crest-derived progenitor cells and presumptive satellite glia are able to acquire Schwann cell features. Given the in vivo expression of Erm in peripheral ganglia, we suggest that ganglionic Erm-positive cells may be precursors of Schwann cells.

Embryonic gene expression resolved at the cellular level by fluorescence in situ hybridization

Tyramide signal amplification has successfully been applied to enhance detection limits of both immunological reactions and in situ hybridization methods. The technique uses short-range deposition of activated tyramide mediated by horseradish peroxidase. We have adapted this method to fluorescence in situ hybridization on embryonic tissue sections using fluorophore-labeled tyramide. The sensitivity of the procedure was sufficient to analyze the embryonic expression of mRNAs encoding both transcription factors and structural proteins. Combining fluorescence in situ hybridization and immunofluorescence with confocal microscopy allows the simultaneous detection of distinct mRNA species or of mRNAs together with proteins on the cellular level. Thus, the cell types expressing a particular gene at a given developmental stage can be studied even if no antibody to the gene product of interest is available. Moreover, the technique allows to study in situ the combinatorial marker expression that characterizes progenitor stages of a given cell lineage.