CDK4 mutation

We achieved a remarkable response in the metastatic lesions with minor toxicity issues. This case highlights the importance of utilizing up-to-date therapeutic agents and reactive decision-making during personalized cancer treatment.

No recurrence was observed during the follow-up period of 8 months. This study aims to improve our understanding of PF by analyzing the clinicopathological characteristics of this case, including immunohistochemical (IHC) and genetic examination, and reviewing relevant literature.

CDK4 high-level copy number increase coexists with other pathogenic mutations in AM. CDK4 appears to be a promising target for AM treatment and is expected to be combined with other targeted therapies.

Estrogen receptor one (ESR1) gene mutations, driving resistance to aromatase inhibitors (AIs), may guide the use of fulvestrant or emerging oral selective estrogen receptor degraders (SERDs) like elacestrant. Targeting mutations like breast cancer gene 1 and 2 (BRCA 1/2) with Poly (ADP-ribose) polymerase (PARP) inhibitors or the PI3K/AKT/mTOR pathway provides therapeutic options. The advent of antibody-drug conjugates (ADCs) like trastuzumab deruxtecan (T-DXd) and novel agents targeting Trophoblast cell surface antigen-2 (Trop-2) introduces further complexity, underscoring the need for early intervention targeting specific genomic alterations in metastatic BC.

For patients whose disease progressed on a prior CDK4/6i, we demonstrated comparable median TTFs for patients rechallenged with the same CDK4/6i (4.3 months, 95%CI 3.2-5.5) and with a different CDK4/6i (4.7 months, 95%CI 3.7-6.0) when compared to the recent PACE, PALMIRA, and MAINTAIN trials. Exploratory genomic analysis suggested that the presence of mutations known to confer CDK4/6i resistance, such as TP53 mutations, CDK4 amplifications, and RB1 or FAT1 loss of function mutations may be molecular biomarkers predictive of CDK4/6i retrial failure.

In sum, there is strong evidence that GBMs acquire novel mutations to survive outside the CNS. In some cases, tumor cells likely mutate after seeding scalp tissue during surgery, and in others, they mutate and spread without surgery. Future studies and genetic profiling of primary and metastatic lesions may help uncover the mechanisms of spread.

Our findings support that targeting PLK1 and PI3Kα with onvansertib and alpelisib, respectively, may be a promising strategy for patients with PIK3CA-mutant HR+ breast cancer failing ET + CDK4/6i therapies and warrant clinical evaluation.

THCQ and TP are not effective in patients with advanced PDAC harboring KRAS mutations or alterations in MAPK/CDKN2A/B.

P2, N=124, Recruiting, Alliance for Clinical Trials in Oncology | Trial completion date: Oct 2024 --> Jan 2028 | Trial primary completion date: Oct 2024 --> Jan 2026

These findings suggest an alternative therapeutic strategy using sequential targeting of HRD in g BRCA- associated breast cancers through PARP inhibitors prior to CDK4/6i therapy to intercept deleterious RB1 -loss trajectories and thus suppress the emergence of CDK4/6 inhibitor resistance. More broadly, our findings demonstrate how germline-somatic driven genomic configurations shape response to systemic therapy and can be exploited therapeutically as part of biomarker-directed clinical strategies.

Preliminary results of the MatchMel study revealed a variety of molecular mutations in WT melanoma pts. NF1 alterations appeared to be linked with Hi-TMB, which was associated with response to immunotherapy.

The primary endpoint is distant metastasis free survival and secondary endpoints are invasive disease-free survival, relapse-free survival, overall survival, safety and quality of life. Recruitment started in December 2023 in Belgium and is planned to open in 11 more countries in 2024: Cyprus, France, Germany, Greece, Italy, Ireland, the Netherlands, Portugal, Spain, Sweden, and Switzerland.

In our practice, a significant proportion of patients were prescreened with a smaller NGS panel. Despite this fact, we still found actionable alterations in 23,8% of the patients, which is in line with those reported in the literature (22-61%). Our results demonstrate that CGP can provide useful additional information and can be beneficial in the clinical management of patients with mesenchymal tumours.

No abstract available

Clinical trials are needed to determine the mechanism behind this finding and its clinical utility. In conclusion, our results demonstrate autophagy inhibitor combined targeting MEK and CDK4/6 that concurrently block multiple metabolic processes may be an effective therapeutic approach for gastric cancer.

IDH-mutant gliomas with deletion of CDKN2A/B are sensitized to CDK4/6 inhibitors. These results support investigation of the use of these agents in a clinical setting.

P3, N=240, Not yet recruiting, MedSIR

Mutations in ESR1 and in PI3K pathway genes at T0 were associated with worse prognosis in palbociclib-treated patients. We describe the emergence of newly acquired mutations in palbociclib-treated patients, which might potentially affect subsequent treatment.

Tumors with PIK3CA mutation found in either tumor and/or plasma are candidates for PI3K inhibitor (eg. Alpelisib) by applying PCR based method- or sequencing...Another recent phase lll trial randomizing patients to switch to fulvestrant + CDK4/6i from aromatase inhibitor + CDK4/6i at time of plasma ESR1 mutation positive or stay on AI + CDK4/6i, reported longer progression survival for early switch to fulvestrant...AKT inhibitor (eg.Capivasertib) has recently been approved for patients with PI3K/AKT/PTEN pathway alteration including PTEN loss, AKT activating mutation and the renown PI3KCA mutations...While liquid biopsy technology holds promise for both advanced and early breast cancers for its ability to potentially identify patients and guide decisions, it is crucial to select appropriate method for each clinical setting and purposes. With limited number of studies investigating the relevant correlation/comparison between each methods and pipelines, clinicians should bear in mind to deeply understand each methodology selected for each clinical trials before bringing them into real patients.

Overall, in our uLMS analysis, CDK4 and/or MDM2 amplification was identified in a small subset (2%) of uLMS, the majority of which are TP53/RB1-wildtype. This may suggest that CDK4/MDM2 amplification can be an alternative tumorigenic mechanism in this distinct class of uLMS, which may have therapeutic clinical implications, including possible use of specific cyclin-dependent kinase inhibitors.

Overall, in our uLMS analysis, CDK4 and/or MDM2 amplification was identified in a small subset (2%) of uLMS, the majority of which are TP53/RB1-wildtype. This may suggest that CDK4/MDM2 amplification can be an alternative tumorigenic mechanism in this distinct class of uLMS, which may have therapeutic clinical implications, including possible use of specific cyclin-dependent kinase inhibitors.

Our observations suggest that F3T3-positive GBM is a distinct molecular subgroup of the IDH-wildtype GBM. Both clinicians and pathologists should consider this rare entity in the differential diagnosis of diffuse astrocytic glioma to make an accurate diagnosis and to ensure appropriate therapeutic management.

P=N/A, N=550, Recruiting, Oxford University Hospitals NHS Trust | Trial completion date: Aug 2025 --> Feb 2026 | Trial primary completion date: Aug 2023 --> Feb 2024

Lasofoxifene plus abemaciclib had an acceptable safety profile, was well tolerated, and exhibited meaningful antitumor activity in women with ESR1-mutated, ER+/HER2- mBC after disease progression on prior CDK4/6i. Observed decreases in ESR1-mutant ctDNA with lasofoxifene concordant with clinical response suggest target engagement. If the ELAINE 2 findings are confirmed in the initiated, phase III, ELAINE 3 trial, these data could be practice-changing and help address a critical unmet need.

Our comprehensive analysis is the first to show distinct mutational profiles according to TP53 mut status, and differential expression of immune-related genes and TME cell infiltration independent of TP53 mut in CDK4/6 high vs low dMMR/MSI-H CRC. In our series, CDK6 expression correlated with ICI treatment benefit in TP53 mut tumors, warranting further studies to explore the potential of targeting the CDK4/6 axis to enhance ICI efficacy in CRC.

Further inhibition of phosphorylated RB with cyclin-dependent kinase (CDK) 4/6 inhibitors, combined with the EGFR-TKI osimertinib, enhanced G0/G1 cell cycle accumulation and growth inhibition of the EGFR-mutant NSCLC in both in vitro and in vivo models...Our study demonstrated that the CDK4/6-RB signal axis, maintained by the MAPK pathway, attenuates the efficacy of EGFR-TKIs in EGFR-mutant NSCLC, and targeting CDK4/6 enhances this efficacy. Thus, combining CDK4/6 inhibitors and EGFR-TKI could be a novel treatment strategy for TKI-naïve EGFR-mutant NSCLC.

These studies identified the epigenetic cause of obese-pregnancy associated liver diseases and suggest a potential therapy based on inhibition of cdk4-ph-S193-C/EBPα-p300 pathway.

A novel disulfide bond in cyclin D-CDK4 acts as a rapid switch to inhibit kinase activity and halt cell proliferation. This oxidative modification forms at a critical cysteine residue, which is unique to CDK4, offering the potential for the design of a selective covalent inhibitor predicted to be beneficial in PH.

Our trial demonstrates activity of alpelisib in patients with PIK3CA mutated advanced breast cancer in later lines of treatment after treatment with CDK4/6 inhibitors with a clinical benefit rate of 26.3%. Discontinuation of therapy due to toxicity was seen in only 8% of patients, although toxicity induced dose reduction was needed in 29% of patients. These findings support the results of the BYLieve trial and additionally show efficacy of alpelisib in later lines of treatment for hormone receptor-positive advanced breast cancer.

The genomic landscape of progressive disease after CDK4/6i exposure is significantly different from the genomic alterations detectable in treatment-naïve pts, which could potential impact future treatment strategies for patients with disease progression after adjuvant CDK4/6i exposure. Our data suggest that the choice of second-line treatment could potentially be guided by the identification of actionable mutation by ctDNA, although further prospective studies are needed to validate the clinical utility of this approach.

In this trial, we investigate talazoparib and atezolizumab combination compared with talazoparib monotherapy in premenopausal women with HR+/HER2- metastatic breast cancer with HRD-scar after failure with 1st line palbociclib and endocrine treatment combination. A total of 178 subjects are required to detect hazard ratio of 0.62 (median PFS2 of at least 10.5 months with talazoparib and atezolizumab combination vs 6.5 months with talazoparib alone), to achieve 80% power at a two-sided a significance level at 10%, considering drop-out rate of 5%. The study period is expected to be 72 months overall(36 months for accrual and randomization and 24 months of follow-up for primary endpoint PFS2).

Selective estrogen receptor downregulator (SERD) such as elacestrant or fulvestrant is suggested as second-line treatment, but the progression-free survival (PFS) outcome of second-line treatment is reported up to 3.78 months in patients who harbour ESR1 mutation...If patients received adjuvant tamoxifen, patients with TFI less than 12 months can be also enrolled for the study...Secondary endpoint included PFS, overall survival (OS), emergence and frequency of ESR1 mutation, overall response rate (ORR) and clinical benefit rate (CBR). The analysis is planned after completion of 30 months of follow-up, which provides approximately 90% power to detect superiority 24 months-PFS rate assumed by Kaplan-Meier curve of letrozole + fulvestrant + ribociclib versus letrozole + ribociclib using a log-rank test, assuming a hazard ratio of 0.64 at a two-sided alpha of 0.2.

When treated with palbociclib + fulvestrant or palbociclib + estrogen-free medium (mimicking estrogen suppression in patients treated with aromatase inhibitors), cells harboring the Y537S and D538G mutations displayed an 11.2 to 46.9-fold increase in the IC50 of palbociclib. ESR1 mutations are enriched following treatment with CDK4/6i in a cohort of 3,958 patients with ER+/HER2- metastatic breast cancer. Mutations in ESR1 in ER+ breast cancer cells directly promote resistance to CDK4/6i alone or CDK4/6i + antiestrogens in vitro and in vivo.

We demonstrate the synergistic effects of WEE1 inhibitor (MK1775/AZD1775) and PKMYT1 inhibitor (RP6306) in a panel of TNBC and ER+ve breast cancer cells with acquired palbociclib resistance (PalboR). Overall, this study highlights the potential therapeutic benefits of dual inhibition of WEE1 and PKMYT1 in overcoming CDK4/6 inhibitor resistance in TNBC and ER+ve breast cancer patients. These findings provide a rationale for future clinical trials aimed at exploring the clinical utility of this combination therapy.

Of the 29 patients (median age 60 yrs) enrolled, mutations in ESR1 were identified in 26 by Guardant360; all these 26 patients had received prior CDK4/6i, 21 (81%) prior fulvestrant, and 12 (46%) prior chemotherapy for mBC. Using Guardant360 ctDNA profiling from patients in ELAINE 2, we demonstrate that other baseline genomic alterations are frequently detected concurrently with mESR1 in the endocrine resistant setting, but without apparent compromise on the efficacy of LAS plus Abema. These results should be interpreted with caution considering the small numbers of patients and the exploratory nature of the analysis. The ELAINE 2 study suggests the potential of LAS plus Abema for treating ESR1-mutated, ER+/HER2- mBC in the post-CDK4/6i setting.

COP/FUL/intermittent ABE can be safely administered with fair overall tolerability. Preliminary anti-tumor activity was observed, which will be further examined in the randomized phase II trial (NCT 03939897). Table 1 Dose-limiting Toxicities by Dose Level

Conclusions The PACE trial offers one of the largest clinical trial cohorts describing the genomic landscape of HR+/HER2- MBC post-CDK4/6 exposure. Results from this correlative study provide a comprehensive mutational landscape post-CDK4/6i, demonstrate associations between mutations and clinical outcomes, and suggest the potential value of early ctDNA dynamics in this setting.

Prior fulvestrant (FUL) was received by 53% of patients in the GIR + INAVO arm (n = 8). Safety summary Data are % of patients. AE, adverse event; GIR, giredestrant; INAVO, inavolisib; TRAE, treatment-related adverse event; tx, treatment.

MCF7 wild-type (WT) and two NF1-knockout (KO) clones were treated with palbociclib ± estrogen deprivation, followed by cell viability assays... Using multicenter clinical and real-world evidence, we demonstrate that NF1-MUT is associated with inferior duration and worse outcomes on CDK4/6i in MBC. Pts with baseline pNF1-MUT on 1L CDK4/6i and endocrine therapy had a median PFS below typical responses expected in clinical practice. A link between NF1 loss and CDK4/6i resistance was supported by in vitro experiments in HR+ breast cancer cells.

P2, N=324, Recruiting, Royal Marsden NHS Foundation Trust | Trial completion date: Aug 2024 --> Sep 2026 | Trial primary completion date: Aug 2023 --> Sep 2026