◥Purpose: Lorlatinib is a third-generation anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor with proven efficacy in patients with ALK-rearranged lung cancer previously treated with firstand second-generation ALK inhibitors. Beside compound mutations in the ALK kinase domain, other resistance mechanisms driving lorlatinib resistance remain unknown. We aimed to characterize the mechanisms of resistance to lorlatinib occurring in patients with ALK-rearranged lung cancer and design new therapeutic strategies in this setting.Experimental Design: Resistance mechanisms were investigated in 5 patients resistant to lorlatinib. Longitudinal tumor biopsies were studied using high-throughput next-generation sequencing. Patient-derived models were developed to characterize the acquired resistance mechanisms, and Ba/F3 cell mutants were generated to study the effect of novel ALK compound mutations. Drug combi-natory strategies were evaluated in vitro and in vivo to overcome lorlatinib resistance.Results: Diverse biological mechanisms leading to lorlatinib resistance were identified. Epithelial-mesenchymal transition (EMT) mediated resistance in two patient-derived cell lines and was susceptible to dual SRC and ALK inhibition. We characterized three ALK kinase domain compound mutations occurring in patients, L1196M/D1203N, F1174L/G1202R, and C1156Y/ G1269A, with differential susceptibility to ALK inhibition by lorlatinib. We identified a novel bypass mechanism of resistance caused by NF2 loss-of-function mutations, conferring sensitivity to treatment with mTOR inhibitors.Conclusions: This study shows that mechanisms of resistance to lorlatinib are diverse and complex, requiring new therapeutic strategies to tailor treatment upon disease progression.

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Breast cancers over-express the human epidermal growth factor receptor 2 (HER2) in about 15% of patients. This transmembrane tyrosine kinase receptor activates downstream signaling pathways and leads to proliferation of cancer cells. Trastuzumab, an anti-HER2 monoclonal antibody, improves outcome in women with early and metastatic breast cancer. Resistance to trastuzumab involves the phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) pathway, truncation of the Her2 receptor or lack of immune response. The last decade has seen major advances in strategies to overcome resistance to trastuzumab. This includes the development of antibody-drug conjugates, dual HER2 inhibition strategies, inhibition of PI3K/mTOR pathway and development of modulators of immune checkpoints.

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Key Points Question Is there a role for platinum-based treatment in molecularly selected patients with advanced prostate cancer? Findings In a case series of 508 patients, platinum-based therapy was associated with antitumor activity, especially among patients with known DNA repair gene aberrations. In patients with DNA repair gene aberrations, nearly half had a decrease in prostate-specific antigen levels of at least 50% and experienced soft tissue responses. Meaning In patients with prostate cancer and DNA repair gene aberrations, platinum-based therapy may be considered a treatment option.

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BackgroundProstate cancer is one of the most common cancers in men and the fourth leading cause of cancer mortality worldwide. Although major progress has been achieved in the last years for patients with metastatic castrate-resistant prostate cancer (mCRPC), thanks to next-generation androgen receptor axis targeted drugs, taxanes, and bone-targeted agents, immunotherapy has not been widely approved and used for the treatment of prostate cancer. Two large studies with ipilimumab, an anti-CTLA-4 (cytotoxic T-lymphocyte antigen 4) antibody reported improved progression-free survival, but not statistically improved overall survival at the primary analysis (CA184 043 and CA184 095).Case presentationHere, we report on two patients who received ipilimumab in these trials and are still in long-term complete remission with a follow-up of 64 and 52 months respectively after the initiation of ipilimumab. Immunohistochemical staining for hMLH1, hMSH2, hMSH6 and PMS2 was performed on archival prostate biopsy samples from one of the two patients; they exhibited normal protein expression. Interestingly for this patient, a high CD3+ and CD8+ T cell infiltration was observed on archival prostate biopsies as well as Treg FoxP3+ T cells.ConclusionIpilimumab produces clinical activity in patients with CRPC, including very long responders with no detectable residual disease.

Background: Baseline steroids before ICI have been associated with poor outcomes, particularly when introduced due to cancer symptoms. Methods: Retrospective analysis of advanced NSCLC patients treated with ICI. We collected the use of intercurrent steroids (≥10 mg of prednisone-equivalent) within the first eight weeks of ICI. We correlated steroid use with patient outcomes according to the indications. Results: 413 patients received ICI, 299 were steroids-naïve at baseline. A total of 49 patients received intercurrent steroids (16%), of whom 38 for cancer-related symptoms and 11 for other indications, such as immune-related events. Overall, median (m) progression-free survival (PFS) was 1.9 months (mo.) [95% CI, 1.8-2.4] and overall survival (OS) 10 mo. [95% CI, 8.1–12.9]. Intercurrent steroids under ICI correlated with a shorter PFS/OS (1.3 and 2.3 mo. respectively, both p < 0.0001). Intercurrent steroids for cancer-related symptoms correlated with poorest mPFS [1.1 mo.; 95% CI, 0.9–1.5] and mOS [1.9 mo.; 95%CI, 1.5–2.4; p < 0.0001)]. No mOS and mPFS differences were found between cancer-unrelated-steroid group and no-steroid group. Steroid use for cancer-related symptoms was an independent prognostic factor for poor PFS [HR 2.64; 95% CI, 1.2–5.6] and OS [HR 4.53; 95% CI, 1.8–11.1], both p < 0.0001. Conclusion: Intercurrent steroids during ICI had no detrimental prognostic impact if the indication was unrelated to cancer symptoms.