The rise of cyclin-dependent kinase (CDK)4/6 inhibitors has rapidly reshaped treatment algorithms for hormone receptor (HR)-positive metastatic breast cancer, with endocrine treatment (ET) plus a CDK4/6-inhibitor currently representing the standard of care in the first line setting. However, treatment selection for those patients experiencing progression while on ET + CDK4/6-inhibitors remains challenging due to the suboptimal activity or significant toxicities of the currently available options. There is also a paucity of data regarding the efficacy of older regimens, such as everolimus + exemestane, post-CDK4/6 inhibition. In this setting of high unmet need, several clinical trials of novel drugs have recently reported encouraging results: the addition of the AKT-inhibitor capivasertib to fulvestrant demonstrated a significant improvement in progression-free survival (PFS); the oral selective estrogen receptor degrader (SERD) elacestrant prolonged PFS compared to traditional ET in a phase 3 trial, particularly among patients with detectable ESR1 mutations; finally, PARP inhibitors are available treatment options for patients with pathogenic BRCA1/2 germline mutations. Overall, a plethora of novel endocrine and biologic treatment options are finally filling the gap between first-line ET and later line chemotherapy. In this review article, we recapitulate the activity of these novel treatment options and their potential role in future treatment algorithms.

The treatment landscape for EGFR-mutated metastatic non-small cell lung cancer (mNSCLC) has evolved significantly with multiple combination regimens demonstrating superiority over single agent Osimertinib over the past two years. Recent trials such as FLAURA2 and MARIPOSA have explored intensified front-line regimens, with FLAURA2 demonstrating improvement in PFS with the addition of chemotherapy to Osimertinib and MARIPOSA, showing both a PFS and OS benefit with a novel combination regimen of Amivantamab and Lazertinib. However, these regimens are associated with significantly higher toxicity to patients and pose a huge financial and logistical burden to the health care system; therefore, treatment selection must therefore be individualized, considering disease biology, patient fitness, and toxicity burden. Post-progression strategies remain challenging due to resistance mechanisms like EGFR C797S mutations and MET amplification and the lack of data post-progression on novel first-line combinations. Ongoing trials are investigating fourth-generation EGFR TKIs, MET inhibitors, antibody–drug conjugates, and bispecific antibodies in subsequent lines. While regimens like Amivantamab-Lazertinib show promise even in second-line settings, toxicity, cost, and access remain barriers. As therapeutic options expand, biomarker-driven sequencing and personalized care will be critical to optimizing long-term outcomes in EGFR-mutated mNSCLC.

The treatment landscape for EGFR-mutated metastatic non-small cell lung cancer (mNSCLC) has evolved significantly with multiple combination regimens demonstrating superiority over single agent Osimertinib over the past two years. Recent trials such as FLAURA2 and MARIPOSA have explored intensified frontline regimens with FLAURA2 demonstrating improvement in PFS with addition of chemotherapy to Osimertinib and MARIPOSA showing both a PFS and OS benefit with a novel combination regimen of Amivantamab and Lazertinib. However, these regimens are associated with significantly higher toxicity to patients and pose a huge financial and logistical burden to the health care system, therefore, treatment selection must therefore be individualized, considering disease biology, patient fitness, and toxicity burden. Post-progression strategies remain challenging due to resistance mechanisms like EGFR C797S mutations and MET amplification and lack of data post progression on novel 1st line combinations. Ongoing trials are investigating fourth-generation EGFR TKIs, MET inhibitors, antibody-drug conjugates, and bispecific antibodies in subsequent lines. While regimen like Amivantamab-Lazertinib show promise even in second-line settings, toxicity, cost, and access remain barriers. As therapeutic options expand, biomarker-driven sequencing and personalized care will be critical to optimizing long-term outcomes in EGFR-mutated mNSCLC.

Background: The use of cyclin-dependent kinase 4/6 inhibitors (CDK 4/6i) with endocrine therapy (ET) is a first-line standard treatment for hormone receptor-positive (ER+) Human Epidermal Growth factor Receptor-2-negative (HER2-) advanced breast cancer. The data supporting incorporation of CDK 4/6i + ET beyond progression are variable. Here, we report a pooled analysis of this strategy. Methods: A systematic review identified reports of both observational and clinical studies, which evaluated the continuation of CDK4/6i beyond progression. The mean overall response rate (ORR) and progression-free survival (PFS) weighted by the study sample size were calculated. Meta-regression comprising linear regression weighted by the sample size (mixed effects) was performed to explore the association between disease and treatment-related factors and the benefit from continuing CDK4/6i. Quantitative significance was assessed using the Burnand criteria. Results: Thirteen studies comprising 1530 patients were included. The median age was 58 years, 50.8% had visceral metastases, and 48% had ESR1 mutations; the median lines of prior therapies were 1 (range 1–5), and 96.3% received palbociclib as the initial CDK4/6i. Eight studies tested a CDK4/6i switch as the intervention. The median PFS was 5.3 months, and the ORR was 14%. In randomized studies, statistically significant differences were observed between CDK4/6i continuation and control, although it is uncertain whether the magnitude of the effect is clinically meaningful. Increasing age, lack of prior chemotherapy, no visceral metastasis or ESR1 mutations, and a switch to a non-palbociclib CDK4/6i were associated with better outcomes. Conclusion: Continuing a CDK 4/6i + ET beyond progression yields modest benefits. Switching CDK4/6i likely results in improved ORR and PFS. Continuing palbociclib beyond progression is likely ineffectual.

Background: (Neo)adjuvant systemic treatments aim to improve overall survival by reducing recurrence risk; however, there can be challenges, such as reliance on surrogate endpoints, censoring, loss to follow-up, and impact on quality of life. We examine the design, reporting, and outcomes of US Food and Drug Administration–approved drugs for solid tumors. Methods: We searched Food and Drug Administration (neo)adjuvant approvals for solid tumors 2010-2023 with time-to-event endpoints. Trial characteristics, endpoints, and censoring were evaluated descriptively. Statistical designs and sample size calculations were assessed for reproducibility and transparency. Results: A total of 24 studies supporting 25 approvals met inclusion criteria. Common tumor types included melanoma (7 of 24, 29%), breast (6 of 24, 25%), and non-small cell lung cancer (6 of 24, 25%). Among 21 trials reporting overall survival, 52% (11 of 21) showed benefit at any time, but only 36% (4 of 11) reported overall survival benefits at the time of approval and/or primary publication. In 21 (88%) trials the expected number of events could be reproduced, in 11 (46%) trials sample size calculations could be attempted (though calculations often differed), and only 14 (58%) stated expected absolute numerical outcomes. Censoring rules were applied inconsistently; only 36% defined rules adequately. Quality-of-life outcomes were reported in 79%, with 31% reporting clinically meaningful declines in one or more domains. Conclusions: (Neo)adjuvant trials often lack transparency in sample size justifications and censoring rules. Approximately half demonstrated an overall survival improvement at any time, and one-third showed a decline in quality of life. Greater standardization in trial designs and reporting is needed to ensure trials align with patient and health-care priorities.