FL118

Interestingly, although both 7h and SN38 exhibited similar inhibitory effects on Top1 activity, only 7h, and not SN38, could inhibit DDX5. These findings not only pave the way for deeper mechanistic explorations of FL118 and its derivatives in cancer research but also position the identified compound 7h as a promising candidate for further development.

Given that SN38 is the active metabolite of irinotecan, FL118 reduces cell viability and RAD51 in SN38-resistant LOVO cells. Our findings provide effective insights into the antitumor activity of FL118 and its potential as a therapeutic agent for overcoming irinotecan resistance in CRC.

Furthermore, FL118 potently induced apoptosis not only in Ba/F3 cells expressing BCR-ABL, but also in those expressing the BCR-ABL T315I mutant, which is resistant to BCR-ABL inhibitors. Collectively, these results revealed that DDX5 is a critical therapeutic target in CML and that FL118 is an effective candidate compound for the treatment of BCR-ABL inhibitor-resistant CML.

P1, N=84, Not yet recruiting, Roswell Park Cancer Institute | Trial completion date: May 2027 --> Oct 2027 | Initiation date: Apr 2024 --> Oct 2024 | Trial primary completion date: May 2027 --> Oct 2027

P1, N=84, Not yet recruiting, Roswell Park Cancer Institute

We also provide new data showing that FL118, a molecular glue DDX5 degrader, selectively works against current treatment-resistant prostate cancer organoids/cells. Altogether, current studies demonstrate that DDX5 may represent a unique oncotarget for effectively conquering cancer with minimal toxicity to normal tissues.

All the FL118 analogues showed significant cytotoxic activities in vitro with IC values in the nanomolar range and were more potent than topotecan. It is noteworthy that 9c also demonstrated potent inhibition of drug-resistant tumor growth in NCI-H446/Irinotecan and NCI-H446/EP xenograft models, the tumor growth inhibition rates were 93.42% and 84.46%, respectively. Taken together, these findings indicated that compound 9c displays outstanding antitumor activity and drug-resistance in small-cell lung cancer both in vivo and in vitro, which could be worth further research as a novel anti-tumor drug against small-cell lung cancer.

DDX5 is a bona fide FL118 direct target and can act as a biomarker for predicting PDAC and CRC tumour sensitivity to FL118. This would greatly impact FL118 precision medicine for patients with advanced PDAC or advanced CRC in the clinic. FL118 may act as a 'molecular glue degrader' to directly glue DDX5 and ubiquitination regulators together to degrade DDX5.

We then present our data to show the anticancer drug FL118 modulation of these protein targets and RCC cell/tumor growth. Finally, we include additional data to show a promising FL118 analogue (FL496) for treating the specialized type 2 papillary RCC.

Our in vivo studies in animal models further confirmed that SW620 tumors are the most sensitive tumor to FL118 treatment; SNU-C2B tumors are the second most sensitive tumor to FL118 treatment; and the DLD-1 tumors are the least sensitive tumor. These findings would be useful for predicting FL118 sensitivity to patients' CRC tumors with the defined Kras mutation subtypes under the defined p53/APC genetic status.

We have recently shown the strong negative impact of multiple myeloma (MM)-bone marrow mesenchymal stromal cell (BMMSC) interactions to several immunotherapeutic strategies including conventional T cells, chimeric antigen receptor (CAR) T cells, and daratumumab-redirected NK cells...Consistent with our earlier findings, the BMMSCs protected MM cells against KHYG-1 and DR5-agonistic antibodies by inducing resistance mechanisms that were largely abrogated by the small molecule FL118, an inhibitor of multiple antiapoptotic proteins including Survivin, Mcl-1, and XIAP. Importantly, the BMMSC-mediated immune resistance was also significantly diminished by engineering KHYG-1 cells to express the CD38-CAR or the TRAIL-variant. These results emphasize the critical effects of microenvironment-mediated immune resistance on the efficacy of immunotherapy and underscores that this mode of immune escape can be tackled by inhibition of key antiapoptotic molecules or by increasing the overall efficacy of immune killer cells.

These results extend our findings on the negative impact of the microenvironment against immunotherapies and suggests that outcome of CAR T cell or conventional CTL therapies could benefit from inhibition of anti-apoptotic proteins upregulated in MM cells through BMMSC interactions.