Image_1_PSMA-Specific CAR-Engineered T Cells for Prostate Cancer: CD28 Outperforms Combined CD28-4-1BB “Super-Stimulation”.jpeg

Prostate cancer (PCa) is the second leading cause of malignancy-related mortality in males in the Western world. Although treatment like prostatectomy and radiotherapy for localized cancer have good results, similar positive outcomes are not achieved in metastatic PCa. Consequently, these aggressive and metastatic forms of PCa urgently need new methods of treatment. We already described an efficient and specific second-generation (2G) Chimeric Antigen Receptor (CAR) against Prostate Specific Membrane Antigen (PSMA), a glycoprotein overexpressed in prostate cancer and also present on neovasculature of several tumor entities. In an attempt to improve efficacy and in vivo survival of anti-PSMA 2G CAR-T cells, we developed a third generation (3G) CAR containing two costimulatory elements, namely CD28 and 4-1BB co-signaling domains, in addition to CD3ζ. Differently from what described for other 3G receptors, our third generation CAR disclosed an antitumor activity in vitro similar to the related 2G CAR that comprises the CD28 co-signaling domain only. Moreover, the additional costimulatory domain produced detrimental effects, which could be attributed to an increased activation-induced cell death (AICD). Indeed, such “superstimulation” resulted in an exhausted phenotype of CAR-T cells, after prolonged in vitro restimulation, a higher frequency of cell death, and an impairment in yielding sufficient numbers of transgenic T lymphocytes. Thus, the optimal combination of costimulatory domains for CAR development should be assessed cautiously and evaluated case-by-case.</p

[^99mTc][Tc(N)PNP43]-Labeled RGD Peptides As New Probes for a Selective Detection of αvβ₃ Integrin: Synthesis, Structure–Activity and Pharmacokinetic Studies

New integrin-selective molecules suitable for therapeutic or imaging purposes are currently of interest in development of effective personalized medical platforms. RGDechi is a bifunctional peptide selective for integrin αvβ3. Herein, RGDechi and three truncated derivatives functionalized with a cysteine (1–4) were synthesized and labeled with the [99mTc]­[Tc­(N)­PNP43]-synthon ([PNP43 = (CH3)2P­(CH2)2N­(C2H4OCH3)­(CH2)2P­(CH3)2]) (99mTc1–4) as a basis for selective integrin recognition. The pharmacological parameters of all radiolabeled peptides were assessed along with the pharmacokinetic profiles of the most promising 99mTc1 and 99mTc2 compounds both on healthy and melanoma-bearing mice. Their metabolism and metabolite identification are also reported. 99mTc1–2 are able to discriminate between endogenously expressed integrins αvβ3 and αvβ5 and possess favorable pharmacokinetics characterized by low liver uptake and rapid elimination from nontarget tissues resulting in positive target-to-nontarget ratios. Results are encouraging; the presented construct can be considered the starting point for the development of agents for the selective detection of αvβ3 expression by SPECT