A Randomized Placebo-Controlled Phase 2 Study of Metformin for the Prevention of Progression of Monoclonal Gammopathy of Undetermined Significance and Smoldering Multiple Myeloma
Phase: PHASE2
Conditions: Monoclonal Gammopathy of Undetermined Significance, Smoldering Multiple Myeloma
Sponsor: Dana-Farber Cancer Institute



DFCI Protocol #: 21-008 Version Date: 06FEB2024 
2 
 
 
 
SCHEMA 
 
N=60 
 
Diseases: 
MGUS–Monoclonal 
Gammopathy of Undetermined 
Significance 
SMM- Smoldering multiple 
myeloma 
 Stratify 
R 
A 
MGUS v. 
N 
SMM 
D 
Heavy v. light chain 
O 
M 
I 
Z 
E 
Treatment 
 
ARM A: 
Metformin 
6-months 
 
 
ARM B: Placebo 
6-months 
Optional 
 
 
Crossover to open- 
label metformin for 6- 
months 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
3 
 
 
 
TABLE OF CONTENTS 
SCHEMA ............................................................................................................................. 3 
1. 
OBJECTIVES ...................................................................................................................... 6 
1.1 
Study Design ............................................................................................................ 6 
1.2 
Primary Objectives ................................................................................................... 6 
1.3 
Secondary Objectives ............................................................................................... 6 
2. 
BACKGROUND .................................................................................................................. 6 
2.1 
Myeloma (MM) and its Precursor Conditions .......................................................... 6 
2.2 
Clinical Management of MGUS and SMM and Status of Treatment ....................... 7 
2.3 
Metformin ................................................................................................................ 8 
2.4 
Trial Rationale .......................................................................................................... 8 
2.5 
Correlative Studies Background ............................................................................. 10 
3. 
PARTICIPANT SELECTION ........................................................................................... 11 
3.1 
Eligibility Criteria .................................................................................................. 11 
3.2 
Exclusion Criteria ................................................................................................... 12 
3.3 
Inclusion of Women and Minorities ....................................................................... 13 
4. 
REGISTRATION AND RANDOMIZATION PROCEDURES ........................................ 13 
4.1 
Recruitment ............................................................................................................ 13 
4.2 
Registration process ............................................................................................... 14 
5. 
TREATMENT PLAN ........................................................................................................ 15 
5.1 
Unblinding .............................................................................................................. 15 
5.2 
Treatment Regimen ................................................................................................ 16 
Please refer to section 6.1 for criteria and guidance for dose escalation ........................................ 16 
5.3 
General Concomitant Medication and Supportive Care Guidelines ....................... 17 
5.4 
Prohibited Medications and Procedures ................................................................. 18 
5.5 
Agent Administration ............................................................................................. 18 
5.6 
Participant Diary ..................................................................................................... 19 
5.7 
Removing a Participant from Treatment (Off Treatment) ...................................... 19 
5.8 
Duration of Follow Up ........................................................................................... 19 
5.9 
Removing a Participant from Study (Off Study/Off Follow Up)............................ 20 
6. 
DOSING DELAYS/DOSE MODIFICATIONS ................................................................ 20 
6.1 
Criteria to Escalate- Gastrointestinal Toxicity........................................................ 21 
6.2 
Criteria to Dose Escalate - Other Toxicities ........................................................... 21 
6.3 
Dose Modification Schedule .................................................................................. 22 
6.4 
Toxicity Management Guidelines For Toxicity After Escalation Period ............... 23 
7. 
ADVERSE EVENTS: LIST AND REPORTING REQUIREMENTS ............................. 24 
7.1 
Expected Toxicities ................................................................................................ 24 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
4 
 
 
7.2 
Adverse Event Characteristics ................................................................................ 24 
7.3 
Adverse Event Reporting ....................................................................................... 25 
7.4 
Reporting to the Food and Drug Administration .................................................... 25 
7.5 
Reporting to Hospital Risk Management ............................................................... 26 
7.6 
Routine Adverse Event Reporting .......................................................................... 26 
8. 
PHARMACEUTICAL INFORMATION .......................................................................... 26 
8.1 
Metformin Hydrochloride....................................................................................... 26 
9. 
STUDY MEASURES ........................................................................................................ 29 
9.1 
Screening/Baseline Assessments ............................................................................ 29 
9.2 
Final assessments ................................................................................................... 30 
9.3 
Endpoint assessment .............................................................................................. 30 
9.4 
Correlative Studies ................................................................................................. 31 
10. 
STUDY CALENDAR ........................................................................................................ 38 
Calendar for Extended TREATMENT (Crossover Arm) ............................................................... 41 
11. 
DATA REPORTING / REGULATORY REQUIREMENTS ............................................ 43 
11.1 
Data Reporting ....................................................................................................... 43 
11.2 
Data Safety Monitoring .......................................................................................... 43 
12. 
STATISTICAL Methods .................................................................................................... 43 
12.1 
Study Design/Endpoints Sample Size and Power ................................................... 43 
12.2 
Statistical Analysis ................................................................................................. 44 
12.3 
Sample Size, Accrual Rate and Study Duration ..................................................... 44 
12.4 
Stratification Factors .............................................................................................. 45 
12.5 
Interim Monitoring Plan ......................................................................................... 45 
12.6 
Analysis of Primary Endpoints ............................................................................... 45 
12.7 
Analysis of Secondary Endpoints ........................................................................... 45 
12.8 
Reporting and Exclusions ....................................................................................... 46 
12.9 
Stopping Rules for Safety ....................................................................................... 46 
13. 
PUBLICATION PLAN ...................................................................................................... 47 
14. 
REFERENCES ................................................................................................................... 48 
APPENDIX A 
PERFORMANCE STATUS CRITERIA ................................................... 53 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
5 
 
 
 
1. OBJECTIVES 
 
 
1.1 
Study Design 
 
We will conduct a randomized placebo-controlled trial in patients with higher-risk monoclonal 
gammopathy of undetermined significance (MGUS) and low-risk smoldering multiple myeloma 
(SMM) to test the efficacy of metformin in reducing clinical indicators of disease progression in 
MGUS and SMM patients. The target enrollment of the trial is 60 patients. After informed consent 
is signed, participants will be randomized in equal numbers to metformin or its corresponding 
placebo. The treatment period for the trial is 6-months, with study assessments for the trial’s 
primary outcome occurring at baseline and at the end of the 6-month treatment period. Participants 
will have the option to learn their treatment assignment after primary (6-month) outcome 
assessments are complete, and individuals randomized to metformin will have the opportunity to 
continue to take metformin for an additional 6-months to allow for the observation of potentially 
longer-term treatment response. Participants who choose to be unblinded and are taking placebo 
will discontinue study medication. Passive follow-up via medical record review will occur for up 
to 5 years post-randomization. 
 
1.2 
Primary Objectives 
 
To determine whether metformin can reduce or stabilize serum monoclonal (M-)protein 
concentrations from baseline to 6-months in patients with MGUS and SMM. 
 
 
1.3 
Secondary Objectives 
• Identify changes in m-protein/light chains using mass spectrometry. 
• Identify changes in hemoglobin concentrations among patients treated with metformin vs. 
placebo. 
• To examine molecular evolution of the tumor cells in response to metformin. 
• To determine the impact of metformin on the immune landscape of individuals with 
MGUS/SMM. 
• To explore the degree to which metformin changes plasma metabolites and metabolomic 
signatures. 
• To examine the impact of the metformin on changes in quality-of-life indicators form 
baseline to 6-months. 
• To understand patients’ willingness to continue to take metformin beyond the 6-month 
primary assessment period. 
• To examine the response trajectory in individuals who choose to take metformin for up to 
1-year. 
 
 
2. BACKGROUND 
 
2.1 
Myeloma (MM) and its Precursor Conditions. 
Multiple Myeloma (MM) is an incurable and fatal malignancy, with a 5-year survival rate of just 
over 50%.1 The incidence rate of MM in the US has been steadily rising; few cancers have 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
6 
 
 
 
demonstrated a greater increase in incidence since 2004.1 MM is a plasma cell dyscrasia 
characterized by the proliferation of clonal plasma cells in the bone marrow and the production of 
monoclonal immunoglobulin and/or light chain, with subsequent end organ damage.2 
 
MM always evolves from precursor states of monoclonal gammopathy of undetermined 
significance (MGUS) and smoldering MM (SMM), which are relatively common blood conditions 
affecting ~3% of the general population over 50 years.2 Both conditions are often clinically 
detected through the presence of abnormal proteins called “monoclonal (M-)proteins” in the blood 
and/or urine. In 2010 the International Myeloma Working Group (IMWG) defined monoclonal 
gammopathy of undetermined significance (MGUS) by the presence of serum M-protein < 3g/dL, 
clonal plasma cell population in the bone marrow < 10%, and the absence of end-organ damage 
such as hypercalcemia (serum calcium ≥ 11.5 mg/dL), renal insufficiency (serum creatinine ≥ 2 
mg/dL), anemia (hemoglobin value below the lower limit of normal by more than 2 g/dL or 
hemoglobin value < 10 g/dL) and lytic bone lesions (CRAB features) that can be attributed to the 
plasma cell proliferative disorder.3 Smoldering multiple myeloma was defined by the presence of 
serum M-protein ≥ 3 g/dL or IgA> 2g/ dL or urinary monoclonal protein > 500 mg/ dL and/or 
clonal bone marrow plasma cells ≥ 10% and the absence of CRAB features clinically. 
 
In general, MGUS progresses to overt MM at a slow rate of 1% per year, but in some patients, the 
risk may be as high as 58% in 20 years.4,5 SMM has an annual risk of progression of 10%, but in 
some patients, risk is considerably higher.4 These conditions also confer a decreased life 
expectancy compared to the general population6,7, raising the possibility that there are other 
disorders associated with MGUS and SMM that have yet to be determined. 
 
2.2 
Clinical Management of MGUS and SMM and Status of Treatment. 
The cornerstone of management for both entities is to delay therapy until progression to MM, at 
which time patients have overt end-organ damage.8,9 It is therefore unsurprising that patients with 
MGUS and SMM report high levels of anxiety and distress about their conditions,10 and cure is 
seldom achieved.11 However, this paradigm may change as there are already clinical trials that 
show that early use of MM therapies in the precursor setting may alter the natural history of the 
disease12, and importantly, may improve survival.13 For example, in a randomized open-label 
phase 3 trial 13, 119 patients with high-risk smoldering myeloma were randomized to treatment or 
observation. Patients in the treatment group received an induction regimen (lenalidomide at a dose 
of 25 mg per day on days 1 to 21, plus dexamethasone at a dose of 20 mg per day on days 1 to 4 
and days 12 to 15, at 4-week intervals for nine cycles), followed by a maintenance regimen 
(lenalidomide at a dose of 10 mg per day on days 1 to 21 of each 28-day cycle for 2 years). The 
primary endpoint was time to progression to symptomatic disease. Secondary endpoints were 
response rate, overall survival, and safety. After a median follow-up of 40 months, the median time 
to progression was significantly longer in the treatment group than in the observation group 
(median not reached vs. 21 months; hazard ratio for progression, 0.18; 95% confidence interval 
[CI], 0.09 to 0.32; P<0.001). The 3-year survival rate was also higher in the treatment group (94% 
vs. 80%; hazard ratio for death, 0.31; 95% CI, 0.10 to 0.91; P=0.03). A partial response or better 
was achieved in 79% of patients in the treatment group after the induction phase and in 90% during 
the maintenance phase. Toxic effects were mainly grade 2 or lower. Early treatment for patients 
with high-risk smoldering myeloma delays progression to active disease and increases overall 
survival. (NCT00480363). 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
7 
 
 
 
 
Despite the promise of early treatment in the precursor MM disease setting, it has remained highly 
controversial given the high cost and risk of toxicity and harm to patients who may never progress 
to overt MM.14-16 For example, the treatments currently being investigated in the precursor disease 
setting carry considerable short- and long-term risks, including but not limited to arterial 
thromboembolic events, neutropenia and thrombocytopenia, and increased risk for secondary 
malignancies.17 These toxicities, in effect, mostly limit the use of existing therapies to the highest 
risk patient subsets. Therefore, the identification lower-risk, cost-effective strategies to prevent 
disease progression in patients with less aggressive forms of MGUS and SMM is of considerable 
importance. 
 
2.3 
Metformin 
Metformin is a biguanide derivative that is FDA approved for the treatment of type 2 diabetes but 
is also considered safe for use in non-diabetic populations;18 serious adverse events are rare and 
are mostly limited to lactic acidosis. Metformin decreases hepatic glucose production, decreases 
intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose 
uptake and utilization. Metformin, at therapeutic doses, does not cause hypoglycemia when used 
alone in man or in the non-diabetic animal, except when using a near lethal dose. Metformin has 
no effects on the pancreatic beta cells. 
 
Metformin absorption is relatively slow, is delayed to some extent by food consumption, and 
may extend over a period of hours. The drug is excreted in urine at high renal clearance rate of 
about 642 mL/min, which varies based on dosage. The initial elimination of metformin is rapid 
with a plasma elimination half-life of approximately 6.2 hours. Metformin is not metabolized 
and is therefore excreted unchanged in the urine. 
 
2.4 
Trial Rationale 
 
2.4.1.1 
Clinical experience in cancer prevention 
There is a growing body of literature indicating a benefit to the repurposing metformin in the 
cancer prevention setting, by demonstrating its efficacy in improving biological systems 
putatively associated with cancer prognosis among non-diabetics. For examples, in an 
observational cohort study using UK-based record-linkage databases, there was a significantly 
reduced risk of cancer associated with metformin use, with a hazard ratio for metformin reported 
to be 0.63 (95% CI, 0.53– 0.75). In this same study, total and cancer-specific mortality were also 
significantly lower among metformin users.19 In addition, a 2008 study among 32 non-diabetic 
breast cancer patients, which demonstrated that a 6-month intervention consisting of 1500mg of 
metformin significantly reduced fasting insulin and improve insulin sensitivity.20 More recently, 
a univariate interim analysis among 492 non-diabetic breast cancer survivors enrolled in the 
NCIC Clinical Trials Group (NCIC CTG) MA.32 trial of metformin vs. placebo found 
metformin use for 6-months to be associated with improved glucoregulation (insulin, glucose, 
HOMA-IR), in addition to leptin and C-reactive protein.21 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
8 
 
 
 
2.4.2 Rationale for investigation in precursor MM 
Metformin is of particular interest as a disease interception tool in the precursor MM setting given 
that it is relatively inexpensive and is sustainable for long-term risk reduction,22—all of which are 
characteristics that the current investigational therapies do not possess. The converging lines of 
evidence supporting the benefit of metformin in preventing MGUS/SMM progression are briefly 
outlined below: 
 
In vivo and in vitro xenograft models have demonstrated metformin’s ability to inhibit MM cell 
proliferation by inducing apoptosis and cell cycle arrest through mechanisms of action that include 
the IGF-1R/PI3K/AKT/mTOR signaling pathway;23 it also appears to work synergistically with 
other MM therapies, including dexamethasone,23 bortezomib24 and ritonavir25 to limit MM cell 
proliferation. Metformin has also been shown to regulate other aspects of the bone marrow 
microenvironment in ways that may inhibit myelomagenesis, including but not limited to reducing 
bone marrow adipose tissue, which is a highly active endocrine organ that resides directly in the 
bone marrow niche and supports MM cell proliferation, as well as immune cells.26,27 
 
Data from observational studies further support the use of metformin in preventing disease 
progression in individuals with MGUS/SMM. For example, metformin use was associated with a 
statistically significant 53% reduced risk of MM in a cohort of 2,003 diabetics diagnosed with 
MGUS (95% CI: 0.25, 0.87),28 and similar observations were reported in an independent cohort 
of MGUS patients from The Health Improvement Network.29 Given the consistent laboratory 
science and epidemiologic evidence suggesting a beneficial role of metformin in regulating the 
activity of MM and other bone marrow niche cells, a number of ongoing clinical trials are testing 
its efficacy (in combination with other drugs) for the treatment of MM patients with relapsed and 
refractory disease (see ClinicalTrials.gov). However, we are not aware of any ongoing or planned 
clinical trials investigating the use of metformin in patients with MGUS or SMM. 
 
2.4.3 M-Protein and Light-chain Concentrations as Clinically Relevant Disease Endpoints. 
 
Monoclonal (M-)proteins and light chains produced in excess by an abnormal clonal proliferation 
of plasma (MM) cells that can be measured in the serum using Serum Protein Electrophoresis 
(SPEP) and the Serum Free Light Chain Assay. These quantitative tests usually correlate with 
overall tumor burden, and thus the SPEP is one of the most common clinical tests used to monitor 
patients with all stages of the disease continuum (MGUS, SMM and MM). Importantly, 
concentrations of these biomarkers have been repeatedly shown to reduce after treatment with a 
range of mild and aggressive MM therapies,30-32 underscoring their utility as a sensitive and 
measurable marker of tumor response to treatment.33 
 
2.4.4 Mass Spectrometry 
 
Quantitative immunopurification mass spectrometry (QIP-MS) combines Ig immunopurification 
with mass spectrometry resulting in a methodology that is more sensitive and specific than serum 
protein electrophoresis (SPEP) and immunofixation (IFX). The technique works by first isolating 
Ig’s using isotype specific beads. Purified Ig’s are then separated into light chains and heavy 
chains by the addition of a reducing agent. A mass spectrometer is then used to detect a 
monoclonal light chain from an M-protein observed as a peak above the normal polyclonal 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
9 
 
 
 
background. Mills et al. demonstrated that QIP-MS could detect an M-protein in patient serum 
when SPEP and IFX were negative.34 They also showed in serial dilution studies that a 
monoclonal light chain peak could be detected by QIP-MS at a level < 0.05 g/L; a level that was 
negative when analyzed by SPEP and IFX. The specificity of QIP-MS is provided by the 
superior resolving capability and mass measurement accuracy of the mass spectrometer. 
Barnidge and colleagues demonstrated that molecular mass could be used to monitor a specific 
monoclonal kappa light chain in a patient GK MM over a 7-year period.35 The monoclonal light 
chain could easily be detected in samples that were negative by SPEP and IFX. Multiple clones 
can be easily identified in serum using QIP-MS technology since the mass spectrometer provides 
superior resolution compared to gel electrophoresis. M-protein quantification is performed by 
comparing monoclonal light chain peak intensities with an internal reference. 
 
 
2.5 
Correlative Studies Background 
 
 
2.5.1 Immune cell characterization in the peripheral blood and bone marrow 
 
Tumors are complex ecosystems characterized by interactions between heterogeneous cell types, 
including malignant cells and immune cells36. An important step in the progression of tumors is 
their ability to evade and suppress the host immune system in a way that fosters immune escape 
and tumor growth.37,38 Therefore, therapies that modify immune microenvironment may be 
effective 
anti-myeloma 
therapies.39 
For 
example, 
metformin 
can 
interfere 
with 
immunopathological mechanisms implicated in MGUS/SMM disease progression,40 including but 
not limited to the T helper 17/regulatory T cell balance, cytokine synthesis, and natural killer cell 
response,39,41,42 suggesting that the putative benefits of metformin on the prevention of disease 
progression in MGUS/SMM may be mediated, in part, through the effects on the immune 
microenvironment. 
 
2.5.2 Value of Metabolomics 
 
Metabolomics, e.g., the high-throughput identification and quantification of small molecule 
metabolites produced by metabolism, can yield novel insights into pathogenesis and risk of cancer 
and chronic disease.43,44 Metabolomics is the study of metabolic changes in biological systems and 
provides the small molecule fingerprints that reflect the complex relationships between diet, 
lifestyle (obesity), genes, and disease processes.44 We believe that metabolomics offers a unique 
lens to study progression in the precursor MM, given that of all molecular entities (e.g., genes, 
transcripts, proteins, metabolites), metabolites have the closest relationship to expressed 
phenotype, as they are the final endpoints of biochemical processing.45 Despite the growing 
interest and application of metabolomics to cancer and chronic disease research, metabolomics- 
based studies of MM, MGUS, or SMM are sparse.46-51 One small study by Ludwig et al identified 
25 bone marrow metabolites that differed between 10 MGUS and 10 MM patients,46 but this work 
has not yet been expanded in larger samples with clinical and lifestyle data. A larger metabolomics 
investigation of precursor MM patients could contribute important knowledge regarding the 
landscape of the metabolic changes underlying the disease, and ultimately lend important insights 
into interception strategies and druggable targets. Particularly important categories of metabolites 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
10 
 
 
 
in cancer and metabolic disease are metabolites of glycolysis and the TCA cycle. These are of 
interest to the current study because of their critical role in tumor growth52,53 and because they 
have been shown to be obesity related.54 Importantly, these metabolite categories have consistently 
shown to be sensitive to metformin55-57—likely because of their relationship to the mammalian 
target of rapamycin (mTOR),58,59 which is the cellular signaling cascade that serves as a master 
regulator of metabolism, cell growth, and proliferation.60 
 
2.5.3 Quality of life in the Precursor Disease Setting 
 
As an exploratory objective, given the high rates of anxiety and distress document in individuals 
with MGUS and SMM61,62 and lack of evidence-based risk reduction strategies available for 
preventing disease progression to MM, we will explore the psychosocial benefits of offering a 
low-risk pharmacologic intervention to this patient population. 
 
 
3. PARTICIPANT SELECTION 
 
3.1 
Eligibility Criteria 
 
 
3.1.1 Diagnosed with high-risk MGUS or low-risk SMM63 defined below: 
 
Higher-Risk MGUS: bone marrow plasma cell concentration <10%# AND either serum M- 
protein level ≥1.5 g/dL to <3 g/dL, abnormal free light-chain (FLC) ratio (<0.26 or >1.65), or 
IgA MGUS. 
Note: individuals with an abnormal FLC ratio that are classified as light-chain only are eligible. 
Light-chain only patients are defined as complete loss of immunoglobulin heavy-chain, 
accompanied by abnormal FLC ratio with an increased level of the appropriate involved light- 
chain (increased kappa FLC in patient with ratio >1.65, and increased lambda FLC in patients 
with ratio <0.26). 
 
Low-Risk Smoldering Myeloma: bone marrow plasma cells ≥10%# with the absence of 
additional high-risk features, which are further defined in the exclusion criteria (3.2.1)64 
 
#A new bone marrow biopsy is preferred for plasma cell determination at screening; however, 
determination of eligibility can be made from most recent bone marrow biopsy performed as 
long as it was within 2 years of enrollment. 
 
3.1.2 Absence of evidence of CRAB criteria* or new criteria of active MM or active WM 
which including the following (note if one or more criteria has not been evaluated (e.g., 
no MRI), the criteria for active MM or WM for that feature is considered unmet): 
• Increased calcium levels (corrected serum calcium >0.25 mmol/dL 
above the upper limit of normal or >.275 mmol/dL) related to MM 
• Renal insufficiency (attributable to MM) 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
11 
 
 
 
• Anemia (Hb 2g/dL below the lower limit of normal or <10g/dL) 
related to MM 
• Bone lesions (lytic lesions or generalized osteoporosis with 
compression fractures) 
• Bone marrow plasma cells ≥60% 
• Serum involved/uninvolved FLC ratio ≥100, provided the absolute 
level of the involved free light chain is at least 100 mg/L and repeated 
twice (light chain smoldering myeloma as described in section 2.4 is 
not an exclusion criteria). 
• MRI with two or more focal lesion that is at least 5 mm or greater in 
size 
• Hyperviscosity symptoms per WM guidelines for symptomatic WM 
*Participants with CRAB criteria that are attributable to conditions other 
than the disease under study may be eligible 
 
3.1.3 At least 18 years of age. 
 
3.1.4 Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2. 
 
3.1.5 The following laboratory values obtained prior to the first dose of study drug/placebo: 
• AST and ALT < 1.5 x institutional ULN 
• Serum bilirubin < institutional ULN (in patients with Gilbert’s Disease, 
direct bilirubin < institutional ULN) 
• Calculated creatinine clearance ≥ 45 mL/min 
o Estimation of renal function will be assessed using the CrCl 
calculated based on the Cockcroft-Gault formula: 
o CrCl (mL/min) = (140-age) (weight [kg]/72 (serum 
creatinine [mg/dL]; for females the formula is multiplied by 
0.85 
• Random glucose < 160 mg/dL or fasting glucose < 126 mg/dL (other 
values require workup to rule out undiagnosed diabetes that may require 
treatment) 
 
3.1.6 Ability to understand and the willingness to sign a written informed consent document 
 
3.1.7. For participants who wish to enroll in the open label extended treatment (crossover arm), 
participants can be unblinded and learn of their drug group AFTER completing primary endpoint 
collection. Patient must be randomized to metformin in order to continue taking metformin for 6 
additional months. 
 
3.2 
Exclusion Criteria 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
12 
 
 
 
 
3.2.1 Presence of high-risk smoldering myeloma, as defined by IMWG/Mayo 2018 “20-2-20” 
Criteria (at least 2 of the following) 
o 
Bone marrow plasmacytosis ≥20% 
o 
≥2g/dl M protein 
o 
≥20 involved: uninvolved serum free light chain ratio 
3.2.2 Diagnosed or treated for another malignancy within the study period. 
 
3.2.3 Currently on medications for diabetes treatment 
• Patients with hyperglycemia (random glucose < 160 mg/dL or fasting glucose 
< 126 mg/dl) but who are not on any drug treatment are eligible 
 
3.2.4 Participants who are receiving any other investigational agents. 
 
3.2.5 Women who are pregnant or who are unable or unwilling to use contraception during the 
study period are excluded from this study because it is a class B agent which is known to 
cross the placenta rapidly and is unbound in serum. 
 
3.2.6 Any condition associated with increased risk of metformin-associated lactic acidosis 
(prior renal failure or liver failure, history of acidosis of any type) or habitual intake of 3 
or more alcoholic beverages per day. 
 
3.2.7 Known intolerance to metformin 
 
3.2.8 Known malabsorption syndrome or diagnosis with a medical condition that may alter 
gastrointestinal absorption of medications including but not limited to inflammatory 
bowel disease impacting the small intestine or recent history of bariatric surgery. 
 
3.2.9 Any other condition that, in the investigator’s judgment, would contraindicate the use of 
metformin or otherwise interfere with participation in the trial 
 
 
3.3 
Inclusion of Women and Minorities 
 
Both men and women of all races and ethnic groups are eligible for this trial. 
 
4. REGISTRATION AND RANDOMIZATION PROCEDURES 
 
4.1 
Recruitment 
 
Participants will be primarily recruited from the Center for the Prevention of Progression 
(CPOP) Clinic at Dana-Farber, but we may expand recruitment to other Mass General Brigham 
sites. We will utilize multiple active recruitment techniques to maximize participation and 
generalizability. We will use the following strategies to identify potential participants: 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
13 
 
 
 
 
• We will review clinic schedules and patient lists at DFCI and other Partners Healthcare 
institutions. HIPAA waivers will be obtained prior to review of these patient lists. 
 
Once a potential participant is identified, they will be contacted by phone/email by a study 
coordinator to solicit interest, or during a clinic visit or through other approved methods of 
communication. 
 
Interested subjects identified through these recruitment strategies will be pre-screened by study 
staff either in person or by phone initially and if potentially eligible, he or she will 
meet with a member of the study staff to review the protocol and sign informed consent. 
 
Consenting will occur in person or remotely via 45 CFR part 46, local CON-100 and 21 CFR part 
11 compliant Adobe eSign. Adobe eSign consent may be utilized for patients who have recently 
been seen by study clinicians, but who live far away/ out of state and are unwilling to return to 
the main campus to consent to study. Participants that are consented electronically will utilize 
the same version as the paper version of the consent form. Patients will be provided with a copy 
of the consent form. They will have the opportunity to discuss and ask questions about the study 
with their clinician prior to signing consent form and discuss any potential questions with study 
staff. Once review of the consent has concluded, the study staff will email another consent form 
via Adobe eSign Consent through an official Dana-Farber email to the participant’s 
authenticated and confirmed email address that is on file in their medial record. 
 
4.2 
Registration process 
 
All eligible participates who consent and wish to enroll in the intervention will be registered 
in the Clinical Trials Management System (CTMS) OnCore. Registrations must occur prior to 
the initiation of any protocol-specific therapy or intervention. Any participant not registered to 
the protocol before protocol-specific therapy or intervention begins will be considered ineligible 
and registration will be denied. Any participant who wishes to become unblinded after primary 
endpoint completion and is interested and eligible to enroll in the open-label crossover arm of the 
study must be registered to the crossover arm in OnCore. 
 
An investigator will confirm eligibility criteria and a member of the study team will complete the 
protocol-specific eligibility checklist. 
 
The eligibility checklist(s) and all pages of the consent form(s) will be faxed or emailed to ODQ 
at 617-632-2295. The ODQ will (a) review the eligibility checklist, (b) register the participant on 
the protocol, and (c) randomize the participant. 
 
Randomization can only occur during ODQ business hours (8:30am - 5pm Eastern Time, 
Monday through Friday excluding holidays). 
 
The ODQ Protocol Systems Coordinator is responsible for randomizing subjects to treatment 
arms for investigator-sponsored research 
 
The statistician in the Department of Biostatistics and Computational Biology provides ODQ 
with any necessary randomization sheets and instructions specific to the protocol. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
14 
 
 
 
For blinded protocols: The ODQ Protocol Systems Coordinator conveys the randomization 
assignment to the appropriate departments as directed by the randomization instructions. 
 
 
An email confirmation of the registration and/or randomization will be sent to the study 
coordinator(s) from the registering site, treating investigator and registering person immediately 
following the registration and/or randomization. 
 
Following registration, participants may begin protocol-specific therapy and/or intervention. 
Issues that would cause treatment delays should be discussed with the Principal Investigator (PI) 
of the registering site. If the subject does not receive protocol therapy following registration, the 
subject must be taken off study in the CTMS (OnCore) with an appropriate date and reason 
entered. 
 
4.2.1 Registration Process for DF/HCC Sites 
 
DF/HCC Standard Operating Procedure for Human Subject Research Titled Subject Protocol 
Registration (SOP #: REGIST-101) must be followed. 
 
Following registration, patients will be randomized to the metformin/placebo. Initiation of 
metformin/placebo should begin within 4 weeks of screening/baseline blood collection. 
 
 
5. TREATMENT PLAN 
 
We will conduct a randomized placebo-controlled trial in patients with higher-risk monoclonal 
gammopathy of undetermined significance (MGUS) and low-risk smoldering multiple myeloma 
(SMM). After informed consent is signed, total of 60 eligible and evaluable participants will be 
randomized 1:1 either to metformin or placebo. Stratification factors will be disease stage (MGUS 
vs. SMM) and heavy vs. light-chain status. The treatment period will be 6 months and primary 
outcome assessments as outlined below will occur at baseline and after 6 months of treatment or 
for those that discontinue medication, as close to the 6-month timepoint as possible. To explore 
participants’ willingness to continue to take metformin after the 6-month treatment period and 
observe longer-term response, participants will be given the option to learn their treatment 
assignment after completing the primary study endpoints. Any participant randomized to the 
metformin group will be invited to continue to take metformin for an additional 6 months. 
Treatment will be administered on an outpatient basis. Reported adverse events and potential risks 
are described in Section 7. Appropriate dose modifications are described in Section 6. 
 
Participants will dose escalate in a stepwise fashion beginning with 500mg and increasing by 
500mg until they reach 1500mg. The duration of this study and corresponding treatment period is 
6 months. 
No investigational or commercial agents or therapies other than those described below may be 
administered with the intent to treat the participant's premalignancy. 
 
 
5.1 
Unblinding

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
15 
 
 
In the event of a medical emergency where breaking the blind is required to provide medical care 
to the subject, the primary investigator or treating investigator with approval by the primary- 
investigator may obtain the treatment assignment directly from the research pharmacy. Blinding 
of study treatment is critical to the integrity of this clinical trial and therefore, if a subject’s 
treatment assignment is disclosed to the investigator, the subject will have study treatment 
discontinued. Documentation of the decision to unblind will be recorded in the subject’s medical 
record. 
 
After primary outcome measures are collected (blood collection at 6 month end of treatment 
visit), participants will have the option to learn their treatment assignment (be unblinded) and 
any patients randomized to the metformin arm will be invited to continue to take metformin for 
an additional 6 months on a crossover arm. Participants randomized to the placebo will 
discontinue study medication at the 6-month time point. 
 
In addition, at the end of the study the PI will obtain a list from the research pharmacy of each 
patient’s randomization for data analysis. 
 
 
5.2 
Treatment Regimen 
 
Metformin and its corresponding placebo are the proposed pharmacological treatments. 
Metformin can be safely used in nondiabetics without significantly impacting quality of life. 
Minor adverse events associated with this agent are nausea/vomiting, diarrhea, or constipation. 
All patients will be cautioned against excessive alcohol intake, either acute or chronic, when 
taking metformin, since alcohol intake potentiates the effect of metformin on lactate metabolism. 
 
A cycle is defined as 28 days. In the absence of toxicity, withdrawal or other event, treatment 
may continue for up to 6 cycles. The metformin dose will be 1500 mg/day, provided in 500 mg 
pills. To minimize gastrointestinal symptoms, metformin will be started at a low dose of 500 mg 
(1 pill) and the patient will be advised to take it with food at water. A drug dairy/schedule will be 
provided for each patient for the duration of the treatment period, and telephone contact will be 
made periodically to assess compliance and toxicity. 
 
As noted in the study calendar, adherence to the medication will be assessed throughout the 
study period by means of telephone calls at day 7, day 28, day 48 (optional at the discretion of 
clinical team), at the end of cycle 3, and at the end of study visit within the window specified 
(Section 10 Study Calendar footnote 10). All remaining pills will also be returned to study staff 
and counting will occur in the DFCI research pharmacy. 
 
Please refer to section 6.1 for criteria and guidance for dose escalation. 
As this is a blinded study, all participants will be asked to adhere to this dosing schedule and the 
pill-taking guidelines specified below. Therefore, the dosing regimen for the placebo is the same 
as described above for metformin. 
 
 
Week 1 (Days 1-7) 
Agent 
Dose 
Route 
Schedule 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
16 
 
 
 
Metformin/Placebo 
500mg 
Oral 
Once daily with 
meals and at least 8 
ounces of water 
 
Week 2-4 (Days 8-28) 
Agent 
Dose 
Route 
Schedule 
Metformin/Placebo 
1000mg 
Oral 
Once daily with 
meals and at least 8 
ounces of water 
 
Week 5 through week 24 (Day 29 through end of study) 
Agent 
Dose 
Route 
Schedule 
Metformin/Placebo 
1500mg 
Oral 
Once daily with 
meals and at least 8 
ounces of water 
 
 
NOTE: The participant will be required to maintain a medication diary of each dose of 
medication. The medication diary will be returned to clinic staff at their 6-month/end of study 
visit or mailed back along with any extra medication to the study team to perform accountability 
per local policies. 
 
Patients will be invited to continue to take metformin for an additional 6 months on a crossover 
arm after completing the study’s primary endpoints. This option will only be available to 
individuals who are taking metformin during the blinded study phase. Patients taking placebo 
will discontinue all study medication at the 6-month timepoint. 
 
 
Optional Extended Treatment Period (crossover arm): Week 24-48. 
Agent 
Dose 
Route 
Schedule 
Metformin 
1500mg 
or 
highest 
tolerated 
dose 
Oral 
Once daily with 
meals and at least 8 
ounces of water 
 
NOTE: A new open-label metformin diary will be provided to participants who wish to 
participate in the optional extended treatment period. As done previously, the medication diary 
will be returned to clinic staff at the end of the additional 6-month treatment period or mailed 
back along with extra medication to the study team to perform accountability per local policies. 
 
 
5.3 
General Concomitant Medication and Supportive Care Guidelines 
 
Participants may receive any supportive care necessary to address side effects of metformin so 
long as it is not considered investigational. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
17 
 
 
 
 
5.4 
Prohibited Medications and Procedures 
 
There are several medications and procedures which may increase the risk of lactic acidosis 
associated with metformin. Medical records will be reviewed for potential metformin 
contraindications including but not limited to the following: acetazolamide (Diamox), 
dichlorphenamide (Keveyis), methazolamide, topiramate (Topamax, in Qsymia), or zonisamide 
(Zonegran). In addition, participants will be advised to tell the study team if they plan to have 
surgery or any medical procedures requiring iodinated contrast agents, which can also increase 
the risk of lactic acidosis. In the event of a surgery or procedure that requires a contrast agent, 
participants will be advised to stop taking study medication 48 hours prior to the procedure and 
to refrain from re-starting study medication until they have undergone a blood test showing 
normal kidney function. 
 
Participants are also prohibited from taking any investigational medications, or any cancer 
directed therapy during the study. In the event that a cancer-directed therapy is clinically 
warranted (e.g., progression to MM), participants will come off study so that appropriate care 
can be received. 
 
5.5 
Agent Administration 
 
Participants will be provided 3 months of study medication at study entry after randomization; 
the remaining pills will be mailed to the patient at a later date to minimize drug waste per local 
policies. A drug diary will also be provided for participants to record study drug 
compliance/adherence. Participants in the extended treatment (crossover arm) will receive a 3- 
month supply of medication in person or by mail at the 6-month visit if eligible. To minimize 
drug waste and ensure patient safety, the final 3-month supply will be sent to participants at a 
later date once safety labs are reviewed by the research team. 
 
The Office of Data Quality (ODQ) will have a randomization schedule which has been prepared 
and provided by the Study Statistician. Study agent randomization to placebo or active SDG will 
be provided for each sequential post-randomization study ID number and sent by ODQ to the 
research pharmacy. 
 
Both Metformin and matched placebo are to be provided by the DFCI Research Pharmacy. 
Metformin (containing 500 mg of the active ingredient) placebo (containing the same filler 
material but without the active ingredient) will be given to all trial participants for the 6 months 
of participation (two shipments each containing a 3-month supply). All subjects should have off- 
study procedures ideally no later than 7 days of the last dose of Metformin or placebo. However, 
if a participant stops study agent prematurely in an unscheduled situation, s/he should come in 
for re-assessment as early as possible. Participants in the crossover arm will be provided 1500 
mg Metformin by the DFCI Research Pharmacy. As indicated previously, the pills will be given 
in two batches, each containing a 3-month supply. All participants in the crossover arm should 
also have off-study procedures ideally no later than 7 days of the last dose of Metformin. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
18 
 
 
 
Metformin/Placebo tablets (Study Drug) are to be taken orally and tablets are to be taken whole, 
not broken or crushed. Study drug will be administered or dispensed only to eligible patients 
under the supervision of the investigator or identified sub investigator(s). As described above, it 
is recommended that all tablets are taken with food to minimize gastrointestinal side effects. 
 
Please refer to section 8 for further information about the study agent. 
 
5.6 
Participant Diary 
 
Participants should be instructed to document all oral study drug administration on a patient 
diary and return unused tablet and packaging for review of compliance at the end of the study. 
Sites are responsible to maintain the diary as source documentation. 
 
5.7 
Removing a Participant from Treatment (Off Treatment) 
 
Duration of therapy will depend on individual response, evidence of disease progression and 
tolerance. In the absence of toxicity or withdrawal from therapy, treatment may continue for up 
to 6 cycles when each cycle is defined as 28 days (or 12 cycles for those in the crossover arm), or 
until one of the following criteria applies: 
 
• 
Disease progression to overt MM 
 
• 
Intercurrent illness that prevents further administration of treatment 
 
• 
Unacceptable adverse event(s) or co-morbid condition 
 
• 
Participant demonstrates an inability or unwillingness to comply with the oral 
medication regimen and/or documentation requirements 
 
• 
Participant decides to withdraw from the protocol therapy 
 
• 
General or specific changes in the participant's condition render the participant 
unacceptable for further treatment in the judgment of the treating investigator 
 
Participants will be removed from the protocol therapy when any of these criteria apply. The 
reason for removal from protocol therapy, and the date the participant was removed, must be 
documented in the case report form (CRF). Alternative care options will be discussed with the 
participant. 
 
When a participant is removed from protocol therapy and/or is off of the study, the participant’s 
status must be updated in OnCore in accordance with REGIST-OP-1. 
 
 
5.8 
Duration of Follow Up 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
19 
 
 
 
The total study intervention period is 6 months, with the final assessment occurring at the end of 
the scheduled 6-month treatment period. However, some participants may choose to be 
unblinded after primary outcome assessments are complete and will agree to continue to take 
metformin for an additional 6-month observational period (crossover arm). In addition, 
participants will be followed for survival and disease events via medical record review for up to 
5-years after randomization. 
 
5.9 
Removing a Participant from Study (Off Study/Off Follow Up) 
 
Participants will be removed from study when any of the following criteria apply: 
• Lost to follow-up 
• Withdrawal of consent for data submission 
• Death 
• Progression to overt MM 
 
The reason for taking a participant off study, and the date the participant was removed, must be 
documented in the case report form (CRF). In addition, the study team will ensure the 
participant’s status is updated in OnCore in accordance with REGIST-OP-1. 
 
 
6. DOSING DELAYS/DOSE MODIFICATIONS 
 
The major toxic effects of which limit metformin dose are gastrointestinal (nausea, abdominal 
bloating, diarrhea). Dose adjustments, for reasons of toxicity will be as in the tables below. 
Please note that none of the recommended dose adjustments require splitting of the study drug. 
 
If multiple adverse events are seen, dose modifications should be based on the worst preceding 
toxicity. The AE should be attributed to a specific drug, if possible, so that the dose 
modifications can be made accordingly. Reduction of the study drug is appropriate if toxicity is 
thought to be primarily related to the agent under study. 
 
The dose modification guidelines should be regarded as guidelines and should be followed 
unless otherwise discussed with the principal investigator. 
 
Reductions are based on toxicity noted within a cycle and may contribute to the dose level for 
the subsequent cycle. Dose re-escalation can be considered after discussion with the treating 
investigator. Each cycle is defined as 28 days. 
 
Dose delays and modifications will be made as indicated in the following table(s). The 
descriptions and grading scales found in the revised NCI Common Terminology Criteria for 
Adverse Events (CTCAE) version 5.0 will be utilized for dose delays and dose modifications. A 
copy of the CTCAE version 5.0can be downloaded from the CTEP website 
http://ctep.cancer.gov/protocolDevelopment/electronic_applications/ctc.htm. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
20 
 
 
 
6.1 
Criteria to Escalate- Gastrointestinal Toxicity 
 
6.1.1 Criteria to Escalate from 500mg to 1000mg 
 
1. Participants must not have any gastrointestinal toxicity > Grade 1 on day of anticipated 
escalation 
• If toxicity is Grade 2, hold for one week, and re-evaluate 
 If in one week, the toxicity has not resolved to Grade 1 or better, hold 
treatment for a second week and re-evaluate 
 If the participant is unable to dose escalate after 3 weeks beyond the 
expected escalation date, consider treatment at 500mg for the duration of 
the study or discontinuation at PI discretion 
• If toxicity is Grade 3, hold medication for 1 week, and re-evaluate 
 If in one week, toxicity has not resolved to Grade 1 or better, consider 
holding for one additional week, and re-evaluate 
 If the participant is unable to dose escalate after 3 weeks beyond the 
original expected escalation date, or without resolution of symptoms to 
Grade 1, maintain 500mg as final dose for the duration of the study, or 
discontinue altogether at the investigator’s discretion 
 
6.1.2 Criteria to Escalate from 1000mg to 1500mg 
 
1. Participants must not have any gastrointestinal toxicity > Grade 1 on day of anticipated 
escalation 
• If toxicity is Grade 2, hold for one week, and re-evaluate 
 If in one week, the toxicity has not resolved to Grade 1 or better, hold 
treatment for a second week and re-evaluate 
 If after the second week the toxicity has not resolved to Grade 1 or better, 
consider holding for one additional week 
 If the participant is unable to dose escalate after 3 weeks beyond the 
expected escalation date maintain at 1000mg or reduce to 500mg for the 
duration of the study or discontinue treatment at PI discretion 
• If toxicity is Grade 3, hold for 1 week, and re-evaluate 
 If in one week toxicity has not resolved to Grade 1 or better, consider 
holding for one additional week, and re-evaluate 
 If the participant is unable to dose escalate after 3 weeks beyond the 
expected escalation date, or without resolution of symptoms to Grade 1 or 
better, discontinue treatment at PI discretion. 
 
 
6.2 
Criteria to Dose Escalate - Other Toxicities 
 
For all other toxicities thought to be possibly, probably or definitely related to the study 
medication, the following guidance for dose escalation is advised: 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
23 
 
 
 
lower permanently for remainder of study. 
Grade 2 
Hold until ≤ Grade 1. Resume at one dose level lower, if indicated at 
PI discretion. 
Grade 3 
Hold until < Grade 1. Resume at 1-2 dose levels lower, if indicated at 
PI discretion. 
Grade 4 
Off protocol therapy 
* all other toxicities include any other hematologic or non-hematologic toxicity that is not listed 
specifically above. 
 
 
7. ADVERSE EVENTS: LIST AND REPORTING REQUIREMENTS 
 
Adverse event (AE) monitoring and reporting is a routine part of every clinical trial. The 
following list of reported and/or potential AEs (Section 7.1) and the characteristics of an 
observed AE (Section 7.2) will determine whether the event requires expedited reporting in 
addition to routine reporting. 
 
 
7.1 
Expected Toxicities 
 
7.1.1 Adverse Events List for Metformin 
 
Lactic acidosis is an uncommon but serious adverse event associated with metformin 
administration. The reported incidence of lactic acidosis in patients receiving metformin 
hydrochloride is very low (approximately 0.03 cases / 1000 patient/years with approximately 
0.015 fatal cases / 1000 patient/years). 
 
Other side effects include: Diarrhea, Nausea, Vomiting, Flatulence, Lack of energy/weakness 
(asthenia), Abdominal pain, Constipation, Distention of the stomach/abdomen, Dyspepsia 
(heartburn), Dizziness, Headache, Upper respiratory infection, Change or disturbance of taste 
Abnormal stools, Low blood sugar (hypoglycemia), Muscle aches (myalgias), Lightheadedness, 
Dyspnea (shortness of breath), Nail changes, Rash. Increased sweating, Chest discomfort, Chills, 
Flu-like syndrome, Flushing, and Heart palpitations 
 
7.2 
Adverse Event Characteristics 
 
• CTCAE term (AE description) and grade: The descriptions and grading scales found 
in the revised NCI Common Terminology Criteria for Adverse Events (CTCAE) version 
5.0 will be utilized for AE reporting. All appropriate treatment areas should have access 
to a copy of the CTCAE version 5.0. A copy of the CTCAE version 5.0 can be 
downloaded from the CTEP web site 
http://ctep.cancer.gov/protocolDevelopment/electronic_applications/ctc.htm. 
 
• For expedited reporting purposes only: 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
24 
 
 
 
- 
AEs for the agent(s) that are listed above should be reported only if the adverse event 
varies in nature, intensity or frequency from the expected toxicity information which 
is provided. 
- 
Other AEs for the protocol that do not require expedited reporting are outlined in the 
next section (Expedited Adverse Event Reporting) under the sub-heading of Protocol- 
Specific Expedited Adverse Event Reporting Exclusions. 
 
• Attribution of the AE: 
- 
Definite – The AE is clearly related to the study treatment. 
- 
Probable – The AE is likely related to the study treatment. 
- 
Possible – The AE may be related to the study treatment. 
- 
Unlikely – The AE is doubtfully related to the study treatment. 
- 
Unrelated – The AE is clearly NOT related to the study treatment. 
 
7.3 
Adverse Event Reporting 
 
7.3.1 In the event of an unanticipated problem or life-threatening complications treating 
investigators must immediately notify the PI. 
 
7.3.2 Investigators must report to the PI any adverse event (AE) that occurs after the initial 
dose of study treatment, during treatment, or within 30 days of the last dose of treatment 
on the local institutional SAE form. 
 
7.3.3 Adverse Event Reporting Guidelines 
 
All participating sites will report AEs to the Sponsor-Investigator per DF/HCC 
requirements, and the IRB of record for each site as applicable per IRB policies. The 
table below indicates which events must be reported to the DF/HCC Sponsor- 
Investigator. 
 
 
 CTCAE Grade 2 and Grade 3 Events – that are Unexpected and there is a 
Reasonable Possibility that the Adverse Event is related to the study intervention. 
 CTCAE Grade 4 Events – Report all events that are Unexpected. Events that are 
Expected and listed within the protocol and/or current consent form do not need 
to be reported to the DFCI IRB. Please note, an event that presents at a higher 
severity than what is currently listed within the protocol and/or current consent as 
expected would be considered unexpected and reportable. See protocol for 
additional reporting requirements (to sponsor, FDA, etc.). 
 ALL CTCAE Grade 5 Events 
 
 
7.3.4 Protocol-Specific Adverse Event Reporting Exclusions 
 
Only events that are considered possibly, probably or definitely related to the study drug 
will be captured on the database for the purpose of this study. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
25 
 
 
 
 
7.4 
Reporting to the Food and Drug Administration 
 
The Investigator will be responsible for all communications with the FDA. The Investigator will 
report to the FDA, regardless of the site of occurrence, any serious adverse event that meets the 
FDA’s criteria for expedited reporting following the reporting requirements and timelines set by 
the FDA. 
 
7.5 
Reporting to Hospital Risk Management 
 
Participating investigators will report to their local Risk Management office any participant 
safety reports, sentinel events or unanticipated problems that require reporting per institutional 
policy. 
 
7.6 
Routine Adverse Event Reporting 
 
Any Adverse Events related to metformin administration that led to dose-reductions or 
discontinuation of study medication must be reported in routine study data submissions to the PI 
on the toxicity case report forms. AEs reported through expedited processes (e.g., reported 
to the IRB, FDA, etc.) must also be reported in routine study data submissions. 
 
 
8. PHARMACEUTICAL INFORMATION 
 
A list of the adverse events and potential risks associated with the investigational agent 
administered in this study can be found in Section 7.1. 
 
8.1 
Metformin Hydrochloride 
 
8.1.1 Description 
 
Metformin HCl is a white crystalline powder soluble in water and 95% ethyl alcohol. It is 
practically insoluble in ether and in chloroform. Melting Point: 218-220 
 
Metformin HCl is a biguanide derivative producing an antihyperglycemic effect which can only 
be observed in man or in the diabetic animal and only when there is insulin secretion. Metformin, 
at therapeutic doses, does not cause hypoglycemia when used alone in man or in the non-diabetic 
animal, except when using a near lethal dose. Metformin has no effects on the pancreatic beta 
cells. Metformin absorption is relatively slow and may extend over about 6 hours. The drug is 
excreted in urine at high renal clearance rate of about 450 mL/min. The initial elimination of 
metformin is rapid with a half-life varying between 1.7 and 3 hours. The terminal elimination 
phase accounting for about 4 to 5 % of the absorbed dose is slow with a halflife between 9 and 
17 hours. Metformin is not metabolized. Its main sites of concentration are the intestinal mucosa 
and the salivary glands. The plasma concentration at steady-state ranges about 1 to 2 mcg/mL. 
Patients should be cautioned against excessive alcohol intake, either acute or chronic, when 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
26 
 
 
 
taking metformin HCl, since alcohol intake potentiates the effect of metformin on lactate 
metabolism. 
 
8.1.2 Form of Medication 
 
Metformin tablets will be purchased from commercially available source. 
 
8.1.3 Storage and Stability 
 
Metformin HCL should be stored at room temperature (15 to 30C) in well closed containers. 
 
8.1.4 Handling 
 
There are no special requirements for the handling of metformin HCl. 
 
8.1.5 Availability 
 
Metformin or it’s corresponding placebo will be provided at no cost to research participants. The 
drug/placebo combination will be purchased by research pharmacy. 
 
8.1.6 Preparation 
 
Metformin capsules and matched placebo will be prepared at DFCI Research Pharmacy. 
 
Metformin Active Drug capsules: Metformin tablets (500 mg ER) will be encapsulated in empty 
capsules (opaque, “000” size). The remaining capsule space will be filled by cellulose 
microcrystalline (NF). 
 
Matched Placebo capsules: The identical empty capsules will be filled with cellulose 
microcrystalline (NF) to prepare matched placebo capsules. 
 
6-Month Crossover Metformin Active Drug capsules: Patients will receive the metformin tablets 
(500 mg ER) directly from stock bottles within the DFCI Research Pharmacy. 
 
Active Drug and Matched Placebo capsules look identical in appearance. 
 
8.1.7 Administration 
 
The institutional research pharmacy will dispense ample medication for the duration of the 6- 
month treatment phase based on the randomization schedule provided by institutional 
statisticians and the Office of Data Quality. 
 
All subjects will be dispensed and mailed a 3-month supply of the study agent after the baseline 
visit, once eligibility is confirmed and randomization occurs. The remainder of the medication 
will be shipped at the end of cycle 3, after a safety assessment is completed. If additional study 
agent is required because of extended delays in scheduling, it may be shipped to the subject per 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
27 
 
 
 
local policies. At the end of the 6-month treatment phase at the end of study visit, the unused 
study agent will be counted for compliance and returned to the study team. 
 
For participants in the optional extended treatment (crossover arm), a 3-month supply of 
metformin will be dispensed at the 6-month visit or by mail shortly after the visit. The remainder 
of the medication will be shipped after the next safety assessment is completed (end of extended 
treatment cycle 9). If additional study agent is required because of extended delays in scheduling, 
it may be shipped to the subject per local policies. 
 
The study team may give instructions to take pills at approximately the same time of day in 
conjunction with intake of food and at least eight ounces of water and to keep track of missed 
doses or lost pills on their study diary. 
 
Participants are to be given the following drug administration instructions: 
• Keep capsules in the bottle(s) provided and do not transfer them to any other container. 
Store at room temperature. Capsules are to be taken whole, and not broken or emptied. 
• Please take your medication by mouth at the same time every day per the instructions on 
the study diary or as directed by instructions on the label of your study drug bottle. 
• Your medication should be taken with food and water, preferably in the evening to avoid 
gastrointestinal side effects. If your dose is more than one capsule, please take all 
capsules at the same time. 
• If you vomit after taking a capsule, do NOT take another dose. Please note any 
vomiting in the Comments section of the diary on the next page. 
• If you miss a dose of study drug, take it as soon as you remember on the same day. If you 
miss taking study drug for the entire day, take your regular dose the next scheduled day 
(do NOT take double your regular dose to make up for the missed dose). 
• If you miss a full dose (all of your assigned medication capsules), please record “0” for 
Number Taken on your diary 
• If you are taking 500 mg (1 capsule) and accidentally take an extra capsule, skip the 
following day’s dose and resume your assigned schedule on the third day, and record 
the extra capsule on your diary. 
• If you are taking 1000mg (2 capsules) and accidently take an extra capsule, resume 
your assigned schedule the following day and record the extra capsule on your dairy 
• If you are taking 1500mg (3 capsules) and accidently take an extra capsule, resume 
your assigned schedule the following day and record the extra capsule on your dairy 
• Please bring any unused metformin and all empty containers and diary to your next visit. 
 
8.1.8 Blinding and Unblinding Methods 
 
In the event of a serious adverse event or other circumstance requiring unblinding, the 
investigator will contact the research pharmacy, who will then unblind the subject to the 
investigator if necessary. If the treatment blind is broken, the reason and the date should be 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
28 
 
 
 
recorded and signed by the investigator. Participants will have the option to be unblinded after 
the primary outcome measures have been collected. 
 
8.1.9 Ordering and dispensing 
 
The active drug or placebo will be dispensed in blinded fashion by research pharmacy based on 
randomization result. Each bottle will be labeled with a label identifying study specific 
information, such as protocol number, dosing instructions, and a caution statement indicating 
that the agent is limited by United States law to investigational use only and the agent should be 
kept out of reach of children. 
 
For those participants who are unblinded, found to be on Metformin, and wishing to continue 
taking Metformin after the 6-month primary treatment/outcome period is complete, an unblinded 
supply of metformin will be provided. Again, each bottle will be labeled with a label identifying 
study specific information, such as protocol number, dosing instructions, and a caution statement 
indicating that the agent is limited by United States law to investigational use only and the agent 
should be kept out of reach of children. 
 
 
8.1.10 Accountability 
 
The investigator, or a responsible party designated by the investigator, should maintain a careful 
record of the inventory and disposition of the agent using the NCI Drug Accountability Record 
Form (DARF) or another comparable drug accountability form. (See the NCI Investigator’s 
Handbook for Procedures for Drug Accountability and Storage.) 
 
It is necessary to maintain a careful record of the inventory and disposition of all study agent 
using a drug accountability record form. The Investigational Pharmacy at each participating site 
is required to maintain adequate records of receipt, dispensing and final disposition of study 
agent. Include on receipt record from whom the agent was received and to whom study agent 
was shipped, date, quantity and batch or lot number. On dispensing record, note quantities and 
dates study agent was dispensed to and returned by each participant. 
 
8.1.11 Destruction and Return 
 
At the end of the treatment phase, unused or expired supplies of the study drug should be 
returned to the research pharmacy and destroyed according to institutional policies after 
accountability is performed. Destruction will be documented in the Drug Accountability Record 
Form. 
 
 
9. STUDY MEASURES 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
29 
 
 
 
9.1 
Screening/Baseline Assessments 
 
After the prospective participant signs the informed consent form, eligibility will be assessed 
including review of medical history and clinical blood tests. To minimize additional visits to 
DFCI during the COVID-19 pandemic, all in-person screening assessments as well as any 
baseline measures that require in-person collection will occur at the time of a scheduled clinical 
appointment at DFCI. 
 
All clinical blood tests to confirm eligibility will be reviewed by a clinician; any values outside 
the normal range will be discussed with the patient’s primary oncologist. Participants meeting 
eligibility criteria will be randomized to metformin or it’s corresponding placebo and ideally will 
be mailed the medication/placebo no later than 5 business days after randomization occurs unless 
a later date is requested by the participant. The participant will be instructed to begin taking the 
study medication upon receipt. 
 
9.1.1 Pregnancy Screening 
 
For women of child-bearing potential, a urine pregnancy test will be collected. A serum 
pregnancy test can be waived in certain conditions, such as post-hysterectomy. A urine or 
serum pregnancy test will only be performed as a Screening/Baseline assessment. As noted in 
Exclusion Criteria 3.2.5, “Women who are pregnant or who are unable or unwilling to use 
contraception during the study period are excluded from this study because it is a class B agent 
which is known to cross the placenta rapidly and is unbound in serum.” Although maternal use 
of metformin is generally considered safe during pregnancy and is not associated with any 
teratogenic effects to a fetus, any woman who becomes pregnant during the study period will be 
removed from treatment to avoid any unknown harm. 
 
9.2 
Final assessments 
 
 
End of Study primary outcome assessments should ideally be done within 7 days of completing 6 
months of treatment, or for those that were not able to complete 6 months of treatment, as close 
to the 6 month timepoint as possible. At this visit, a study staff member will collect pill bottles in 
person or by mail (empty and unused), participants will have 6-month research blood draw and 
clinical labs performed, bone marrow samples collected if being done as part of standard of care 
procedures, have weight measured and recorded, and be asked to complete the Final 
Questionnaire. For individuals who agree to continue to take metformin for an additional 6- 
months after primary outcomes are assessed, these secondary outcomes will ideally be done 
within 7 days of completing 12-months of treatment, or as close to that timepoint as possible. 
Similar to the 6-month assessment, a study staff member will collect pill bottles in person or by 
mail, participants will have a research blood draw and clinical labs performed, and bone marrow 
core biopsy/aspirate samples collected if being done as part of standard of care procedures. At 
this time, weight will be measured and recorded. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
31 
 
 
Specimens should be labeled with the following: 
 
• Subject Initials 
• Subject study number (will include protocol number) 
• Visit at which sample was drawn 
• Date sample drawn (mm/dd/yyyy) 
• Time sample drawn (24-hour clock) 
 
 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
33 
 
 
 
Sample Time Point 
Recipient 
Sample Type 
Shipping Method 
Container1,2 
Baseline/Pre-Treatment 
DFCI 
Peripheral Blood 
Same day delivery to 
Ghobrial Lab 
3x 10mL Purple Top 
1x6ml Red Top 
Bone Marrow Aspirate4 
2x10mL Purple 
Top1 
End of Study 
(6 month visit) 
DFCI 
Peripheral Blood 
Same day delivery to 
Ghobrial Lab 
3x 10mL Purple Top 
1x6ml Red Top 
Bone Marrow Aspirate4 
2x10mL Purple Top 
1 Purple Top= K2EDTA Tube; Red Top= No Additive 
2 Samples at these time points are voluntary, and do not exclude patients from treatment 
3 Cell Secure tubes or other tube may be used in place of listed tube types where necessary at the request of the 
Ghobrial Lab 
4 Bone marrow aspirate/biopsy only collected if being done as part of routine clinical care. These sample collections are 
highly encouraged, but are optional 
 
 
9.4.4 DNA and RNA sequencing of tumor cells from the bone marrow 
 
The "clonal evolution" model of cancer emerged amid ongoing advances in technology, especially 
in recent years during which next generation sequencing has provided ever higher resolution 
pictures of the genetic changes in cancer cells and heterogeneity in tumors where tumor 
progression proceeds in a branching rather than in a linear manner, leading to substantial clonal 
diversity and coexistence of wide genetic heterogeneity49,50. The genomic complexity in MM was 
recently corroborated by massive parallel-sequencing studies displaying the lack of a universal 
driving mutation35. Recent studies have shown intraclonal heterogeneity that occurs at different 
stages of MM36,37. Most recently, exome sequencing confirmed that the heterogeneity observed in 
MM and how it is likely to be an essential feature of clonal evolution and disease progression51,52. 
Although treatment is very effective in MM patients nowadays; however, new resistant clones may 
arise in certain patients causing disease relapse and resistance to maintenance treatment. Moreover, 
the recent advances in RNA sequencing technologies, like single cell RNA(ScRNA) sequencing 
is now enabling us to better understand the composition and state of the tumor microenvironment 
including immune cells and stromal cells. ScRNA sequencing coupled with bulk RNA sequencing 
will allow us to accurately identify expression levels of CD38 and other proteins on both tumor 
and immune cells at different time points, and how this would affect treatment response and disease 
course. 
 
Circulating cell-free DNA (cfDNA) and tumor cells (CTCs) are considered emerging and 
promising approaches to capture the genomic landscape and heterogeneity of the tumor cells in 
bone marrow, but from blood samples. We published a proof of concept study in Nature 
Communication on how blood biopsies were good surrogates for the mutational profile in bone 
marrow. We plan to expand on this by studying serial samples from patients throughout treatment 
as a tool for detecting minimal residual disease and new mutations that can rise during treatment. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
34 
 
 
 
We plan to perform exome sequencing and RNA sequencing studies on tumor cells obtained at the 
time of screening as well as from subsequent bone marrow biopsy samples to examine clonal 
heterogeneity, resistant clones at best response and at time of end of study or at disease progression. 
 
The tumor research samples will be collected at the time of scheduled bone marrow biopsies. From 
these samples, high quality DNA and RNA for both exome sequencing and RNA sequencing of 
tumor cells will be obtained. In brief, BM aspirates will be obtained after informed consent. The 
tumor cells will be collected using CD138+ bead selection (over 90% purity based on prior 
publications)35,36. For samples that have a small fraction of plasma cells, we will use flow sorting 
for CD138/CD38/CD56 and CD19-ve to obtain a pure malignant plasma cell population based on 
prior published markers of malignant plasma cells55. 
 
WES of tumor and germline DNA 
 
WES will be performed on all samples pre and post-treatment on the clinical trial to study clonal 
evolution of malignant cells. DNA will be isolated and libraries will be hybridized to Illumina 
human whole exome capture kit as previously described. All sequencing studies will be performed 
at the Genomic Platform of the Broad Institute. Samples will be multiplexed and sequenced on 
Illumina Novaseq to obtain an average depth of coverage of 175x for tumors and 70x for germlines 
to have enough sensitivity for mutation detection 41. 
 
9.4.3 WGS of tumor and germline DNA 
 
Considering the emerging importance of structural variants like, jumping translocations 
involving important oncogenes, Chromothripsis, and Chromoplexy in MM, we will use an 
innovative approach to study translocations in MM by low pass WGS (12x mean coverage). 
Libraries will be prepared using new HiseqX technology (Illumina®) which offers long range 
phased (i.e. barcoded) reads which enable much more accurate structural characterization. 
Libraries will be sequenced on a HiSeq X Ten sequencer available at the Broad Institute. This 
will be performed on the same samples of WES. 
 
9.4.4 Targeted deep sequencing: 
 
To be able to analyze small sub-clones, we will design a specific hybrid capture targeted panel of 
baits to detect the main MM drivers by deep sequencing. This panel includes exons of 
significantly mutated genes in MM as well as those identified in WES of our samples, baits on 
the main CNA regions (17p, 1q, 13q) and baits on the IGH, IGL, IGK and MYC loci, enabling 
us to detect somatic mutations, CNAs and translocations. The total size of the bait set is 2Mb. 
This will be used for samples at the time of best response and in those samples that do not have 
enough DNA for WES or WGS. Libraries will be prepared using Agilent’s SureSelect XT library 
prep kit and hybridized to a customized targeted bait set. Samples will be multiplexed and 
sequenced on Illumina Novaseq with the goal of an average depth of coverage of 1500x to have 
enough sensitivity for mutation detection at low allelic fraction (1%)41. 
 
9.4.5 Computational analysis and expected outcome. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
35 
 
 
 
All bioinformatics and statistical analyses will be performed with guidance of the biostatistics 
and bioinformatics Core B. Briefly, BAM files aligned to the hg19 human genome will be 
produced using Illumina sequencing reads and the Picard pipeline42. SNVs will be determined 
using the MuTect2 algorithm43, in single mode for targeted sequencing with additional filters for 
mutation call such as 1000 genome and COSMIC mutations. Indels and translocations will be 
determined by the algorithms IndelLocator37 and dRanger, respectively. Focal as well as arm- 
level copy number variations will be determined based on WES and subsequent application of 
the GISTIC44 algorithm. We will use MutSigCV45 to detect candidate cancer genes using three 
signals of positive selection: (i) increased mutation burden as compared to a background model; 
(ii) clustering of mutations along the gene; and (iii) enrichment of mutations at likely functional 
sites. The output of MutSigCV consists of a list of the most significantly genomic events across 
samples. False-discovery rates (q values) ≤ 0.1 will be considered as significantly mutated. All 
candidate SNVs/indels/CNVs will be reviewed in the IGV46. 
 
9.4.6 
RNA sequencing of tumor cells. 
 
For RNA Sequencing, poly-A selection and cDNA synthesis will be performed, followed by 
library preparation, sequencing (76bp or 101bp paired reads), and sample identification with 
quality control. Details of experimental design are described in62,63-65. We will perform library 
construction using a non-strand specific Illumina TruSeq Protocol and sequence coverage to 100M 
total reads. Analysis will be performed as described in the preliminary data and in previous 
studies63-65. 
 
The DNA and or RNA library will be prepared at the Ghobrial Lab, and then sequencing will be 
done at the following external lab: 
Broad Institute Genomics Services 
320 Charles Street 
Cambridge, MA 02141 
 
Sequencing data will then be provided back to Ghobrial lab in the form of BAM file. The 
samples that are sent for analysis are exhausted during the process, and thus not able to be 
returned. 
 
 
9.4.7 
Single-cell sequencing of the tumor microenvironment. 
 
Single-cell RNA sequencing (RNA-seq) of the tumor microenvironment can define genotypic and 
phenotypic states of tumor cells and surrounding microenvironment, and that the 
microenvironment affected the gene expression program of tumor cells and their resistance to 
therapy. We will apply 10X genomics in this study to evaluate the tumor microenvironment and 
assess specific changes in cell type and transcriptional signature of BM niche cells that correlate 
with tumor progression or resistance to therapy. 
 
9.4.8 cfDNA and circulating tumor cells (CTCs) from the peripheral blood. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
36 
 
 
 
cfDNA sequencing can be challenging because of the small fragment size of DNA in the peripheral 
blood (average of 166bp), the low yield of DNA and the usual low allelic fraction of tumor-derived 
DNA among the cfDNA. Therefore, we developed two different approaches to sequence cfDNA. 
The first approach applies WES and is performed by the Blood Biopsy Group at the Broad Institute. 
After high-speed centrifugation of frozen samples to eliminate residual cells from plasma, cfDNA 
was extracted using the Qiagen circulating nucleic acid kit. As little as 5ng of cfDNA was then 
subjected to library preparation using the Kapa HyperPlus kit, which enables us to prepare libraries 
from small DNA fragments and minimal DNA yield. CfDNA libraries were initially qualified for 
further sequencing using ultra-low-pass whole genome sequencing (ULP- WGS). The ULP-WGS 
is a low-cost approach developed by the Blood Biopsy Group to nominate samples containing 
sufficient tumor fraction in cfDNA samples for WES. Large numbers of cfDNA libraries were 
multiplexed and sequenced to an average of 0.1X genome-wide sequencing coverage. 
 
9.4.9 Whole-exome sequencing of cfDNA and CTCs: 
 
These studies will be performed at the Blood Biopsy Group at the Broad Institute in collaboration. 
As described in the preliminary data, cfDNA and CTCs will be subjected to library preparation 
using the Kapa HyperPlus kit and initially qualified for WES by ULP-WGS. The ULP-WGS will 
be used to nominate samples containing sufficient fraction of tumor-derived DNA for WES. 
Qualified matched samples will be hybridized to the Agilent XT v5 enrichment kit, with additional 
baits on MYC, IGH, IGL and IGK loci. For both cfDNA and CTCs, the coverage goal will be 
increased to 200x, which enables us to accurately call mutations even with low allelic fraction 
samples. 
 
All analyses concerning the ULP-WGS will be performed by the bioinformatics team of the Getz 
Lab and Blood Biopsy Group at the Broad Institute. WES analyses will be performed through the 
FireCloud, including MuTect43, IndelLocator37, dRanger, GISTIC2.044 and ABSOLUTE18 
algorithms to evaluate SNVs, Indels, translocations, CNVs and mutated cancer fractions. We will 
further study the correlation of mutated cancer fractions between matched cfDNA, CTCs and 
BM tumor cells for each patient to characterize the mutational spectrum in the 3 compartments; 
thus identify their overlapping landscape as well as their potential specificities. Based on our 
preliminary data, we expect to identify in cfDNA and CTCs more than 80% of the somatic 
mutations present in BM. 
 
9.4.10 Metabolomics 
 
Blood and bone marrow supernatant samples will be sent to Metabolon for quantification using 
the Global Metabolomic Platform, which consists of four independent methods: ultrahigh 
performance liquid chromatography/tandem mass spectrometry (UHLC-MS/MS) with positive ion 
mode electrospray ionization, UPLC-MS/MS with negative ion mode electrospray ionization, and 
UPLC-MS/MS polar platform (negative ionization).65 LC-MS will be performed on a Waters 
ACQUITY ultra-performance liquid chromatography (UPLC) and a Thermo Scientific Q-Exactive 
high resolution/accurate mass spectrometer interfaced with a heated electrospray ionization (HESI- 
II) source and Orbitrap mass analyzer operated at 35,000 mass resolution. All analytes will undergo 
quality control and curation processes, which are designed to ensure accurate, consistent 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
37 
 
 
 
identification, and to minimize system artifacts, mis-assignments, and background noise.65 Library 
matches for each compound will be verified for each sample. It is notable that the median intraclass 
correlations between duplicate samples on Metabolon’s platform has been shown to be 0.96 (25th 
– 75th percentile: 0.82–0.99), and the average coefficient of variation across all named metabolites 
has been shown to be 0.16 (25th – 75th percentile: 0.06–0.20).66 
 
Metabolite features will be analyzed as measures of peak areas, which are proportional to feature 
concentration and can be compared for any given metabolite. The metabolite variables will be 
standardized to a mean of 0 and standard deviation of 1. 
 
9.4.11 Longer-Term Benefit 
It is notable that the vast majority of interventions investigated in clinical trials have involved 
aggressive pharmacologic agents. The proposed trial is the first to examine preliminary evidence 
of efficacy that metformin is a low-risk strategy to prevent progression in this population of higher- 
risk MGUS and low-risk SMM patients. Although we are powered to detect small but clinically 
relevant between group differences in M-protein concentrations from baseline to six months, we 
acknowledge the possibility that a six-month treatment period is too short in some patients to 
demonstrate a clinical benefit. To maximize the learning opportunity but maintain the rigor of the 
trial’s short-term primary endpoints, we will allow participants to become unblinded after the 
primary outcome assessments are complete and participants randomized to the metformin arm of 
the study will be invited to continue to take metformin for an additional six months. 
 
We will descriptively report the number of participants randomized to the metformin arm who 
wish to continue taking metformin, which will provide an assessment of participant’s willingness 
to take metformin for longer-term risk-reduction. In addition, we will utilize well-established 
measures of response to therapy using a modified version of the International Myeloma Working 
Group Response Criteria defined below, as well as mass spectrometry-based estimates of minimal 
residual disease. 
 
 
 
 
 
Response 
Criteria for Response 
Complete 
Response (CR) 
Negative immunofixation on the serum and <5% plasma cells in 
bone marrow (if performed clinically), or normalization of serum 
free light chain ratio if followed by serum free light chain. 
Normalization is defined as the serum free light chain ratio being 
within the normal range. If the serum free light chain ratio is not 
within the normal range, but the individual kappa and lambda light 
chain values are within normal range, this may be considered CR. 
Very Good 
Partial 
Response 
Serum M-protein detectable by immunofixation but not on 
electrophoresis or 90% or greater reduction in serum M-protein. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
38 
 
 
 
(VGPR) 
Partial 
Response (PR) 
> 50% reduction of serum M-protein. 
If only measurable parameter is serum immunoglobulins free light 
chain (FLC), EITHER of the following changes qualify as partial 
response: 
- A 50% decrease in the difference between involved and 
uninvolved FLC levels; OR 
- A 50% decrease in the level of involved FLC AND a 50% 
decrease (normalization) in the ratio of involved/uninvolved FLC 
Stable Disease 
(SD) 
Not meeting criteria for CR, VGPR, PR or progressive 
disease. 
 
 
 
10. STUDY CALENDAR 
 
Registration and randomization should be conducted within 28 days (4 weeks) of baseline 
assessments. The 3-month safety labs should ideally be performed within 7 days of scheduled 
day 84 (preferably before). End of study/6- (or 12-) month assessment should ideally be 
completed within 7 days of last dose of study drug for those who completed 6 (or 12) months of 
treatment, or for those who were not able to complete 6 months of treatment, within 7 days of the 
6 month timepoint or as close as feasible. Assessments must be performed prior to administration 
of any study agent and only after signing consent unless done as part of standard of care 
procedure. Each cycle is defined as 28 days. 
> 25% increase of serum M-protein (which must also be an absolute 
increase of > 0.5 g/dL). PD is also measured by an absolute 
increase in bone marrow plasma cells > 10%. If only measurable 
parameter is serum immunoglobulins free light (FLC), either of the 
following qualify as progression: 
- 50% increase in the difference between involved and uninvolved 
FLC levels from the lowest response level, which must also be an 
absolute increase of at least 10 mg/dL; OR 
- 50% increase in the level of involved FLC AND a 50% increase 
in the ratio of involved/uninvolved FLC from the lowest response 
level. 
Progressive 
Disease (PD) 

40 
 
 
DFCI Protocol #: 21-008 
Version Date: 02AUG2022 
 
Survival and Event 
Collection11 
X 
N/A 
1 Enough drug will be supplied for 3 cycles at a time. Labs will be reviewed prior to shipment of any medication. Participants may be shipped drug directly to 
their home following local policy, and will be instructed to return any unused drug, empty bottles, and completed diaries in pre-labeled return packaging to the 
lead site if they do not present in person to clinic. 
2 Study staff will contact the participant on day 7, day 28, and Day 168 (+/-3 days) to document AEs and assess study adherence. Day 48 is optional at the 
discretion of the clinical team. AEs and adherence will also be assessed at the End of Study Visit. Generally, End of Study assessments will be done in person, 
and interim assessments will be made by telephone, however exceptions can be made given COVID-19 precautions. 
3 Questionnaires may be completed in person, through RedCap, by mail, or other acceptable method. 
4 Physical exams may be waived or modified due to COVID precautions or travel restrictions with approval from a study MDbut if done, should include review 
of critical body systems. 
5 Labs will be drawn as part of routine care and may include WBC with differential, Hgb, platelet count and ANC, as determined by the patient’s clinical team. 
6 Labs will be drawn as part of routine care, and may include sodium, potassium, chloride, bicarbonate, BUN, creatinine, calcium, glucose, albumin, ALT 
(SGPT), total protein, AST (SGOT), total bilirubin, magnesium, phosphorus, B2M, and LDH, as determined by the patient’s clinical team. The only labs that are 
required at the 3-month timepoint are AST, ALT, bilirubin, creatinine, and glucose, to ensure patient safety. These select safety labs are also required to determine 
eligibility. 
7 Research bone marrow samples are not required but highly encouraged. If a bone marrow aspirate is performed at any time following consent, please 
refer to sample collection section 9.4 for biobanking protocols. 
8 Research blood sample collection at the time of routine clinical blood draw any time prior to treatment – Please refer to Sample Collection Table in section 9.4 
9 Adverse events should be collected up to 30 days after the last dose of study drug. Any event that is thought related to metformin should be followed until 
resolution or stabilization. 
10 End of Study assessments should ideally be done within 7 days of completing 6 months of treatment, or for those that were not able to complete 6 months of 
treatment, as close to the 6 month timepoint as possible, ideally within 7 days. 
11 Survival status and data relating to disease response, treatment and status may be collected for up to 5 years from end of treatment. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
42 
 
 
 
11. DATA REPORTING / REGULATORY REQUIREMENTS 
 
Adverse event lists, guidelines, and instructions for AE reporting can be found in Section 7.0 
(Adverse Events: List and Reporting Requirements). 
 
11.1 Data Reporting 
 
11.1.1 Method 
 
The DF/HCC Office of Data Quality (ODQ) will collect, manage, and perform quality checks 
on the data for this study. 
 
11.1.2 Responsibility for Data Submission 
 
Investigative sites are responsible for submitting data and/or data forms to the Office of Data 
Quality (ODQ) in accordance with DF/HCC policies. 
 
 
11.2 Data Safety Monitoring 
 
The DF/HCC Data and Safety Monitoring Board (DSMB) will review and monitor study 
progress, toxicity, safety and other data from this study. The Board is chaired by a medical 
oncologist from outside of DF/HCC and its membership composed of internal and external 
institutional representation. Information that raises any questions about participant safety or 
protocol performance will be addressed by the Sponsor-Investigator, statistician and study team. 
Should any major concerns arise, the DSMB will offer recommendations regarding whether or 
not to suspend the study. 
 
The DSMB will meet twice a year to review accrual, toxicity, response and reporting 
information. Information to be provided to the DSMB may include: participant accrual; 
treatment regimen information; all adverse events and serious adverse events reported across all 
sites by category; summary of any deaths on study; audit results; and a summary provided by the 
study team. Other information (e.g. scans, laboratory values) will be provided upon request. 
 
12. STATISTICAL METHODS 
 
12.1 Study Design/Endpoints Sample Size and Power 
 
 
We powered the study to detect clinically meaningful changes in the primary endpoint of M- 
protein and levels.67-69 To facilitate precise baseline calculations, we ascertained M-protein level 
data from a representative clinical sample of MGUS and SMM patients at Dana-Farber. 
Accordingly, assuming a standard deviation of 0.99 g/dL, a type I error rate of 0.05, 60 
participants will provide 80% statistical power to detect a between group difference of 0.73 g/dL, 
and 90% power to detect a between group difference of 0.84 g/dL which are considered 
clinically meaningful changes.69-71 Specifically, a change of 0.73 g/dL indicates that we are 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
43 
 
 
 
powered to detect > a 10% change in M-protein within the 6-month intervention period. Notably, 
a 10% change is consistent with the definition of “evolving M-protein” concentrations by Ravi et 
al and others68 and evolving M-protein concentrations of this magnitude are associated with a 
shorter time to progressing than patients with non-evolving disease. It is also notable that 
although this trial should have a minimal drop-out rate or MM-defining events (and need to 
initiate standard MM treatment) during the 6-month intervention period. 
 
 
12.2 Statistical Analysis 
 
The primary hypothesis being tested in this trial is that patients randomized to metformin will 
experience a significant reduction in M-protein levels compared to patients randomized to the 
placebo. This parameter has been selected as the primary endpoint because of its known clinical 
utility in predicting progression to overt MM in MGUS and SMM patients;67-69 Changes in this 
endpoint will be evaluated from baseline to follow-up in the two groups using a repeated 
measures mixed-effects model that accounts for the correlation between baseline and follow-up 
measures and is generally robust to missing data. The baseline value of the dependent variable 
(M-protein level) and disease subtype will be included as covariates in the regression models. 
Group-by-time interaction terms will be included as fixed-effects in the regression model. Model 
fit will be assessed using standard methods. Primary analysis of this endpoint will utilize 
stratified testing and intention-to-treat methods, using data from all participants randomized to an 
intervention group.72 Secondary/exploratory analyses will evaluate the influence of metformin on 
M-protein level in a per-protocol analysis. 
 
A study project manager who is not involved in the statistical analysis will request information 
on treatment allocation from the DFCI Research Pharmacy. The Research Pharmacy is permitted 
to give the project manager information after the trial is closed to accrual and data collection on 
primary endpoints have been completed. However, all individuals performing the statistical 
analysis will remain blind to treatment group (metformin vs. placebo) for the primary outcome 
analysis. 
 
 
12.3 Sample Size, Accrual Rate and Study Duration 
 
Our estimated target accrual is 60 participants over 24 months, which requires a monthly accrual 
of 3-4 participants per month. Our goal for accrual into the study is 4 or more participants per 
month. Up to an additional 6 months of follow-up will be required on the last participant accrued 
to observe the participant’s response after the 6 months of taking metformin/placebo, for a total 
study duration of 2.5 years. Estimated accrual targets are provided below: 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
44 
 
 
 
 
 
 
Ethnic Category 
Sex/Gender 
Females 
Males 
Total 
Hispanic or Latino 
1 
+ 
2 
= 
Not Hispanic or Latino 
30 
+ 
27 
= 
Ethnic Category: Total of all subjects 
(A1) + 
(B1) = 
(C1) 
Racial Category 
American Indian or Alaskan Native 
1 
+ 
1 
= 
Asian 
2 
+ 
1 
= 
Black or African American 
4 
+ 
4 
= 
Native Hawaiian or other Pacific 
Islander 
0 
+ 
1 
= 
White 
24 
+ 
22 
= 
Racial Category: Total of all subjects 
(A2) + 
(B2) = 
(C2) 
 
(A1 = A2) 
(B1 = B2) 
(C1 = C2) 
Accrual Targets 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
45 
 
 
 
12.4 Stratification Factors 
 
Randomization will be stratified by disease stage (MGUS vs. SMM) and heavy- vs light-chain 
status. 
 
12.5 Interim Monitoring Plan 
 
Refer to section 11.2 
 
12.6 Analysis of Primary Endpoints 
 
Refer to section 12.2 
 
12.7 Analysis of Secondary Endpoints 
The secondary endpoint of this trial will be changes in a variety of biomarkers detailed in section 
1.2. Changes in continuous variable outcomes will be evaluated from baseline to follow-up in the 
two groups using a repeated measures mixed-effects model that accounts for the correlation 
between baseline and follow-up measures and is generally robust to missing data. The baseline 
value of the dependent variable and disease subtype will be included as covariates in the regression 
models. Group-by-time interaction terms will be included as fixed-effects in the regression model. 
Model fit will be assessed using standard methods. All primary analyses will utilize stratified 
testing and intention-to-treat methods.72 
For changes in gene expression patterns, the precise methods are subject to change pending 
advancements in technology, but a general overview is provided below: 
 
Paired-ended reads will be aligned against UCSC hg19 human annotation using Tophat 2.0.10; 
read counts for each gene will be determined using HTSeq 0.5.4. A subset of cells with more 
than 100,000 total reads across all genes will be selected for further analysis (70-80% of cells). 
To determine population average gene expression, the read counts observed in each cell will be 
normalized by the effective library size, determined by edgeR ‘calcNormFactors’ method. NMF- 
based consensus clustering will be used to cluster all single-cell RNA profiles. We will use 
coexpression networks-based gene prioritization tool GRAIL 
(https://www.broadinstitute.org/mpg/grail/) to select the most promising genes using gene 
expression signature as seeds. Cufflinks and Cuffdiff will be used to identify differentially 
expressed genes between the treatment arms.73 
 
Metabolite features will be analyzed as measures of peak areas, which are proportional to 
feature concentration and can be compared for any given metabolite. The metabolite variables 
will be standardized to a mean of 0 and standard deviation of 1. 
 
For optional treatment extenders, this analysis is exploratory. We will assess the proportion of 
participants who are willing to take metformin for an additional 6 months. We will also evaluate 
response, duration of response, and depth of response according to modified IMWG criteria, or 
by mass spectrometry assessment. 
 
 
12.8 Reporting and Exclusions 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
46 
 
 
 
As mentioned in 12.2, all primary analyses will utilize intention-to-treat methods. 
 
12.9 Stopping Rules for Safety 
 
All participants will be evaluable for treatment-related toxicity from the time of therapy initiation 
to 30 days after the last dose of study treatment. The severe adverse event is defined as grade 4/5 
hematologic or non-hematologic AEs that are considered related to study treatment. 
 
We anticipate that the rate of SAE is low in this study population. However, if 2 or more SAEs 
(as defined above) are observed at any time in the first 20 enrolled, further patient enrollment 
will be paused. 
 
In addition to the above, the study team will also halt accrual for analysis and safety review at 
any time if the following Grade 4 or 5 toxicities are observed: 
 
• Grade 4 hematologic adverse event (AEs) thought to be related to the study combination 
• Grade 4 non-hematologic AEs thought to be related to the study combination with the 
exception of Grade 4 diarrhea that rapidly responds to best supportive care. 
 
In addition to the events listed above, the study team will halt accrual for analysis and safety 
review at any time the following treatment-related deaths are observed: 
• Grade 5 hematologic adverse events (AEs) thought to be related to the study drug 
• Grade 5 non-hematologic AEs thought to be related to the study drug 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
47 
 
 
 
 
13. PUBLICATION PLAN 
 
The results should be made public within 24 months of reaching the end of the study. The end of 
the study is the time point at which the last data items are to be reported, or after the outcome 
data are sufficiently mature for analysis, as defined in the section on Sample Size, Accrual Rate 
and Study Duration. If a report is planned to be published in a peer-reviewed journal, then that 
initial release may be an abstract that meets the requirements of the International Committee of 
Medical Journal Editors. A full report of the outcomes should be made public no later than three 
(3) years after the end of the study. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
48 
 
 
 
14. REFERENCES 
 
1. 
Howlander N, Noon AM, Krapacho M, et al. SEER Cancer Statistics Review, 1975-2013, 
National Cancer Institute. Bethesda, MD, http://seer.cancer.gov/csr/1975_2013/, based on 
November 2015 SEER data submission, posted to the SEER web site, April 2016. 
2. 
Kyle RA, Therneau TM, Rajkumar SV, et al. Prevalence of monoclonal gammopathy of 
undetermined significance. The New England journal of medicine 2006; 354(13): 1362-9. 
3. 
Kyle RA, Durie BG, Rajkumar SV, et al. Monoclonal gammopathy of undetermined 
significance (MGUS) and smoldering (asymptomatic) multiple myeloma: IMWG consensus 
perspectives risk factors for progression and guidelines for monitoring and management. 
Leukemia 2010; 24(6): 1121-7. 
4. 
Landgren O. Monoclonal gammopathy of undetermined significance and smoldering 
multiple myeloma: biological insights and early treatment strategies. Hematology / the Education 
Program of the American Society of Hematology American Society of Hematology Education 
Program 2013; 2013: 478-87. 
5. 
Kyle RA, Durie BG, Rajkumar SV, et al. Monoclonal gammopathy of undetermined 
significance (MGUS) and smoldering (asymptomatic) multiple myeloma: IMWG consensus 
perspectives risk factors for progression and guidelines for monitoring and management. 
Leukemia 2010; 24(6): 1121-7. 
6. 
Gregersen H, Ibsen J, Mellemkjoer L, Dahlerup J, Olsen J, Sorensen HT. Mortality and 
causes of death in patients with monoclonal gammopathy of undetermined significance. Br J 
Haematol 2001; 112(2): 353-7. 
7. 
Kristinsson SY, Bjorkholm M, Andersson TM, et al. Patterns of survival and causes of 
death following a diagnosis of monoclonal gammopathy of undetermined significance: a 
population-based study. Haematologica 2009; 94(12): 1714-20. 
8. 
Kyle RA, Rajkumar SV. Management of monoclonal gammopathy of undetermined 
significance (MGUS) and smoldering multiple myeloma (SMM). Oncology (Williston Park) 
2011; 25(7): 578-86. 
9. 
Go RS, Rajkumar SV. How I manage monoclonal gammopathy of undetermined 
significance. Blood 2018; 131(2): 163-73. 
10. 
Kyle RA, Rajkumar S. Monoclonal gammopathy of undetermined significance and 
multiple myeloma. JAMA Oncology 2015; 1(2): 174-5. 
11. 
Salem KZ, Ghobrial IM. The road to cure in multiple myeloma starts with smoldering 
disease. Expert Opin Orphan Drugs 2015; 3(6). 
12. 
Korde N, Roschewski M, Zingone A, et al. Treatment With Carfilzomib-Lenalidomide- 
Dexamethasone With Lenalidomide Extension in Patients With Smoldering or Newly Diagnosed 
Multiple Myeloma. JAMA Oncol 2015; 1(6): 746-54. 
13. 
Mateos MV, Hernandez MT, Giraldo P, et al. Lenalidomide plus dexamethasone for 
high-risk smoldering multiple myeloma. The New England journal of medicine 2013; 369(5): 
438-47. 
14. 
Caers J, Fernandez de Larrea C, Leleu X, et al. The Changing Landscape of Smoldering 
Multiple Myeloma: A European Perspective. Oncologist 2016; 21(3): 333-42. 
15. 
Ghobrial IM, Landgren O. How I treat smoldering multiple myeloma. Blood 2014; 
124(23): 3380-8. 
16. 
Rajkumar SV, Landgren O, Mateos M-V. Smoldering multiple myeloma. Blood 2015; 
125(20): 3069-75. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
49 
 
 
 
17. 
Kumar SK. Timing of treatment of smoldering myeloma: delay until progression. Blood 
Adv 2018; 2(21): 3050-3. 
18. 
Hampton T. Researchers probe targeted agents' clinical potential for cancer prevention. 
JAMA 2010; 303(2): 115-6. 
19. 
Libby G, Donnelly LA, Donnan PT, Alessi DR, Morris AD, Evans JM. New users of 
metformin are at low risk of incident cancer: a cohort study among people with type 2 diabetes. 
Diabetes Care 2009; 32(9): 1620-5. 
20. 
Goodwin PJ, Pritchard KI, Ennis M, Clemons M, Graham M, Fantus IG. Insulin-lowering 
effects of metformin in women with early breast cancer. Clin Breast Cancer 2008; 8(6): 501-5. 
21. 
Goodwin PJ, Stambolic V. Impact of the obesity epidemic on cancer. Annu Rev Med 
2015; 66: 281-96. 
22. 
Diabetes Prevention Program Research G. Long-term safety, tolerability, and weight loss 
associated with metformin in the Diabetes Prevention Program Outcomes Study. Diabetes Care 
2012; 35(4): 731-7. 
23. 
Zi FM, He JS, Li Y, et al. Metformin displays anti-myeloma activity and synergistic 
effect with dexamethasone in in vitro and in vivo xenograft models. Cancer Lett 2015; 356(2 Pt 
B): 443-53. 
24. 
Jagannathan S, Abdel-Malek MA, Malek E, et al. Pharmacologic screens reveal 
metformin that suppresses GRP78-dependent autophagy to enhance the anti-myeloma effect of 
bortezomib. Leukemia 2015; 29(11): 2184-91. 
25. 
Dalva-Aydemir S, Bajpai R, Martinez M, et al. Targeting the metabolic plasticity of 
multiple myeloma with FDA-approved ritonavir and metformin. Clin Cancer Res 2015; 21(5): 
1161-71. 
26. 
Bornstein S, Moschetta M, Kawano Y, et al. Metformin Affects Cortical Bone Mass and 
Marrow Adiposity in Diet-Induced Obesity in Male Mice. Endocrinology 2017; 158(10): 3369- 
85. 
27. 
Gamez B, Edwards CM. Contributions of the Bone Microenvironment to Monoclonal 
Gammopathy of Undetermined Significance Pathogenesis. Curr Osteoporos Rep 2018; 16(6): 
635-41. 
28. 
Chang SH, Luo S, O'Brian KK, et al. Association between metformin use and 
progression of monoclonal gammopathy of undetermined significance to multiple myeloma in 
US veterans with diabetes mellitus: a population-based retrospective cohort study. Lancet 
Haematol 2015; 2(1): e30-6. 
29. 
Boursi B, Mamtani R, Yang YX, Weiss BM. Impact of metformin on the progression of 
MGUS to multiple myeloma. Leuk Lymphoma 2017; 58(5): 1265-7. 
30. 
Golombick T, Diamond TH, Manoharan A, Ramakrishna R. Monoclonal gammopathy of 
undetermined significance, smoldering multiple myeloma, and curcumin: a randomized, double- 
blind placebo-controlled cross-over 4g study and an open-label 8g extension study. Am J 
Hematol 2012; 87(5): 455-60. 
31. 
Ross DM, To LB, Horvath N. Assessment of early paraprotein response to vincristine- 
doxorubicin-dexamethasone chemotherapy may help guide therapy in multiple myeloma. Intern 
Med J 2004; 34(9-10): 576-8. 
32. 
Schaar CG, Kluin-Nelemans JC, le Cessie S, Franck PF, te Marvelde MC, Wijermans 
PW. Early response to therapy and survival in multiple myeloma. Br J Haematol 2004; 125(2): 
162-6. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
50 
 
 
 
33. 
Shah J, Blade J, Sonneveld P, et al. Rapid early monoclonal protein reduction after 
therapy with bortezomib or bortezomib and pegylated liposomal doxorubicin in 
relapsed/refractory myeloma is associated with a longer time to progression. Cancer 2011; 
117(16): 3758-62. 
34. 
Mills JR, Kohlhagen MC, Dasari S, et al. Comprehensive Assessment of M-Proteins 
Using Nanobody Enrichment Coupled to MALDI-TOF Mass Spectrometry. Clin Chem 2016; 
62(10): 1334-44. 
35. 
Mills JR, Barnidge DR, Dispenzieri A, Murray DL. High sensitivity blood-based M- 
protein detection in sCR patients with multiple myeloma. Blood Cancer J 2017; 7(8): e590. 
36. 
Hanahan D, Weinberg RA. Hallmarks of cancer: the next generation. Cell 2011; 144(5): 
646-74. 
37. 
Swann JB, Smyth MJ. Immune surveillance of tumors. J Clin Invest 2007; 117(5): 1137- 
46. 
38. 
Quail DF, Joyce JA. Microenvironmental regulation of tumor progression and metastasis. 
Nat Med 2013; 19(11): 1423-37. 
39. 
Ursini F, Russo E, Pellino G, et al. Metformin and Autoimmunity: A "New Deal" of an 
Old Drug. Front Immunol 2018; 9: 1236. 
40. 
Dhodapkar MV. MGUS to myeloma: a mysterious gammopathy of underexplored 
significance. Blood 2016; 128(23): 2599-606. 
41. 
Li L, Wang L, Li J, et al. Metformin-Induced Reduction of CD39 and CD73 Blocks 
Myeloid-Derived Suppressor Cell Activity in Patients with Ovarian Cancer. Cancer Res 2018; 
78(7): 1779-91. 
42. 
Pryor R, Cabreiro F. Repurposing metformin: an old drug with new tricks in its binding 
pockets. Biochem J 2015; 471(3): 307-22. 
43. 
Beger RD. A review of applications of metabolomics in cancer. Metabolites 2013; 3(3): 
552-74. 
44. 
Kim YS, Maruvada P, Milner JA. Metabolomics in biomarker discovery: future uses for 
cancer prevention. Future Oncology 2008; 4(1): 93-102. 
45. 
Rattray NJW, Deziel NC, Wallach JD, et al. Beyond genomics: understanding 
exposotypes through metabolomics. Human Genomics 2018; 12(1): 4. 
46. 
Ludwig C, Williams DS, Bartlett DB, et al. Alterations in bone marrow metabolism are 
an early and consistent feature during the development of MGUS and multiple myeloma. Blood 
Cancer Journal 2015; 5: e359. 
47. 
Piszcz J, Lemancewicz D, Dudzik D, Ciborowski M. Differences and similarities 
between LC-MS derived serum fingerprints of patients with B-cell malignancies. 
Electrophoresis 2013; 34(19): 2857-64. 
48. 
Kuliszkiewicz-Janus M, Baczynski S. Chemotherapy-associated changes in 31P MRS 
spectra of sera from patients with multiple myeloma. NMR Biomed 1995; 8(3): 127-32. 
49. 
Lodi A, Tiziani S, Khanim FL, et al. Proton NMR-based metabolite analyses of archived 
serial paired serum and urine samples from myeloma patients at different stages of disease 
activity identifies acetylcarnitine as a novel marker of active disease. PLoS One 2013; 8(2): 
e56422. 
50. 
Puchades-Carrasco L, Lecumberri R, Martinez-Lopez J, et al. Multiple myeloma patients 
have a specific serum metabolomic profile that changes after achieving complete remission. Clin 
Cancer Res 2013; 19(17): 4770-9. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
51 
 
 
 
51. 
Steiner N, Muller U, Hajek R, et al. The metabolomic plasma profile of myeloma patients 
is considerably different from healthy subjects and reveals potential new therapeutic targets. 
PLoS One 2018; 13(8): e0202045. 
52. 
Anderson NM, Mucka P, Kern JG, Feng H. The emerging role and targetability of the 
TCA cycle in cancer metabolism. Protein Cell 2018; 9(2): 216-37. 
53. 
Hsu PP, Sabatini DM. Cancer Cell Metabolism: Warburg and Beyond. Cell 2008; 134(5): 
703-7. 
54. 
Doerstling SS, O'Flanagan CH, Hursting SD. Obesity and Cancer Metabolism: A 
Perspective on Interacting Tumor-Intrinsic and Extrinsic Factors. Front Oncol 2017; 7: 216. 
55. 
Janzer A, German NJ, Gonzalez-Herrera KN, Asara JM, Haigis MC, Struhl K. Metformin 
and phenformin deplete tricarboxylic acid cycle and glycolytic intermediates during cell 
transformation and NTPs in cancer stem cells. Proc Natl Acad Sci U S A 2014; 111(29): 10574- 
9. 
56. 
Griss T, Vincent EE, Egnatchik R, et al. Metformin Antagonizes Cancer Cell 
Proliferation by Suppressing Mitochondrial-Dependent Biosynthesis. PLoS Biol 2015; 13(12): 
e1002309. 
57. 
Liu X, Romero IL, Litchfield LM, Lengyel E, Locasale JW. Metformin Targets Central 
Carbon Metabolism and Reveals Mitochondrial Requirements in Human Cancers. Cell Metab 
2016; 24(5): 728-39. 
58. 
Ramanathan A, Schreiber SL. Direct control of mitochondrial function by mTOR. Proc 
Natl Acad Sci U S A 2009; 106(52): 22229-32. 
59. 
Shimobayashi M, Hall MN. Making new contacts: the mTOR network in metabolism and 
signalling crosstalk. Nat Rev Mol Cell Biol 2014; 15(3): 155-62. 
60. 
Shaw RJ, Lamia KA, Vasquez D, et al. The kinase LKB1 mediates glucose homeostasis 
in liver and therapeutic effects of metformin. Science 2005; 310(5754): 1642-6. 
61. 
Hildebrandt MAT, Callender RA, Belachew AA, et al. Quality of life and cancer worry in 
a follow-up cohort of patients with asymptomatic monoclonal gammopathies. Journal of Clinical 
Oncology 2018; 36(15_suppl): 8049-. 
62. 
Maatouk I, He S, Hummel M, et al. Patients with precursor disease exhibit similar 
psychological distress and mental HRQOL as patients with active myeloma. Blood Cancer J 
2019; 9(2): 9. 
63. 
Korde N, Kristinsson SY, Landgren O. Monoclonal gammopathy of undetermined 
significance (MGUS) and smoldering multiple myeloma (SMM): novel biological insights and 
development of early treatment strategies. Blood 2011; 117(21): 5573-81. 
64. 
Rajkumar SV, Landgren O, Mateos MV. Smoldering multiple myeloma. Blood 2015. 
65. 
Evans A, Bridgewater B, Liu Q, et al. High resolution mass spectrometry improves data 
quantity and quality as compared to unit mass resolution mass spectrometry in high-throughput 
profiling metabolomics. Metabolomics 2014; 4(132). 
66. 
Dougan MM, Li Y, Chu LW, et al. Metabolomic profiles in breast cancer:a pilot case- 
control study in the breast cancer family registry. BMC Cancer 2018; 18(1): 532. 
67. 
Fernández de Larrea C, Isola I, Pereira A, et al. Evolving M-protein pattern in patients 
with smoldering multiple myeloma: impact on early progression. Leukemia 2018; 32(6): 1427- 
34. 
68. 
Ravi P, Kumar S, Larsen JT, et al. Evolving changes in disease biomarkers and risk of 
early progression in smoldering multiple myeloma. Blood Cancer J 2016; 6(7): e454. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
52 
 
 
 
69. 
Rosinol L, Cibeira MT, Montoto S, et al. Monoclonal gammopathy of undetermined 
significance: predictors of malignant transformation and recognition of an evolving type 
characterized by a progressive increase in M protein size. Mayo Clin Proc 2007; 82(4): 428-34. 
70. 
Atrash S, Robinson M, Slaughter D, et al. Evolving changes in M-protein and 
hemoglobin as predictors for progression of smoldering multiple myeloma. Blood Cancer J 
2018; 8(11): 107. 
71. 
Rosinol L, Blade J, Esteve J, et al. Smoldering multiple myeloma: natural history and 
recognition of an evolving type. Br J Haematol 2003; 123(4): 631-6. 
72. 
Gupta SK. Intention-to-treat concept: A review. Perspect Clin Res 2011; 2(3): 109-12. 
73. 
Trapnell C, Williams BA, Pertea G, et al. Transcript assembly and quantification by 
RNA-Seq reveals unannotated transcripts and isoform switching during cell differentiation. Nat 
Biotechnol 2010; 28(5): 511-5. 

DFCI Protocol #: 21-008 Version Date: 06FEB2024 
53 
 
 
 
APPENDIX A 
PERFORMANCE STATUS CRITERIA 
 
ECOG Performance Status Scale 
Karnofsky Performance Scale 
Grade 
Descriptions 
Percent 
Description 
 
0 
Normal activity. Fully active, able 
to carry on all pre-disease 
performance without restriction. 
100 
Normal, no complaints, no evidence 
of disease. 
90 
Able to carry on normal activity; 
minor signs or symptoms of disease. 
 
 
1 
Symptoms, but ambulatory. 
Restricted in physically strenuous 
activity, but ambulatory and able 
to carry out work of a light or 
sedentary nature (e.g., light 
housework, office work). 
80 
Normal activity with effort; some 
signs or symptoms of disease. 
70 
Cares for self, unable to carry on 
normal activity or to do active work. 
 
 
2 
In bed <50% of the time. 
Ambulatory and capable of all 
self-care, but unable to carry out 
any work activities. Up and about 
more than 50% of waking hours. 
60 
Requires occasional assistance, but 
is able to care for most of his/her 
needs. 
50 
Requires considerable assistance and 
frequent medical care. 
 
3 
In bed >50% of the time. Capable 
of only limited self-care, confined 
to bed or chair more than 50% of 
waking hours. 
40 
Disabled, requires special care and 
assistance. 
30 
Severely disabled, hospitalization 
indicated. Death not imminent. 
 
4 
100% bedridden. Completely 
disabled. Cannot carry on any 
self-care. Totally confined to bed 
or chair. 
20 
Very sick, hospitalization indicated. 
Death not imminent. 
10 
Moribund, fatal processes 
progressing rapidly. 
5 
Dead. 
0 
Dead.