EXHIBIT 99.1

CONTACT:
Tim Lynch
Chief Financial Officer
InterMune
650-409-2028
tlynch@intermune.com

Lilian Stern
Stern Investor Relations
212-315-0145
lilian@sternir.com

Steve Cragle
Edelman Public Relations
415-433-5381
steve.cragle@edelman.com

INTERMUNE LICENSES INFERGEN FROM AMGEN

FOR IMMEDIATE RELEASE:

BURLINGAME, CA, June 15, 2001,InterMune, Inc. (Nasdaq: ITMN) today announced that it has signed an agreement to license Infergen (Interferon alfacon-1) from Amgen Inc. Infergen is a therapeutic approved by the FDA for the treatment of chronic hepatitis C infections, which was developed and commercialized by Amgen.

The agreement provides InterMune with exclusive rights to develop and commercialize Infergen, as well as an early stage pegylated interferon product candidate being developed by Amgen, in the United States and Canada. Amgen will supply Infergen to InterMune. The agreement includes a $21 million up-front payment to Amgen, near-term performance milestone payments of up to $8 million, additional milestone payments on the pegylated interferon program and royalties on both products.

W. Scott Harkonen, M.D., Chairman and Chief Executive Officer of InterMune, said, "We are delighted to form this relationship with Amgen, a world leader in biotechnology. With Infergen, InterMune now has three marketed products. We expect that over the next 18 months, four ongoing studies totaling over 1,000 patients will provide new clinical data relating to Infergen. In addition, we see further development potential for Infergen, which fits well with our existing programs for Actimmune in the areas of oncology and liver fibrosis associated with hepatitis C infections."

Kevin Sharer, Chairman and Chief Executive Officer of Amgen, said, "Infergen is valuable but fell outside our defined therapeutic areas of interest. We are pleased to be able to license Infergen to InterMune, a company with the focus, development resources and commercialization team able to maximize Infergen's potential."

Infergen is currently approved as treatment for adult patients with chronic hepatitis C infections, including therapy for patients who have never been treated with interferons and for patients following relapse or treatment non-response to certain previous treatments. Infergen is the only interferon approved for the treatment of patients who have failed other treatments for chronic hepatitis C infections.

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INTERMUNE LICENSES INFERGEN FROM AMGEN
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Hepatitis C virus is the most common form of chronic hepatitis infection in North America and Europe, with close to four million adults infected in the United States. If not detected and treated, hepatitis C may lead to chronic liver disease, including liver cancer, and ranks second to alcoholism as a cause of cirrhosis.

InterMune will hold a conference call at 2:00 p.m. Eastern Time on Friday, June 15, 2001 to discuss the license of Infergen from Amgen and updated financial guidance. Interested investors and others may listen to the call live through an Internet webcast, which may be accessed by visiting InterMune's website at http://www.intermune.com and clicking on the "Investor Relations" icon. InterMune is developing and commercializing innovative products for the treatment of serious pulmonary and infectious diseases and cancer. InterMune markets its lead product, Actimmune, for the treatment of chronic granulomatous disease (CGD) and severe, malignant osteopetrosis. InterMune is currently conducting a Phase III clinical trial with Actimmune for the treatment of idiopathic pulmonary fibrosis (IPF). InterMune is also conducting or planning clinical trials of Actimmune for the treatment of multidrug-resistant tuberculosis (MDR TB), atypical mycobacterial infections, ovarian cancer, cryptococcal meningitis, cystic fibrosis, liver fibrosis and non-Hodgkin's lymphoma. InterMune also markets Amphotec worldwide for the treatment of invasive aspergillosis.

Except for the historical information contained herein, this press release contains certain forward-looking statements concerning the possible development and commercial benefits of Infergen and the pegylated form of Infergen that involve risks and uncertainties. All forward-looking statements and other information included in this press release are based on information available to InterMune as of the date hereof, and InterMune assumes no obligation to update any such forward-looking statements or information. InterMune's actual results could differ materially from those described in InterMune's forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed under the heading "Risk Factors" and the risks and factors discussed in InterMune's most recent periodic reports (i.e., 10-K, 10-Q, and 8-K) and Form S-3 filed with the SEC. In sum, these significant risks include, but are not limited to: the uncertainty of success of InterMune's efforts in research, development, commercialization, product acceptance, third-party manufacturing and capital raising; the uncertain, lengthy and expensive regulatory process; uncertainties associated with: obtaining and enforcing patents important to its business, being an early-stage company and relying on third-party payors' reimbursement policies; competition from other products; and product liability lawsuits.

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EXHIBIT 99.1

Exhibit 99.2

CONTACT:

Tim Lynch
Chief Financial Officer
InterMune
650-409-2028
tlynch@intermune.com

Lilian Stern
Stern Investor Relations
212-315-0145
lilian@sternir.com

Steve Cragle
Edelman Public Relations
415-433-5381
steve.cragle@edelman.com

INTERMUNE ANNOUNCES UPDATED 2001 FINANCIAL GUIDANCE AND
CONFERENCE CALL
2001 Revenue Goal For Actimmune Increased to $31 Million

BURLINGAME, CA, June 15, 2001 InterMune, Inc. (Nasdaq: ITMN) announced today updated 2001 financial guidance, including new product revenue goals. The new financial guidance reflects the Company's recent corporate development activities, including the license of Infergenfrom Amgen Inc. (Nasdaq: AMGN) also announced today, as well as the expansion of development programs for Actimmune and other activities since the Company's previous guidance on February 15, 2001.

The Company's 2001 net revenue goal for Actimmune is now $31 million, a $5 million increase over the Company's 2001 net revenue goal for Actimmune of $26 million most recently stated on April 25, 2001. Quarterly net sales goals for Actimmune for the remainder of 2001 are now $7.0 million in the second quarter, $8.6 million in the third quarter, and $10.5 million in the fourth quarter. The 2001 goal for the Company's total net product sales for Actimmune, Infergen and Amphotec combined is $35 million.

The Company's guidance for its 2001 research and development expenses was approximately $32 million, as of February 15, 2001. Since then, the Company has expanded its development activities through the following:

The exclusive license of Infergen from Amgen, including the assumption of ongoing clinical activities for Infergen and the rights to Amgen's pegylation program and technology surrounding Infergen. The FDA has approved Infergen for the treatment of chronic hepatitis C infections. The Company plans to initiate additional clinical trials for the treatment of chronic hepatitis C infections, and believes that Infergen may have potential for the treatment of hepatitis B and cancer.







A strategic partnership with Boehringer Ingelheim International GmbH to develop and commercialize interferon gamma-1b in Europe and other parts of the world.







A program to develop Actimmune for the treatment of liver fibrosis associated with hepatitis C infection. The Company plans to initiate a Phase II clinical trial in the fourth quarter of 2001.







A program to develop Actimmune in combination with Rituxan as second-line therapy for the treatment of non-Hodgkin's lymphoma. The Company plans to initiate a Phase II clinical trial in the fourth quarter of 2001.







The acceleration of the Company's plans to initiate a Phase III trial of Actimmune as first-line combination therapy for the treatment of ovarian cancer.

A collaboration with MoliChem Medicines, Inc. to develop and commercialize Moli1901 for the treatment of a range of pulmonary indications, including cystic fibrosis.

With the broad expansion of the Company's development activities and resources, including new clinical programs for Actimmune and Infergen which address major commercial opportunities, research and development expenses are currently expected to be approximately $40-$44 million in 2001, as compared with the Company's earlier guidance of $32 million.

The Company's guidance for its 2001 selling, general and administrative expenses was approximately $24 million as of February 15, 2001. Selling, general and administrative expenses are currently expected to be approximately $28-$30 million in 2001 as a result of the Company's re-launch of Infergen and increased corporate infrastructure to support expanded activities.

The Company's February 15, 2001 guidance for its 2001 net losses was approximately $36 million. Net losses are currently expected to be approximately $50-$55 million in 2001, including contribution from product sales, interest income on existing cash balances and approximately $10 million in recurring non-cash expenses, such as amortization of product rights and deferred compensation. Accordingly, 2001 net operating cash burn associated with net losses (which excludes the approximately $10 million in recurring non-cash expenses) is expected to be approximately $40-$45 million. The net loss guidance for 2001 does not reflect up to $8 million in near-term milestone payments to Amgen related to the license of Infergen and the pegylated Infergen program, some or all of which may occur in 2001. InterMune continues to target profitability by the end of 2003.

InterMune will hold a conference call at 2:00 p.m. Eastern Time on Friday, June 15, 2001 to discuss the license of Infergen from Amgen and updated financial guidance. Interested investors and others may listen to the call live through an Internet webcast, which may be accessed by visiting InterMune's website at http://www.intermune.com and clicking on the "Investor Relations" icon.

InterMune is developing and commercializing innovative products for the treatment of serious pulmonary and infectious diseases and cancer. InterMune markets its lead product, Actimmune, for the treatment of chronic granulomatous disease (CGD) and severe, malignant osteopetrosis. InterMune is currently conducting a Phase III clinical trial with Actimmune for the treatment of idiopathic pulmonary fibrosis (IPF). InterMune is also conducting or planning clinical trials of Actimmune for the treatment of multidrug-resistant tuberculosis (MDR TB), atypical mycobacterial infections, ovarian cancer, cryptococcal meningitis, cystic fibrosis, liver fibrosis and non-Hodgkin's lymphoma. InterMune recently acquired rights to Infergen, which is marketed in the United States and Canada for the treatment of chronic hepatitis C infections. InterMune also markets Amphotec worldwide for the treatment of invasive aspergillosis.

Except for the historical information contained herein, this press release contains certain forward-looking statements, concerning the possible revenues, expenses and programs of InterMune, that involve risks and uncertainties. All forward-looking statements and other information included in this press release are based on information available to InterMune as of the date hereof, and InterMune assumes no obligation to update any such forward-looking statements or information. InterMune's actual results could differ materially from those described in InterMune's forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed under the heading "Risk Factors" and the risks and factors discussed in InterMune's most recent periodic reports (i.e., 10-K, 10-Q and 8-K) and Form S-3 filed with the SEC. In sum, these significant risks include, but are not limited to: the uncertainty of success of InterMune's efforts in research, development, commercialization, product acceptance, third-party manufacturing and capital raising; the uncertain, lengthy and expensive regulatory process; uncertainties associated with: obtaining and enforcing patents important to its business, being an early-stage company and relying on third-party payors' reimbursement policies; competition from other products; and product liability lawsuits.

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QuickLinks

Exhibit 99.2

EXHIBIT 99.1

IMMUNOMEDICS IN DISCUSSIONS TO REGAIN

DEVELOPMENT RIGHTS FROM AMGEN

FOR EPRATUZUMAB

Morris Plains, NJ, November 11, 2003 Immunomedics, Inc. (Nasdaq: IMMU) today announced that it is in advanced discussions with Amgen (Nasdaq: AMGN) concerning the possible return to Immunomedics of North American and Australian development rights of epratuzumab, the humanized monoclonal antibody therapeutic licensed to Amgen in December 2000. Several months ago, the parties had attempted to negotiate an expanded license agreement that would have given Amgen global development rights, but were unable to agree on terms. More recently, Amgen advised Immunomedics that due to a reassessment of its product portfolio, Amgen had decided not to proceed with a registration trial.

While it is too early to determine where these discussions will lead, we are in agreement with Amgen that the foremost objective is the continued development and commercialization of epratuzumab, only now potentially on a worldwide basis. Epratuzumab offers hope to patients suffering from non-Hodgkins lymphoma (NHL) where other treatments have failed, and we are pleased that Amgen shares our interest in our completing the development of this drug as quickly as possible. We hope to be in a position to identify an appropriate licensing partner without a significant delay and with the ability to complete the global development of the product, commented Company President and Chief Executive Officer, Cynthia L. Sullivan. We do not anticipate that this change will impact the ongoing trials being pursued by the National Cancer Institutes two study groups, ECOG and SWOG, Ms. Sullivan further commented.

In both single- and multi-center clinical trials of epratuzumab given alone or in combination with rituximab, the agent has been found to be safe, well-tolerated in 1-hour infusions, and active in the treatment of NHL patients, as communicated at various scientific meetings over the past two years as well as in an article published recently in TheJournal of Clinical Oncology, remarked Ivan D. Horak, M.D., Executive Vice President, Research and Development, and Chief Scientific Officer at Immunomedics.

We are pleased with the additional clinical data being presented by Amgen investigators at the forthcoming meeting of the American Society of Hematology (ASH), showing further evidence of both the safety and activity of epratuzumab in NHL. The efficacy results in the multi-center trial of epratuzumab combined with rituximab are lower than those observed at the single-institution study at New York Hospital, presented at ASH in the past, suggesting that different patient populations were studied. This points to the need of a randomized trial, as is usually conducted in such settings, Dr. Horak elaborated.

Dr. Horak also said: We now have early evidence that epratuzumab is also well-tolerated in patients with autoimmune disease, and are moving forward rapidly to complete the single-agent Phase I trial in these potentially new indications.

Immunomedics is a biopharmaceutical company focused on the development, manufacture and commercialization of diagnostic imaging and therapeutic products for the detection and treatment of cancer and other serious diseases. Integral to these products are highly specific monoclonal antibodies and antibody fragments designed to deliver radioisotopes and chemotherapeutic agents to tumors and other sites of disease. Immunomedics has six therapeutic product candidates in clinical development and has two marketed diagnostic imaging products. The most advanced therapeutic product candidates are LymphoCide (epratuzumab), for which certain Phase II clinical trials for the treatment of non-Hodgkins lymphoma have already been completed, and CEA-Cide (labetuzumab), which is in Phase I/II clinical trials for the treatment of certain solid tumors.

This release, in addition to historical information, contains forward-looking statements made pursuant to the Private Securities Litigation Reform Act of 1995. Such statements, including statements regarding clinical trials, involve significant risks and uncertainties and actual results could differ materially from those expressed or implied herein. Factors that could cause such differences include, but are not limited to, risks associated with new product development (including clinical trials outcome and regulatory requirements/actions), competitive risks to marketed products and availability of financing and other sources of capital, as well as the risks discussed in the Companys Annual Report on Form 10-K for the year June 30, 2003.

Company Contact: Investor Relations, (973) 605-8200. Visit the Companys web site at http://www.Immunomedics.com