Outcome of cutaneous squamous cell carcinoma with microscopic residual disease after surgery and usefulness of postoperative radiotherapy: a retrospective cohort study.

BACKGROUND: Microscopic residual disease (MRD) after surgery can be a challenging situation in cutaneous squamous cell carcinoma (CSCC) and there is a lack of evidence concerning its management. OBJECTIVE: To evaluate the prognosis of CSCC with MRD and the usefulness of postoperative radiotherapy (PORT) in CSCC with MRD. METHODS: Retrospective cohort study of CSCC with MRD through a 10-year period (2010-2019) (n = 244). Disease-free survival and event-free survival were assessed using R (v.3.4.1), considering competing risks. Evaluated outcomes were local recurrence (LR), nodal metastases (NMs), and disease-specific death (DSD). RESULTS: Median age was 88y (IQR: 10.5). A total of 145 (59.43%) were men and 69 (28.28%) were immunosuppressed. Median tumour diameter and thickness were 19 and 6.4 mm (IQR 11 and 5.5 mm). Patients treated by re-excision had a relapse rate of 4.3% compared with 11.30% and 29.71% in those who received PORT and observation (P = 0.045). The use of PORT was associated with a lower risk of LR compared with observation (HR = 0.206 [0.049-0.859], P = 0.030), but not with a lower risk of NMs or DSDs. In the multivariable models, PORT was again associated with a lower risk of LR than observation (HR = 0.167 [0.039-0.708], P = 0.014), but not with lower risk of metastasis and death. CONCLUSIONS: We always should try to obtain clear margins after surgery. PORT improves local control in CSCC with MRD, but when administered to the tumour bed, it does not reduce the risk of NM and DSD.

Postoperative radiotherapy provides better local control and long-term outcome in selective cases of cutaneous squamous cell carcinoma with perineural invasion.

BACKGROUND: Perineural invasion (PNI) is a feature of poor prognosis in cutaneous squamous cell carcinoma (CSCC). The benefit of postoperative radiotherapy (PORT) in the management of CSCC with PNI is still not well established. OBJECTIVES: We aimed to evaluate the usefulness of PORT in the treatment of CSCC with PNI so as to determine which patients would best benefit from this type of treatment. METHODS: A retrospective multicenter cohort of 110 CSCCs with PNI was evaluated. Eighteen recurrent cases were excluded for subsequent analysis. We searched for the types of PNI associated with poor outcome and analysed the effectiveness of PORT on different groups of CSCC with PNI. We also assessed for the usefulness of PORT depending on the surgical margin status (either clear or positive). RESULTS: Postoperative radiotherapy showed clear benefit over observation in CSCC with PNI and positive margins after surgery, where the management by observation increased the risk of poor outcome events 2.43 times (P = 0.025), and especially in those with positive margins and PNI ≥0.1 mm, where the risk of poor prognosis is eight times greater following a management by observation (P = 0.0065). Multivariate competing risk analysis preserved statistical significance. CONCLUSIONS: The use of PORT on patients with CSCC with PNI and positive margins after surgery, especially in PNI ≥0.1 mm, significantly improves long-term outcome. The benefit of PORT in cases with clear margins is not as evident, especially in those with PNI of small-calibre nerves. Clinical trials are imperative.

In vivo murine model of acquired resistance in myeloma reveals differential mechanisms for lenalidomide and pomalidomide in combination with dexamethasone.

The development of resistance to therapy is unavoidable in the history of multiple myeloma patients. Therefore, the study of its characteristics and mechanisms is critical in the search for novel therapeutic approaches to overcome it. This effort is hampered by the absence of appropriate preclinical models, especially those mimicking acquired resistance. Here we present an in vivo model of acquired resistance based on the continuous treatment of mice bearing subcutaneous MM1S plasmacytomas. Xenografts acquired resistance to two generations of immunomodulatory drugs (IMiDs; lenalidomide and pomalidomide) in combination with dexamethasone, that was reversible after a wash-out period. Furthermore, lenalidomide-dexamethasone (LD) or pomalidomide-dexamethasone (PD) did not display cross-resistance, which could be due to the differential requirements of the key target Cereblon and its substrates Aiolos and Ikaros observed in cells resistant to each combination. Differential gene expression profiles of LD and PD could also explain the absence of cross-resistance. Onset of resistance to both combinations was accompanied by upregulation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK pathway and addition of selumetinib, a small-molecule MEK inhibitor, could resensitize resistant cells. Our results provide insights into the mechanisms of acquired resistance to LD and PD combinations and offer possible therapeutic approaches to addressing IMiD resistance in the clinic.

Phenotypic identification of subclones in multiple myeloma with different chemoresistant, cytogenetic and clonogenic potential.

Knowledge about clonal diversity and selection is critical to understand multiple myeloma (MM) pathogenesis, chemoresistance and progression. If targeted therapy becomes reality, identification and monitoring of intraclonal plasma cell (PC) heterogeneity would become increasingly demanded. Here we investigated the kinetics of intraclonal heterogeneity among 116 MM patients using 23-marker multidimensional flow cytometry (MFC) and principal component analysis, at diagnosis and during minimal residual disease (MRD) monitoring. Distinct phenotypic subclones were observed in 35/116 (30%) newly diagnosed MM patients. In 10/35 patients, persistent MRD was detected after 9 induction cycles, and longitudinal comparison of patient-paired diagnostic vs MRD samples unraveled phenotypic clonal tiding after therapy in half (5/10) of the patients. After demonstrating selection of distinct phenotypic subsets by therapeutic pressure, we investigated whether distinct fluorescence-activated cell-sorted PC subclones had different clonogenic and cytogenetic profiles. In half (5/10) of the patients analyzed, distinct phenotypic subclones showed different clonogenic potential when co-cultured with stromal cells, and in 6/11 cases distinct phenotypic subclones displayed unique cytogenetic profiles by interphase fluorescence in situ hybridization, including selective del(17p13). Collectively, we unravel potential therapeutic selection of preexisting diagnostic phenotypic subclones during MRD monitoring; because phenotypically distinct PCs may show different clonogenic and cytogenetic profiles, identification and follow-up of unique phenotypic-genetic myeloma PC subclones may become relevant for tailored therapy.

SNP-based mapping arrays reveal high genomic complexity in monoclonal gammopathies, from MGUS to myeloma status.

Genetic events mediating transformation from premalignant monoclonal gammopathies (MG) to multiple myeloma (MM) are unknown. To obtain a comprehensive genomic profile of MG from the early to late stages, we performed high-resolution analysis of purified plasma cells from 20 MGUS, 20 smoldering MM (SMM) and 34 MM by high-density 6.0 SNP array. A progressive increase in the incidence of copy number abnormalities (CNA) from MGUS to SMM and to MM (median 5, 7.5 and 12 per case, respectively) was observed (P=0.006). Gains on 1q, 3p, 6p, 9p, 11q, 19p, 19q and 21q along with 1p, 16q and 22q deletions were significantly less frequent in MGUS than in MM. Although 11q and 21q gains together with 16q and 22q deletions were apparently exclusive of MM status, we observed that these abnormalities were also present in minor subclones in MGUS. Overall, a total of 65 copy number-neutral LOH (CNN-LOH) were detected. Their frequency was higher in active MM than in the asymptomatic entities (P=0.047). A strong association between genetic lesions and fragile sites was also detected. In summary, our study shows an increasing genomic complexity from MGUS to MM and identifies new chromosomal regions involved in CNA and CNN-LOH.