“Knowledge has a beginning but no end.”
To complement The ASCO Post’s continued comprehensive coverage of the 2020 American Society of Hematology (ASH) Annual Meeting & Exposition, here are three abstracts selected from the meeting proceedings focusing on novel therapies for multiple myeloma. For full details of these study abstracts, visit ashpublications.org.
Syed Ali Abutalib, MD
Kenneth C. Anderson, MD, FASCO
Bortezomib Plus ‘Immunotherapy With a Sting’
ABSTRACT 665: Bortezomib and immunogenic cell death—Bortezomib induces antimyeloma immune response mediated by cyclic GMP‐AMP synthase/stimulator of interferon genes (cGAS/STING) pathway activation, type 1 interferon secretion, and immunogenic cell death: Clinical application.1
Background: Activation of the STING protein by its natural ligand, cyclic guanosine monophosphate–adenosine monophosphate, triggers signaling responses, inducing the release of type I interferons and other proinflammatory cytokines. STING-controlled interferon production is involved in antiviral defense as well as antitumor immunity.2 Immune escape underlies progression of disease and resistance to therapy in myeloma, and dysfunction of both innate and adaptive immunity highlights the urgent need for scientifically informed strategies to restore antimyeloma immunity and improves patient outcome.
Methods and Results: The investigators first showed that bortezomib induces hallmarks of immunogenic cell death in both human and murine myeloma cell lines, including exposure of endoplasmic reticulum protein calreticulin (CALR), which functions as an “eat me” signal. Next, they validated these findings in two in vivo syngeneic models. Subsequently, they performed RNA sequence analysis of bortezomib-treated vs untreated tumors from both CALRWT and CALRKO cells growing in immunocompetent mice; they then carried out an integrative analysis of RNA sequence data from clinically annotated patients with myeloma (n = 327) uniformly treated with bortezomib-based regimens (as described in the IFM/DFCI 2009 trial).
The investigators identified a specific immunogenic cell death signature induced by bortezomib only in CALRWT tumors in mice; of note, they found that increased expression of the human orthologs of this immunogenic cell death signature was strongly and positively correlated with clinical outcome (overall survival, P = .01). Moreover, the predictive value of this signature was confirmed in an independent data set of bortezomib-treated patients (GSE9782; overall survival, P = .024).
Bortezomib increases genomic instability/micronuclei formation in myeloma cells and activates the innate cGAS/STING immune pathway, thereby stimulating a type I interferon response. Pharmacologic activation of STING with a STING agonist induced potent antimyeloma activity in vivo, and the combination of a STING agonist with bortezomib further potentiated this in vivo antimyeloma response, with increased T-cell infiltration into retrieved tumors, as evidenced by immunohistochemistry analysis.
Clinical Implications: The study delineates a novel mechanism—“immunotherapy with a sting”3—whereby bortezomib triggers antimyeloma immune responses and shows that STING agonists can enhance this response through potentiation of the cGAS/STING immune pathway. These findings provide the framework for clinical evaluation of STING agonists in combination with bortezomib to induce potent antimyeloma immune responses and thereby improve patient outcomes in the future. Importantly, similar characterization of known and novel myeloma therapies for the induction of immunogenic cell death may inform their use both as single agents and in combination immunotherapies.
Use and Sequencing of High-Dose Melphalan
ABSTRACT 61: Further insight into IFM/DFCI 2009 Study—High-dose melphalan significantly increases mutational burden in multiple myeloma cells at relapse: Results from a randomized study in multiple myeloma (ClinicalTrials.gov identifier NCT01191060).4
Background: High-dose melphalan followed by autologous hematopoietic cell transplant (auto-HCT) as first-line therapy in young patients (age < 66 years) with myeloma significantly improves progression-free survival (IFM/DFCI 2009 study).5,6
Methods: The investigators profiled samples from the IFM/DFCI 2009 study to identify genomic changes induced by high-dose melphalan and observed at relapse. They analyzed paired purified myeloma cells collected at diagnosis and at relapse using deep (75×) whole-genome sequencing. Among 68 patients, 45 were treated with lenalidomide, bortezomib, and dexamethasone (RVd) alone, whereas 23 received RVd followed by high-dose melphalan. There was no significant difference between the two groups in regard to disease characteristics including gender, age, cytogenetic risk, and best response. Median follow-up was similar (29 vs 31 months, respectively), removing longer follow-up as a confounding variable.
Results: The mutational load increased in both groups; there was a significantly higher increase in the number of mutations and indels in the high-dose melphalan arm compared with RVd alone (mutations = 5,686 vs 1,745, P = 1.4e-5; and indels = 467 vs 360, P = .02, respectively). Using a model incorporating the number of new mutations, depth, and purity, the investigators found that high-dose melphalan causes a 4.1-fold higher mutation accumulation rate per month than RVd alone (158.3 vs 38.3 mutations/month; P = .003). Importantly, newly acquired mutations were localized to regions that overlap with transcribed regions and accumulated at a significantly higher rate in the high-dose melphalan group (P = .009). Investigating the mutational signature utilization in newly acquired mutations alone identified four signatures: APOBEC, HR Double Strand Repair, clock-like signature, and unknown.
Clinical Implications: This study shows a higher mutational burden and rate of ongoing mutations at the time of relapse after RVd induction and high-dose melphalan therapy than in patients at relapse after RVd therapy. In the same study (IFM/DFCI 2009), and of practical importance with 8 years of follow-up, the incidence of invasive second primary cancer was not significantly different between the two groups (front-line transplant vs delayed transplant; P = .38).
This fundamental molecular change in the disease at relapse is an important consideration as clinical trials assess the optimal use and sequencing of high-dose melphalan and transplantation in the era of novel and improved therapies. It highlights the importance of assessing not only clinical efficacy, but also potential short- and long-term toxicities, as clinical trials evaluate the role of high-dose melphalan and transplantation. It further stresses the urgent need for novel targeted and immune strategies to treat minimal residual disease and thereby prevent clinically relevant genomic evolution underlying relapse of the disease.
Importance of MRD Status
ABSTRACT 491: Further insight into FORTE Study—Impact of measurable residual disease (MRD, formerly defined as minimal residual disease) by multiparameter 8-color flow cytometry (sensitivity = 10−5) and next-generation sequencing on outcome: Results of transplant-eligible (age ≤ 65 years) newly diagnosed multiple myeloma (NCT02203643).7
Background: Recent attempts have focused on the identification of residual tumor cells in the bone marrow using flow cytometry or gene sequencing, given the high rates of complete response seen with new treatment approaches in patients with multiple myeloma.8
Methods: Patients were randomly assigned (R1) to receive the proteasome inhibitor carfilzomib, the immunomodulatory drug lenalidomide, and dexamethasone (KRd) induction followed by auto-HCT and KRd × 4 cycles of consolidation (KRd/auto-HCT/KRd) vs 12 cycles of KRd (KRd12), vs carfilzomib, cyclophosphamide, and dexamethasone (KCd) induction followed by auto-HCT and 4 cycles of KCd consolidation (KCd/auto-HCT/KCd). After consolidation, patients were further randomly assigned (R2) to carfilzomib/lenalidomide vs lenalidomide maintenance.
The aims of this analysis were the evaluation of (1) the rate of conversion from MRD positivity to MRD negativity with multiparameter 8-color flow cytometry and next-generation sequencing during maintenance and (2) the impact on progression-free survival and overall survival of MRD negativity with both techniques in different subgroups, including different treatment arms. For these analyses, cytometry-positive patients included those who were positive by MRD plus those with less than a very good partial response, whereas next-generation sequencing–positive patients included those who were MRD-positive plus less than a complete response (excluding complete response patients not evaluable by next-generation sequencing).
The 1-year sustained MRD negativity by cytometry and next-generation sequencing was evaluated in patients with at least two samples available at least 1 year apart. MRD was assessed every 6 months by 8-color second-generation flow cytometry (sensitivity = 10−5) in patients with at least a very good partial response (VGPR). In patients achieving at least a complete response, MRD was also assessed by next-generation sequencing at the same time points (sensitivity = 10−5 to 10−6).
Results: In the intent-to-treat analysis, after a median follow-up of 45 months from R1, patients who were MRD-negative before maintenance by both techniques showed a superimposable prolonged progression-free survival and overall survival vs patients who were MRD-positive:
The impact of premaintenance MRD negativity by multiparameter 8-color flow cytometry on progression-free survival was explored in different treatment arms:
Clinical Implications: MRD-negative patients receiving KRd and upfront transplant showed a longer progression-free survival (88% at 3 years) than patients in the other two arms, further supporting the proteasome inhibitor/immunomodulatory drug induction therapy as well as the role of high-dose melphalan and transplantation. Of note, carfilzomib/lenalidomide maintenance induced a high rate of conversion from MRD positivity to MRD negativity, by both multiparameter 8-color flow cytometry and next-generation sequencing. The outcomes of patients who were MRD-negative by cytometry and next-generation sequencing at 10−5 were similar, as well as those of patients with 1-year sustained MRD negativity both by cytometry and next-generation sequencing.
These clinical findings highlighted the importance of achieving a sustained MRD-negative state and confirmed a high degree of concordance between these two techniques for measuring MRD in this study. Interestingly, carfilzomib/lenalidomide vs lenalidomide significantly prolonged progression-free survival, even in patients who were MRD-negative before maintenance therapy, highlighting the importance of MRD-guided ongoing and future studies to best identify patient subgroups who may benefit most from novel maintenance therapies. Ultimately, further studies will determine whether we can discontinue maintenance therapy in patients with persistent MRD-negative status, allowing for patients to be disease free and off all treatment.
Dr. Abutalib is Associate Director of the Hematology and BMT/Cellular Therapy Programs and Director of the Clinical Apheresis Program at the Cancer Treatment Centers of America, Zion, Illinois; Associate Professor at Rosilind Franklin University of Medicine and Science; and Founder of Advances in Cell and Gene Therapy. Dr. Anderson is Program Director of the Jerome Lipper Multiple Myeloma Center and LeBow Institute for Myeloma Therapeutics and Kraft Family Professor of Medicine at the Harvard Medical School.
DISCLOSURE: Dr. Abutalib has served on the advisory board for AstraZeneca and Partner Therapeutics. Dr. Anderson has been an advisor or consultant for Amgen, Janssen, Pfizer, Sanofi, Oncopeptides, and Precision Biosciences.
1. Gulla A, Morelli E, Samur MK, et al: Bortezomib induces anti-multiple myeloma immune response mediated by cGAS/STING pathway activation, type I interferon secretion, and immunogenic cell death: Clinical application. 2020 ASH Annual Meeting & Exhibition. Abstract 665. Presented December 7, 2020.
2. Pan BS, Perera SA, Piesvaux JA, et al: An orally available non-nucleotide STING agonist with antitumor activity. Science 369:eaba6098, 2020.
3. Gajewski TF, Higgs EF: Immunotherapy with a sting. Science 369:921-922, 2020.
4. Samur MK, Roncador M, Aktas-Samur A, et al: High-dose melphalan significantly increases mutational burden in multiple myeloma cells at relapse: Results from a randomized study in multiple myeloma. 2020 ASH Annual Meeting & Exhibition. Abstract 61. Presented December 5, 2020.
5. Perrot A, Lauwers-Cances V, Cazaubiel T, et al: Early versus late autologous stem cell transplant in newly diagnosed multiple myeloma: Long-term follow-up analysis of the IFM 2009 trial. 2020 ASH Annual Meeting & Exhibition. Abstract 143. Presented December 5, 2020.
6. Attal M, Lauwers-Cances V, Hulin C, et al: Lenalidomide, bortezomib, and dexamethasone with transplantation for myeloma. N Engl J Med 376:1311-1320, 2017.
7. Oliva S, Genuardi E, Petrucci MT, et al: Impact of minimal residual disease by multiparameter flow cytometry and next-generation sequencing on outcome: Results of newly diagnosed transplant-eligible multiple myeloma patients enrolled in the FORTE trial. 2020 ASH Annual Meeting & Exposition. Abstract 491. Presented December 6, 2020.
8. Kumar S, Paiva B, Anderson KC, et al: International Myeloma Working Group consensus criteria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol 17:e328-e346, 2016.