Adcitmer® , a new CD56-targeting monomethyl auristatin E-conjugated antibody, is a potential therapeutic approach in Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive skin cancer, whose tumour cells often express CD56. While immune checkpoint inhibitors constitute a major advance for treating patients with MCC with advanced disease, new therapeutic options are still urgently required.

OBJECTIVES

To produce and evaluate the therapeutic performance of a new antibody-drug conjugate (Adcitmer^® ) targeting CD56 in preclinical models of MCC.

METHODS

CD56 expression was evaluated in a MCC cohort (immunohistochemistry on a tissue microarray of 90 tumour samples) and MCC cell lines. Interaction of an unconjugated CD56-targeting antibody with CD56⁺ MCC cell lines was investigated by immunohistochemistry and imaging flow cytometry. Adcitmer^® product was generated by the bioconjugation of CD56-targeting antibody to a cytotoxic drug (monomethyl auristatin E) using the McSAF Inside^® bioconjugation process. The chemical properties and homogeneity of Adcitmer^® were characterized by hydrophobic interaction chromatography. Adcitmer^® cytotoxicity was evaluated in vitro and in an MCC xenograft mice model.

RESULTS

Similar to previous reports, CD56 was expressed by 66% of MCC tumours in our cohort, confirming its relevance as a therapeutic target. Specific binding and internalization of the unconjugated CD56-targeting antibody was validated in MCC cell lines. The high homogeneity of the newly generated Adcitmer^® was confirmed by hydrophobic interaction chromatography. The CD56-mediated cytotoxicity of Adcitmer^® was demonstrated in vitro in MCC cell lines. Moreover, Adcitmer^® significantly reduced tumour growth in a MCC mouse model.

CONCLUSIONS

Our study suggests that Adcitmer^® should be further assessed as a therapeutic option in patients with MCC, as an alternative therapy or combined with immune checkpoint inhibitors.

[Penis fracture]

Fracture of the penis is a rare condition caused by blunt trauma to the erect penis resulting in tearing of the tunica albuginea. The injury occurs mainly during sexual intercourse or as a result of forceful manipulation. Two cases are described. Diagnosis is based on the patient's narrative and the clinical findings. One patient was treated by immediate surgery, while the other was treated by corrective surgery for his disabling posttraumatic penile deformity. Based on available literature and our own observations we recommend immediate surgical repair in order to avoid serious complications.

Energy cost during ambulation in transfemoral amputees: a knee joint with a mechanical swing phase control vs a knee joint with a pneumatic swing phase control

The aim of the study was (i) to evaluate the preference of transfemoral amputees for a 4-bar linked knee joint with either a mechanical swing phase control or a pneumatic swing phase control, and (ii) to compare the energy expenditure in transfemoral amputees using a prosthesis with a mechanical swing phase control with that of the same amputees using a prosthesis with a pneumatic swing phase control. The study included 28 unilateral transfemoral amputees amputated for reasons other than chronic vascular disease. All patients had a prosthesis with a knee joint with mechanical swing phase control (the Otto Bock 3R20) before entering the study. The amputees changed their knee joint to one with pneumatic swing phase control (the Tehlin knee joint) at random either after the first or second assessment. The amputees were asked for their preference at the second and third assessments. The energy expenditure while walking at speeds of 2 and 3 km/h was measured at each assessment. After having tried both knee joints, 19 patients preferred the Tehlin knee, 6 patients preferred the Otto Bock 3R20, and 3 patients had no preference. The energy expenditure measurement showed that walking with the Tehlin knee required more energy than walking with Otto Bock 3R20. Because of the limited number of patients included in the study and the fact that a double-blind design was impossible to achieve, conclusions should be drawn with caution.

The gait of unilateral transfemoral amputees

The aim of this study was to describe the gait of persons with a unilateral transfemoral amputation by means of a questionnaire, gait analysis and measurement of energy expenditure, and to find correlations among the variables studied. The study included 29 transfemoral amputees amputated for other reasons than a chronic vascular disease. The patients were assessed using the following methods: 1) A questionnaire rating the walking distance and walking difficulty in different circumstances. 2) Gait analysis measuring temporal variables and goniometry of hips and knees. 3) Measurement of energy expenditure during sitting and walking. Scores on the questionnaire showed a correlation with socket design, a negative correlation with age and energy expenditure, and a positive correlation with fast speed. The gait of transfemoral amputees was asymmetrical as far as temporal variables were concerned, and for most amputees also for the range of motion of hip and knee. The walking speed of the amputees was lower than that of non-amputees and showed a positive correlation with hip extension-flexion range of motion and a negative correlation with age and stride time. The energy expenditure of the amputees during ambulation was higher than that of non-amputees, and seemed to correlate with residual limb length and the hip abduction-adduction range of motion.