Lyell Immunopharma (LYEL) Risk Factors

We are seeking to identify and develop a broad pipeline of product candidates using our proprietary technology platforms. The scientific research that forms the basis of our efforts to develop product candidates with our technology platforms is still ongoing. Further, the scientific evidence to support the feasibility of developing therapeutic treatments based on our technology platforms is both preliminary and limited. Additionally, although IMPT-314 is in, and LYL119 is entering, Phase 1 clinical development, our current clinical data are limited, and nonclinical data from murine tumor models and in vitro experiments with tumor cell lines may not translate into humans or may not accurately predict the safety and efficacy of our product candidates in humans. As a result, we are exposed to a number of unforeseen risks, and it is difficult to predict the types of challenges and risks that we may encounter during development of our product candidates. Given the novelty of our technology platforms, we intend to work closely with the FDA and comparable foreign regulatory authorities to perform the requisite scientific analyses and evaluation of our methods to obtain regulatory approval for our product candidates; however, the regulatory pathway with the FDA and comparable regulatory authorities may be more complex and time-consuming relative to other more well-known therapeutics. Even if we obtain human data to support our product candidates, the FDA or comparable foreign regulatory authorities may lack sufficient experience in evaluating the safety and efficacy of our product candidates developed using our technology platforms, which could result in a longer than expected regulatory review process, increase our expected development costs and delay or prevent commercialization of our product candidates. The validation process takes time and resources, may require independent third-party analyses and may not be accepted or approved by the FDA and comparable foreign regulatory authorities. There can be no assurance as to the length of clinical development, the number of patients that the FDA or comparable foreign regulatory authorities may require to be enrolled in clinical trials to establish the safety, purity and potency of our product candidates or the acceptability to the FDA or comparable foreign regulatory authorities of data generated in these clinical trials to support marketing approvals. We cannot be certain that our approach will lead to the development of approvable or marketable products, alone or in combination with other therapies.

We rely on our third-party research institution collaborators for some research capabilities. However, the research we are funding constitutes only a small portion of the overall research of each research institution. Other research being conducted by these institutions may at times receive higher priority than research on the programs we are funding. We typically have less control of the research, clinical trial protocols and patient enrollment than we might with activity led by our employees. The clinical trial investigators and study teams and outside scientists who conduct the research and development upon which portions of our product candidate pipeline depends are not our employees; rather, they serve as either independent contractors or the primary investigators under research collaboration agreements that we have with their sponsoring academic or research institution. Such investigators, study staff, scientists and collaborators may have other commitments that would limit their availability to us. Although our scientific advisors generally agree not to do competing work, if an actual or potential conflict of interest between their work for us and their work for another entity arises, we may lose their services. These factors could adversely affect the timing of the clinical trials, the timing of receipt and reporting of clinical data, the timing of our U.S. regulatory submissions and comparable foreign applications and our ability to conduct our current and planned clinical trials. It is also possible that some of our valuable proprietary knowledge may become publicly known through these clinical investigators and study staff or scientific advisors if they breach their confidentiality agreements with us, which would cause competitive harm to, and have an adverse effect on, our business.

Success in research, nonclinical studies and early clinical trials does not ensure that later clinical trials will generate similar results and otherwise provide adequate data to demonstrate the efficacy and safety of an investigational product. Clinical trials may show that one or more of our product candidates are not safe or effective, in which event we may need to abandon development of such product candidates. In fact, a number of companies in the pharmaceutical and biotechnology industries, including those with greater resources and experience than us, have suffered significant setbacks in early- and late-stage clinical trials, even after seeing promising results in earlier nonclinical studies or clinical trials. Thus, even if the results from our initial research, nonclinical activities or early clinical results appear positive, we do not know whether the current Phase 1 or subsequent clinical trials we may conduct will demonstrate adequate efficacy and safety to result in regulatory approval to market any product candidates. Moreover, final study results may not be consistent with interim study results, and results in one indication may not be predictive of results for the same product candidate in another indication. If later-stage clinical trials do not produce favorable results, our ability to achieve regulatory approval for any of our product candidates may be adversely impacted. Even if we believe that we have adequate data to support an application for regulatory approval to market any of our product candidates, the FDA or other regulatory authorities may not agree and may require that we conduct additional clinical trials. Additionally, even if clinical trials show promising early results, clinical trials of the same product candidate in another indication may fail to show similar results, and market acceptance of our product candidate, if approved, may be limited.

We currently have no products approved for commercial sale, and we are in the first phase of clinical development of our product candidates. IMPT-314 is in Phase 1 clinical development and LYL119 is entering Phase 1 clinical development. The future success of our business is substantially dependent on our ability to obtain regulatory approval for our product candidates, and any product candidates we acquire, for the indications we seek, and, if approved, to successfully commercialize one or more product candidates in a timely manner. Each of our programs and product candidates will require clinical development, regulatory approval, obtaining manufacturing supply, capacity and expertise, building a commercial organization or successfully outsourcing commercialization, substantial investment and significant marketing efforts before we generate any revenue from product sales. We do not have any products that are approved for commercial sale, and we may never be able to develop or commercialize marketable products. We cannot commercialize product candidates in the United States without first obtaining regulatory approval for the product from the FDA; similarly, we cannot commercialize product candidates outside of the United States without obtaining regulatory approval from comparable foreign regulatory authorities. Before obtaining regulatory approvals for the commercial sale of any product candidate for a target indication, we must demonstrate with substantial evidence from well-controlled clinical trials, and to the satisfaction of the FDA and comparable foreign regulatory authorities, that the product candidate is safe, pure and potent for use for that target indication and that the manufacturing facilities, processes and controls are adequate with respect to such product candidate to assure safety, purity and potency. The time required to obtain approval by the FDA and comparable foreign regulatory authorities is unpredictable but typically takes many years following the commencement of nonclinical studies and clinical trials and depends upon numerous factors, including the substantial discretion of the regulatory authorities. In addition, approval policies, regulations or the type and amount of clinical data necessary to gain approval may change during the course of a product candidate's clinical development and may vary among jurisdictions. We have not obtained regulatory approval for any product candidate, and it is possible that none of our existing product candidates or any future product candidates will ever obtain regulatory approval. Furthermore, the regulatory approval process for novel product candidates, such as T-cell product candidates and next-generation T-cell programs, can be more complex and consequently more expensive and take longer than for other, better known or extensively studied pharmaceutical or other product candidates. Even if a product candidate were to successfully obtain approval from the FDA and comparable foreign regulatory authorities, any approval might contain significant limitations related to use restrictions for specified age groups, warnings, precautions or contraindications, or may be subject to burdensome post-approval study or risk management requirements. If we are unable to obtain regulatory approval for one of our product candidates in one or more jurisdictions, or any approval contains significant limitations, we may not be able to obtain sufficient funding to continue the development of that product or generate revenues attributable to that product candidate. Also, any regulatory approval of our current or future product candidates, once obtained, may be withdrawn.

Successful and timely completion of clinical trials require that we enroll and retain a sufficient number of study participants. Any clinical trials we conduct may be subject to delays for a variety of reasons, including as a result of patient enrollment taking longer than anticipated, manufacturing failures resulting in patients being unable to be treated, patient withdrawal or adverse events. These types of developments have in the past, and could in the future, cause us to delay a trial or halt further development. Our clinical trials compete with other clinical trials that are in the same therapeutic areas as our product candidates, and this competition reduces the number and types of patients available to us, as some patients who might have opted to enroll in our trials may instead opt to enroll in a trial being conducted by one of our competitors. We may also encounter additional challenges and slower than anticipated enrollment in our clinical trials if any of our competitors obtain FDA approval before us in the same therapeutic areas as our product candidates. Moreover, enrolling patients in clinical trials for diseases in which there is an approved standard of care is challenging, as patients will first receive the applicable standard of care. Many patients who respond positively to the standard of care do not enroll in clinical trials. This may limit the number of eligible patients able to enroll in our clinical trials who have the potential to benefit from our product candidates and could extend development timelines or increase costs for these programs. Patients who fail to respond positively to the standard of care treatment will be eligible for clinical trials of unapproved drug candidates. However, these prior treatment regimens may render our therapies less effective in clinical trials. Because the number of qualified clinical investigators and clinical trial sites is limited, we expect to conduct some of our clinical trials at the same clinical trial sites that some of our competitors use, which will reduce the number of patients who are available for our clinical trials at such clinical trial sites. We may experience delays in enrollment in our current and planned clinical trials due to factors outside our control. For example, some patients may not be able to comply with clinical trial protocols due to lack of healthcare support or potential interruptions of healthcare services. Our ability to recruit and retain patients, principal investigators and site staff may also be hindered, which would adversely affect our trial operations. Patient enrollment depends on many additional factors, including: - the size and nature of the patient population;- the severity of the disease under investigation;- eligibility criteria for the trial;- the proximity of patients to clinical sites;- the design of the clinical protocol;- the ability to obtain and maintain patient consents;- perceived risks and benefits of the product candidate under evaluation, including any perceived risks associated with genetically-modified product candidates;- the ability to recruit clinical trial investigators with the appropriate competencies and experience;- the risk that patients enrolled in clinical trials will drop out of the trials before the administration of our product candidates or trial completion;- the availability of competing clinical trials;- the availability of new drugs approved for the indication that the clinical trial is investigating; and - clinicians' and patients' perceptions as to the potential advantages of the drug being studied in relation to other available approved or investigational therapies. These factors may make it difficult for us to enroll enough patients to complete our clinical trials in a timely and cost-effective manner. Delays in the completion of any clinical trial of our product candidates will increase our costs, slow down our product candidate development and approval process and delay or potentially jeopardize our ability to commence product sales and generate revenue. In addition, some of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of our product candidates.

We are in the first phase of clinical development of our product candidates. IMPT-314 is in Phase 1 clinical development, and LYL119 is entering Phase 1 clinical development. The risk of failure of our product candidates, or any product candidates we acquire, is high. The clinical trials and manufacturing of our product candidates, or any product candidates we acquire, are, and the manufacturing and marketing of such product candidates, if approved, will be, subject to extensive and rigorous review and regulation by numerous government authorities in the United States and in other countries where we intend to test and market our product candidates. Before obtaining regulatory approvals for the commercial sale of any of our product candidates, we must demonstrate through lengthy, complex and expensive nonclinical testing and clinical trials that our product candidates are both safe and effective for use in each target indication. In particular, because our product candidates are subject to regulation as biological products, we will need to demonstrate that they are safe, pure and potent for use in their target indications. Each product candidate must demonstrate an adequate risk versus benefit profile in its intended patient population and for its intended use. The clinical testing that will be required for any product candidates we choose to advance is expensive and can take many years to complete, and its outcome is inherently uncertain. The FDA may not clear the IND submissions for any planned clinical trials. Even if cleared by the FDA and initiated, we cannot guarantee that any clinical trials will be conducted as planned or completed on schedule, if at all. Failure can occur at any time during the clinical trial process. Even if our current and planned clinical trials are completed as planned, we cannot be certain that their results will support the safety and effectiveness of our product candidates for their targeted indications or support continued clinical development of such product candidates. Product candidates in later stages of clinical trials may fail to show the desired safety and efficacy traits despite having progressed through nonclinical and clinical trials. In addition, even if such trials are successfully completed, we cannot guarantee that the FDA or comparable foreign regulatory authorities will interpret the results as we do, and more trials could be required before we submit our product candidates for approval. Moreover, results acceptable to support approval in one jurisdiction may be deemed inadequate by another regulatory authority to support regulatory approval in that other jurisdiction. To the extent that the results of the trials are not satisfactory to the FDA or comparable foreign regulatory authorities for support of a marketing application, we may be required to expend significant resources, which may not be available to us, to conduct additional trials in support of potential approval of our product candidates. To date, we have not fully enrolled or completed any clinical trials required for the approval of our product candidates. We may experience delays in initiating, enrolling or conducting our current and planned clinical trials, and we do not know whether clinical trials will begin or enroll patients on time, will need to be redesigned, will achieve expected enrollment rates or will be completed on schedule, if at all. Our inability to identify candidates with ROR1-positive tumors, to successfully manufacture cell product candidates for enrolled patients or to obtain sufficient amounts of specific reagents and raw materials to manufacture product candidates in a timely manner or at all could delay or preclude our ability to execute and complete the clinical trials. There can be no assurance that the FDA or comparable foreign regulatory authorities will not put clinical trials of any of our product candidates on clinical hold in the future. Clinical trials can be delayed, suspended or terminated for a variety of reasons, including in connection with: - inability to generate sufficient nonclinical, toxicology or other in vivo or in vitro data to support the initiation of clinical trials;- delays in sufficiently developing, characterizing or controlling a manufacturing process suitable for advanced clinical trials;- delays in reaching agreement with the FDA or other regulatory authorities, including comparable foreign regulatory authorities, as to the design or implementation of our clinical trials;- obtaining regulatory authorization to commence a clinical trial;- change in our strategy;- reaching an agreement on acceptable terms with clinical trial sites or prospective CROs, the terms of which can be subject to extensive negotiation and may vary significantly among different clinical trial sites;- obtaining IRB approval at each trial site or positive ethics committees opinions;- recruiting suitable patients to participate in a clinical trial;- having patients complete a clinical trial or return for post-treatment follow-up;- inspections of clinical trial sites or operations by applicable regulatory authorities, or the imposition of a clinical hold;- clinical sites, CROs or other third parties deviating from trial protocol or dropping out of a trial;- failure to perform in accordance with applicable regulatory requirements, including the FDA's and comparable foreign regulatory authorities' GCP requirements, or other applicable regulatory requirements;- addressing patient safety concerns that arise during the course of a trial, including occurrence of adverse events associated with the product candidate that are viewed to outweigh its potential benefits;- adding a sufficient number of clinical trial sites;- manufacturing sufficient quantities of product candidates for use in clinical trials; or - suspensions or terminations by IRBs or ethics committees of the institutions at which such trials are being conducted, by the independent Data Safety Monitoring Committee for such trial or by the FDA or other regulatory authorities, including comparable foreign regulatory authorities, due to a number of factors, including those described above. Further, a clinical trial may be suspended or terminated by us, the IRBs or ethics committees for the institutions in which such trials are being conducted, the independent Data Safety Monitoring Committee for such trial or the FDA or other regulatory authorities, including comparable foreign regulatory authorities, due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols, inspection of the clinical trial operations or trial site by the FDA or other regulatory authorities, including comparable foreign regulatory authorities, resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side effects, failure to demonstrate a benefit from using a product candidate, changes in governmental regulations or administrative actions or lack of adequate funding to continue the clinical trial. We cannot predict with any certainty whether or when we might complete a given clinical trial, if at all. If we experience delays or quality issues in the conduct, completion or termination of any clinical trial of our product candidates, the approval and commercial prospects of such product candidate will be harmed, and our ability to generate product revenues from such product candidate will be delayed. In addition, any delays in completing our clinical trials will increase our costs, slow down our product candidate development and approval process and jeopardize our ability to commence product sales and generate revenues. Many of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may ultimately lead to the denial of regulatory approval of our product candidates. Our product candidates may cause undesirable side effects or have other properties that could delay or prevent their regulatory approval, limit the commercial profile of an approved label or result in significant negative consequences following any regulatory approval. Additionally, our product candidates, if approved, could be subject to labeling and other restrictions and market withdrawal, and we may be subject to penalties if we fail to comply with regulatory requirements or experience unanticipated problems with our products. Undesirable side effects caused by our product candidates could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or other comparable foreign regulatory authority. As a result of safety or toxicity issues that we may experience in our clinical trials, we may not continue the development of nor receive approval to market any product candidates, which could prevent us from ever generating product revenues or achieving profitability. For example, previous clinical trials utilizing CAR T cells to treat hematologic tumors have shown an increased risk of CRS and ICANS, and approved CAR T products carry a boxed warning concerning the risk of developing secondary T-cell malignancies. A prior clinical trial of LYL797, a ROR1-targeted CAR T-cell product candidate was discontinued due to a narrow therapeutic window and safety reports of pneumonitis. Adverse events may also be associated with the lymphodepletion utilized with cellular therapies. If additional adverse events or other side effects are observed in any of our clinical trials that are atypical of, or more severe than, the known side effects of cellular therapies, we may have difficulty recruiting patients to our clinical trials, patients may drop out of our trials or we may be required to abandon those trials or our development efforts of one or more product candidates altogether. If such effects are more severe, less reversible than we expect or not reversible at all, we may decide or be required to perform additional studies or to halt or delay further clinical development of any of our product candidates, which could result in the delay or denial of regulatory approval by the FDA or other regulatory authorities. Additionally, ROR1 is expressed on a number of normal tissues. As a result, ROR1 could cause on-target, off-tumor toxicity. c-Jun is also potentially an oncogene and could cause healthy cells to transform into malignant cells. Results of our trials could reveal an unacceptably high severity and incidence of side effects, or side effects outweighing the benefits of our product candidates. In such an event, our trials could be suspended or terminated, and the FDA or comparable foreign regulatory authorities could order us to cease further development or deny approval of our product candidates for any or all targeted indications. The side effects experienced could affect patient recruitment or the ability of enrolled patients to complete the trial or result in potential product liability claims. In the event that any of our product candidates receives regulatory approval and we or others later identify undesirable or unacceptable side effects caused by such products, a number of potentially significant negative consequences could result, including: - regulatory authorities may withdraw or limit approvals of such products and require us to take our approved product off the market;- regulatory authorities may require the addition of labeling statements, specific warnings, a contraindication or field alerts to physicians and pharmacies, or issue other communications containing warnings or other safety information about the product;- regulatory authorities may require a medication guide outlining the risks of such side effects for distribution to patients, or that we implement a risk evaluation and mitigation strategy (REMS) plan or risk management plan to ensure that the benefits of the product outweigh its risks;- we may be required to change the dose or the way the product is administered, conduct additional clinical trials or change the labeling of the product;- we may be subject to limitations on how we may promote or manufacture the product;- sales of the product may decrease significantly;- we may be subject to litigation or product liability claims; and - our reputation may suffer. Any of these events could prevent us or our potential future partners from achieving or maintaining market acceptance of the affected product or could substantially increase commercialization costs and expenses, which in turn could delay or prevent us from generating significant revenue from the sale of any products.

From time to time, we may publicly disclose interim, topline or preliminary data from our nonclinical studies and clinical trials, which are based on a preliminary analysis of then-available data, and the results and related findings and conclusions are subject to change following a more comprehensive review of the data related to the particular study or trial. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. Further, modifications or improvements to our manufacturing processes for a therapy may result in changes to the characteristics or behavior of the product candidate that could cause our product candidates to perform differently and affect the results of our ongoing clinical trials. As a result, the topline results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results, once additional data have been received and fully evaluated. Topline data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. As a result, topline data should be viewed with caution until the final data are available. From time to time, we may also disclose preliminary or interim data from our nonclinical studies and clinical trials. Preliminary or interim data from clinical trials are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. Adverse differences between preliminary or interim data and final data could significantly harm our business prospects. Additionally, disclosure of preliminary or interim data by us or by our competitors could result in volatility in the price of our common stock. Further, others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular program, the approvability or commercialization of the particular product candidate and our company in general. If the interim, topline or preliminary data we report differ from actual results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize, any of our potential product candidates may be harmed, which could harm our business, operating results, prospects or financial condition.