Real-world treatment outcomes in HR+ HER2- metastatic breast cancer patients treated with CDK4/6 inhibitors: Results from a reference center in Brazil

BACKGROUND

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) have been recently developed and introduced into clinical practice.

METHODS

We retrospectively analyzed data from patients with confirmed HR+/HER2 metastatic breast cancer treated with hormonal therapy in combination with ribociclib (R), palbociclib (P), or abemaciclib (A).

OUTCOMES

median progression-free survival (mPFS), time to treatment discontinuation (mTTD), and objective response rate (ORR).

RESULTS

Between January 2016 - June 2021, 142 patients were treated with an CDK4/6i (79 P, 42 R, 21 A). The median age was 59 years and 67.6% had recurrent disease. Roughly 35.2%, 36.6%, 28.2% of the patients had 1, 2 or 3+ metastatic sites, respectively, and 55.6% of the patients received CDK4/6i as a first-line treatment. The mPFS was 28m(R) vs. 14m(P) vs. 6m(A) (P = 0.002), with a higher proportion of patients receiving R in the first-line setting. However, no difference was seen when the analysis was restricted to the first-line scenario (P = 0.193). Sixty-four patients required one dose reduction, and 19 patients required two. ORR was 76.2% (R) vs 62% (P) vs 42.9% (A). More patients achieved a complete response with R and P, with no difference in the incidence of partial response and stable disease. Adverse events occurred in 94.4% of the population, with the most common grade 3-4 AE being neutropenia (59.1%).

CONCLUSIONS

Our results confirm the efficacy and tolerability of CDK4/6i in routine clinical practice. This is the first real-world data describing and comparing the efficacy and toxicity of CDK4/6i in the Brazilian population.

Genomic and biological study of fusion genes as resistance mechanisms to EGFR inhibitors

The clinical significance of gene fusions detected by DNA-based next generation sequencing remains unclear as resistance mechanisms to EGFR tyrosine kinase inhibitors in EGFR mutant non-small cell lung cancer. By studying EGFR inhibitor-resistant patients treated with a combination of an EGFR inhibitor and a drug targeting the putative resistance-causing fusion oncogene, we identify patients who benefit and those who do not from this treatment approach. Through evaluation including RNA-seq of potential drug resistance-imparting fusion oncogenes in 504 patients with EGFR mutant lung cancer, we identify only a minority of them as functional, potentially capable of imparting EGFR inhibitor resistance. We further functionally validate fusion oncogenes in vitro using CRISPR-based editing of EGFR mutant cell lines and use these models to identify known and unknown drug resistance mechanisms to combination therapies. Collectively, our results partially reveal the complex nature of fusion oncogenes as potential drug resistance mechanisms and highlight approaches that can be undertaken to determine their functional significance.

Unique SLC12A2-ROS1 fusion is associated with marked response to crizotinib in lung adenocarcinoma

Chromosomal rearrangements involving the c-ros oncogene 1 (ROS1) gene define a subset of non-small cell lung cancers highly sensitive to small-molecule tyrosine kinase inhibitors. However, little is known about the impact of different fusion partners on tyrosine kinase inhibitor efficacy. We herein describe a case of a 26-year-old never-smoker patient from southern Africa with metastatic lung adenocarcinoma driven by SLC12A2-ROS1 fusion, who had a pronounced and durable response to crizotinib. The present case underscores the importance of pursuing actionable alterations in patients with similar clinical and epidemiological characteristics. In addition, provides the second report of crizotinib activity against lung malignancies harboring the unique SLC12A2-ROS1 fusion and highlights the importance of a deeper understanding of molecular alterations in underrepresented subgroups of patients to tailor the decision-making in daily practice.

Phase III randomized clinical trials global distribution and funding: Trends and disparities

e18563

Background: Phase III clinical trials (PIIICT) constitute the cornerstone of the progress and development of new therapeutic strategies. However, their complexity and costs in a scenario of limited funding sources impose important limitations in their scope and reach. Methods: We searched in clinicaltrials.gov to identify PIIICT evaluating pharmacological interventions in adjuvant, neoadjuvant and metastatic settings between 2010-2020 in breast, cervix, colorectal cancer (CRC), lung, melanoma, prostate and penile cancer. Trials identified were categorized according to disease site, funding source and world region/country (R/C). Case incidence in 2020 was collected from the IARC website. Results: Of 825 clinical trials, 72.7% were industry-sponsored (IS). Trials by R/C, not including multicentric studies (61.8%): (A) USA 76 trials, 53.9% non-industry sponsored (NIS); (B) Europe/UK 112, 59.8% NIS; (C) Asia (excluding China) 62, 27.4% NIS and (D) China 183, 43.7% NIS. There was a statistically significant association between location and funding source (p= 0.0003). NIS source was detected in higher proportion of trials ongoing in regions A and B (59%). IS was statistically less frequent in uterine cervix/penis (42.8%) and CRC (49.6%) IS was significantly higher in lung and prostate trials (both 81%) (p<0.0001). Table summarizes our results by tumor sites. We also found a statistically significant association between the incidence of malignancies in the selected primary sites and the amount of registered clinical trials, overall (p<0.0001) and IS as well (p<0.0001). The database is under expansion to include other disease sites as well as other geographic areas separately (Africa, Russia, South America, India, and Oceania). Cervix and penile results were combined given their biological and epidemiological similarities. Conclusions: There is a significant disparity between the number of clinical trials and tumor prevalences as well as among the distribution of IS trials funding.[Table: see text]

[Haemoglobin AIc in patients on venesection therapy for haemochromatosis (author's transl)]

Haemoglobin AIc values measured in diabetic patients with idiopathic haemochromatosis tended to be lower than in diabetics without haemochromatosis. The observed difference was analysed with respect to different parameters related to diabetes or haemochromatosis and their treatment (sex, age, duration of diabetes, insulin-dependency, frequency and volume of blood withdrawn) which could possibly explain these low values. Among the twenty-eight subjects with haemochromatosis, thirty-two non-diabetics, twenty-six insulin-dependent diabetics, and twenty-four non-insulin-treated diabetics, we observed that the more frequently venesection therapy was performed, the lower the levels of haemoglobin HbAIc, HbAIa+b tended to be. Thus, the decreased HbAIc rates observed in haemochromatosis patients may be ascribed to the venesection therapy, which induces an increased turnover of red cells, and consequently a decrease of the time available for their glycosylation.

HLA-A3, B7 linkage disequilibrium in hemochromatotic patients with or without insulin dependent diabetes

Sixty-six idiopathic hemochromatotic French patients were HLA-A, B typed. The previously known strong association with A3 was confirmed (RR = 10.6, P less 10(-9)) and our results indicate clearly that a gene implicated in idiopathic hemochromatosis (IH) determinism is located in the HLA-A region. The linkage disequilibrium between A3 and B7 was found to be far greater in IH patients than in controls. The authors have therefore hypothesized that this might be due to a selective advantage of this haplotype in IH. The A3, B7, Dw2 HLA haplotype has been shown to exert a protective effect against common insulin dependent diabetes (IDD). Thus the patients were divided into two groups according to the presence or absence of a definite IDD. B7 was found more frequently in IH patients without IDD but the difference is not significant. In this context, the strong linkage disequilibrium between A3 and B7 might be due to the protective effect of the B region of this haplotype against IH secondary IDD.

[Idiopathic hemochromatosis linkage with the HLA system (author's transl)]

Fourteen selected families containing two or more subjects suffering from idiopathic hemochromatosis and 34 unrelated cases have been studied for their HLA markers. A 3 was present in 75% of the unrelated cases vs 26% in the normal population (p less than 10(-8)). The frequencies of B 7 (38% vs 19%) and B 14 (23% vs 9%) were also increased (p lessthan 0,05). Inevitably, in most cases both antigens in the B locus were associated with A 3. Seven of nine affected sib pairs shared both HLA haplotypes, while two shared only one. Significant association between HLA haplotypes and diseases segregation has been demonstrated in family studies. These facts are consistent with the recessive inheritance of a strongly A 3 linked "disease" gene responsible for abnormal iron stores in the heterozygote state. This hypothesis would account for 64% of our present cases. Most of discordances (26%) were females who are physiologically protected, or children under 17 who might later develop the disease. The remaining 10% of disordant cases could be explained by crossing-over between "disease" gene and HLA loci or by an heterogeneity of the disease. This provides a method for screening for high risk subjects and perhaps an opportunity for anticipatory prevention.

Idiopathic hemochromatosis: linkage with HLA

Forty-eight unrelated patients with idiopathic hemochromatosis were found to have a significantly higher frequency of three HLA antigens (A3, B7 and B14) than 591 healthy controls. A significant association between HLA haplotypes and disease segregations was demonstrated in 14 family studies. A recessive inheritance of a strongly A3-linked disease gene responsible for abnormal iron stores in the heterozygote state is postulated. The lod score value (4.415 for theta = 0.025) is compatible with this hypothesis. However, the excess of HLA-identical pairs of affected sibs does not exclude the possibility of a pseudo-recessiveness due to two codominant genes both HLA-linked. For the first time, a means of screening for high risk subjects is available and therefore offers the possibility of a preventive approach.

Iron stimulation of ferritin synthesis. II.-Involvement of polysomal kc1 extracts in the mechanism of stimulation

The iron stimulation of ferritin synthesis is a translational phenomenon. Iron acts through a modification of the microsomal apparatus as shown previously. In the present study we have shown that the factor(s) involved in this stimulation are present in the KC1 extracts from polysomes of iron-treated rats.