The following discussion and analysis of our financial condition and results of operations should be read in conjunction with the financial statements and notes appearing elsewhere in this Quarterly Report on Form 10-Q. In addition to historical financial information, the following discussion contains forward-looking statements that reflect our plans, estimates and beliefs. Some of the numbers included herein have been rounded for the convenience of presentation. As a result of many factors, including those factors set forth in the "Risk Factors" section of this Quarterly Report, our actual results could differ materially from the results described in, or implied by, these forward-looking statements.

Overview

We are a clinical stage biotechnology company pioneering a new class of therapeutics and seeking to develop functional cures for patients with chronic diseases by providing stable and durable levels of therapeutic molecules to patients. We have developed our Shielded Living Therapeutics, or SLTx, platform, which combines advanced cell engineering with cutting-edge innovations in biocompatible materials and enables our product candidates to produce a wide range of therapeutic molecules that may be missing or deficient, such as proteins (including therapeutic proteins and antibodies) and hormones. We are designing our product candidates to be off-the-shelf, durable, controllable and redosable, without requiring modification of the patient's genes or complete suppression of the patient's immune system.

Since our inception, we have devoted substantially all of our efforts to raising capital, obtaining financing, filing and prosecuting patent applications, organizing and staffing our company and incurring research and development costs related to advancing our biomedical platform. We do not have any products approved for sale and have not generated any revenue from product sales. To date, we have funded our operations primarily with proceeds from sales of common stock and convertible preferred stock, payments received under our collaboration agreement with Lilly and proceeds from borrowings under our credit facilities. Through June 30, 2022, we have received gross proceeds of $144.9 million from the sale of common stock in the IPO, $142.4 million from sales of our convertible preferred stock and net proceeds of $19.8 million through borrowings under our loan and security agreement with Oxford Finance LLC, or the 2020 Credit Facility, partially offset by the $15.0 million repayment of debt from our 2019 Credit Facility. We have also partnered one of our encapsulation technology programs with Lilly. Under the terms of the partnership, we received an upfront payment of $62.5 million and we are eligible to receive additional milestone payments of up to $165.0 million upon achievement of certain regulatory milestones and payments of up to $250.0 million upon achievement of sales-based milestones for SIG-002. We are also eligible to receive tiered royalty payments in the mid-single digit to low-double digit percentages based on certain sales thresholds. Finally, Lilly is obligated to reimburse us for costs incurred to perform the research and development activities for the first developed product candidate, including costs incurred over $47.5 million.

We have incurred significant operating losses since our inception. Our ability to generate any product revenue sufficient to achieve profitability will depend on the successful development and eventual commercialization of one or more of our product candidates. We reported a net loss of $14.3 million and $28.2 million for the three and six months ended June 30, 2022. As of June 30, 2022, we had an accumulated deficit of $241.4 million and cash, cash equivalents and marketable securities totaling $88.2 million. Based on our current operating plans, we believe our cash will be sufficient to fund our anticipated level of operations, capital expenditures and satisfy debt repayments for a period of at least 12 months from the issuance date of this Quarterly Report. We expect to generate operating losses for the foreseeable future. Accordingly, we will seek additional funding through equity financings, debt financing, or additional collaboration agreements. If we are unable to raise additional funds through equity financing, debt financings or additional collaboration agreements we may be required to delay, limit, reduce or terminate product development or future commercialization efforts or grant rights to develop and market products or product candidates that we would otherwise prefer to develop and market itself.

Our Shielded Living Therapeutics Platform and Prioritized Areas of Development

Our SLTx platform is comprised of two primary elements: the cells and the sphere. We engineered cells to express the therapeutic molecule of choice, which are subsequently encapsulated in our proprietary spheres. Our human cell line for our internal product candidates was selected for its safety, durability, scalability and engineerability, which has been extensively tested in preclinical and clinical settings. The spheres are composed of an Afibromer outer layer, an alginate



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conjugated with a novel, proprietary anti-fibrotic small molecule, which was derived from 10 years of work in the MIT labs of Professors Robert Langer and Daniel Anderson. We developed an inner compartment consisting of a proprietary conjugation of alginate and peptide molecules to enhance cell survival and productivity.

Modularity, a key attribute of our SLTx platform, is comprised of three pillars: the cells, the sphere and the manufacturing process. In addition to the cells and the sphere described above, we have also spent significant time and resources to create a state-of-the-art modular manufacturing platform for all potential product candidates developed using our cell and sphere components. This cost-effective manufacturing platform is designed to provide a true "off-the-shelf" product for patients. Furthermore, virtually all aspects of the platform, from raw materials to processing steps, are shared across our development programs, enabling a potentially streamlined path from discovery to clinical trials.

In December 2021, we announced a strategic reprioritization focusing our development efforts on mucopolysaccharidosis type 1, or MPS-1, diabetes and platform optimization. Our programs and most advanced clinical-stage and pre-clinical product candidates are outlined below:

MPS-1: SIG-005 is our product candidate that contains a cell line genetically modified with a non-viral vector to express human ?-L-iduronidase, or IDUA, encapsulated within our spheres. SIG-005 is being developed to treat the non-neurological manifestations of mucopolysaccharidosis type 1, or MPS-1, in patients with the disease. We were granted Orphan Drug designation for SIG-005 for the treatment of MPS-1 by the U.S. Food and Drug Administration, or FDA, in December 2020 and by the European Commission in October 2021. We have completed pre-IND and scientific advisory meetings with the FDA, the Medicines and Healthcare products Regulatory Agency, or MHRA, and the Brazilian Health Regulatory Agency, or ANVISA. We received a Clinical Trial Application, or CTA, clearance, for SIG-005 in the United Kingdom in the third quarter of 2021 and a CTA acceptance for SIG-005 in Brazil in the first quarter of 2022. Subject to our ongoing investigations, prior to initiating this study, we expect to submit amendments to the CTAs for SIG-005 in the United Kingdom and Brazil in the second half of 2022.

We believe our product candidates for lysosomal diseases can leverage the well understood mechanism of enzyme replacement therapies, or ERTs, by using engineered cells to express functional human enzyme or other protein that more closely resemble normal physiology in a continuous manner. We are also developing next-generation product candidates to address the neurological manifestations of lysosomal diseases, starting with MPS-1, using transporter molecules designed to penetrate the blood brain barrier and molecules designed to extend plasma half-life.

Diabetes: SIG-002 is our product candidate designed to replace islet cells for the treatment of Type 1 Diabetes, or T1D. In T1D, the immune system attacks and destroys the insulin-producing beta cells within the endocrine islets of the pancreas. Insulin deficiency results in dysregulation of glucose metabolism. In April 2018, we partnered with Eli Lilly and Company, or Lilly, to develop cell therapies for the treatment of T1D, including SIG-002. Under the terms of the partnership, we are currently leading execution of the program through Investigational New Drug, or IND, submission and Lilly, a global leader in diabetes, will develop and commercialize the program worldwide. We expect to conduct IND-enabling studies for SIG-002 in 2023.

Platform optimization: We are continuing to optimize our Shielded Living Therapeutics, or SLTx, platform, which combines advanced cell engineering with cutting-edge innovations in biocompatible materials to pioneer a new class of therapeutics. In November 2021, we reported that spheres covered with pericapsular fibrotic overgrowth, or PFO, were observed during a retrieval procedure in its Phase 1/2 study of SIG-001 in severe or moderately severe hemophilia A. With the modularity of the SLTx platform, we are evaluating changes designed to modulate or otherwise reduce the potential for a patient's immune response to our product candidates, including SIG-005.

Impact of COVID-19

The COVID-19 pandemic has impacted and may continue to impact the clinical sites and startup activities for our Phase 1/2 clinical trials, including third-party manufacturing and logistics providers, which would disrupt our clinical supply chain or the availability or cost of materials, and it may affect our ability to timely complete our clinical trials and



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delay the initiation and/or enrollment of any future clinical trials, disrupt regulatory activities or have other adverse effects on our business and operations.

We are monitoring the potential impact of the COVID-19 pandemic on our business and financial statements. We cannot be certain what the overall impact of the COVID-19 pandemic will be on our business and prospects. The extent to which the COVID-19 pandemic will directly or indirectly impact our business, results of operations, financial condition and liquidity, including planned and future clinical trials and research and development costs, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19, the actions taken to contain or treat it, the effects of any variants as new strains evolve, vaccination efforts, and the duration and intensity of the related effects.

Components of Results of Operations

Revenue

To date, we have not generated any revenue from product sales and do not expect to generate any revenue from the sale of products in the near future. Substantially all of our revenue to date has been derived from the collaboration agreement with Lilly, which we entered into in 2018.

If our development efforts for our product candidates are successful and result in regulatory approval or if we enter into license or collaboration agreements with third parties, we may generate revenue in the future from product sales, payments from license or collaboration agreements that we may enter into with third parties, or any combination thereof. We expect that our revenue for the next several years will be derived primarily from our collaboration agreement with Lilly as well as any additional collaborations that we may enter into in the future. We cannot provide assurance as to the timing of future milestone or royalty payments or that we will receive any of these payments at all.

Collaboration Revenue

In April 2018, we entered into a License and Collaboration Agreement with Lilly, or the 2018 Lilly Agreement. Under the 2018 Lilly Agreement, we granted Lilly an exclusive worldwide, royalty-bearing license, including the right to grant sublicenses, to our encapsulation technology applied to islet cells. We are responsible for our own costs and expenses associated with pre-clinical development of a product candidate, and completion of the studies and other criteria required for filing the first IND, up to $47.5 million; provided, however, pursuant to an amendment to the 2018 Lilly Agreement entered in May 2022, Lilly may take on certain research and development activities, at its own cost and expense, including supply and manufacturing activities. Lilly is responsible for filing the first IND, all subsequent clinical development and commercialization, all research, development and commercialization for any subsequent product candidates, as well as reimbursing us for research and development costs required for filing the first IND related to the first developed product candidate that exceed $47.5 million.

We evaluated the 2018 Lilly Agreement under ASC 606 and concluded at the outset that there were two performance obligations under the arrangement: (1) exclusive license to research, develop, manufacture and commercialize licensed products, initial technology transfer, research activities (including pre-IND supply), cell line development and supply and product trademark election, or the Combined Performance Obligation; and (2) requirement to supply Lilly with the licensed product related to Phase 1 clinical trial, or Phase 1 Supply. We determined that the $62.5 million upfront payment represents the entirety of the consideration to be included in the transaction price as of the outset of the arrangement. We allocated $56.6 million of the transaction price to the Combined Performance Obligation and $5.9 million of the transaction price to the Phase 1 Supply at the outset of the arrangement. We recognize revenue for the Combined Performance Obligation as the research and development services are provided using an input method, based on the cumulative costs incurred compared to the total estimated costs expected to be incurred to satisfy the Combined Performance Obligation. The transfer of control to the customer occurs over the time period that the research and development services are to be provided by us, and this cost-to-cost method is, in management's judgment, the best measure of progress toward satisfying this performance obligation. We have determined that the Phase 1 Supply will be satisfied at a point in time when the customer obtains control of each unit of product. Therefore, we will recognize revenue as shipments of the Phase 1 Supply are made to Lilly.



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We reevaluate the transaction price and our total estimated costs expected to be incurred at the end of each reporting period and as uncertain events, such as changes to the expected timing and cost of certain research, development and manufacturing activities that we are responsible for, are resolved or other changes in circumstances occur, and, if necessary, we will adjust our estimate of the transaction price or our total estimated costs expected to be incurred.

Additional information regarding the 2018 Lilly Agreement can be found in Note 8 to our financial statements in this Quarterly Report on Form 10-Q.

Operating Expenses

Research and Development Expenses

Research and development expenses consist primarily of costs incurred for our research activities, including our drug discovery efforts and the development of our platform and product candidates. We expense research and development costs as incurred, which include:

employee-related expenses, including salaries, bonuses, benefits, stock-based

? compensation, other related costs for those employees involved in research and

development efforts;

expenses incurred in connection with the clinical and preclinical development

? of our product candidates and research programs, including under agreements

with third parties, such as consultants, contractors, and CROs;

the cost of raw materials and developing and scaling our manufacturing process

? and manufacturing product candidates for use in our research and preclinical

studies, including under agreements with third parties, such as consultants,

contractors, and CMOs;

? laboratory supplies and research materials;

? facilities, depreciation, and other expenses, which include direct and

allocated expenses for rent and maintenance of facilities and insurance; and

? payments made under third-party licensing agreements.

We expense research and development costs as incurred. Non-refundable advance payments that we make for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered. Upfront payments under license agreements are expensed upon receipt of the license, and annual maintenance fees under license agreements are expensed in the period in which they are incurred. Milestone payments under license agreements are accrued, with a corresponding expense being recognized, in the period in which the milestone is determined to be probable of achievement and the related amount is reasonably estimable.

Our direct external research and development expenses are tracked on a program-by-program basis, including our early-stage programs, and consist of costs that include fees, reimbursed materials, and other costs paid to consultants, contractors, contract manufacturing organizations or CMOs, and contract research organizations or CROs, in connection with our preclinical and manufacturing activities. Except for personnel expenses related to SIG-002, we do not allocate employee costs, costs associated with our discovery efforts, laboratory supplies and facilities expenses, including depreciation or other indirect costs, to specific product development programs because these costs are deployed across multiple programs and our platform and, as such, are not separately classified. The personnel expenses allocated to SIG-002 do not include stock-based compensation expense.



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Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later stage clinical trials. We expect that our research and development expenses will increase substantially in connection with our planned preclinical and clinical development activities in the near term and in the future. At this time, we cannot accurately estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any of our product candidates. The successful development and commercialization of our product candidates is highly uncertain. This is due to the numerous risks and uncertainties associated with product development and commercialization, including the following:

? investigation of the preliminary results from our Phase 1/2 clinical trial for

SIG-001, including the finding of spheres with PFO and the reported SAE;

? the timing and progress of preclinical and clinical development activities;

? the number and scope of preclinical and clinical programs we decide to pursue;

? raising additional funds necessary to complete preclinical and clinical

development of and commercialize our product candidates;

? the progress of the development efforts of parties with whom we may enter into

collaboration arrangements;

? our ability to maintain our current research and development programs and to

establish new ones;

? our ability to establish new licensing or collaboration arrangements;

the successful initiation and completion of clinical trials with safety,

? tolerability and efficacy profiles that are satisfactory to the FDA, or any

comparable foreign regulatory authority;

? the receipt and related terms of regulatory approvals from applicable

regulatory authorities;

? the availability of raw materials for use in production of our product

candidates;

? our ability to consistently manufacture our product candidates for use in

clinical trials;

? our ability to establish and operate a manufacturing facility, or secure

manufacturing supply through relationships with third parties;

? our ability to obtain and maintain patents, trade secret protection and

regulatory exclusivity, both in the United States and internationally;

? our ability to protect our rights in our intellectual property portfolio;

? the commercialization of our product candidates, if and when approved;

? obtaining and maintaining third-party insurance coverage and adequate

reimbursement;

? the acceptance of our product candidates, if approved, by patients, the medical

community and third-party payors;

? competition with other products; and

? a continued acceptable safety profile of our therapies following approval.




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A change in the outcome of any of these variables with respect to the development of any of our product candidates could significantly change the costs and timing associated with the development of these product candidates. We may never succeed in obtaining regulatory approval for any of our product candidates.

General and Administrative Expenses

General and administrative expenses consist primarily of salaries and personnel expenses, including stock-based compensation, for our personnel in executive, legal, finance and accounting, human resources, and other administrative functions. General and administrative expenses also include legal fees relating to patent and corporate matters; professional fees paid for accounting, auditing, consulting, and tax services; insurance costs; travel expenses; and facility costs not otherwise included in research and development expenses.

We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support our continued research activities and development of our product candidates. We also anticipate that we will incur significantly increased accounting, audit, legal, regulatory, compliance and director and officer insurance costs as well as investor and public relations expenses associated with operating as a public company. Additionally, if and when we believe a regulatory approval of a product candidate appears likely, we anticipate an increase in payroll and other employee-related expenses as a result of our preparation for commercial operations, especially as it relates to the sales and marketing of that product candidate.

Other Income (Expense)

Interest Income

Interest income consists of interest earned on our cash, cash equivalents and marketable securities balances. We expect our interest income will fluctuate based on the timing and ability to raise additional funds as well as the amount of expenditures for our platform development and ongoing business operations.

Interest Expense

Interest expense consists of interest expense on outstanding borrowings under our loan and security agreements as well as amortization of debt discount and deferred financing costs.

Other Income (Expense)

Other expense consists primarily of losses on the disposal of fixed assets, net foreign exchange losses and net sublease income from subleasing a portion of our facilities.

Income Taxes

Since our inception in 2015, we have not recorded any U.S. federal or state income tax benefits for the net losses we have incurred in each year or our earned research and development tax credits, due to our uncertainty of realizing a benefit from those items. We did not provide for any income taxes in the six months ended June 30, 2022 or 2021.

Critical Accounting Estimates

Our condensed consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States. The preparation of these condensed consolidated financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, costs and expenses, and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates on historical experience, known trends and events, and various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We evaluate our estimates and assumptions on an ongoing basis. Our actual results may differ from these estimates under different assumptions or conditions. The accounting estimates and policies discussed in our Annual Report on Form



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10-K for the fiscal year ended December 31, 2021, filed with the SEC on March 14, 2022, or the Annual Report, are considered by management to be the most important to an understanding of the consolidated financial statements because of their significance to the portrayal of our financial condition and results of operations. There have been no material changes to that information disclosed in our Annual Report on Form 10-K for the year ended December 31, 2021 filed with the SEC on March 14, 2022.

Results of Operations

Comparison of the Three Months ended June 30, 2022 and 2021

The following table summarizes our results of operations for the three months ended June 30, 2022 and 2021:



                                      Three Months Ended
                                          June 30,               Increase
                                      2022          2021        (Decrease)

                                        (in thousands)
Revenue
Collaboration revenue              $    2,883    $    2,704    $        179
Operating expenses:
Research and development               11,877        17,751         (5,874)
General and administrative              5,042         4,992              50
Total operating expenses               16,919        22,743         (5,824)
Loss from operations                 (14,036)      (20,039)           6,003
Other income (expense):
Interest income                           178            71             107
Interest expense                        (543)         (494)            (49)
Other expense                              55            25              30
Total other expense, net                (310)         (398)              88

Net loss and comprehensive loss $ (14,346) $ (20,437) $ 6,091

Revenue

Revenue was $2.9 million for the three months ended June 30 2022, compared to 2.7 million for the three months ended June 30, 2021. The increase in revenue of $0.2 million was due to the timing of costs of the activities performed under the 2018 Lilly Agreement. We recognize revenue under the 2018 Lilly Agreement based on the input method and as the costs incurred increased by $0.3 million from the three months ended June 30, 2021 to the three months ended June 30, 2022, which was offset by the increase in the total estimated costs expected to be incurred.



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Research and Development Expenses

The following table summarizes our research and development expenses for the three months ended June 30, 2022 and 2021:



                                                             Three Months Ended
                                                                 June 30,              Increase
                                                              2022         2021       (Decrease)

                                                               (in thousands)

Direct research and development expenses by program: SIG­005

$    2,551    $  1,777    $        774
SIG­002                                                         2,650       2,137             513
SIG­001                                                         1,011       1,545           (534)
SIG­007                                                             8         938           (930)
Platform and pipeline development                               2,430       5,876         (3,446)

Unallocated expenses Personnel expenses (including stock­based compensation) 2,563 4,370 (1,807) Facility related and other

                                        664       1,108           (444)
Total research and development expenses                    $   11,877    $ 17,751    $    (5,874)

Research and development expenses were $11.9 million for the three months ended June 30, 2022, compared to $17.8 million for three months ended June 30, 2021. The decrease in research and development expenses was primarily related to decreased ongoing platform and pipeline development activities, personnel expenses and our SIG-007 program and SIG-001 programs, which were offset by increases in our SIG-005 and SIG-002 programs. The decrease in platform and pipeline development, personnel expenses and SIG-007 and the increase in SIG-005 and SIG-002 is primarily due to our reprioritization of the development of MPS-1, diabetes and platform optimization following the Company's restructuring activities in December 2021.

General and Administrative Expenses

General and administrative expenses for each of the three months ended June 30, 2022 and 2021 were $5.0 million.

Other expense, net

Other expense, net, was $0.3 million for the three months ended June 30, 2022, compared to $0.4 million for the three months ended June 30, 2021. The decrease was primarily due to increased interest income associated with our marketable securities.



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Comparison of the Six Months ended June 30, 2022 and 2021

The following table summarizes our results of operations for the six months ended June 30, 2022 and 2021:



                                  Six Months Ended
                                     June 30,              Increase
                                 2022          2021       (Decrease)

                                   (in thousands)
Revenue
Collaboration revenue         $    6,048    $    5,662    $       386
Operating expenses:
Research and development          23,495        33,736       (10,241)
General and administrative        10,066        10,532          (466)
Total operating expenses          33,561        44,268       (10,707)
Loss from operations            (27,513)      (38,606)         11,093
Other income (expense):
Interest income                      242           157             85
Interest expense                 (1,034)         (982)           (52)
Other income (expense):              100            21             79
Total other expense, net           (692)         (804)            112
Net loss                      $ (28,205)    $ (39,410)    $    11,205


Revenue

Revenue was $6.0 million for the six months ended June 30, 2022, compared to $5.7 million for the six months ended June 30, 2021. The increase in revenue of $0.4 million was due to the timing of costs of the activities performed under the 2018 Lilly Agreement. We recognize revenue under the 2018 Lilly Agreement based on the input method and as the costs incurred increased by $0.5 million from the six months ended June 30, 2021 to the six months ended June 30, 2022, which was offset by the increase in the total estimated costs expected to be incurred.

Research and Development Expenses

The following table summarizes our research and development expenses for the six months ended June 30, 2022 and 2021:



                                                             Six Months Ended
                                                                June 30,            Increase
                                                             2022        2021      (Decrease)

                                                              (in thousands)

Direct research and development expenses by program: SIG­005

$  4,422    $  3,341    $     1,081
SIG­002                                                       5,376       4,753            623
SIG­001                                                       2,468       3,126          (658)
SIG­007                                                         204       1,633        (1,429)
Platform and pipeline development                             4,436      10,336        (5,900)

Unallocated expenses Personnel expenses (including stock­based compensation) 5,075 8,400 (3,325) Facility related and other

                                    1,514       2,147          (633)
Total research and development expenses                    $ 23,495    $ 33,736    $  (10,241)

Research and development expenses were $23.5 million for the six months ended June 30, 2022, compared to $33.7 million for six months ended June 30, 2021. The decrease in research and development expenses was primarily



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related to decreased ongoing platform and pipeline development activities, personnel expenses and our SIG-007 and SIG-001 programs, which were offset by increases in our SIG-005 and SIG-002 programs. The decrease in platform and pipeline development, personnel expenses, SIG-001 and SIG-007 and the increase in SIG-005 and SIG-002 is primarily due to our reprioritization of the development of MPS-1, diabetes and platform optimization following the Company's restructuring activities in December 2021.

General and Administrative Expenses

General and administrative expenses for the six months ended June 30, 2022 were $10.1 million, compared to $10.5 million for the six months ended June 30, 2021. General and administrative expenses for the six months ended June 30, 2022 compared to June 30, 2021 decreased by $0.4 million as a result of decreased personnel expenses primarily in connection with our restructuring activities that occurred in December 2021.

Other expense, net

Other expense, net, was $0.7 million for the six months ended June 30 2022, compared to $0.8 million for the three months ended June 30, 2021. The decrease was primarily due to increased interest income associated with our marketable securities.

Liquidity and Capital Resources

Sources of Liquidity

Since our inception, we have incurred significant operating losses. We have not yet commercialized any of our product candidates and we do not expect to generate revenue from sales of any product candidates for the foreseeable future, if at all. To date, we have funded our operations primarily with proceeds from sales of common stock, convertible preferred stock, payments received under our collaboration agreement with Lilly and proceeds from borrowings under our credit facilities. Through June 30, 2022, we had received net proceeds of $131.8 million from the sale of common stock in the IPO, $141.9 million from the net sales of our convertible preferred stock and net proceeds of $19.8 million through borrowings under the 2020 Credit Facility. We have also partnered one of our encapsulation technology programs with Lilly. Under the terms of the partnership, we received an upfront payment of $62.5 million and we are eligible to receive additional milestone payments of up to $165.0 million upon achievement of certain regulatory milestones and sales-based milestones of up to $250.0 million for SIG-002. We are also eligible to receive tiered royalty payments in the mid-single digit to low-double digit percentages based on certain sales thresholds. Finally, Lilly is obligated to reimburse us for costs incurred to perform the research and development activities for the first developed product candidate that exceed $47.5 million. We are also eligible to receive additional payments upon the achievement of specified regulatory and sales milestones and royalty payments. As of June 30, 2022, we had cash, cash equivalents and marketable securities of $88.2 million.

On April 14, 2022, we entered into an Equity Distribution Agreement with Canaccord Genuity LLC, or Canaccord, pursuant to which we may issue and sell shares of common stock, from time to time, having an aggregate offering price of up to $10.0 million. Sales of common stock through Canaccord may be made by any method that is deemed an "at the market" offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended. We are not obligated to make any sales of its common stock under the Equity Distribution Agreement. Any sales under the Equity Distribution Agreement will be made pursuant to our registration statement on Form S-3 (File No 333- 264296), which became effective on April 22, 2022 and the prospectus relating to such offering.



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Cash Flows

The following table summarizes our sources and uses of
cash, cash equivalents and restricted cash for each of the
periods presented:8.2
                                                                   Six Months Ended
                                                                      June 30,
                                                                  2022          2021

                                                                    (in thousands)
Net cash used in operating activities                          $ (34,269)    $ (38,660)
Net cash used in investing activities                            (38,377)         (997)
Net cash provided by financing activities                              48             9

Net decrease in cash, cash equivalents and restricted cash $ (72,598) $ (39,648)

Operating Activities

During the six months ended June 30, 2022, operating activities used $34.3 million of cash, primarily resulting from our net loss of $28.2 million and net cash used in changes in our operating assets and liabilities of $12.3 million, partially offset by non-cash charges of $6.2 million. Net changes in our operating assets and liabilities for the six months ended June 30, 2022 consisted primarily of a $6.0 million decrease in deferred revenue, $3.5 million decrease in accounts payable and accrued expenses and other current liabilities, $2.3 million decrease in lease liabilities, $0.9 million decrease in prepaid expenses and other current assets, $0.3 million increase in other liabilities and less than $0.1 million increase in accounts receivable. The decrease in deferred revenue was due to recognition of revenue related to our collaboration agreement. The decrease in accounts payables and accrued expenses and other current liabilities was the result of timing of payments for services performed by our vendors. The decrease in lease liabilities was primarily due to payment of rent for our leased property. The decrease in prepaid expenses and other current assets were the result of timing of payments for services to be performed in future periods. The decrease in accounts payables and accrued expenses and other current liabilities was the result of timing of payments for services performed by our vendors. The increase in accounts receivable was the result of timing of collections.

During the six months ended June 30, 2021, operating activities used $38.7 million of cash, primarily resulting from our net loss of $39.4 million and net cash used in changes in our operating assets and liabilities of $6.0 million, partially offset by non-cash charges of $6.7 million. Net changes in our operating assets and liabilities for the six months ended June 30, 2021 consisted primarily of a $5.5 million decrease in deferred revenue, a $2.5 million decrease in lease liabilities and a $1.9 million increase in prepaid expenses and other current assets, partially offset by a $3.0 million increase in accounts payable and a $0.9 million increase in accrued expenses and other current liabilities. The decrease in deferred revenue was due to recognition of revenue related to our collaboration agreement. The increases in prepaid expenses and other current assets were the result of timing of payments for services to be performed in future periods. The increase in accounts payables and accrued expenses and other current liabilities was the result of timing of payments for services performed by our vendors. The decrease in lease liabilities was primarily due to payment of rent for our leased property.

Investing Activities

During the six months ended June 30, 2022, cash used in investing activities was $38.4 million and consisted mainly of $38.0 million of net purchases of marketable securities and $0.5 million in purchases of laboratory equipment and furniture and fixtures, offset by proceeds from the sale of fixed assets of $0.2.

During the six months ended June 30, 2021, net cash used in investing activities was $1.0 million and consisted of purchases of laboratory equipment and furniture and fixtures.

Financing Activities

During the six months ended June 30, 2022, cash provided by financing activities was less than $0.1 million and consisted of proceeds from employee equity plans.



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During the six months ended June 30, 2021, net cash provided by financing activities was less than $0.1 million. The cash provided by financing activities consisted of $0.6 million of proceeds from the exercise of common stock options and was offset by $0.6 million for the payment of deferred offering costs associated with our initial public offering.

Loan and security agreement

In September 2020, we entered into the 2020 Credit Facility, with Oxford Finance LLC, or Oxford, and paid off in full our borrowings under the 2019 Credit Facility with a portion of the proceeds from the 2020 Credit Facility. The 2020 Credit Facility provided for an initial term loan borrowing in an aggregate amount of $20.0 million. The Company elected not to borrow any additional eligible borrowings under the 2020 Credit Facility. Borrowings under the 2020 Credit Facility bear interest at an annual rate equal to the greater of 8.40% and the sum of U.S. Dollar LIBOR rate reported on the Wall Street Journal plus 8.23%.

Borrowings under the 2020 Credit Facility are collateralized by substantially all of our personal property, other than our intellectual property. There are no financial covenants associated with the 2020 Credit Facility; however, we are subject to certain affirmative and negative covenants to which we will remain subject until maturity. These covenants include limitations on dispositions, mergers or acquisitions; encumbering our intellectual property; incurring indebtedness or liens; paying dividends; making certain investments; and engaging in certain other business transactions. Obligations under the 2020 Credit Facility are subject to acceleration upon the occurrence of specified events of default, including a material adverse change in our business, operations or financial or other condition.

As of June 30, 2022 and December 31, 2021, the interest rate applicable to borrowings under the 2020 Credit Facility was 9.35% and 8.40%, respectively.

As of June 30, 2022, we were in compliance with all covenants pursuant to the 2020 Credit Facility. We cannot be assured that we will be able to obtain additional covenant waivers or amendments in the future which may have a material adverse effect on our results or operations or liquidity.

Funding requirements

We expect our expenses to increase substantially in connection with our ongoing activities, particularly as we advance the preclinical activities and clinical trials for our product candidates in development. In addition, we expect to continue to incur additional cost associated with operating as a public company. The timing and amount of our operating and capital expenditures will depend largely on:

the costs of our investigation of the serious adverse event and PFO reported in

? our Phase 1/2 clinical trial for SIG-001 in Hemophilia A and the costs of

additional preclinical or clinical studies as may be requested by the FDA;

the cost of patient treatment for medical events related to the serious adverse

? event reported in our Phase 1/2 clinical trial for SIG-001 if and when we are

asked to pay for such treatments;

the costs of continuing to develop our SLTx platform, including the cost of any

? changes to our cells, spheres or manufacturing processes and the costs of any

additional preclinical studies we may conduct as a result of our ongoing

investigation into the results of our Phase 1/2 clinical trial of SIG-001;

? the costs of acquiring licenses for the components and engineered cell lines

that will be used with our current and future product candidates;

the scope, progress, results, and costs of discovery, preclinical development,

? formulation development, and clinical trials for our current and future product


   candidates;


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the costs of preparing, filing, and prosecuting patent applications,

? maintaining and enforcing our intellectual property and proprietary rights, and

defending intellectual property-related claims;

? the costs, timing, and outcome of regulatory review of SIG-005 or any other

product candidates;

the costs of future activities, including product sales, medical affairs,

? marketing, manufacturing, distribution, coverage and reimbursement for SIG-005

or any other product candidates for which we receive regulatory approval;

the cost of developing and expanding our manufacturing capabilities and

? advancing these manufacturing capabilities to manufacture product candidates

that are commercially viable;

? the potential additional expenses attributable to adjusting our development

plans (including any supply-related matters) due to the COVID-19 pandemic;

? our ability to establish and maintain additional collaborations on favorable

terms, if at all;

? the success of any collaborations that we may establish and of our license

agreements;

? the achievement of milestones or occurrence of other developments that trigger

payments under any additional collaboration agreements we obtain; and

? the extent to which we acquire or in-license product candidates, intellectual

property and technologies.

We believe that our existing cash will enable us to fund our operating expenses and capital expenditure requirements into 2024. We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we expect.

Until such time, if ever, as we can generate substantial product revenue, we expect to finance our operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and marketing, distribution or licensing arrangements. To the extent that we raise additional capital through the sale of equity or convertible debt securities, the ownership interest of our stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our common stockholders. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making acquisitions or capital expenditures or declaring dividends. If we raise additional funds through additional collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates, or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings or other arrangements when needed, we may be required to delay, limit, reduce or terminate our research, product development or future commercialization efforts, or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

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