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Kaposi's sarcoma (KS) is a multifocal neoplasm of lymphatic endothelium-derived cells infected with human herpesvirus 8. Four clinical subtypes are distinguished: the classic, the endemic, the epidemic subtype in HIV positive patients and the iatrogenic subtype. The diagnosis is primarily based on clinical features and confirmation by histology with immunohistochemistry. Cutaneous distribution and severity, mucosal, nodal and visceral involvement depend on the type of KS with in general indolent behaviour and chronic evolution in the classic subtype and the more severe forms in iatrogenic or epidemic subtypes. Management should aim at achieving disease control. For localised lesions, several local therapies have been developed without randomised trial comparisons. Radiotherapy, intralesional chemotherapies and electrochemotherapy have high response rates. Topical treatmentsdimiquimod or topical 9-cis-retinoid aciddcan also be used. Systemic treatments are reserved for locally aggressive extensive and disseminated KS: the recommended first-line agents are pegylated liposomal doxorubicin (PLD) and paclitaxel. In CKS, PLD or low-dose interferon-alfa are the recommended first-line agents in younger patients. In AIDS-related KS, combination antiretroviral therapy is the first treatment option; specific systemic treatment is needed only in case of extensive disease and in the prevention and treatment of immune reconstitution inflammatory syndrome. In post-transplant KS, tapering down immunosuppressive therapy and switching to mammalian target of rapamycin (m-TOR) inhibitors are used. Follow-up schedules for patients with KS disease depend on aggressiveness of the disease.

Disclosure: Dr. Dingemans has received honoraria for serving on advisory board for BMS, MSD, Roche, Eli Lilly, Takeda, Pfizer, Boehringer Ingelheim (all to her institution) and has received a research grant from BMS (to her institution) outside the submitted work. Dr. Hendriks has received research funding from Roche and Boehringer Ingelheim (both to her institution); received honoraria for serving on advisory boards for Boehringer Ingelheim (to her institution) and BMS (to both her institution and herself); received travel reimbursement from Roche and BMS; participated in a mentorship program with key opinion leaders that was funded by AstraZeneca

Purpose RECIST evaluation does not take into account the pre-treatment tumor kinetics and may provide incomplete information regarding experimental drug activity. Tumor Growth Rate (TGR) allows for a dynamic and quantitative assessment of the tumor kinetics. How TGR varies along the introduction of experimental therapeutics and is associated with outcome in phase I patients remains unknown. Experimental designs Medical records from all patients (n=253) prospectively treated in 20 phase I trials were analyzed. TGR was computed during the pre-treatment period (REFERENCE) and the EXPERIMENTAL period. Associations between TGR, standard prognostic scores (RMH score) and outcome (PFS, OS) were computed (multivariate analysis). Results We observed a reduction of TGR between the REFERENCE vs. EXPERIMENTAL periods (38% vs. 4.4%, P<.00001). Although most patients were classified as stable disease (65%) or progressive disease (25%) by RECIST at the first evaluation, 82% and 65% of them exhibited a decrease in TGR, respectively. In a multivariate analyses, only the decrease of TGR was associated with PFS (P=.004), whereas the RMH score was the only variable associated with OS (P=.0008). Only the investigated regimens delivered were associated with a decrease of TGR (P<.00001, multivariate analysis). Computing TGR profiles across different clinical trials reveals specific patterns of antitumor activity. Conclusions Exploring TGR in phase I patients is simple and provides clinically relevant information: (i) an early and subtle assessment of signs of antitumor activity; (ii) indpendent association with PFS; and (iii) It reveals drug-specific profiles; suggesting potential utility for guiding the further development of the investigational drugs.

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Moderate and severe toxicities occur regularly after the first cycle in phase I trials of MTAs and may deserve increased attention in the RP2D process for these agents.

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Although promising new radiation therapy techniques such as hadrontherapy are currently being evaluated in the treatment of head and neck malignancies, local control of head and neck squamous cell carcinoma (HNSCC) remains low. Here, we investigated the involvement of cancer stem-like cells (CSCs) in a radioresistant HNSCC cell line (SQ20B). Stem-like cells SQ20B/SidePopulation(SP)/CD44(+)/ALDH(high) were more resistant to both photon and carbon ion irradiation compared with non-CSCs. This was confirmed by a BrdU labeling experiment, which suggests that CSCs were able to proliferate and to induce tumorigenicity after irradiation. SQ20B/SP/CD44(+)/ALDH(high) were capable of an extended G2/M arrest phase in response to photon or carbon ion irradiation compared with non-CSCs. Moreover, our data strongly suggest that resistance of CSCs may result from an imbalance between exacerbated self-renewal and proliferative capacities and the decrease in apoptotic cell death triggering. In order to modulate these processes, two targeted pharmacological strategies were tested. Firstly, UCN-01, a checkpoint kinase (Chk1) inhibitor, induced the relapse of G2/M arrest and radiosensitization of SQ20B-CSCs. Secondly, all-trans retinoic acid (ATRA) resulted in an inhibition of ALDH activity, and induction of the differentiation and radiosensitization of SQ20B/SP/CD44(+)/ALDH(high) cells. The combination of ATRA and UCN-01 treatments with irradiation drastically decreased the surviving fraction at 2Gy of SQ20B-CSCs from 0.85 to 0.38 after photon irradiation, and from 0.45 to 0.21 in response to carbon ions. Taken together, our results suggest that the combination of UCN-01 and ATRA represent a promising pharmacological-targeted strategy that significantly sensitizes CSCs to photon or carbon ion radiation.