Real-world analysis of teclistamab in 123 RRMM patients from Germany

Teclistamab, a B-cell maturation antigen (BCMA) × CD3 directed bispecific antibody, has shown high response rates and durable remissions in the MAJESTEC-1 trial in patients with relapsed and refractory multiple myeloma (RRMM). We retrospectively assessed efficacy and tolerability in 123 patients treated at 18 different German centers to determine whether outcome is comparable in the real-world setting. Most patients had triple-class (93%) or penta-drug (60%) refractory disease, 37% of patients had received BCMA-directed pretreatment including idecabtagene vicleucel (ide-cel) CAR-T cell therapy (21/123, 17.1%). With a follow-up of 5.5 months, we observed an overall response rate (ORR) of 59.3% and a median progression-free survival (PFS) of 8.7 months. In subgroup analyses, we found significantly lower ORR and median PFS in patients with extramedullary disease (37%/2.1 months), and/or an ISS of 3 (37%/1.3 months), and ide-cel pretreated patients (33%/1.8 months). Nonetheless, the duration of response in ide-cel pretreated patients was comparable to that of anti-BCMA naive patients. Infections and grade ≥3 cytopenias were the most frequent adverse events. In summary, we found that teclistamab exhibited a comparable efficacy and safety profile in the real-world setting as in the pivotal trial.

Multi-parametric whole-body MRI evaluation discerns vital from non-vital multiple myeloma lesions as validated by 18F-FDG and 11C-methionine PET/CT

PURPOSE

We tested a novel multi-parametric (mp) whole body (WB)-MRI evaluation algorithm for medullary lesions in comparison to positron emission tomography (PET) radiotracers ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and ¹¹C-methionine (¹¹C-MET).

METHODS AND MATERIALS

This retrospective single-center study included 44 MM patients, who received both ¹⁸F-FDG-PET and WB-MRI within ten days. MRI classified focal lesions as vital when showing 1) significant diffusion-restriction, 2) a fat fraction (FF) less than 20 % and 3) homogenous hypointensity on T2-weighted images. On a lesion-by-lesion level the findings were compared to ¹⁸F-FDG PET by using a 5-point scoring system (analogous to the Deauville score [DS]). In 24/44 (55 %) patients additional comparison to ¹¹C-MET PET was available.

RESULTS

Among two radiologists, an excellent inter-observer reliability for mpWB-MRI in a total of 84 medullary lesions was observed (ICC = 1, k = 1, p <.01). 16/17 (94.1 %) MRI-classified vital lesions had a DS of 4 or 5 on either ¹⁸F-FDG-PET or ¹¹C-MET-PET. MRI-rated non-vital lesions correlated with PET-based DS ≤ 3. When results of mpWB-MRI were compared to ¹⁸F-FDG, a fair inter-observer agreement was recorded (ICC = 0.52, k = 0.53, p <.01), while for ¹¹C-MET, an excellent concordance rate was achieved (ICC = 0.81, k = 0.79, p <.01).

CONCLUSION

The proposed mpWB-MRI interpretation algorithm allowed to assess tumor activity of myeloma lesions with high inter-observer reproducibility. We observed a substantial concordance between the mpWB-MRI classification of lesions and PET assessment based on a semi-automatically calculated 5-point scoring system analogous to the Deauville scores.

Panel sequencing for clinically oriented variant screening and copy number detection in 142 untreated multiple myeloma patients

We employed a customized Multiple Myeloma (MM)-specific Mutation Panel (M³P) to screen a homogenous cohort of 142 untreated MM patients for relevant mutations in a selection of disease-specific genes. M³Pv2.0 includes 77 genes selected for being either actionable targets, potentially related to drug–response or part of known key pathways in MM biology. We identified mutations in potentially actionable genes in 49% of patients and provided prognostic evidence of STAT3 mutations. This panel may serve as a practical alternative to more comprehensive sequencing approaches, providing genomic information in a timely and cost-effective manner, thus allowing clinically oriented variant screening in MM.

Whole genome analyses of a well-differentiated liposarcoma reveals novel SYT1 and DDR2 rearrangements

Liposarcoma is the most common soft tissue sarcoma, but little is known about the genomic basis of this disease. Given the low cell content of this tumor type, we utilized flow cytometry to isolate the diploid normal and aneuploid tumor populations from a well-differentiated liposarcoma prior to array comparative genomic hybridization and whole genome sequencing. This work revealed massive highly focal amplifications throughout the aneuploid tumor genome including MDM2, a gene that has previously been found to be amplified in well-differentiated liposarcoma. Structural analysis revealed massive rearrangement of chromosome 12 and 11 gene fusions, some of which may be part of double minute chromosomes commonly present in well-differentiated liposarcoma. We identified a hotspot of genomic instability localized to a region of chromosome 12 that includes a highly conserved, putative L1 retrotransposon element, LOC100507498 which resides within a gene cluster (NAV3, SYT1, PAWR) where 6 of the 11 fusion events occurred. Interestingly, a potential gene fusion was also identified in amplified DDR2, which is a potential therapeutic target of kinase inhibitors such as dastinib, that are not routinely used in the treatment of patients with liposarcoma. Furthermore, 7 somatic, damaging single nucleotide variants have also been identified, including D125N in the PTPRQ protein. In conclusion, this work is the first to report the entire genome of a well-differentiated liposarcoma with novel chromosomal rearrangements associated with amplification of therapeutically targetable genes such as MDM2 and DDR2.

Genome-wide studies in multiple myeloma identify XPO1/CRM1 as a critical target validated using the selective nuclear export inhibitor KPT-276

RNA interference screening identified XPO1 (exportin 1) among the 55 most vulnerable targets in multiple myeloma (MM). XPO1 encodes CRM1, a nuclear export protein. XPO1 expression increases with MM disease progression. Patients with MM have a higher expression of XPO1 compared with normal plasma cells (P<0.04) and to patients with monoclonal gammopathy of undetermined significance/smoldering MM (P<0.0001). The highest XPO1 level was found in human MM cell lines (HMCLs). A selective inhibitor of nuclear export compound KPT-276 specifically and irreversibly inhibits the nuclear export function of XPO1. The viability of 12 HMCLs treated with KTP-276 was significantly reduced. KPT-276 also actively induced apoptosis in primary MM patient samples. In gene expression analyses, two genes of probable relevance were dysregulated by KPT-276: cell division cycle 25 homolog A (CDC25A) and bromodomain-containing protein 4 (BRD4), both of which are associated with c-MYC pathway. Western blotting and reverse transcription-PCR confirm that c-MYC, CDC25A and BRD4 are all downregulated after treatment with KPT-276. KPT-276 reduced monoclonal spikes in the Vk*MYC transgenic MM mouse model, and inhibited tumor growth in a xenograft MM mouse model. A phase I clinical trial of an analog of KPT-276 is ongoing in hematological malignancies including MM.

The clinical significance of cereblon expression in multiple myeloma

Cereblon (CRBN) mediates immunomodulatory drug (IMiD) action in multiple myeloma (MM). We demonstrate here that no patient with very low CRBN expression responded to IMiD plus dexamethasone therapy. In 53 refractory MM patients treated with pomalidomide and dexamethasone, CRBN levels predict for decreased response rates and significant differences in PFS (3.0 vs. 8.9 months, p<0.001) and OS (9.1 vs. 27.2 months, p=0.01) (lowest quartile vs. highest three quartiles). While higher CRBN levels can serve as a surrogate for low risk disease, our study demonstrates that low CRBN expression can predict resistance to IMiD monotherapy and is a predictive biomarker for survival outcomes.

Molecular mechanism of action of immune-modulatory drugs thalidomide, lenalidomide and pomalidomide in multiple myeloma

Although several mechanisms have been proposed to explain the activity of thalidomide, lenalidomide and pomalidomide in multiple myeloma (MM), including demonstrable anti-angiogenic, anti-proliferative and immunomodulatory effects, the precise cellular targets and molecular mechanisms have only recently become clear. A landmark study recently identified cereblon (CRBN) as a primary target of thalidomide teratogenicity. Subsequently it was demonstrated that CRBN is also required for the anti-myeloma activity of thalidomide and related drugs, the so-called immune-modulatory drugs (IMiDs). Low CRBN expression was found to correlate with drug resistance in MM cell lines and primary MM cells. One of the downstream targets of CRBN identified is interferon regulatory factor 4 (IRF4), which is critical for myeloma cell survival and is down-regulated by IMiD treatment. CRBN is also implicated in several effects of IMiDs, such as down-regulation of tumor necrosis factor-α (TNF-α) and T cell immunomodulatory activity, demonstrating that the pleotropic actions of the IMiDs are initiated by binding to CRBN. Future dissection of CRBN downstream signaling will help to delineate the underlying mechanisms for IMiD action and eventually lead to development of new drugs with more specific anti-myeloma activities. It may also provide a biomarker to predict IMiD response and resistance.